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C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | 2γ
vitamin A. The purest preparations of Karrer and his co-workers are capable of maintaining growth in rats when fed in a daily dosage of 0.5γ
3
. Since the vitamin requirement is appreciably greater for curing diseased rats than for maintaining growth in normal animals, the agreement is adequate.
中文
Some time af... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | 英文
我已经发现在青蛙、羊、猪和牛的视紫红质溶液、完整视网膜以及色素脉络膜层中都含有相当高浓度的维生素A。这些眼组织的非皂化提取物明确地显示出含维生素A油所具有的全部特性。
英文
视网膜和脉络膜层的提取物能与三氯化锑发生显色反应呈现蓝色,如果用光谱法进行检测,会发现在620 nm(维生素A的特征吸收)处有尖锐、强烈的吸收带。浓度更高的提取物还会在580 nm处出现较弱的特征吸收带,最近的研究表明这是因为提取物中有一种外来物质,无论浓度如何变化它在天然油中总是与维生素A同时存在[1]
。在与三氯化锑混合后,两条谱带迅速减弱,同时在500 nm附近出现了一个次级吸收,它是造成反应后期出现红色着色的原因。最后这个现象也说明维生素... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | K. A small fraction of particles in a gas at typical solar temperatures would also have such velocities, suggesting that light atoms may undergo such disintegrations in stars.
中文
A
BOUT thirteen disintegrations of neon nuclei have been obtained in 3,200 pairs, and approximately 100 disintegrations of nitrogen nucle... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | cm. per sec., so only neutrons of a velocity higher than this should be effective in disintegrating carbon of mass 12. The smallness of the yield of disintegrations which we have obtained with carbon is thus to be expected, especially since probably less than one-fifth of the neutrons have velocities higher than this.
... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | A part of this work was presented by Harkins on June 23 at a symposium on nuclear disintegration under the auspices of the Century of Progress Exposition, Chicago. Other papers were presented by Cockcroft, Lawrence and Tuve, and a general discussion of the theory was given by Bohr.
中文
(132
, 358; 1933)
William D. H... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | 英文
(王耀杨 翻译;朱永生 审稿)
Extremely Low Temperatures
W. J. de Haas
Editor's Note
Physicist Wander Johannes de Haas of the University of Leiden reports here on recent experiments reaching extremely low temperatures using the method of “adiabatic demagnetisation.” In this method, a material magnetised by being held in a str... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | If we wish to obtain easily seen results, the following points require special attention: (1) the elementary magnets shall not exert a directing influence upon each other (no ferromagnetic body); (2) the elementary magnets shall have a moment as large as possible, subject to the restriction of (1); (3) at low temperatu... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | We know that finally this temperature has been reached, because the salt is the indicator of its own temperature. This paramagnetic body is drawn into the field (31 k. gauss) by a force K=M.dH/dx
, where M
is the total moment of the body. As M
=φ
(H
, T
) and as H
remains constant, we easily see, by measuring K
... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | . More recent experiments with dysprosium ethyl sulphate gave the upper limit 0.17°K
. Finally, the experiments of July last made with cerium ethyl sulphate gave as the upper temperature limit 0.085°K
.
中文
It is possible that with the same experimental arrangement much lower temperatures can be reached. The choice... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | A reservation must be made, however, for the case that at very low temperatures the substances used might become ferro-magnetic or might show a new kind of ferro-magnetism. In this case little might be said about the temperature.
中文
Another great difficulty is this: if by means of the magnetic method we wish to cool... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | 力K=M.dH/dx
将顺磁体吸入磁场中(强度为31,000高斯),其中M
是顺磁体的总磁矩。由于M
=φ
(H, T
),且H
是保持不变的,我们很容易通过测量K
而看出T
是何时变为恒定的。
英文
一旦满足了以上所说的情况,就通过降低磁场给顺磁体退磁,在头几次实验中把磁场降至2,700高斯,而在以后的实验中降到了1,000或500高斯。
英文
在这种弱场中,测量了作为时间的函数的力K
。这样,我们得到了图2所示的曲线。
英文
图2
英文
曲线上的A
点对应于最低温度时力的值,而长时间后的渐近线趋近于温度为1.26 K时力的值。曲线在开始时急剧下降是因为在抽成真空的小杜瓦瓶中,为了保证... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | for such discussions by describing life as a chemical process, for example in terms of enzyme catalysis and metabolism. After the later focus on genetics, biochemical energetics is today enjoying a revival as a fundamental aspect of living systems.
中文
I
T
HE British Association returns to Leicester with assurance ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | aspects which are non-metrical. I would have you believe, however, that the data of modern biochemistry which will be the subject of my remarks were won by quantitative methods fully adequate to justify the claims based upon them.
中文
Though speculations concerning the origin of life have given intellectual pleasure ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | associated with life's earliest stages. Existing organisms illustrate what was perhaps an earlier method. The so-called autotrophic bacteria obtain energy for growth by the catalysed oxidation of materials belonging wholly to the inorganic world; such as sulphur, iron or ammonia, and even free hydrogen. These organisms... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | In any event, every living unit is a transformer of energy however acquired, and the science of biochemistry is deeply concerned with these transformations. It is with aspects of that science that I am to deal, and if to them I devote much of my address, my excuse is that since it became a major branch of inquiry, bioc... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | In any event, I feel fortunate in a belief that what I have to say will not, if rightly appraised, raise the old issues. To claim, as I am to claim, that a description of its active chemical aspects must contribute to any adequate description of life is not to imply that a living organism is no more than a physico-chem... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | the goal suggested would have proved elusive, and the path of endeavour has followed other lines.
中文
So long as the term “protoplasm” retains a morphological significance as in classical cytology, it may be even now convenient enough, though always denoting an abstraction. In so far, however, as the progress of meta... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | The oxygen which enters the muscle from the blood is not involved in immediate oxidations, but is built up into the substance of the muscle. It disappears into some protoplasmic complex on which its presence confers instability. This complex, like all living substance, is to be regarded as incessantly undergoing change... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | happening is indispensable for the progress of the next stage, namely, the production of lactic acid from the sugar, which is an anaerobic process.
中文
The precise happenings to the hexose sugar while in combination with phosphoric acid are from a chemical point of view remarkable. Very briefly stated they are these.... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | The sequence of these chemical reactions in muscle has been followed and their relation in time to the phases of contraction and relaxation is established. The means by which energy is transferred from one reacting system to another has until lately been obscure, but current work is throwing light upon this interesting... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | I must perforce limit the field of my discussion, and in what follows, my special theme will be the importance of molecular structure in determining the properties of living systems. I wish you to believe that molecules display in such systems the properties inherent in their structure even as they do in the laboratory... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | It is well known that a catalyst is an agent which plays only a temporary part in chemical events which it nevertheless determines and controls. It reappears unaltered when the events are completed. The phenomena of catalysis, though first recognised early in the last century, entered but little into chemical thought o... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | long ago Emil Fischer recognised that enzymic action distinguishes even between two optical isomers and spoke of the necessary relation being as close as that of key and lock.
中文
There is an important consequence of this high specificity in biological catalysis to which I invite special attention. A living cell is t... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | directed into some one of the paths of metabolism.
中文
It must here be remembered, moreover, that enzymes as specific catalysts not only promote reactions, but also determine their direction. The glucose molecule, for example, though its inherent chemical potentialities are, of course, always the same, is converted i... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | molecules may so modify existing equilibria as to affect profoundly the observed behaviour of the cell.
中文
Such relations, though by no means confined to them, reach their greatest significance in the higher organisms, in which individual tissues, chemically diverse, differentiated in function and separated in space... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | Moreover, evidence is accumulating to show that in the case of other nerves belonging to the same morphological group as the vagus, but supplying other tissues, this same liberation of acetyl choline accompanies activity, and the chemical action of this substance upon such tissues again produces effects identical with ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | I shall here be on familiar ground, for that such agencies exist, and bear the name of hormones, is common knowledge. I propose only to indicate how many and diverse are their functions as revealed by recent research, emphasising the fact that each one is a definite and relatively simple substance with properties that ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | so functions as to bring about all those changes in the female body which make secure the fertilisation of the ovum. On the discharge of the ovum new tissue, constituting the so-called corpus luteum
, arises in its place. This then produces a special hormone which in its turn evokes all those changes in tissues and or... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | a hormone. In practice the distinction may be of great importance, but for an understanding of metabolism the functions of these substances are of more significance than their origin.
中文
The present activity of research in the field of vitamins is prodigious. The output of published papers dealing with original inve... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | In this very brief discussion of hormones and vitamins I have so far referred only to their functions as manifested in the animal body. Kindred substances, exerting analogous functions, are, however, of wide and perhaps of quite general biological importance. It is certain that many microorganisms require a supply of v... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | to chemists as the isoprene structure. These are condensed in a long carbon chain which is attached to a ring structure of a specific kind. Such a constitution relates it to other biological compounds, in particular to certain vegetable pigments, one of which, a carotene, so called, is the substance which I have mentio... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | constituent rings is not hydrogenated. In a sense, therefore, the chemical nature of oestrin links vitamin D with that of cancer-producing substances. Further, it is found that substances with pronounced cancer-producing powers may produce effects in the body like those of oestrin.
中文
It is difficult when faced with... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | methods of research which chemistry is inheriting from physics: X-ray analysis; the current studies of unimolecular surface films and of chemical reactions at surfaces; modern spectroscopy; the quantitative developments of photo-chemistry; no branch of inquiry stands to gain more from such advances in technique than do... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | statements in his writings which directly encourage the methods of biochemistry.
中文
In the teachings of J. S. Haldane, however, the value of such methods have long been directly challenged. Some will perhaps remember that in an address to Section I, twenty-five years ago, he described a philosophic point of view whi... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | entities but, like the biologist, with organisms such as the atom proves to be. Is it not then enough for my present purpose to remark on the significance of the fact that not until certain atoms were found spontaneously splitting piecemeal into parts, and others were afterwards so split in the laboratory, did we reall... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | a substance than the cell divisions and cell differentiation which intervene between the fertilised ovum and the finished embryo. Yet it would seem that a transmitted substance, a hormone in essence, may play an unmistakable part in that remarkable drama. It has for some years been known that, at an early stage of deve... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | It is surely right, however, to claim that in passing from its earlier concern with dead biological products to its present concern with active processes within living organisms, biochemistry has become a true branch of progressive biology. It has opened up modes of thought about the physical basis of life which could ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | universe. It may be small in extent, but is the seat of all the most significant events. In too many current publications, purporting to summarise scientific progress, biology is left out or receives but scant reference. Brilliant expositions of all that may be met in the region where modern science touches philosophy ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | A few years ago the Cambridge philosopher, Dr. C. D. Broad, who is much better acquainted with scientific data than are many philosophers, remarked upon the misfortune involved in the unequal development of science; the high degree of our control over inorganic Nature combined with relative ignorance of biology and psy... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | experiment—the study of nutrition has shown that the needs of the body are much more complex than was earlier thought, and in particular that substances consumed in almost infinitesimal amounts may, each in its way, be as essential as those which form the bulk of any adequate dietary. This complexity in its demands wil... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | The importance of detail is no less in evidence when the demands of the body for a right mineral supply are considered. A proper balance among the salts which are consumed in quantity is here of prime importance, but that certain elements which ordinary foods contain in minute amounts are indispensable in such amounts ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | Allow me just one final reference to another field of nutritional studies. Their great economic importance in animal husbandry calls for full recognition. Just now agricultural authorities are becoming acutely aware of the call for a better control of the diseases of animals. Together these involve an immense economic ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | Apropos, I find difficulty as today's occupant of this important scientific pulpit in avoiding some reference to impressive words spoken by my predecessor which are still echoed in thought, talk and print. In his wise and eloquent address at York, Sir Alfred Ewing reminded us with serious emphasis that the command of N... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | But Sir Alfred Ewing told us of “the disillusion with which, now standing aside, he watches the sweeping pageant of discovery and invention in which he used to make unbounded delight”. I wish that one to whom applied science and Great Britain owe so much might have been spared such disillusion, for I suspect it gives h... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | With regard to the latter, it is surely right that those in touch with science should insist that the replacement of human labour will continue. Those who doubt this cannot realise the meaning of that positive acceleration in science, pure and applied, which now continues. No one can say what kind of equilibrium the di... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | that part of the community which it would specially benefit.
中文
In parenthesis allow me a brief further reference to “planning”. The word is much to the front just now, chiefly in relation with current enterprises. But there may be planning for more fundamental developments; for future adjustment to social reconstru... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | ) to those of Bacon's fancy? A House devoid of politics, concerned rather with synthesising existing knowledge, with a sustained appraisement of the progress of knowledge, and continuously concerned with its bearing upon social readjustments. It is not to be pictured as composed of scientific authorities alone. It woul... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | 霍普金斯这次演讲的目的不是为了总结任何一种能够清晰阐述生命如何起源的理论,而是为了引导大家去探讨生命过程的化学本质,例如,从酶催化和新陈代谢的角度上进行分析。生物学研究在后来的一大段时间内转向了遗传学,而如今生物化学能量学作为生命系统的基本特征又一次得到了复兴。
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I
英国科学促进会这一次重返莱斯特必定会受到和26年前一样的隆重欢迎和盛情款待。在新一次的邀请与爽快的答复之中都谈及了双方在此前的交往经历中萌生出的相互欣赏。今天,主宾双方均有理由相互祝贺。在英国科学促进会的第二次来访中,我们发现莱斯特发生了一些重要的变化。如今,她已变成一座获得正式特许权的城市,成为主教辖区的中心。在这里,我们看到了一所研究中心、许多在初次来访... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | 我将要讨论的就是科学的这些方面,而如果我的讲演过多地集中在这里的话,我的解释是,自从生物化学成为一个主要的研究分支以来,还没有一个像我这样有幸占据主席位置的人来阐释过。
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作为一个不断发展的学科,它属于当前这个世纪。从上世纪的实验生理学家那里,生物化学获得了作为学科的认可,又从它自身的几位先驱者那里获得了成功的希望;但是就对其根本目标的促进而言,那个世纪留给它的遗产只是少许的事实和方法。而它的根本目标或者说最终目标,我本人认为,是对活细胞和组织中的分子动力学行为进行充分和可接受的描述。
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II
当英国科学促进会于1831年成立时,第一个人工合成的生物制品只有三岁。人们就是在那个时候才认识到了,最初关于有机与无机之... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | “我们还不能描绘——”福斯特谈道,“氧从血液进入肌肉物质直到与碳结合生成碳酸排出之间所经历的各个步骤。生命的全部奥秘就隐藏在这个过程之中,而目前我们必须满足于只知道开始和结束的情况。”
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如同我曾提议的那样,我们需要一种不同的语言来谈及目前已确知的有关肌肉和与其活动相关的事件的呼吸作用,而且对于那些对技术性化学内容不感兴趣的人来说,在语言上的这种转变也许还是很重要的。肌肉物质作为一个整体连续合成与分解的概念只含有很少量的真实成分。可以说,凝胶状肌肉结构,即使作为一个整体在新陈代谢正常时也是相对稳定的系统,而且其核心部分的稳定性极高。在我看来,该系统中发生的化学反应具有令人惊叹的完整性。与在系统中不同,碳水化合物储备(在某些... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | 如果不具备催化剂的话,每个活体单元都将是一个静止的体系。
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众所周知,催化剂是一种只暂时性地参与化学反应却对化学反应起着决定和控制作用的试剂。反应完成后,它又恢复了原状。尽管催化现象早在上个世纪就已经被首先认识到,但很少有人对它进行化学上的研究和探索,直到几年前人们发现催化对于工业的重要意义之后。催化是自然界最重要的机制之一,因为它把能量转换者这一基本特征赋予了生命体系,而且所有的证据都表明,它从进化的最早阶段起到现在一直在生命体系中起着不可或缺的作用。
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活细胞的催化剂是酶结构,它在胶体颗粒表面或在细胞中的其他表面上发挥着自己的作用。当前的研究使我们可以从活细胞和组织中分离出来的酶或者可以在其中识别出来的酶的庞... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | 英文
这些关系,尽管绝不仅限于它们,在高等有机体中具有最重要的意义;在高等有机体中,单个组织虽然化学组成不同,功能有所区别,在空间中也是分离的,却能通过在循环中传输的化学物质而彼此影响,从而通过化学运输协调机体作为一个整体的活动。我们今天必须认识到,统一借助化学手段是所有这一类有机体的一个根本方面。在它们之中都有如下事实,神经系统作为组织化影响的最高场所具有首要地位,但是今天我们知道,即使是这种影响也经常(如果并非总是如此的话)通过化学分子所固有的性质显现出来。对于我的一般主题来说,实际上最重要的是意识到,当一个神经脉冲到达组织时,位于神经末端处的一种确定化学物质的突然生成对于该组织对冲动的反应来说可能是至关重要的。
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... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | 英文
要完整把握化学物质通过其特有的分子结构来控制与协调动物体内发生响应的程度,最好在考虑激素的功能时不要把它与维生素的功能过分地割裂开。它们一起构成了一大类物质,其中每一种都通过化学作用对生理反应施加着自己必不可少的影响。
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激素是机体自身产生的,而维生素则必须要靠饮食来供应。这种区分方式在通常情况下是合理的。不过,偶尔我们也会遇到某种动物能够不需要外部供应这种或那种维生素。但是有证据表明,与大多数动物不同,这类物种的个体能够在新陈代谢过程中为自己合成该维生素。合成的维生素随即变成一种激素。在实践中这种区分可能是有重要意义的,但是从理解新陈代谢的角度来看,这些物质的功能比它们的来源更要紧。
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目前在维生素这一... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | 因此,在某种意义上,雌激素的化学本质将维生素D与致癌物质的化学本质联系起来。此外,目前已发现,具有显著致癌能力的物质在体内可以产生与雌激素相似的效果。
英文
当面对这种关系时,很难不去猜测在正常情况下可以产生一种刺激生理发育的物质的甾醇代谢,是否会在极为特殊的环境中异常到足以使活细胞内产生一种刺激病变发育的物质。不过,用现在的知识来看,这样一种提法一定要十分谨慎地对待。它完全没有实验上的证据。我在此谈到这组极为有趣的关系的主要目的,是想再次强调化学结构在生物学活动领域中的重要性。
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只有当具有适当结构的少量物质为活细胞和组织带来很大的影响时,我们才能在完好无损的人或动物体内观测到最终的结果。毫无疑问,由于每个组织细胞... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | 我现在还不足以去评论这件事的重要意义,只有在我们发现某些原子能够自发破裂成几个部分,随后发现另外一些原子在实验室中也能这样分裂之后,我们才能真正了解到原子作为一个整体的所有情况。
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然而就这一点而言,我希望你们不要猜测我会宣称:生物系统的所有属性乃至于其中较为明显的部分必定只能建立在化学组织的基础之上。我已经表达过我自己的观点,化学组织足以解释每个活细胞所具有的惊人特性——即在各种环境中保持其动态个性的能力。活细胞还呈现出其他更具自身特性的属性;它们生长、繁殖、继承品性并将其传承下去。尽管要在这样的系统中区分组织水平可能要对现实加以抽象,但我们仍然有理由相信,这些属性是基于在某种意义上高于化学水平的组织水平之上的。于是从生... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | 亨利·戴尔爵士曾经谈到“今天值得考虑的是:就普通人的思维方式和关注点以及对技术和工业发展的意义而言,物理科学的卓越成就是否并未在我们的教育与公共政策中掩盖了生物学的成果,以至于达到了科学自身以及我们希望建筑在科学基础之上的文明有可能出现片面发展的程度。”沃尔特·弗莱彻爵士在去年的离世使这个国家失去了一位贤明的导师,他生前曾在一次面向全国的广播中讲了一句在我看来几乎使公众震惊的话,他说“只有我们越来越将生物学真理的指导引入治国方法时,才能找到安全与进步”。高高在上的治国之术会与生物学理论有关系,这对于很多听众来说是一种新观念。
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几年之前,剑桥哲学家布罗德博士——他对科学领域的熟悉程度远远超过许多其他的哲学家——曾评论过科学... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | 它们在畜牧业中的巨大经济价值还有待于全面的了解。农业专家在不久之前开始敏锐地认识到有必要对动物疾病进行更好的控制。动物染病会给农场主带来巨大的经济损失,也会给国家带来损失。无疑地,尽管不该夸大它的影响,根据阿伯丁郡洛维特研究所以及在其他地方所进行的研究,不合理的食物对于引发某些疾病起着不小的作用。还有更多能带来巨大效益的工作有待于进行。
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VII
在最近这些年里,每个科学分支中的研究活动都明显增加了。所有的人都会认识到这一点,但只有那些能够仔细考察局势的人才能估计出增长量的大小。我曾想到有一份关于在英国进行的研究活动,尤其是有关国家资助的研究组织的评估,它也许很适合作为今天演讲的一部分。但想描述自己工作进展的欲望使我放弃了... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | 我们不应该完全抹杀,真正充足的休息与可能是充满疲惫的极为短暂的休息之间存在的差异;或者存在于强制性劳动与自觉工作之间的差异。
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此外,我们不得不描绘一下英国社会的反应,在最近几年中,大多数英国人都表现出了一定的可塑性。我并不认为相信下面的事是不切实际的:我们高效的国家广播设施,以及短波长传输将为我们提供的越来越多的机会,在教师们通过个人影响帮助青少年学会利用它们之后,就可以很好地实现对青少年的系统教育。这并不是一种技术性的教育,而是追求闲暇的教育。最初可能只是少数人能聆听系统的教育课程;但最终将在这部分受益非常大的社会群体中成为习惯。
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附带言之,请允许我再简短地谈一谈“计划”。眼下这个词非常热门,主要是与当前的... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | single cells or distinct brain regions. And foreshadowing the beliefs of many modern neuroscientists, Adrian adds that the “ceaseless electrical pulsations” of nerve cells will help researchers unravel the workings of the nervous system.
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S
INCE the biologist seeks to understand life, he cannot be accused of lack... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | thought as well as action, we must face the prospect of becoming psychologists and metaphysicians as well. Fortunately, we need not yet go to such extremes.
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The nervous system, the brain, spinal cord and peripheral nerves, is made up of a large number of living cells which grow, maintain themselves by the metabol... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | supernumerary limbs, eyes, noses, and even spinal cords. The growing nervous system is faced with these unusual bodily arrangements, and by studying the changes induced in it we can form some idea of the factors which determine its normal structure.
中文
A review published this summer by Detweiler gives a vivid impres... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | their function of conducting messages, and we can detect the same kind of pulsating activity in the nerve cells of the brain.
中文
The evidence comes from the analysis of minute electric changes, for cell activity sets up electrical eddies in the surrounding fluid, and these can be measured with a minimum of interfere... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | The impulses in a given nerve fibre are all alike in magnitude, rate of travel, etc., but the frequency at which they recur depends on the intensity of the stimulus, rising sometimes so high as 300 a second in each fibre, or falling so low as 10. All the nervous messages take this form.
中文
The conducting threads or ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | So far we have only considered what happens in nerve fibres. We can tap the messages which pass along the wires between the front line and headquarters, but this does not tell us how they are elaborated there. A great deal has been found out already by the analysis of reflexes—that is, by sending in a known combination... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | structures where most of the neurons are acting in unison, the waves may have a regular rhythm (5–90 or more a second), which rises and falls when the stimulus changes in intensity. It is often possible to make out both the abrupt nerve fibre impulses and the slower nerve cell waves, and to show that they occur togethe... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | In spite of this, we can claim to have some of the main outlines of neurone activity. Our nervous system is built up of cells with a specialised structure and reactions, but the reactions are of a type to be found in many other cells. The rhythmic beat of the heart is probably due to surface reactions not far different... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | gave us diagrams of nerve centres and pathways which were valuable enough when they referred to known anatomical structure, but not when they referred, as they often did, to hypothetical centres and to pathways canalised by use. These too may exist, but they are not the whole explanation of cortical activity.
中文
Cli... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | It has often been pointed out that we learn to recognise shapes—the letters of the alphabet, for example—however they are presented to us. The pattern of black and white made on our retina by the letter A need not fall on a particular set of retinal endings connected with particular cortical neurons. We have learnt to ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | development of a new visual region or motor region in the brain. Though they were originally localised, there is no longer any one part of the cortex which is essential.
中文
In reactions where there is no evidence of localisation (for example, the learning of maze habits in the rat), Lashley finds that the important ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | possible, for example, to find out how many neurons must be combined to give a system which reacts in this way and what kind of structure they must form. The nervous systems of insects may provide the clue, for these may contain a few thousand nerve cells in place of the ten thousand million in the human brain. It is p... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | points, and they might be formed with less distortion in a large pond than in a small one.
中文
This does not take us vary far: in fact, the major problems of the central nervous system are left in greater obscurity than ever. But no one can observe these ceaseless electrical pulsations without realising that they pro... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | 或许最好的方法是沿着巴甫洛夫的脚步看看如果不考虑精神层面我们能够发现多少东西,如果用神经细胞的活动既解释思想又解释行为,那么我们就不得不面临同时成为心理学家和精神疗法家的可能。幸运的是,我们现在还不需要走这样的极端。
英文
神经系统,即脑、脊髓和外周神经,是由大量活细胞组成的,这些活细胞利用食物代谢进行生长发育并维持活性,还要完成生物体的所有复杂行为。这里有太多的问题需要解决;然而我们关心的不是活细胞所具有的一般特性,而是那些使神经细胞发挥自身功能的特殊性质。神经细胞的功能是使生物体迅速而有效地对环境的改变作出反应,为了实现这个功能,它们形成了自己的特殊结构并在有机体内部形成了复杂的组织方式。它们发出长长的细胞质突起,用于快速... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | 两者都是神经元的特殊部分,具备特殊的反应,但值得一提的是这些反应并非神经系统所独有。从中胚层发育而来专门用来收缩的肌纤维也能传递冲动,与神经纤维传递的冲动仅存在时间关系上的差别,在各种盐溶液的作用下它们也能像感觉末梢那样工作。比如,在氯化钠溶液中,当肌肉受到牵拉时就会产生一系列的冲动,这些冲动就好像发生在一个唯一功能是充当“牵张感受器”的感觉器官之中。肌纤维并不是神经纤维的良好复制品,因为它只能间断性地作出反应而且冲动经常在传导过程中被损毁,但两者的基本作用机制是相同的。
英文
因此在有关快速传递和冲动规律性形成的行为中,神经系统的细胞所具有的性质看上去与其他组织没有什么不同。
英文
到目前为止我们只考虑了神经纤维中的情... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | 模型为我们提供了神经中枢和通路的概况,但是仅当其所指的是已知的解剖结构时才有足够的价值,如果像过去那样指的是假设的中枢和改造的通路,那价值就不明显了。它们也可能是存在的,但不能完全解释皮质的活动。
英文
临床神经病学因为将重点放在准确的定位上而备受指责。神经病学家们只有通过分析症状才能定位脑肿瘤;因此他们乐意接受在皮层中进行最细小的功能定位,并且发现解剖模型与观察结果可以相互关联。毫无疑问,大脑中存在清晰的神经通路、明显不同的细胞结构以及不同部位的局部活动。弗尔斯特最近关于人类皮层电刺激的研究为我们增加了最新的证据,他发现刺激颞叶可以使意识中出现声音和语言,刺激枕叶可以出现光或图像。巴德在观察了猫的某些姿势反射之后,给出了另一... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | 当集体节奏出现的时候,这些神经元表现得像是形成了一个整体。没有必要认为树突形成了一个连续的网络,因为电场力完全可以打通它们之间的间隙,但树突会形成一个能使兴奋在各个方向上自由传播的系统。这种系统中的兴奋形式就像池塘表面的涟漪,不同之处在于有些涟漪可能是自发产生的,而另一些是由于接受了传入的信息而产生的。因此,干涉图和振动节点都非常重要。至少它们提供了在不需要进行特定点激发的情况下识别成三角形或成正方形等的关系的基础,而且在大池塘中可能比在小池塘中失真度更低。
英文
我们并没有因此取得很大的进步:事实上,中枢神经系统的主要问题比以前更令人困惑。但是每一个看到这些持续不断的电振荡的人都会认为它们提供了新的数据,而且可能会为大脑的研... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | entertainment or of its being put to other commercial uses. The received images were recognisable, but blurred and flickering, and to many scientific workers, a proof of the impossibility of advance in television by a mechanical system of transmission and reception. Other scientific observers, though less antipathetic ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | For the Leeds demonstration “noctovision” was used, the person televised being shielded from the direct glare of the lamps by a sheet of ebonite. In the meantime, however, Baird had made a further notable advance by his invention of the light spot method of scanning. To quote the text of his patent: “The scene or objec... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | in mid-ocean. According to the chief staff engineer of the vessel, the “image varied from time to time in clarity, but movements could be clearly seen, and the image, when clear, was unmistakable”. In these transmissions the wave-length used was 45 metres. The following year, using light spot transmission and cathode g... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | Meanwhile, researches into the possibilities of cathode ray television were engaging the attention of a large number of scientific workers in the laboratories of the Radio Corporation of America and its associated enterprises, independently by the Philco and other American companies, and by the Fernseh A. G. of Berlin,... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | In 1932 five major events in the progress of television took place. Fernseh A. G., the company organised to develop the Baird processes in Germany, built and installed a complete transmission equipment for the Ente Italiano per le Audizione Radiofoniche in Rome; the Derby was televised and projected at the time of its ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | mirror-drum. The Fernseh A. G. laboratories have constructed beautifully accurate mirror-screws with 90 and 120 reflecting surfaces of stainless steel. Dr. Vladimir Zworykin, the American research engineer, has made sensational claims for what he terms his iconoscope, which has been described as consisting of two devic... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | Again and again in the last two years, it has been urged that finer resolution than that obtainable with the 30-line standard, 2.4:1 ratio, picture is necessary before television will become popular. This may or may not be so, but the true nature of the present position should now be realised. In the first place, it is... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | established service throughout the country is achieved. In the meantime, further problems arise in connexion with distortion in amplifiers against which the weapons provided by Oliver Heaviside, to whose classic researches on the underlying electrical principles of distortion in communication engineering too little cre... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | 正如阿奇博尔德·丘奇在这篇评论文章中所说的:当约翰·贝尔德在1926年首次向公众演示那些模糊和闪烁的电视图像时,人们普遍对此持怀疑态度,但现在这项技术正如火如荼地发展着。1932年,有人把德比马赛拍摄下来并实时传送给伦敦的观众;而且英国广播公司也已经安装了贝尔德电视有限公司的转播设备。现在工程师们正在想办法把阴极射线投射到荧光屏上以改善图像的质量,并使现场直播成为可能。这需要有较高的屏幕分辨率,而且还需要在广播频带中为电视信号安插一定的位置。
英文
电视技术的所有发展都是最近涌现出来的。从约翰·贝尔德第一次获得简单静态物体,例如马尔他十字形的电视图像到现在还不到10年时间。在1926年1月27日,贝尔德第一次演示了“真正”的电... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | 同一年,年轻的冯阿登爵士在德国开始了他对电视的研究,他采用自己研制的、专用于传送和接收电视图像的阴极射线示波管,在不到一年的时间里,他就因第一个向公众展示能与机械式接收系统性能相媲美的阴极射线接收器而声名卓著。起初,冯阿登接收的是通过机械手段传送的图像,但是后来他利用一个速度可变、强度不变的阴极电子流来代替速度不变、强度变化的电流,这样就使他的阴极射线管既能传送图像又能接收图像了。
英文
与此同时,对阴极射线电视的研究吸引了许多在美国无线电公司及其联营企业,主要是飞歌公司和其他美国公司,以及在德国柏林电视机股份公司工作的科学工作者们的注意,在柏林电视机股份公司中,贝尔德公司与博世公司、蔡司伊康公司以及洛伊公司的股权地位相当。洛... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | 英文
人们在过去的两年中一直认为:为了使电视得到普及,就必须研制出图像清晰度高于已有的30线标准、画面比例为2.4:1的电视。事实可能是这样,也可能不是这样,但我们应该清楚现在的真实情况。首先,很容易证明(实际上已经有人提出过)当带宽为10千赫时,一个频道的信息–时间传输特性(为了使闪烁最小化,应达到一个合理的图像速率,如每秒12.5次)采取这样的线数和比率最为经济。
英文
目前,利用今年研制出的阴极射线接收设备所得到的图像的质量明显优于机械式接收设备重组而成的30线图像。贝尔德公司在英国科学促进会今年在莱斯特召开的会议上首次公开展示了这种质量的图像,洛伊公司、柏林电视机股份公司等其他公司在柏林无线电展览上也展示了同样的产品... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | HE mass of the hydrogen atom, 1.00778±0.00015, found by Aston with the mass-spectrograph, appeared to be in very satisfactory agreement with the chemical atomic weight, which is one of the most accurately determined (A. Scott; Morley; Burt and Edgar). The discovery of the isotopes of oxygen, however, made it clear that... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | was calculated as 4,000, which would explain very nicely the discrepancy just noted, but this result has since been shown to be incorrect. The isotope effect was also found in the Lyman series of hydrogen produced by a discharge in the vapour of “heavy” water5
.
中文
The presence of H2
was then demonstrated by means... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | in natural terrestrial hydrogen might depend on the particular sample examined, since there might have been some separation in the method used in preparing the hydrogen. It has also been found that H2
tends to “clean up” in a discharge tube12
, so that estimates of relative abundance based on optical emission spectra... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | When water is distilled through a fractionating column, a large separation of the isotopes of hydrogen and oxygen can be effected, especially if the distillation is carried out under reduced pressure15
. A 20-ft. column was used and in two modes of operation: (i) the ordinary isotopic composition was maintained at the... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | OH, and again dehydrating, the two changes proceeding with great velocity, and as the fourth hydrogen of the ammonium group is exactly like the others, each hydrogen has an equal chance of being lost on dehydration. A rapid interchange of such hydrogen isotope as is present will give a nearly random distribution betwee... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | Practically pure “heavy water”,
, was obtained by Lewis and Macdonald21
, whose experiments on its physical properties were carried out with 0.12 c.c. of liquid in which the proportion of H1
isotope was probably not greater than 0.01 percent. The freezing point was found to be +3.8° and the boiling point 101.42°. T... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | were thus obtained. Results at five temperatures from 5° to 18° were found. It is assumed that the ratio of equivalent conductance to equivalent conductance at infinite dilution is the same for each electrolyte in the two solvents and that the ratio of the mobilities of the K+
and Cl–
ions is the same in both solvent... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | . A peculiar effect of thermal treatment of water on its capacity for promoting the development of cells of Spirogyra
, reported by Lloyd and Barnes26
, was attributed to the different proportions of polymerised water molecules in freshly condensed steam and freshly melted ice. Ice27
has been regarded as (H2
O)n
,... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | chemical properties of the heavy hydrogen isotope are very probably different from those of ordinary hydrogen. A new organic chemistry, in which each of the compounds containing carbon (of which there are also at least two isotopes, C12
and C13
) and hydrogen is duplicated by the synthesis of a “heavy” partner—at pre... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | 在地球上的天然氢中,比值H1
/H2
可能会依赖于所检验的特定样品,因为用来制备氢的方法可能已经实现了某种程度上的分离。而且,还发现H2
在放电管中有“清除”的趋势[12]
,这使得根据发射光谱方法得到的相对丰度估计值很有可能是错误的。他们发现水在经过长期电解之后,其比重、凝固点和沸点显著升高,而折射率下降[13]
。
英文
刘易斯和麦克唐纳使用20升取自旧电解池的水(其中碱只有半当量浓度)开始进行实验,在250安培条件下用镍电极进行电解,直到液体体积减少了90%为止。取十分之一液体用二氧化碳中和,将剩余液体进行蒸馏。然后将两部分重新混合。重复进行上述过程,直到体积减少到半个立方厘米,电解过程保持在35o以下进行,最... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | 他们建立了蒸气压曲线,得到了如下的p
2
/p
1
值,其中p
1
是普通水的蒸气压,p
2
是重水的蒸气压:
通过常规计算可以得到,重水的蒸发潜热比普通水的大259±3或259±4 g·cal/mol。25o时,重水密度为1.1056,温度为+11.6o时密度最大。下面列出了不同温度下重水的体积与4o下重水体积的比值:
英文
在水作为一种反常液体的各个方面中,重水(
)都表现得更为反常,但是二者之间的差异随着温度升高而逐渐减小。
英文
最近报道了几项关于H2
和
的五花八门的研究成果。H2
的核自旋[22]
(由于不相容)可能是2/2,或者说是H1
核自旋的二倍;由25%H1
H1
、50%... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | 每种含碳(它也有至少两种同位素,C12
和C13
)和氢的化合物都将通过合成其“重”伙伴而得到复制,这种新型的有机化学,尽管从现在看来只不过是一场噩梦,但随着时间的流逝必将成为既成的事实。重水在医疗中的应用还有待于研究。
英文
(王耀杨 翻译;李芝芬 审稿)
Internal Temperature of Stars
G. Gamow and L. Landau
Editor's Note
In the early 1930s astronomers were still at a loss to understand the high internal temperatures of stars, since th... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | is the total number of atoms in a cubic centimeter, σ
the cross-section of collision, and M
the atomic weight of the atoms in question.
中文
Using (11
) and (21
), we obtain from (2):
Accepting N
~N
1
~1024
and σ
~10-18
cm.2
, we obtain for lithium (Z
= 3) the following numbers:
From this table the conclu... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0301. 《自然》百年科学经典（第二卷）(英汉对照版)(1931-1933).epub | .epub | 11,771,588 | 2025-09-26T19:06:58.142679 | applauds the collaboration of botanists and physicists in addressing the structures of biological fibres—a collaboration that is still not unproblematic today. Astbury's description of proteins as “infinitely variable and adjustable molecular patterns”, with structural as well as enzymatic roles, foreshadows the puzzle... | 400套付费套装书 |
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