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C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 英文
(王耀杨 翻译;顾孝诚 审稿)
Molecular Configuration in Sodium Thymonucleate
R. E. Franklin and R. G. Gosling
Editor's Note
This paper reports the X-ray crysyallographic work on DNA by Rosalind Franklin and Raymond Gosling at King's College London, which furnished James Watson and Francis Crick with the crucial information f... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | . Stokes and Wilkins were the first to propose such structures for nucleic acid as a result of direct studies of nucleic acid fibres, although a helical structure had been previously suggested by Furberg (thesis, London, 1949) on the basis of X-ray studies of nucleosides and nucleotides.
中文
Sodium deoxyribose nuclea... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | ; this expression leads to an approximately linear array of intensity maxima of the type observed, corresponding to the first maxima in the functions J
1
, J
2
, J
3
, etc.
中文
If, instead of a smooth helix, we consider a series of residues equally spaced along the helix, the transform in the general case treated ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | If ten phosphorus atoms lie on one turn of a helix of radius 10 A., the distance between neighbouring phosphorus atoms in a molecule is 7.1 A. This corresponds to the P...P distance in a fully extended molecule, and therefore provides a further indication that the phosphates lie on the outside of the structural unit.
... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | , the water in fibres of high water-content being situated outside the structural unit. On this basis we find that a cylinder of radius 10 A. and height 34 A. would contain thirty-two nucleotides. However, there might possibly be some slight inter-penetration of the cylindrical units in the dry state making their effec... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | , we may state the following conclusions. The structure is probably helical. The phosphate groups lie on the outside of the structural unit, on a helix of diameter about 20 A. The structural unit probably consists of two co-axial molecules which are not equally spaced along the fibre axis, their mutual displacement bei... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | We are grateful to Prof. J. T. Randall for his interest and to Drs. F. H. C. Crick, A. R. Stokes and M. H. F. Wilkins for discussion. One of us (R. E. F.) acknowledges the award of a Turner and Newall Fellowship.
中文
(171
, 740-741; 1953)
Rosalind E. Franklin and R. G. Gosling: Wheatstone Physics Laboratory, King's ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 英文
在第1、2、3和第5层线上最内部的极大值近似地分布在从原点辐射出来的一条直线上。对于一个平滑的单链螺旋来说,位于第n
层线上的结构因子可以由下式给出:
其中,J
n
(u
)是u
的n
阶贝塞尔函数,r
是螺旋的半径,而R
和ψ分别是倒易空间中的径向坐标和方位角坐标[2]
。该表达式导致所观测到的强度极大值形成近似线性排列的形式,这些极大值对应于J
1
、J
2
、J
3
等函数的第一个极大值。
英文
如果我们在考虑沿着螺旋等间距排布的一系列残基,而不是把它们当作一条平滑的螺旋来处理时,那么克里克、科克伦和范特所采用的变换通常情况下会更复杂。不过,要是每周螺旋中的残基数m
是整数,那么变换的形... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 英文
因此,我们虽然并未对B
型结构的纤维图提供一个完整详尽的解释,但还是可以陈述如下结论:该结构很可能是螺旋形的。磷酸基团位于结构单元的外侧,在直径大约为20Å的螺旋上。结构单元很可能是由两个同轴分子沿纤维轴不等间距排布形成的,它们之间的相互位移正好可以解释层线上最内部极大值的观测强度的差异。如果一个分子与另一个分子间的位移约为纤维轴周期的
,那就可以解释为何第4层线极大值缺失和第6层线的强度非常微弱。因此,我们的基本观点与沃森和克里克在前面的通讯文章中提出的模型没有矛盾。
英文
此前已经依据其他一些完全不同的推论[1]
得到了磷酸基团位于结构单元外侧这一结论。这主要借助于两条主要论据。第一条论据来自于格兰德及其同事... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | HE importance of deoxyribonucleic acid (DNA) within living cells is undisputed. It is found in all dividing cells, largely if not entirely in the nucleus, where it is an essential constituent of the chromosomes. Many lines of evidence indicate that it is the carrier of a part of (if not all) the genetic specificity of ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | cytosine—are pyrimidines. So far as is known, the sequence of bases along the chain is irregular. The monomer unit, consisting of phosphate, sugar and base, is known as a nucleotide.
中文
The first feature of our structure which is of biological interest is that it consists not of one chain, but of two. These two chai... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | The way in which these are joined together is shown in Figs. 4 and 5. A given pair can be either way round. Adenine, for example, can occur on either chain; but when it does, its partner on the other chain must always be thymine.
中文
Fig. 4. Pairing of adenine and thymine. Hydrogen bonds are shown dotted.
One carbon ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Previous discussions of self-duplication have usually involved the concept of a template, or mould. Either the template was supposed to copy itself directly or it was to produce a “negative”, which in its turn was to act as a template and produce the original “positive” once again. In no case has it been explained in d... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Since the two chains in our model are intertwined, it is essential for them to untwist if they are to separate. As they make one complete turn around each other in 34 A., there will be about 150 turns per million molecular weight, so that whatever the precise structure of the chromosome a considerable amount of uncoili... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | For the moment, the general scheme we have proposed for the reproduction of deoxyribonucleic acid must be regarded as speculative. Even if it is correct, it is clear from what we have said that much remains to be discovered before the picture of genetic duplication can be described in detail. What are the polynucleotid... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | , 402 (1952). Wyatt, G. R., J. Gen. Physiol
., 36
, 201 (1952).
脱氧核糖核酸结构的遗传学意义
沃森,克里克
编者按
在本文发表的一个月前,詹姆斯·沃森和弗朗西斯·克里克发表了一篇短文,提出了DNA的一种结构,当时仅仅暗示了这种结构对于遗传学及遗传的意义。本文中两位研究者进一步阐述了他们的想法。他们指出,双螺旋的两条链是由一种叫做氢键的弱键连接在一起的,其中氢键将四个“核苷酸碱基”与具有良好拟合形状的互补核苷酸碱基特异性地结合在一起。他们指出“如果给出其中一条链的确切的碱基顺序,那么我们就能准确写出另一条链的碱基顺序”。因此,每条链都可以作为其互补链的模板,使得... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 由此可以断定,在大分子中可能存在许多种不同的碱基排列方式,因此,这似乎表明精确的碱基序列就是携带遗传信息的密码。如果双链中一条链的碱基序列是已知的,那么我们就可以准确写出另一条链的碱基序列,因为碱基之间的配对是特异的。因此,一条链是另一条链的互补链,正是这个特点向我们揭示了脱氧核糖核酸分子是如何自我复制的。
英文
此前关于自我复制的讨论常常涉及到模板或者模具的概念。人们认为,或者是模板直接自我复制,或者是模板产生一个“负链”,此“负链”反过来又作为模板再产生一条原来的“正链”。但是任何论述都没能详细解释复制过程在原子和分子水平上是如何进行的。
英文
实际上,我们的脱氧核糖核酸模型可以看作是一对
模板,它们之间是互补的。... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 英文
(郑建全 翻译;王晓晨 审稿)
Piltdown Man
Editor's Note
The discovery of a modern-looking skull with a primitive jaw at Piltdown in southern England in 1912 caused a sensation. As the years passed, Eoanthropus dawsoni
—the name given to this “missing link”—looked increasingly out of step with discoveries from Africa and Asi... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | In their remarkably flat wear the molar teeth in the Piltdown jawbone rèsemble man rather than ape. Microscopical examination of these flatly worn surfaces showed that they are due to artificial abrasion and not to natural wear. The canine is a young tooth with incomplete root, so the fact that it has been worn right d... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | The tests and other investigations reported above were carried out jointly in the Departments of Geology and Mineralogy of the British Museum, in the Department of Anatomy and the Clarendon Laboratory, University of Oxford, and in the Department of the Government Chemist, London.
中文
These investigations serve to con... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 英文
皮尔当人下颌骨上磨损面非常平坦的臼齿,与人类的相似,而非与猿类的相似。对这些平坦的磨损面进行的显微镜检验表明,它们是人工磨损形成的而非自然磨损形成的。犬齿是一颗年轻的牙齿,具有不完整的牙根,所以它表现出来的像在一个老年个体中见到的磨损径直向下到牙髓腔的情况只能通过人工磨损来解释了。
英文
使用一种改进的技术对所有样本的氟含量进行了重新检测,结果表明尽管脑颅与当地上更新世一些化石的氟含量相同,但颌骨和犬齿的氟含量却不超过现代样本。所有样本的有机物含量也已得到检测。颌骨和犬齿的含氮量与新鲜骨和牙齿的相同,但是脑颅中的含量很少,正如在上更新世化石中预期的那样。
英文
最终,已发现的一些证据表明颌骨在被挖掘者“发现”之前... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | as indicating a deliberate attempt to match a modern bone with the mineralized cranial fragments. The actual composition of this bone (3.9 percent nitrogen, less than 0.03 percent fluorine) suffices to prove its modernity; but the chromate staining, combined with the artificially abraded appearance of the molars, indic... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Dawson, C., and Woodward, A. S., Quart. J. Geol. Soc. Lond.
, 69
, 122, footnote 1, pl. xvi, fig. 2 (1913).
对皮尔当工具进行的化学检验
奥克利,韦纳
编者按
这一年,韦纳和奥克利先是揭露了发现于英格兰南部皮尔当的所谓古代前人类化石是一个骗局,随后他们又对此作了进一步的验证。不仅所有的骨经过了染色处理以使其看起来陈旧,而且一些之前被猜测是燧石的石器也经过了同样的处理。给骨染色可能是为了使其硬化以便于保存,但是给燧石石器染色的原因就只能是为了欺骗了。这次揭露事件使一些著名的人类学家受到沉重的一击,并因这个骗局而声名扫地。... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | from South and most probably “Meganthropus africanus
”2
from East Africa. The position of Telanthropus
from the Plesianthropus
layers of Swartkrans is still under dispute.
中文
The large amount of material now at hand leaves no doubt that the Australopithecinae are members of the Hominidae. With this group they sh... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | . This form has retained the “simian gap”, which is a very primitive characteristic which might be expected in an early human forerunner; for Remane, in a very careful study, has shown that even in the dentition of modern man there are peculiarities due to his forerunners having much better developed canines9
. This g... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | but also more than in modern man. In connexion with this reduction, the dental arcade shows a typical shortening, which has been demonstrated by Le Gros Clark11
.
中文
In spite of all these specializations, the roots of the premolars in Paranthropus
do not differ in number from those observed generally in the anthro... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | this point is not so clear), but there is also a tendency towards a complete molarization of this tooth, which reaches a maximum in Plesianthropus transvaalensis
for the upper and in Paranthropus robustus
for the lower molar; in the latter form, except for its size, this tooth is indistinguishable from the second dec... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | There is not a single feature in the original Meganthropus
jaw fragment which cannot be matched with other primitive human jaws. In the corresponding part of the Australopithecus
mandible the two-rooted second premolar must already be regarded as a sign that it belongs to a different category. In fossil human jaws th... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Most probably in their absolute brain capacity the Australopithecinae bridge the gap which exists between the largest brain of the anthropoids (gorilla with 585 c.c.) and the smallest of the Hominidae (Pithecanthropus erectus
II with 775 c.c.). There is, however, this important difference: the greatest brain capacity ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | , which is not found in the smaller species. Apart from the fact that this must be taken as a sign of a limited brain capacity, it is to be noted that a sagittal crest in the anthropoids depends upon the absolute size of the species. It is absent from the small gibbon, very rare in male chimpanzees, normal in male oran... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | von Koenigswald, G. H. R., Rep. Int. Geol. Congr. Great Britain 1948, part IX, 59 (1950).
del Campana, D., Palaeontologia Italica
, 19
,189 (1913).
Remane, A., Z. f. Anat. u. Entwicklungsgesch
., 82
, 391 (1927).
Broom, R., and Robinson, J. T., Transvaal Mus. Mem
., 6
, 1 (1952).
Clark, W. E. Le Gros, J. Roy. Ant... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 傍人粗齿种和智人的上中门齿的最小值分别是7.5毫米和8.0毫米,下中门齿的最小值分别为5.0毫米和4.6毫米。相关数值要高得多,就如傍人粗齿种的第一下臼齿的平均长度是15.0毫米,而现代人的是11.1毫米。两个群体的犬齿大小基本相同。
英文
现代人的第一下前臼齿只比第二下前臼齿略小一点(在某些爱斯基摩人中,我们还发现了相反的情况),平均值是0.3毫米,但是傍人粗齿种的平均值是1.3毫米。中国猿人的第一前臼齿最大,魁人也是,所有的类人猿一般也如此。因此这肯定是原始状态。总体上来说,南方古猿亚科的门齿–犬齿–前臼齿群不仅像爪哇猿人的一样大大减小了,而且比现代人减小的还要多。齿弓也相应显示出典型的缩短现象,勒格罗·克拉克已证实这一点... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 但希望大家不要忘记,只能测量迩人V号这唯一一件头骨,其脑量只有482毫升。
英文
南方古猿亚科很有可能在绝对脑量方面填补了类人猿的最大脑量(大猩猩是585毫升)和人科的最小脑量(直立猿人II的脑量是775毫升)之间存在的空缺。然而,这里有一个重要的差异,即南方古猿亚科的最大脑量与最大臼齿是同时出现的,而在人类中最大脑量却与最小臼齿一起出现。我们曾经尝试用脑–臼齿系数来表示这种关系[15]
,即用以立方厘米为单位的脑量除以以毫米为单位的三颗上臼齿的近中远中径,这两个数据都是对同一头骨测量得到的,结果见表2。
英文
表2.脑–臼齿系数
(括号中的数字表示测量的头骨编号)
英文
正如我们所期望的,现代类人猿形成了一个... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | -band when muscle shortens. The paper was published back-to-back with a manuscript by English biologists Hugh Huxley and Jean Hanson from the Massachusetts Institute of Technology, who used light microscopy to independently arrive at similar results. Together these studies lead to the “sliding filament” model of muscle... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | have endeavoured to exploit this possibility. Their conclusions are, however, open to the objection that they used the ordinary light microscope, which cannot be expected to provide a reliable image of unstained striations (alternate bands of high and low refractive index) the repeat distance of which is 2-3 μ, in a fi... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | ). Note that the threads of sarcoplasm have a refractive index slightly higher than even the A
-bands. Sarcomere length, 3.0 μ
中文
Passive stretch
. The sarcomere length s
could be changed by passive stretch or release from about 2.0 to 4.2 μ, the value at the extended length in the body being 2.5 μ6
. Almost th... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | -band width decreased definitely in all cases; but there were additional phenomena which were not the same in every experiment. The following sets of changes were observed on several occasions:
(a
) Striations became extremely faint on shortening beyond a sarcomere length of about 1.8 μ (cf. Speidel7
).
(b
) The den... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | -bands, as shown in many electron microscope studies, makes very attractive the hypothesis that during contraction the actin filaments are drawn into the A
-bands, between the rodlets of myosin. (This point of view was reached independently by ourselves and by H. E. Huxley and Jean Hanson in the summer of 1953. It has... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | ., 126
, 1 (1909).
Hill, A. V., Proc. Roy. Soc
., B, 136
, 399 (1949).
Buchthal, F., Knappeis, G. G., and Lindhard, J., Skand. Arch Physiol
., 73
, 163 (1936). Buchthal, F., and Knappeis, G. G., Acta Physiol. Scand
., 6
, 123 (1943).
Smith, F. H., prov. Pat. Spec. No. 21996 (1947); complete Pat. Spec. No. 639014... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 在此条件下,用普通光源完全观察不到肌纤维,但是使用相干模式则可以获得极好的条纹图像(还有肌浆、细胞核以及颗粒体的图像)。可以通过改变两个光束之间的背景路径差来控制或者颠倒A
带(折射率较高)和I
带之间的明暗对比,这种调节不会影响带的测量宽度(图1)。通过一个放电管以每隔约20毫秒闪光10次的速度进行系列闪拍,将纤维图像照到移动的底片上,信号可以通过与这些闪拍同步的脉冲电流而得到加强。
英文
图1.肌纤维的负反差(a
)和正反差(b
)图片。(a
)图中亮的部分和(b
)图中暗的部分是A
带(折射率较高)。请注意肌浆丝的折射率甚至比A
带略高。肌节长度为3.0微米。
英文
被动拉伸
通过被动拉伸或者松... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 在这个基础上,我们也可以预期肌肉的肌节越长,肌肉所能产生的张力也应该越大,不过关于这一点我们还不知道任何实验结果。
英文
(张锦彬 翻译;周筠梅 审稿)
Changes in the Cross-Striations of Muscle during Contraction and Stretch and Their Structural Interpretation
H. Huxley and J. Hanson
Editor's Note
In this paper, British biologists Hugh Huxley and Jean Hanson from the Massachusetts Insti... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | has reached similar conclusions about the location of actin and myosin, though his concept of the details of their arrangement is different from ours. We shall now describe evidence that during stretch, and during contraction down to about 65 percent of rest length, the length of the A
-bands remains constant within t... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | the process are difficult to see and record. If fixed and sectioned material is used, it is possible to avoid optical artefacts and the necessity for rapid observation, but other kinds of artefacts are introduced. In spite of all these considerations, a number of workers, notably Speidel7
, have given accounts of chan... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Photographs used for measurement were taken on microfile film at a magnification of ×370 or ×550, and an apochromatic phase-contrast objective of n.a. 1.15 was employed.
中文
Contraction
We have studied and obtained photographic records of the details of contraction in the following systems:
(1) Fibrils contracting fr... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | -band, and is then replaced (at about 85 percent rest length) by a narrow zone which is denser than the rest of the A
-band. At a slightly shorter sarcomere length (about 80 percent rest length), a very dense line becomes visible at either end of the A
-band. The overall density of the A
-bands decreases as the fibr... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | -zones characteristic of rest-length fibrils, and have correspondingly shorter sarcomere lengths. Suspensions of untreated fibrils also include some specimens with sarcomere lengths down to about 65 percent of the rest length. Contraction presumably took place while the muscle was still excitable before glycerol extrac... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | -zone were lengthening; the length of this less dense region increases as stretch proceeds. This process is perfectly reversible: stretched fibrils can be allowed to shorten until contraction bands form, and then re-extended.
中文
If fibrils are stretched without any previous treatment, or in the presence of 10–4
M
a... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | -bands typical of rest length. These observations provide some evidence that the band pattern changes associated with stretch in whole living muscle fibres are similar to those seen in isolated fibrils which have been plasticized. Much more powerful evidence for this is described in the accompanying paper by A. F. Huxl... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | -band, the length of the gap is correspondingly greater (Fig. 6). The ghost fibrils are, however, still structurally continuous; stretched fibrils shorten spontaneously to a little less than rest length during extraction unless stuck to slide or coverslip; they may be reversibly extended again. This can be done with gr... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | is absent from this zone. In stretched muscle which has been subjected to myosin extraction the thick (110 A.) primary filaments are absent, and gaps apparently exist between the groups of thin (40 A.) filaments associated with successive Z
-lines. In sections of glycerol-extracted muscle contracted in adenosine triph... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | -band, and their length is unaltered by stretch or by contraction down to the point where the sarcomere length is equal to the length of the A
-band; when contraction beyond this point takes place, the ends of the myosin filaments fold up and contraction bands form. Thus myosin and actin filaments lie side by side in ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | A possible driving force for contraction in this model might be the formation of actin-myosin linkages when adenosine triphosphate, having previously displaced actin from myosin, is enzymatically split by the myosin. In this way, the actin filaments might be drawn into the array of myosin filaments in order to present ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Hanson, J., and Huxley, H. E., Nature
, 172
, 530 (1953).
Hasselbach, W., Z. Naturforsch
., 8b, 449 (1953).
Jordan, H. E., Amer. J. Anat
., 27
, 1 (1920); “Physiological Reviews”, 13
, 301 (1933).
Buchthal, F., Knappeis, G. G., and Lindhard, J., Skand. Arch. Physiol
., 73
, 163 (1936).
Speidel, C. C., Amer. J. ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 英文
以前曾有人对肌肉拉伸或收缩过程中的横纹变化进行过研究(参见乔丹[5]
以及布克塔尔、纳培斯和林哈德[6]
的综述),并取得了一些结果,但总体上我们认为这些结果是不可靠的,原因如下:由于肌纤维本身的厚度,使用普通光学显微镜对完整的肌纤维进行观察很容易被光学假象误导。(这一难题已经被赫胥黎和尼德格克在相关文章中所述的技术克服。)此外,肌肉的收缩是一个非常迅速的过程,人们很难对这个过程中发生的变化进行观察和记录。如果将样品固定并切片后再观察,虽然可以避免光学假象和需要快速观察的问题,但又引入了其他假象。尽管存在这些难题,许多研究人员特别是斯派德尔[7]
对肌肉拉伸和收缩过程中条带样式的变化还是给出了解释,并且给出了我们认为大... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 图7、图8和图9.肌球蛋白被抽提后的肌原纤维。图7:静息长度;图8:静息长度的90%;图9:静息长度的75%。
图10和图11.肌球蛋白被抽提前(图10)和被抽提后(图11)具有收缩带的肌原纤维(静息长度的50%)。
英文
在甘油抽提前,从缩短到平衡长度(约为静息长度的80%)的肌肉中制备出来的肌原纤维通常缺少静息长度的肌原纤维特征性的H
区。相应地,其肌节长度也较短;未处理过的肌原纤维的悬浮液中也含有长度只有静息长度65%的肌节。收缩可能发生在甘油抽提前肌肉仍具有应激性时。这些肌原纤维显示了同样的特征性条带样式和条带长度,这与腺苷三磷酸诱导的收缩中各肌节长度的记录结果一致。
英文
分离得到的肌原纤维在腺苷三磷酸的诱... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 这很容易做到,显然仅微弱的力就能阻碍这样的拉伸;并且伴随着拉伸我们可以观察到H
带中的间隙逐渐变大,但从Z
线到这一间隙边缘的距离则保持不变,也就是说,此时I
带中的弹性组分没有被拉伸。
英文
从H
区刚刚消失了的处于收缩状态的肌原纤维中得到的鬼影纤维在肌节的中央没有间隙(图8)。那些能缩短到暗线处(存在于A
带中间)的肌原纤维在经过对肌球蛋白的彻底抽提后,这些线仍然存在(图9)。来自收缩程度更强烈的肌原纤维的鬼影纤维中也可以观察到这些暗线(图11)。
英文
这些“鬼影”纤维在腺苷三磷酸的作用下都不会产生收缩反应。
英文
电子显微镜
我们使用电子显微镜分别对拉伸、收缩以及抽提肌球蛋白后的肌肉薄切片进行了初... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 此外,我们不排除在收缩过程中肌球蛋白丝的构象发生重复改变的可能性,而并不伴随那些细丝总长度的变化,也不排除这些构象变化在一定程度上可能导致所观察到的肌动蛋白丝进入A
带的运动。
英文
我们会在别处对上述实验结果进行更详尽的描述。我们非常感谢弗朗西斯·施米特教授对本工作的鼓励,也非常感谢联邦基金和洛克菲勒基金会对我们工作的资助。
英文
(张锦彬 翻译;周筠梅 审稿)
Man-Made Diamonds
F. P. Bundy et al
.
Editor's Note
Scientists had long known that both graphite and diamond are forms of pur... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | those of diamond and giving some carbon dioxide upon combustion. Moissan therefore believed he had made diamond.
中文
In 1880, J. B. Hannay reported he had made diamonds by heating a mixture of hydrocarbons, bone oil and lithium at red heat in sealed wroughtiron tubes. The project was said to be fraught with great dif... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | The phase diagram for carbon as now understood is plotted in Fig. 1. Only the boundary between graphite and its vapour at low pressure is accurately established by experimental measurements. The boundaries at higher pressures between graphite, vapour and liquid are based on the work of Basset, and are not fully accepte... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | attempted to establish a point on the diamond-graphite equilibrium curve in a series of experiments in which diamonds were heated to about 2,500°K. for a few seconds at pressures which were increased until the diamonds failed to graphitize. This pressure was reached at 30,000 kgm./cm.2
. He suggested in his paper that... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Merely making the walls thicker on a pressure vessel contributes very little to its pressure-holding ability after a certain wall thickness is reached. By using multiple support bands on the cylinder part (a technique used years ago in making large gun barrels), and special sealing gasket devices between the piston and... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Fig. 2. New region of pressure and temperature available for research
中文
Diamond Synthesis
The new region of attainable pressure and temperature extended well into the diamond-stable region as defined in Fig. 1. Under these supposed diamond-stable conditions, processes were discovered which yielded diamonds ranging... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | (3) Hardness tests. The laboratory-made diamonds were hard enough to scratch the hardest face, the 111 face, of natural diamond (Fig. 5).
Fig. 5. Scratches made on natural diamond 111 face with man-made diamonds. A large number of scratches appear in a generally vertical direction down through the centre of the pictur... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Moissan, H., C.R. Acad. Sci
., Paris
, 118
, 320 (1894), and 123
, 206, 210 (1896).
Hannay, J. B., Chem. News
, 86
, 173 (1902).
Crookes, W., “Diamonds” (London, 1909).
Ruff, O., Z. anorg. allgem. Chem
., 99
, 73 (1917).
Parsons, C. A., Proc. Roy. Soc
., 79
, 532 (1907); J. Inst. Metals
, 20
, 5 (1918); Phi... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 这似乎为我们提供了将廉价石墨转化为金刚石的希望,但这个转化需要具备如同在地壳内形成金刚石时的那种超高压高温条件。自19世纪后期以来,科学家就试图进行这种转化,但位于斯克内克塔迪通用电气实验室的弗朗西斯·邦迪及其同事们在这篇文章中首次对此转化进行了报道。他们在温度超过1,200°C,压强为50~100,000个大气压的条件下对石墨进行挤压。这是第一次制造出人造金刚石;通用电气公司于1957年开始出售这种人造金刚石。现在人造金刚石已广泛应用于研磨和切割工具上。
英文
20世纪20年代,人们普遍认为在高温高压下碳已能转化为金刚石。事实上这不过是一个引人遐想的故事罢了。这涉及到一些著名的化学家、一个极其引人入胜的课题和一些十分惊人的实... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 如果就是这种情况,那么压强为30,000千克/厘米2
、温度为2,500K这个点还是位于石墨稳定区中。
英文
关于金刚石和石墨热力学稳定性的已知证据使我们相信,在压强处于30,000千克/厘米2
~100,000千克/厘米2
区间而温度为1,000K~3,000K中某点时,是能够形成金刚石的。
英文
压力容器
实际上所有已知的超高压发生器都是基于同样的原理,即将活塞推入圆筒中从而使其中的实验对象受到高压。限制容器内达到最大压强主要取决于其制造材料的强度。最坚硬的钢材在最适合的形状和大小时(例如钢琴丝),其极限抗张强度的数量级可达14,000千克/厘米2
~21,000千克/厘米2
。烧结碳化物的耐压强度的数量级... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 天然金刚石是其中之一,其折射率为2.419,另外4种是:
通过其他的关键性实验排除了这4种矿物的可能性。
英文
经过四年多的努力,本实验室研制出的实验装置能在金刚石稳定区内的压力和温度下一次持续几个小时。合成金刚石已经重复实现了一百多次。很多人都已独立并成功地重复了金刚石的各种合成过程。这些实验室内的人造金刚石可以划伤天然金刚石,并且具有与天然金刚石相同的晶体结构。
英文
(王耀杨 翻译;李芝芬 审稿)
*
参考文献按时间顺序列出,集中了汉内和穆瓦桑在这一领域的主要著作。更早的文献可追溯到1828年,这在梅勒《无机和理论化学总论》第5卷(朗曼格林出版公司,伦敦,1924年)中被提到过。
Errors in Dia... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | In the early 1950s four of us (H. P. B., F. P. B., H. M. S. and R. H. W.), together with H. T. Hall, developed an approach to diamond synthesis at high pressures and temperatures. The pressure scale used in our experiments was Bridgman's “resistance-jump” scale, which was suspected to be in error in absolute terms abov... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | How the natural diamond got into the run 151 experiment is not clear, although it came to light only a week later, when the iron pellet from the run was being polished for metallographic examination. After we found this diamond and took it to be synthetic, Hall used a similar synthetic system of iron/iron sulphide/grap... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 英文
为了研究151轮金刚石的真正本质,最近,我们将它从通用电气公司的档案部门中取出,用酸溶液对其进行清洗并用水漂洗。用装配有IR PLAN显微镜的尼高力740傅里叶变换红外光谱仪进行了红外吸收光谱的测定。图中所显示的这部分光谱类似于天然的含氮Ia型金刚石[4]
的光谱。尤其是在以下几处存在着吸收光谱带的一致性:位于约1,365厘米–1
处(与片晶氮相相关)、1,330厘米–1
处(拉曼频率,由于缺陷和杂质而获得红外活性)、1,280厘米–1
处(来自“A”型聚集态中的氮)和1,175厘米–1
处(来自“B”型聚集态中的氮)。我们还指出:典型的含氮Ib型合成金刚石光谱具有位于1,130厘米–1
和1,343厘米–1
... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | ) are detected independently and the correlation between the low-frequency outputs of the detectors is recorded. The relative phases of the two radio signals are therefore lost, and only the correlation in their intensity fluctuations is measured; so that the principle differs radically from that of the familiar Michel... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | The apparatus is shown in outline in Fig. 2. A light source was formed by a small rectangular aperture, 0.13 mm. × 0.15 mm. in cross-section, on which the image of a high-pressure mercury are was focused. The 4,358 A. line was isolated by a system of filters, and the beam was divided by the half-silvered mirror M
to i... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Assuming that the probability of emission of a photoelectron is proportional to the square of the amplitude of the incident light, one can use classical electromagnetic wave theory to calculate the correlation between the fluctuations in the current from the two cathodes. On this assumption it can be shown that, with t... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | «1, which would apply to an experiment on a visual star, it can be shown that S
(d
), the correlation as a function of d
, is proportional to the square of the Fourier transform of the intensity distribution across the equivalent line source. However, when η ≥1, as in the present experiment, the correlation is deter... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | , the output current was 140 μamp., the quantum efficiency α(v
0
) was of the order of 15 percent and n
0
(v
0
) was of the order of 3×10–3
. After each run a comparison run was taken with the centres of the photocathodes, as viewed from the source, separated by twice their width (d
= 2a
), in which position the ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | We thank the Director of Jodrell Bank for making available the necessary facilities, the Superintendent of the Services Electronics Research Laboratory for the loan of equipment, and Mr. J. Rodda, of the Ediswan Co., for the use of two experimental phototubes. One of us wishes to thank the Admiralty for permission to s... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 在积分电机的旋转计数器上记录乘积的平均值,并对起伏相关系数进行度量。为了得到有意义的结果,必须要对量级1小时的周期进行积分,所以我们非常精心地设计了电子装置,从而消除由漂移、干涉和放大器噪声所造成的影响。
英文
图2.装置的简化图
英文
假设发射一个光电子的概率与入射光的振幅的平方成正比,我们可以用经典电磁波理论计算来自两个阴极的电流起伏之间的相关系数。根据这个假设我们可以证明,两个阴极叠加,相关系数S
(0)由下式表示:
同样地,相应的方均根涨落N
由下式给出:
式中A
是与放大器增益等有关的比例常数;T
是观测时间;α(v
)是光电阴极在频率v
处的量子效率;n
0
(v
)是每秒钟每周带宽入射... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 我们当中的一位作者对英国海军部同意将此文予以发表表示感谢。
英文
(沈乃澂 翻译;熊秉衡 审稿)
Chinese Astronomical Clockwork
J. Needham et al.
Editor's Note
Joseph Needham was born in 1900, the son of a leading physician in London. He studied medicine and biochemistry at the University of London but in the mid-1930s he encountered three young people visitin... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | . They descended, in fact, from a long series of complicated astronomical “clocks”, planetary models, mechanically-rotated star-maps and similar devices designed primarily for exhibition and demonstration rather than accurate time-keeping. Although such devices are of the greatest interest as the earliest complex scien... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | the description, which has yielded more than a hundred and fifty technical terms of eleventh-century mechanics, that it has been possible to prepare detailed working drawings of the clock (Figs. 3 and 4).
中文
Fig. 1. Astronomical clock of A.D. 1088 from Su Sung's “Hsin I Hsiang Fa Yao”, ch. 3, p. 2a
. External appea... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | completed in A.D. 725 by the Tantric monk, I-Hsing, and an engineer named Liang Ling-Tsan, the description of which would not have been comprehensible without thorough prior study of Su Sung's text.
中文
Earlier texts describe celestial globes or demonstrational armillary spheres rotated by clepsydra water. These rang... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | All the texts now translated, with commentary and discussion, will, it is hoped, be published as a special monograph by the Antiquarian Horological Society, to which the results of the investigation have been communicated.
中文
(177
, 600-602; 1956)
Joseph Needham: F.R.S., Caius College, Cambridge.
Wang Ling: Trinity... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 他在伦敦大学学习医学和生物化学,然而在20世纪30年代中期,他遇到了三个参观他实验室的中国年轻人,开始对中国科学的历史产生了浓厚的兴趣。其中一个来访者鲁桂珍是一位中国药师的女儿,教他学习文言文。1942年~1946年间李约瑟和鲁桂珍在中国工作,李约瑟时任中英科学合作馆馆长。在这里他结识了出色的历史学家王铃,并保持密切的合作关系。他在中国工作的主要成果是出版了一套23卷的、名为《中国科学技术史》的书。1995年李约瑟逝世。这篇文章可能是他当时庞大工作中的一部分。
英文
人们通常将机械钟的发明看作是科技史上最重要的转折点之一。按照最近才被人们广为接受的观点[1-4]
,在公元14世纪早期欧洲人首先解决了机械钟转轮变慢的问题,从而... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 此外,对这种以前未获认可、靠水驱动的天文钟的详细描述,使我们可能在印度[9]
、阿拉伯和西班牙摩尔[10]
的史料中也会找到描述不完整的(可能是由于我们不完全知晓)类似装置。虽然欧洲直到14世纪才掌握了水驱动和机械驱动轮装置[11]
,但是这种传播的影响迄今还很难说。这表明,中国时钟制造术传到欧洲的时间是在“十字军”东征的时候(和风车一样),而不是马可波罗时代。
英文
目前我们已经翻译完毕所有相关的史料,添加了注释和讨论,并与古钟协会进行了沟通,希望他们将其作为一本特别专著出版。
英文
(金世超 翻译;沈志侠 审稿)
Structure of Vitamin B12
D. C. Hodgkin et al.
... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | ; for both crystals the reliability indices in the latest structure factor calculations, 36.1 and 30.6 percent, respectively, are now low enough to indicate that the solution we have reached is likely to be essentially correct.
中文
Fig. 1. Electron density-levels from the three-dimensional electron density distributi... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | —swings round the carbon-carbon single bond from a position directed away from, to one in contact with, the cyanide group, when the crystals are removed from their mother liquor; this permits the rather closer packing of the molecules found in the air-dried crystals. Throughout the molecule, as shown by Figs. 1 and 2, ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | . The positions of C29
and C30
, one or other of which would be expected to be out of the plane of the central ring system if only five double bonds were present, are even more significant. In the hexacarboxylic acid they appeared at all stages of the refinement to be within 0.2 A. of this plane, but in the B12
crys... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | The latest series of calculations on wet B12
were carried out on the University of Manchester electronic computer through the generous co-operation of Dr. D. W. J. Cruickshank, Miss Diana Pilling and Mr. J. F. P. Donavan, of the University of Leeds. Those on air-dried B12
and on the hexacarboxylic acid were made on t... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 核糖环转向特定的位置以接近苯并咪唑基团,这样利于磷酸酯、丙醇胺和丙酸残基与D
环平面的基团相连接。苯并咪唑核心要么堆积在由A
环和B
环上的丙酰胺侧链形成的伸展且相互交错的构型的同侧,要么堆积在由位于核糖环上面的C
环丙酰胺侧链形成的邻位交叉构型的一侧。所有的乙酰胺残基都是沿着氰基方向从核心相反一侧投向丙酰胺残基。令人感兴趣的一点是,从母液中分离晶体时,B
环上的乙酰胺残基会绕着碳–碳单键旋转,从定向地远离氰基的位置转到与氰基相近的位置,这使得无水晶体形成更紧凑的分子结构。图1和图2所示为维生素B12
整体分子结构,确定的原子位置符合那些根据较简单分子的研究建立起来的立体化学规则,因此这个结果是非常令人信服的。
英文... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 英文
(刘振明 翻译;吕扬 审稿)
The Neutrino
F. Reines and C. L. Cowan
Editor's Note
The existence of the subatomic particle called the neutrino had been inferred in the early 1930s chiefly as a result of work by Enrico Fermi in Rome and Wolfgang Pauli in Zurich from the phenomenon of radioactive beta-decay: it was supposed to b... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | , and that one could do nothing to the apparatus in which the decay occurred to trap this lost energy2
. One possible explanation was that the conservation laws (upon which the entire structure of modern science is built) were not valid when applied to regions of subatomic dimensions. Another novel explanation, but on... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | While there is no theoretical reason for the expectation of a finite neutrino rest mass, there is some expectation for a small but finite neutrino magnetic moment of perhaps as much as 10–10
Bohr magneton based on a consideration of possible virtual states in which the neutrino may exist effectively dissociated into o... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | identified. The antiparticle corresponding to the neutrino in equation (1) may be obtained by rearrangement of the terms in the following manner:
p
+
→n
0
+ β+
+ v
+
(2)
This process is observed in positron decay of proton-rich radioactive nuclides where the proton and daughter neutron are both constituent nucleon... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | ) is applicable. This cancellation is not possible if the neutrino and antineutrino differ. The half-lives for processes such as equation (4) have been shown by Primakoff13
and by Konopinski14
to be quite different in the two cases, of the order 1019
years for equation (4a
) and 1015
years for equation (4b
), whe... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | While careful reasoning from experimental evidence gathered about all terms in the beta-decay process—except the neutrino—may support the inference that a neutrino exists, its reality can only be demonstrated conclusively by a direct observation of the neutrino itself. If the neutrino is a real particle carrying the mi... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Equation (6) may be employed in an experiment in which a large number of hydrogen atoms are provided as targets for an intense neutrino flux and are watched by a detector capable of recording the simultaneous production of a positron and a neutron. Such a direct experiment is made possible by the availability of high b... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Fig. 1 is a schematic diagram of the detection scheme employed in this experiment. The sequence of events pictured is as follows: a neutrino from the decay of a fission fragment in a reactor causes a target proton to be changed into a neutron with the simultaneous emission of a positron. The positron is captured by an ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | tanks, comprising two essentially independent triads which used the centre detector tank in common. The entire detector was encased in a lead-paraffin shield and located deep underground near one of the Savannah River Plant production reactors of the United States Atomic Energy Commission. Signals from the detectors we... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | (2) Dilution of the light water solution in the target tank with heavy water to yield a proton density of one-half normal caused the reactor signal to drop to one-half its former rate. The efficiency of neutron detection measured with the plutonium-beryllium source was unchanged.
(3) The first pulse of the pair was sho... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | The availability of neutrinos from reactors in sufficiently intense fluxes has opened a number of interesting possibilities. One arises from the use of heavy water to dilute the proton target as described above. This test was valid because the threshold for the neutrino interaction with the deuteron is higher by 2.2 Me... | 400套付费套装书 |
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