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C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | 显然,在这种情况下,必然存在一个“静止系统”Σ°,即一个总动量等于零的洛仑兹参考系。具体来说,这个问题就是要以一种不变量的形式对相对运动进行描述。
英文
我们先把经典推导变为允许进行推广的形式。如果
是两个粒子的位置矢量,
是它们的动量,我们可以得出相对位置的矢量和总动量的矢量为:
我们还可以确定其正则共轭变量,即矢量
。经简单的计算表明,它们并不是唯一确定的,而是具有下列形式:
式中a
是一个任意常数。因此,必须加入另一个条件。
英文
我们假定,动能
满足P
2
/2m
+ π2
/2μ的形式。根据这个条件可以确定三个常数a
、m
和μ,即
将它们代入式(2)可得相对动量和质心的通常表达式。
... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | HE forces between the constituents of a nucleus are “short-range” forces, which have no appreciable effect over distances of more than a few times 10-13
cm. Hence it is impossible to find the laws of force by extrapolation from large-scale observations (as in the case of Coulomb's law) and the only possible lines of a... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | In the experiments on proton-neutron interaction two possible cases are discussed, according to whether the spins of the two colliding particles are parallel or opposite (in the case of like particles, Pauli's principle ensures that, so long as there is no orbital angular momentum, the spins are necessarily opposite) a... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | Actually, all results of this simple theory have to be supplemented by correction terms involving the range. If the experimental data were accurate enough, it should thus be possible to estimate the range of the forces. The use of these correction terms requires greater accuracy than is at present available in the data... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | energy is no longer one with zero orbital angular momentum; it can be shown that the state of motion is a mixture of a state with zero angular momentum and one with two units (S
and D
states in spectroscopic notation). From the electrical quadripole moment one can estimate that the contribution of the D
state amount... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | Turning now to the evidence from nuclei containing more than two particles, this is usually discussed on the basis of the assumption that the forces are additive; that is, that the interaction force between two particles is not affected by the simultaneous presence of a third particle. Beyond its simplicity and the fac... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | He, the observed binding energy ceases to rise rapidly with the number of particles. This fact, often briefly referred to as “saturation”, obviously means that the constituent particles of a large nucleus do not all
attract each other with the same forces with which the constituents of a helium nucleus attract each ot... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | The directional properties of the forces, which must be inferred from the existence of the quadripole moment of the deuteron, may have a bearing on this question, since in a large nucleus different particles must necessarily be arranged in different directions relative to a given particle, and the forces may quite well... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | is the same constant as in (1). In order to obtain a range of the right order of magnitude this mass has to be assumed to be a few hundred times that of the electron. The subsequent discovery of “mesons” of just such a mass in cosmic rays has very much increased our confidence in the “meson theory” of nuclear forces.
... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | , but no meson moment. This law does not agree with experiment in detail, since it gives neither a spin dependence of the force (as required to explain the properties of the neutron-proton scattering) nor a directional dependence that would account for the quadripole moment of the deuteron. The introduction of a “meson... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | in addition to the charged ones14
. There is certain independent evidence for the existence of neutral mesons in cosmic rays15
. If we take the view that the saturation of the nuclear forces is due to their directional dependence and not to their exchange character, it is, in fact, possible to attribute all
nuclear ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | , 158 (1938).
Cf. also Peierls, R., Ann. Rep. Chem. Soc.
, in the press.
*
Based on lectures given at the Royal Institution on January 17, 24 and 31.
核力的理论
*
佩尔斯
编者按
鲁道夫·佩尔斯概述了现有的关于核力的理论。这种力可以很容易地在含有质子和中子的两粒子相互作用中被探测到。散射实验确定这种力的作用距离大约为1.2×10–13
厘米,同时在忽略静电力差别的前提下,实验也支持了作用于中子之间、质子之间和中子–质子之间的核力是相同的这一观点。核力在很大程度上还由方... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | 在低能量的质子–质子相互作用中,我们唯一感兴趣的是自旋相反的情况,其中的作用力一定仍是中心力,这是因为该情况下的合自旋为零,没有产生任何的偏向;对于自旋平行的情况,作用力不是中心力意味着由粒子运动产生的角动量不再是常数,而是有涨落的。因此,粒子在最低能态中的运动不再是轨道角动量为0的状态,研究发现此运动状态是一个包含角动量等于0和2两种情况(用光谱学符号表示为S
态和D
态)的混合态,根据电四极矩我们能估计出D
态的贡献只占几个百分点[6]
。
英文
然而,即使D
态产生的效应很小,我们仍需要一个可观的非中心力来产生这个效应,因为D
态中需要克服一个很强的离心力。因此,非中心力在合力中占有相当大的比重是很有可能的。... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | 英文
在所有尝试从更加基本的现象出发来推导核力的理论中,最令人关注的是基于汤川秀树[11]
关于介子理论的一个构想。汤川秀树认为,核力是由“核场”引起的,这与电磁力是由电磁场引起的相类似。但是,为了产生短程力,这个场必须满足不同的场方程,而如果这个要求与相对性原理相结合,则只可能存在一种形式的波动方程,相互作用的定律也被限制在某种特定类型的定律之中,其中最简单的势能表达形式如下所示:
V = g·e-kr
/r
(1)
式中k
和g是常数,r
是粒子之间的距离。(库仑定律是上式中k
=0时的一种特殊情况。)在量子理论中,正如电磁场是与光量子相联系的,“核场”也将与一种新型的粒子相关联;其波动方程与光的波动方程不同,这... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | True and False Teleology
C. H. Waddington
Editor's Note
Teleology is the notion that a change is induced not solely by the action of physical forces but because it is being drawn toward some ultimate goal. While it normally has no place in physical science, the embryologist Conrad Waddington here argues, the notion d... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | in which he discusses the evolutionary significance of the formation of two different sexes in the diploid phase. He is not content to point out that the separation of the sexes is a mechanism for encouraging cross-breeding, but he contrasts this statement with some sentences, taken from a recent work of mine3
, on th... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | 英文
最近,人们对许多不同繁殖体系的目的论重新燃起了相当大的兴趣,这在很大程度上是由达林顿[1]
的工作引起的。目的论论点的逻辑状态在这种关联性上与其他领域是有很大区别的,因为,在自然选择的影响下,为了加快进化,被提出的“目的”就是条件的满足。也就是说,一个达到其“目的”的遗传体系就为自身的存活提供了途径。这些分析在其他的一些关联上会导致有悖于目的论的论点,因此不能被应用;尽管有人仍然存在疑问:在已有的各种观点中,目的论的表述是否是最令人信服的?
英文
然而,这里存在一个危险:由于与一些它在其中不能成立的领域有着某种联系,目的论的论证方法将无法继续进行下去。从某种程度上来说,这种情况在马瑟[2]
撰写的那篇极有价值的论文... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | confident that Darlington and Waddington would agree with me in regarding adaptation as the outcome of selection and in denying that it was purposeful, whether the discussion concerned genetical or morphological questions.
中文
Secondly, I am criticized for wishing to “dismiss” the “developmental-genetical idea”. This... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | 实际上,这一点是微不足道的,因为我相信,不管涉及的讨论是关于遗传学的还是关于形态学的,达林顿先生和沃丁顿先生都会和我一样认同适应是选择的结果,并且也和我一样否认它是有目的的。
英文
第二,我想“抛弃”“发育–遗传的思想”的想法受到了批评。一般情况下,我并不希望这样,因为很明显发育学的研究非常有助于我们理解遗传学。尽管如此,我确实不同意这个特殊的观点,即在二倍期中,两性的分离实际上是配子分化的结果,显然,沃丁顿和其他很多人都很认同这一观点。在雌雄异体的生物体内,两性的分离和配子的分化在发育上可能是相关的,但是,这不应该使我们忽视它们完全不同的遗传结果。配子的分化自身不能形成正常的杂交繁殖,这一点已经在小麦和豌豆的例子中得到了证实... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | , this method being a universal one, applicable to all elements. Of course, other methods, specifically suitable for uranium, may be found later on. The thermal diffusion method can be used both for liquids and for gases, but it works extremely slowly when applied to liquids. It is much better to use gases. The only vo... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | U would have increased to 6.7 times of its original value, or to about 4.8 percent. If we remove the fluoride after this time from the top of the apparatus, we should get about 62.5 mgm./day of uranium fluoride, or 42.5 mgm./day of uranium, 4.8 percent of the uranium removed being 235
U. In continuous operation we sho... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | 根据上述假定,我们可以计算出管道间距2w
=1.34 mm。
英文
如果顶部储存装置中有5g氟化铀,弛豫时间将会是80天。80天后,235
U的浓度将会增加到初始数值的6.7倍,也就是大约为4.8%。如果80天后将氟化铀从顶部储存装置中移走,我们应该能以大约每天62.5mg的速度得到氟化铀,或者说以每天42.5mg的速度得到铀,取走的铀中有4.8%为235
U。而在连续操作过程中,如果取走的铀中235
U占4.8%的话,我们则只能以大约每天41.7mg的速度得到氟化铀,或者说以每天28.3mg的速度得到铀。
英文
由此,利用一定的设备就可以生产出数量可观的氟化铀,其中235
U的丰度比其天然丰度要大好几倍,而这... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | content of various foods which appear to correspond approximately to those obtained by other workers using biological methods.
中文
A suitable quantity (2-50 gm. containing 10-20 rat units of vitamin B6
4
) of the finely minced or powdered test material was digested with pepsin for twenty-four hours. Protein and its ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | The method described is applicable to all types of foodstuffs. It is probable that in some cases it may be abbreviated. For example, treatment with nitrous acid has been found to be unnecessary in the case of yeast. Possibly the second silver precipitation is not always necessary. A variety of different phenolic reagen... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | 操作中应该可以使用其他的酚试剂,一些具体的细节也可能略有不同。比如,对于酵母和马铃薯,在省略了亚硝酸处理这一步骤时,不管是用对氨基苯磺酸重氮盐还是对硝基苯胺或者酚试剂,所得到的测定结果是类似的。
英文
这些研究更完整的报道将发表在《印度医学研究杂志》上。
英文
(王耀杨 翻译;汪长征 审稿)
The Hydrogen Bond
C. E. H. Bawn
Editor's Note
One of the distinctive developments in the molecular sciences in the 1930s was the recognition of the importance of th... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | and there are many difficulties with questions of terminology.
中文
With the object of clarifying the situation, a general discussion on “The Hydrogen Bond” was held by the Faraday Society on May 17 at the Imperial College of Science and Technology, London. A number of subjects was discussed in the six papers presente... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | finally emerging into groups of interaction which we know as due to van der Waals forces. It seems at present that the only means of characterizing the hydrogen bond in the molecule is the energy required to break it.
中文
The most important and useful method for the discovery of hydrogen bonding is infra-red spectros... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | μ) and an equilibrium
is set up, but it is not possible to decide whether the dimer has the structure,
At higher concentrations polymeric association becomes predominant, and this they conclude is in accordance with an equilibrium between dimer and quadruple molecule.
中文
Numerous infra-red investigations have show... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | extremes, the necessity for this distinction is not accepted by all.
中文
In a short paper Dr. W. Rogie Angus and W. K. Hill described some preliminary results on a general investigation of diamagnetism and hydrogen bonding. There seems to be every indication that hydrogen bonding should be detectable by susceptibilit... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | hydrogen bonds in native starch.
中文
(145
, 846-848; 1940)
C. E. H. Bawn: University of Bristol.
氢键
鲍尔
编者按
20世纪30年代分子科学中最有特色的进展之一便是对氢键的重要性的认识:氢键是指一个基团中包含的一个带轻微正电荷的氢原子与另一个含有高电子度的基团之间相对较弱的相互作用。这种相互作用对蛋白质和核酸结构的形成非常重要,同时也是造成液态水的一些异常性质的原因。1940年5月17日伦敦法拉第学会的这份会议报告,敏锐地提到了氢键在蛋白质分子及其在复合物结构中的潜在重要性。
英文
多年前人们就已知道,在某些条件下,... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | 通过该方法能够直接测得形成氢键的桥原子或桥基团之间的距离,从而证明了在很多种无机和有机结构中存在氢键。可能最有趣的例子就是冰中的氢键,其中每个氧原子被2.76 Å处的另外四个氧原子以四面体形式包围。该结构类型图示如下:
在结晶醇中存在一种类似的结构,分子通过氢键缔和形成无限大的结构:
英文
贝尔纳曾基于X射线分析结果提出,应该区分这两种类型的键,他提议将其分别命名为氢键和羟基键。在前者中,氢原子以同样的紧密程度被两个氧原子束缚,即O---H---O,键能约为8,000 cal,两个氧原子之间距离为2.5~2.65 Å。在后者中,氢原子不对称地被两个氧原子中的一个束缚,即O---H─O,键能为5,000 cal,氧-氧距离为... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | amperes, with a divergence of one degree, is defined by a system of stops, and emerges from an attachment to the vacuum tank of the cyclotron into the “camera” through a mica window covering a hole
in. in diameter. In the camera this narrow proton beam passes down the axis of a tube, which is interrupted for a length... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | The distributions in energy of the protons scattered through 90° from the gases oxygen and neon are shown in Fig. 1. In oxygen a single peak appears, corresponding in energy to protons elastically scattered through 90°. With neon, in addition to the elastically scattered group, there is a peak at lower energy which we ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | With the elements of atomic number greater than that of neon which we have examined, such as chlorine and argon, the ratio of the number of inelastically to elastically scattered particles is very much smaller than in the case of neon, corresponding to the decreasing probability of the protons entering the nucleus with... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | 英文
最近,我们利用一些轻元素进行了质子散射的实验,实验使用利物浦的回旋加速器来产生质子束,并用照相的方法来检测散射粒子。
英文
我们把一束强度为10–8
安培、分散度为1°的质子束,约束于一个静止的系统中,然后将其从回旋加速器的真空罐的附加装置中射出,穿过覆盖了云母窗的直径为1/8英寸的小洞后进入“照相机”。在照相机中,这条狭窄的质子束沿着一个长管轴向穿行,这一长管有个3毫米长的断口,散射粒子能从这个断口中逃逸出来。在与质子束的轴向相平行的方向上放置一块扁平的照相底板,底板与质子束的轴相距1厘米。被充满于照相机中的气体所散射的质子能够穿过长管的断口,并以很小的掠射角射到底板上。这样安置的好处是,假如每个角度区域中都包括适... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | 英文
(王耀杨 翻译;汪长征 审稿)
Considerations Concerning the Fundaments of Theoretical Physics
*
A. Einstein
Editor's Note
Five years before his death, Einstein had been driven to the view that quantum mechanics was a valid description of quantum phenomena but that as a consequence physics had been robbed of its explicit and ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | It is clear that the word foundation in this connexion does not mean something analogous in all respects to the foundations of a building. Logically considered, of course, the various single laws of physics rest upon this foundation. But whereas a building may be seriously damaged by a heavy storm or spring flood, and ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | It is not surprising that Newton would not listen to a wave theory of light; for such a theory was most unsuited to his theoretical foundation. The assumption that space was filled with a medium consisting of material points that propagated light waves without exhibiting any other mechanical properties must have seemed... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | For us, who took in Faraday's ideas so to speak with our mother's milk, it is hard to appreciate their greatness and audacity. Faraday must have grasped with unerring instinct the artificial nature of all attempts to refer electromagnetic phenomena to actions-at-a-distance between electric particles reacting on each ot... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | But if the electromagnetic field could exist as a wave independent of the material source, then the electrostatic interaction could no longer be explained as action-at-a-distance; and what was true for electrical action could not be denied for gravitation. Everywhere Newton's actions-at-a-distance gave way to fields sp... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | Thus physicists held to a field-theory programme. But it could not be called a foundation, since nobody could tell whether a consistent field theory could ever explain on one hand gravitation, on the other hand the elementary components of matter. In this state of affairs it was necessary to think of material particles... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | summarized in one sentence: all natural laws must be so conditioned that they are co-variant with respect to Lorentz transformations. From this it follows that the simultaneity of two distant events is not an invariant concept and that the dimensions of rigid bodies and the speed of clocks depend upon their state of mo... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | These difficulties can be avoided by the following postulate: natural laws are to be formulated in such a way that their form is identical for co-ordinate systems of any kind of states of motion. To accomplish this is the task of the general theory of relativity. On the other hand, we deduce from the restricted theory ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | is Planck's universal constant. During the years following it was shown that light was everywhere produced and absorbed in such energy quanta. In particular, Niels Bohr was able largely to understand the structure of the atom, on the assumption that atoms can have only discrete energy values, and that the discontinuous... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | Now in mechanics the motion of material points is determined by the forces or fields of force acting upon them. Hence it was to be expected that those fields of force would also influence de Broglie's wave fields in an analogous way. Erwin Schrödinger showed how this influence was to be taken into account, re-interpret... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | Let me illustrate these general features of quantum mechanics by means of a simple example: we shall consider a mass point kept inside a restricted region G
by forces of finite strength. If the kinetic energy of the mass point is below a certain limit, then the mass point, according to classical mechanics, can never l... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | probability predictions as to the place and time of the particle hitting the screen (or, for example, its momentum at the time when it hits the screen).
中文
All other cases are analogous. The aim of the theory is to determine the probability of the results of measurement upon a system at a given time. On the other ha... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | For the time being, we have to admit that we do not possess any general theoretical basis for physics which can be regarded as its logical foundation. The field theory, so far, has failed in the molecular sphere. It is agreed on all sides that the only principle which could serve as the basis of quantum theory would be... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | 严格说来,这里并没有什么绝对的基础,因为这些明确的定律只有在引力的超距作用下才成立;而对于别的超距作用,除了作用力
和反作用力
相等这条定律以外,我们不能先验
地得到其他任何定律。此外,牛顿自己也充分地意识到,空间和时间是他的理论体系中的根本有效因子,不过他并未明说。
英文
牛顿的基本理论被证明是卓有成效的,并且直到19世纪末,它一直被视为是物理学的终极理论。它不但解释了天体运动以及其中最详细的细节,而且也建立了描述离散物质和连续物质的力学理论,对能量守恒原理给予了简单的解释且给出了一套完整而天才的热学理论。在牛顿的理论体系中,对电动力学的事实规律的解释是比较牵强的;而到目前为止,用牛顿的理论体系进行解释的所有理论中,最... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | 英文
几十年以来,大多数物理学家都坚信能为麦克斯韦理论找到更基本的力学基础。但是由于他们的努力没有得到令人满意的结果,人们逐渐将场这个新的概念作为物理学不可约化的基础——换句话说,物理学家不得已放弃了力学是物理学基础的想法。
英文
因此,后来物理学家都转而支持场论的研究体系。但是并不能把场论称为基础,因为尚不确定是否有一个统一的场论,既能解释引力,又能解释物质的基本组成成分。在这种情况下,就有必要把物质粒子看作是服从牛顿运动定律的质点。这是洛仑兹在创立其电子论的过程以及研究与运动物体电磁行为有关的理论中都采用了的假设。
英文
以上这些就是我们在世纪之交物理学基本概念的由来。当时对所有新奇现象的理解和理论方面的突破都有了... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | 显然,至少在原子现象的领域里,所发生的每件事情的特征均由分立的状态以及分立的状态之间的不连续的跃迁决定,普朗克常数h
在这里起着决定性的作用。
英文
进一步的工作是由德布罗意完成的。他向自己提出这样一个问题:如何借助现有的物理概念来理解这些分立的状态呢?他突然想到可以类比驻波,把分立的状态理解为如声学中管风琴和弦的基频一样的情况。虽然这里需要的这样一种波动行为还是未知的;但是用上述普朗克常数h
应该可以构造出这种波动作用并且写出相应的数学表达式。德布罗意设想电子绕原子核的旋转是同某种有待证实的波列有关的,并且认为通过相应波的驻波特征能在一定程度上理解玻尔的“允许”轨道的分立特征。
英文
既然力学中质点的运动是由作用在... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | 目前,还完全没有任何一种决定论性的理论既能直接描述事件本身又能同事实相符合。
英文
目前我们还不得不承认,暂时还没有任何全面的物理学的基本理论可被作为物理学的逻辑基础。到现在为止,场论已经被证明不适用于分子领域。人们从各个方面进行考虑,都认为唯一可能作为量子力学根基的原理应是一种能够把场论和量子统计学体系对应统一起来的理论。至于实际上这个原理能否以一种令人满意的方式出现,现在谁也不敢断言。
英文
有些物理学家,包括我自己在内,都不能相信:我们现在甚至将来都必须永远放弃在时空中直接表示物理实在的想法;或者我们必须接受这样的观点,即自然界中发生的事件就像碰运气的赌博一样。每个人都可以选择自己奋斗的方向;而每个人也都可以从莱辛... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | attempted to employ solutions of gum arabic for purposes of infusion. Later, other substances such as gelatin, polyvinyl alcohol, pectin, polyvinylpyrrolidone and others were tested to this end. The infusion of these colloids has, however, been attended by certain difficulties. Some of the substances tested have antige... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | . It has been possible to show that the dextran molecule is built up of glucose units, linked together in long, more or less branched chains2
. The molecular weight of dextran may be very high, of the order of magnitude of many millions3,4,5
. By partial hydrolysis dextran preparations of lower molecular weight, for ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | The therapeutic effect was investigated experimentally in cases of shock from bleeding, histamine shock and contusion shock developed artificially in rabbits and cats. Rapid and lasting effects on the blood pressure, heart action and respiration were always registered6
.
中文
The experiments on animals giving favoura... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | 因此很自然地,生理学家和化学家开始寻找其水溶液可以替代价格高昂且难以保存的血液或血浆的物质。
英文
1914~1918年战争期间,贝利斯[1]
为达到输注的目的曾尝试使用阿拉伯树胶溶液。之后,为此目的还测试了其他物质,例如明胶、聚乙烯醇、果胶和聚乙烯吡咯烷酮等。不过,注射上述胶体总会伴随某些特定的困难。有些测试物质具有抗原性,而另一些则无法被机体降解,因而会在某些器官中累积,尤其是肝脏。
英文
下面简要列出使异源性胶体发挥治疗休克的效果所应满足的条件:
在所有发生休克的情况下,包括失血、挫伤和烧伤,通过液体灌输的方式增加循环血量是必要的。用晶体溶液是不能令人满意地实现这一点的。输入的液体必须含有胶体,且能产生与血浆蛋白... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | is, one can't be sure how big a representative sample must be. He shows that one can estimate p
with a fixed standard error by counting up just the number of items in the sample that have the minority attribute A
, which takes less time and labour.
中文
I
F a fraction p
of a population have the attribute A
, then... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | My friend, Dr. R. A. M. Case, has for some time employed a method substantially equivalent to the above in his haematological work, and found it to result in a considerable saving of labour.
中文
Full details will be published elsewhere.
中文
(155
, 49-50; 1945)
J. B. S. Haldane: Department of Biometry, University C... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | tons. Haldane argues that such energies could have arisen in the early universe. Nearby stars may also have been hit with photons, and may thus also have planets. Haldane's speculations were soon forgotten, but inspired others to ponder the nature of the very early universe.
中文
T
HE hypothesis of Kant and Laplace t... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | +1) has an infinite past, and the fundamental particles are at rest in a public hyperbolic space. The radii of planetary and atomic orbits are constant, as are the periods of planets and electrons, whereas in kinematic time and space the orbital radii and angular momentum increase with t
.
中文
One difficulty of the ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | may have been a photon.
中文
The mass of the Sun is about 2.0×1033
gm., that of the planets about 0.00134 of this value; the solar radius 7×1010
cm.; and the gravitational constant 6.66×10–8
. The mechanical energy of the solar system is almost wholly given by the work required to lift the planets to their present ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | sec. there could, on any hypothesis, have been extremely little visible radiation, as it could not have been produced by the ordinary radiation processes. This argument suggests that radiation of frequency less than t
–1
is impossible, while radiation with a frequency less than about 106
t
–1
is produced, if at all, ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | were formed about 1-2×1010
years earlier than the solar system, on the dynamical scale, in agreement with the arguments based on gravitation, which ascribe to them an age of the order of 1011
years.
中文
To return to the solar system, it may be asked whether it was formed by the absorption of a single photon, or of ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | correspondence principle. In either case a photon would be most likely to be absorbed if it approached in the direction of the solar axis.
中文
Since v
= 1072
, and if T be the corresponding period on the dynamical scale, while t
is the epoch of formation of the solar system, v
= t
0
/t
T; hence if T is about a ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | years. The planets would, however, lose a good deal of matter immediately on formation, so that their original mass was greater than at present. This would give a correction in the opposite direction, while tidal friction would give a smaller correction.
中文
The planets remained gaseous for a very long stretch of dyn... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | Energy is generally thought to be liberated in stars by the breakdown of unstable nuclei generated by thermal nuclear collisions. At present the rate of liberation is limited by the number of effective collisions, and is thus roughly constant in dynamical time. In the remote past nuclear breakdown was the limiting fact... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | = 10–92
sec., or τ
= –5×1011
years. Thus the long time-scale of about 1012
years deduced from a study of gravitational interactions of stars, which are naturally measured in dynamical time, appears as a consequence of Milne's theory.
中文
The above arguments must be regarded as the attempt of a layman to deduce so... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | Doppler effect, and on the kinematical scale appropriate to such a particle, both vary as t
–1
, where t
is the epoch of absorption. Thus the postulated planet-making photons are now trains of electromagnetic waves of a period of the order of a year, and much too small to be observable in practice. The mass of matter... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | 但是在米耳恩的宇宙论里,在给定的过去某段动力学时间里发生一次碰撞的几率绝不比现在同样的一段时间内发生的几率大。也许可以争辩说,由于动力学的过去是无限的,所以碰撞肯定会发生。但是,米耳恩的假说中并没有假设恒星总是存在的。
英文
米耳恩还没有成功地从其少数而简单的假设中推导出量子力学。实际上他的力学理论主要还是经典力学。然而,他还是考虑到了光子的行为。量子参数h
被定义为E/v
,其在运动学时标下是不变的,E
是一次跃迁过程中辐射出的光子能量,v
是光子的频率,这是因为遥远星系的红移现象被解释为星系退行产生的多普勒效应,而一次原子跃迁所辐射出的能量在任何一种尺度下都是不变的。
英文
所有太阳系起源的理论中都要克服一个... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | 由于现在已经远没有在玻尔理论诞生之初时那么惊人了,所以与原子的相似显示了前一个可能是正确的,但是后一种可能性也必须予以考虑。太阳系的形成原则上似乎是不可观测的,因为任何能够对之进行观测的辐射要么是通过它后没有变化,要么就会毁坏它。然而,对应原理却能够被应用到具有这种特征的事件上。在动力学标度上,包含整个太阳系角动量的原初太阳,其自转周期是一天的量级,而如果它比现在大点的话,这个周期还会稍长点,相对应的木星公转的周期大概是12年。当对应原则被应用于一个原子时,我们发现被吸收辐射的频率处于该原子的初态和终态的频率之间。如果行星的形成也是如此的话,那么,在动力学尺度上,产生太阳系(或者仅仅是木星)所需的光子周期具有一年的量级,因此它的频率... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | 英文
如果太阳系是通过吸收九个或者更多的光子而产生的,那么我们周围的大部分恒星也必定吸收了一些光子并由此产生了行星。如果恒星只吸收一个光子,长周期双星的发现频次表明这种情况并不罕见,因此,我们的星系可能包括上百万个行星系统。如果真是这样的话,生物学的领域很可能比一般认为的要更为广阔。
英文
星系质量的数量级为1045
克,相当于一个周期为10–92
秒的光子的质量,这也就是在t
= 10–92
秒时极小光子的质量。即使星系最初是像原子核内粒子那样紧密地聚在一起的物质粒子,因此其大小远小于太阳,要使它们瓦解变成气体所需的能量要比这样一个光子的能量小很多。因此如果星系起源于吸收辐射,在这种情况下米耳恩的某些“基本粒子”仍... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | be extreme, involving enormous energy densities utterly beyond those observable today——and that quantum theory might be needed to describe that situation.
中文
P
ROF. Haldane's idea as developed in the foregoing article seems to me to be fundamentally important. As all may not be familiar with the details of kinemati... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | 中文
I have long been aware that all theories of the origin of the solar system require drastic re-consideration in the light of the fact that at times of the order of t
= 0, when the solar system was born, dynamical and optical conditions were very different. Haldane works with equal facility in either time-scale; but... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | are measured on the t
-scale.) Working again on the t
-scale, the inequality ∆E=h
0
n
>h
0
/t
gives the minimum permissible photon energy. Taking h
0
=6.55×10–27
, at epoch t
=10–72
sec., we get ∆E
>6.5×1045
ergs, so that such photons as were then possible would have sufficient energy to disrupt the Sun and ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | = 0 is a singularity in the optical history of the universe, namely, an epoch at which the frequency of radiation was infinite, because the wave-length had to be zero. Actually we can only make significant statements about the radiation for small
epochs t
, when the frequency would on the whole be very large. A spect... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | 目前,我正在努力解决膨胀宇宙中受引力作用天体线动量守恒的难题,但我不希望被人催促。然而,在1938年《皇家学会学报》(A辑,第165卷,第354页)的一篇文章中,当探讨相应原理对于两种时间标度所起的作用时,我写到:“对于遵循经典力学定律下时间标度为τ
的物质与持续时间t
的辐射,它们之间的相互作用并不是异想天开的猜测;这种现象使得宇宙及时
演化成为可能,也是无机与有机宇宙世界演化活动的根源。”现在霍尔丹指出了这种相互作用的一种可能的模式。
英文
很久之前我就意识到,由于在时间接近t
=0,即太阳系刚刚诞生时,动力学和光学条件与现在非常不同,所以关于太阳系起源的所有理论都需要进行全盘地重新考虑。霍尔丹对于这两种时间标度采... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | 英文
我认为在对霍尔丹想法进行的这一初步探讨中,未对有极高能量的原始光子是如何瓦解一颗恒星的问题进行细节的讨论是非常明智的。详细地论述霍尔丹通过运动相对论推导出的非凡的结果,即在宇宙演化早期存在的光子一定具有极高的能量就已经足够了。
英文
(金世超 翻译;邓祖淦 审稿)
Plant Viruses and Virus Diseases
*
F. C. Bawden
Editor's Note
Towards the end of the Second World War, the scientific community's knowledge of the nature and mechanism of virus... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | disease, we usually mean merely an infectious disease with an invisible cause. Unless the resolving power of the microscope has some unsuspected significance in defining biological types, this obviously tells us nothing specific about the nature of viruses and might well cover a range of different entities.
中文
This ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | symptoms in the same host, whereas the same virus may produce totally different clinical conditions in different hosts. A further complication is that many viruses are unstable and frequently change to give forms that produce different symptoms from those produced by the parent virus. To be recognized, a virus must cau... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | the same virus may give different sequences in different hosts. Potato virus Y, for example, gives local lesions only in one host, local lesions followed by systemic symptoms of two kinds in a second host, whereas in a third it gives no local lesions and systemic symptoms of only one kind.
中文
In addition to altering... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | the only method of transmission known for many virus diseases, and it has almost become the critical test of a plant virus disease.
中文
Infection occurs only through wounds, but wounds that permit one virus to enter may not permit another. Many viruses are readily transmitted by rubbing healthy leaves with sap from d... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | healthy plants for some time, which varies from minutes to days with different viruses, and such vectors remain infective for long periods, often for their whole lives. Some workers believe that viruses of the second type multiply in the insects. There is no obvious reason why they should not, and the theory would expl... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | sp.). This novel method of transmission promises to be valuable in extending the host ranges of some viruses to plants more favourable for study than those in which the viruses occur naturally. One of the greatest differences between individual viruses lies in the numbers of different plants they can attack. Some are k... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | than is usual with organisms. The viruses so far purified have all been obtained in the same chemical form, as nucleoproteins. They all contain nucleic acid of the ribose type, but the proportion of nucleic acid to protein varies with the individual viruses. It is far too early to conclude that all plant viruses are es... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | Solutions of bushy stunt and tobacco necrosis viruses behave very differently and show none of the anomalous properties characteristic of elongated particles. By suitable treatments they can be induced to crystallize in forms characteristic of the individual virus. When mixed with their antisera, they precipitate more ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | aggregation of small particles during the course of preparation. By taking suitable precautions, solutions of tobacco mosaic virus can be made that show little or no anisotropy of flow and behave serologically more like somatic antigens; but these are unstable and readily change into anisotropic solutions with serologi... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | within the host, that at present we must suspend judgment. But it is probably safest to regard the nucleoproteins as the chemical minima—equivalent to reproductive organs or embryonic viruses—which develop into working entities only when placed in an environment containing the materials or enzyme systems they lack in t... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | 英文
许多病毒性疾病的发病过程都可以分成三个明显不同的阶段。由于病毒在侵染部位的增殖,被接种的叶片上首先出现损伤。几天后,病毒会传递到韧皮部,通过韧皮部它就会迅速移动到植株的远端。病毒似乎并不存在自主运动,而只是随着精细营养物质的运输流而移动,避开光合作用活跃的组织,移向活跃生长的区域。那些在植株被病毒感染时已经完全发育的叶片很少表现出症状,正是因为这个原因,而不是因为它们可以抵御病毒感染。因此,全身性感染的结果大多出现在早期还处于活跃生长的叶片中;这种全身性感染的晚期症状经常与最初产生的症状不同,因为此时疾病从急性阶段进入到慢性阶段。这两个阶段经常都会产生严重的病症,例如,在多个马铃薯品种中,条纹落叶病后紧接着会出现严重的花叶病... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | 在一次实验中,一个被感染的卵最后竟然感染了1,000多株植物!这被一些研究人员看作是增殖理论“无可辩驳”的证据,因为他们认为最初的卵里病毒的数量是不足以感染这么多植株的。确实如此吗?如果病毒在昆虫里增殖的程度与病毒在植株中增殖的程度是一样的话,那便无法解释为什么昆虫后代不继续具有无穷的感染性进而感染它们摄食的所有植株。我们目前对这种病毒的大小还一无所知,但是如果它的大小与我们大约知道大小的其他植物病毒处于同一数量级,那么1,000个病毒颗粒的重量应该低于10–14
克,一个叶蝉的卵可以轻易装下比这一数量多许多倍的病毒。
英文
一些病毒的传播是通过寄生植物菟丝子(菟丝子属)将受感染植株与健康植株连接在一起而实现的。这种全新的传... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | 无疑,这些杂质中的任何组分都不是病毒感染特性所必需的;但如果病毒是在细胞内组装而成的话,这些特异性杂质就会被保留在细胞壁以内,并成为病毒整体的一部分,这样一来,病毒颗粒立刻就变得比我们得到的裸露的蛋白质颗粒更加复杂了。
英文
在对病毒感染导致的产物缺乏特异检测方法的情况下,它们在植物中是否的确存在,我们对此还缺乏肯定性的证据。但是源自各方面的证据都表明,纯化过程可能会改变病毒结构。例如,烟草花叶病毒的纯化制备物中就含有宽度在15纳米,长度从小于100纳米到大于1,000纳米不等的颗粒。没有证据表明这些极其伸长的颗粒是在植物中产生的,多方面证据暗示它们是在样品制备过程中由小颗粒通过线性聚集而成。通过采取适当的预防措施,我们能制备... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | , numerous experiments have been undertaken in order to determine the total and differential fall in numbers of different species of bacteria in the mouth and the rate of this fall, under the influence of penicillin. This rate of fall is of particular interest, and as it appears that certain deductions on the mode of a... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | Increased salivation due to the presence of a pastille in the mouth could have been a factor in this rapid fall, and in order to exclude this possibility the experiments were repeated using pastilles made of base alone, without penicillin. Pastilles of this type were maintained in the mouth for one and a half hours, an... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | 在37°C下培育24小时后进行菌落计数。根据这个数值可以估算出每毫升唾液中的细菌总数。
得到第一份唾液样品之后,立即将500单位的青霉素锭剂置入颊齿之间的口腔沟槽内,使其在不被吸入的前提下溶解。接着每隔30分钟置入新的锭剂。每隔15分钟采集一次样品,然后用上述方法估算细菌总数。
英文
在上述实验中,使用经生理盐水稀释过的唾液作为接种物,因此存在于唾液中并被转移到血琼脂平板上的青霉素有可能就足以抑制细菌的生长。为排除这种情况我们向培养基中加入了青霉素酶。
英文
曲线A
显示了这些实验的结果,它代表了3次重复实验的平均值。不过,在用不同强度的青霉素锭剂进行的大量实验中结果一直保持恒定。
英文
从图中可以看出,在使用青... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | . There is ample evidence that low concentrations of the last group stimulate bacterial growth; and it would appear that the period of active proliferation, which frequently precedes bacteriostasis by sulphonamides in higher concentrations, is a manifestation of the same phenomenon. We here report what appears to be an... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | We have been able to study this phenomenon more easily by incubation at temperatures below 37 ̊C. It may be consistently reproduced by overnight (16 hr.) incubation at 24 ̊C. of 20 ml. amounts of nutrient broth containing “Marmite” and dextrose (0.1 percent), with an inoculum of approximately 5,000,000 cocci per ml., f... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | Apart from recording the participation of penicillin in a rather general biological phenomenon, the object of this communication is to direct attention to the accumulating empirical evidence of the similarity penicillin and sulphonamide action. So far as we are aware, the only commonly held conception of the mode of ac... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | . Sulphonamide action is usually biphasic; our observations suggest that this may be true of penicillin. Primary bacterial proliferation preceding bacteriostasis, as occurs with sulphonamides, has recently been noted with penicillin and Leptospira icterohoemorrhagioe
10
. (As mentioned previously, this may well be ano... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | H changes on penicillin action; at present this factor appears more important to sulphonamide action. Organisms can be trained to resist either penicillin or sulphonamides to a surprising degree, and with almost equal ease. Penicillin shares with sulphonamides synergism of antibacterial effect by antibodies and cellula... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | H on penicillin activity13
is, in fact, in striking conformity with what has been reported for sulphonamides. The direct relationship of temperature to penicillin activity has been amplified13,14
. Todd15
has demonstrated the frequency with which primary multiplication occurs in cultures subjected to the influence o... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0302. 《自然》百年科学经典（第三卷）(英汉对照版)(1934-1945).epub | .epub | 24,505,760 | 2025-09-26T19:07:02.019948 | 来自英国皇家海军医务学校的斯隆·米勒、格林和基钦在这篇文章中通过比较青霉素与磺胺类抗生素的相似之处,总结了目前对于青霉素的认识水平。它们都具有选择性和温度敏感性,而且都表现出了两种相反的作用:低浓度时促进细菌生长,而高浓度时抑制细菌生长。他们还认为青霉素和磺胺类药物一样也可以杀死细菌,这一观点由麦格雷戈和朗在之前的文章中提出。很不妙的是,作者们也注意到“有机体对青霉素以及磺胺类药物可产生惊人的耐药性”。
英文
通常认为对细胞有毒性的物质在高度稀释状态下可能会有相反的效果。这种两相行为——高浓度时有抑制作用而低浓度时有促进作用——已经在很多种物质中被观测到,包括麻醉剂、氰化物、吡啶硫胺[1]
和磺胺类药物[2]
。已有充分的... | 400套付费套装书 |
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