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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 | Liquid helium at 1°K. can be solidified under an external pressure of 25 atmospheres. At higher temperatures, greater pressures are required to produce the solid. The properties of liquid helium I are such as would be expected of an ordinary liquid of very low boiling point. It is far otherwise with liquid helium II. I... | 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 | , has recalled a prediction by Einstein that a perfect Bose gas at sufficiently low temperatures should show a discontinuity in the temperature derivative of the specific heat. Applying Einstein's formula to liquid helium, London shows that the discontinuity would occur at 3.09°K. Although Einstein's discontinuity is 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 | C.G.S. units. Moreover, the velocity of flow did not vary linearly with the pressure head. Kapitsa found a velocity proportional to the square root of the pressure head, and interpreted this as evidence that the flow was turbulent. He gave a value of 10-9
C.G.S. units as an upper limit to the viscosity of helium II. G... | 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 | A little light is thrown on these curious results by the experiments of Mendelssohn and Daunt on the creep of liquid helium II in the form of mobile films over solid surfaces. If an open vessel be partially immersed in liquid helium II, it was observed that liquid gradually collected in the vessel until the liquid leve... | 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 | ) becomes negligible and the quantity of liquid flowing per second is directly proportional to the circumference of the capillary.
中文
Heat Conduction
. The first experiments in the transport of heat through liquid helium II were made by Rollin and Keesom; their observations showed that helium II was a most efficien... | 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 | produce the heat current in this case, it is sufficient to shine light on the powder. With this arrangement the liquid may be made to rise right out of the tube, and in fact a steady “fountain” several centimeters in height can easily be produced.
中文
Quantitative measurements on the magnitude of the reaction pressur... | 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 | walls as they are reflected. This has the interesting consequence that the main heat transport in helium II at these temperatures (below 2.19°K.) cannot be due to the propagation of elastic waves as in ordinary liquids and solids, since elastic waves do not carry momentum.
中文
Many and varied hypotheses have been mad... | 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 | 目前利用量子力学解释氦II的这种独特性质,即液体的整体是以“玻色–爱因斯坦凝聚”形态存在——从本质上讲,就是液体作为一个整体在移动。
英文
液氦的性质最好可以从以下两个方面来考虑:(a
)热平衡性质,(b
)输运效应。经过莱顿和其他实验室大量仔细的研究,平衡性质已得到充分证实,其中包括不同温度下比热的确定、不同恒压下密度随温度变化的关系、以及饱和蒸气压与绝对温标的关系。而有关输运效应的研究尚处在初级阶段,诸如液体在管中的流动、热导率及相关效应等,人们对于这些现象还没有一个清晰的认识。在七月国际制冷学大会之后的一次会议,以及在英国科协的剑桥会议上,人们对液氦的输运效应进行了讨论。本文中,我们将主要讨论这个新发现的有趣的输运效... | 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 | 卡皮查发现,流速正比于压位差的平方根,他认为这是湍流的证据。他给出了氦II黏度的上限数值为10–9
单位(厘米克秒制)。加利福尼亚的吉奥克观测了氦II通过环形管的流动,得到黏度随温度变化的范围是从10–6
单位到10–8
单位(厘米克秒制)。艾伦和麦色纳使用更细的毛细管来尽量降低氦II的流速,使之更接近于流线流的条件,研究发现流速随着压位差的不到1/2次幂而变化。而且,毛细管越细,速度对于压位差的依赖性越小。对于半径为0.0015厘米的玻璃毛细管来说,速度随压力的1/6次幂变化,而在使用半径为5×10–5
厘米的毛细管(用平行金属丝将一根金属管子填充,再用一系列拉丝模把管子拉出,即可制得)时,速度变得与驱动压完全无关了。在后... | 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 | 这可能就是热导率随温度梯度明显变化的原因。
英文
当然,要完全理解喷泉效应,有待于一个令人满意的液氦II组成理论的出现。不过,现在已经可以对此作出一些有趣的推论。首先,在上面所描述的简单装置中,使管内液体保持在外部液池液面之上的力,只能来自于某种形式的相互作用,要么是液体与管壁之间,要么是液体与附着的加热导线之间。除此再没有其他支撑的可能,而且管内与液池上方的蒸气压也明显是相等的。其次,这种相互作用必然会在管壁上产生一个向下的推力,其大小等于高于液池液面之上的液体的重量。从原子层面来看,这意味着,参与相互作用的原子在向下的方向上向管壁稳定地传递着动量,就像盛有气体的容器器壁上所受的推力,即意味着原子在被反弹的过程中稳定地向器壁... | 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 making chemical assignments, it was always assumed that these radioactive bodies had atomic numbers near that of the element bombarded, since only particles with one or two charges were known to be emitted from nuclei. A body, for example, with similar properties to those of osmium was assumed to be eka-osmium (Z
=... | 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 discussion of the energies involved in the deformation of nuclei, the concept of surface tension of nuclear matter has been used7
and its value has been estimated from simple considerations regarding nuclear forces. It must be remembered, however, that the surface tension of a charged droplet is diminished by i... | 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 seems to us rather probable, that the periods which have been ascribed to elements beyond uranium are also due to light elements. From the chemical evidence, the two short periods (10 sec. and 40 sec.) so far ascribed to 239
U might be masurium isotopes (Z
= 43) decaying through ruthenium, rhodium, palladium 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 | (143
, 239-240; 1939)
Lise Meitner: Physical Institute, Academy of Sciences, Stockholm.
O. R. Frisch: Institute of Theoretical Physics, University, Copenhagen, Jan. 16.
References:
Fermi. E., Amaldi, F., d'Agostino, O., Rasetti, F., and Segrè, E. Proc. Roy. Soc
., A, 146
, 483 (1934).
See Meitner, L., Hahn, O., 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 | 英文
由此看来,铀核也许只具有较小的稳定性,因为其在俘获中子后可能会分裂为大小基本相同的两个核(两部分大小的精确比例取决于精细结构的特征,可能还有一部分偶然因素)。这两个核将彼此推斥,根据核半径与电荷进行计算,这两个核应该会获得约为200兆电子伏的总动能。似乎可以预期,这一能量值实际上可以利用铀与周期表中部元素的敛集率的差别计算得到。由于涉及的物质质量较大,所以相应的量子力学中的“隧道效应”产生的影响小到可以忽略不计,因此整个“裂变”过程可以使用经典的方式来描述。
英文
具有高中子质子比的铀核分裂成两个新核以后,倾向于再进行β衰变,以使其调整到适合于较轻元素的较小比值。每个新核都可能会引起一条衰变反应链。如果其中一部分是钡[... | 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 | S was first pointed out by Yukawa, it is in principle possible to account for the short-range forces between nuclear particles by the assumption of virtual emission and absorption processes involving intermediary particles of integral spin, the so-called mesons
1
, the mass of which is determined by the range of the 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 | is, actually, applicable to a system consisting of nuclear particles and a meson field. For such a system it is, in fact, possible to find canonical transformations effecting the separation of a “static” interaction between the nuclear particles, defined as the part of the interaction which is obtained when one neglect... | 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 | account is here taken at the outset of at least the static part of the nuclear forces.
中文
As regards the form of these static interactions, it is well known that the type of potential resulting from the four-vector meson field generally considered hitherto has the defect of including a term of dipole interaction ene... | 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 | 介子因其质量介于电子和质子之间而得名。1935年,汤川秀树及其合作者在一本日本杂志中指出,介子可以用来解释核子(质子和中子)间的强力,这与光子可以用来解释所有带电粒子之间的电力类似。哥本哈根的尼尔斯·玻尔的两位高徒——罗森菲尔德和默勒在这篇文章中阐述了怎样用能与轻元素衰变放射出β粒子的实验吻合得更好的特定数学表达式(或称波函数)来满足物理学研究的需要。这个预言后来被证明是正确的。
英文
正如汤川秀树最先指出的,如果假设核子在虚拟的发射和吸收过程中包括具有整数自旋的媒介粒子,即所谓的“介子”[1]
,其质量取决于作用力的范围,那么原则上就可对核子之间的短程作用力作出解释。凯默[2]
的研究表明:可以把最简单的介子波动方程——... | 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 | Otto Hahn and Fritz Strassmann in 1938 had found convincing chemical evidence for the fission of uranium nuclei. After bombarding uranium nuclei with neutrons, they had found traces of barium nuclei, with atomic weight 56, suggesting a roughly equal splitting of the nuclei. Here Otto Frisch of the Institute of Theoreti... | 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 | By means of a uranium-lined ionization chamber, connected to a linear amplifier, I have succeeded in demonstrating the occurrence of such bursts of ionization. The amplifier was connected to a thyratron which was biased so as to count only pulses corresponding to at least 5 ×105
ion pairs. About fifteen particles a mi... | 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 | experiments of Hahn and Strassmann.
中文
Experiments with thorium instead of uranium gave quite similar results, except that surrounding the neutron source with paraffin did not enhance, but slightly diminished, the effect. This gives evidence in favour of the suggestion2
that also in the case of thorium, some, if no... | 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
现已证明脉冲数目与中子源的强度具有线性关系;这是为了排除脉冲源于偶然的较小脉冲累积而产生的可能性。当把放大器与示波器相连时,可以看到在铀发射的α粒子产生的非常小的脉冲背景之上有非常明显的大脉冲。
英文
通过调节闸流管的偏压,可以发现最大脉冲幅度对应于至少200万个离子对,或者说相当于粒子在电离室内损失了70兆电子伏的能量。由于粒子在电离室内的最长路径只有3厘米,并且电离室内充满了一个大气压的氢气,因此,尽管粒子具有至少70兆电子伏的能量,但它们必定会发生强烈的电离以至于在相当于0.8厘米空气的路径上产生了200万个离子对。根据这一结果,假设原子量与有效电荷之间具有合理关联的话,我们就可以估算出电离粒子的原子序数应该至少... | 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 | being the mass of the meson, the interaction becomes very large, leading to Heisenberg explosions, and to greater divergences in some second-order effects than is the case in radiation theory. This has led Heitler2
and others to the view that the meson theory in its present form is quite incorrect for meson energies 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 | →0. But one knows from electrodynamics that although there are circumstances in which the emission of a large number of quanta may be more probable than the emission of a single quantum, as in the so-called “infra-red catastrophe”, this in no way sets a limit to the accuracy of quantum mechanics and does not interfere ... | 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 | has nothing to do with the mass of the meson or the appearance of explosions. Quantum mechanics in its present form cannot be strictly valid since it leads to divergent results connected with the self-energies of point charges; but these limitations are probably due to the fact that it is not the quantization of the co... | 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 | , 154(1938). Bhabha, Nature
, 141
, 117 (1938); Proc. Roy. Soc.
, A, 166
, 501 (1938), referred to above as A; Yukawa, Sakata, and Taketani, Proc. Phys. Math. Soc. Japan.
20
, 319 (1938). Stueckelberg, Helv. Phys. Acta,
11
, 299 (1938).
Heitler, Proc. Roy. Soc.
, A, 166
(1938).
Heisenberg, Z. Phys.
, 110
, 25... | 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
这个论点具体如下:为了简单起见,我们考虑不带电荷的介子[5]
的情况,因为带电情况的变化对这个论题没有本质上的影响,另外我们还用到A(49)式[1]
中给出的哈密顿量。在适当的洛仑兹框架下,当介子动量的变化大到可以和mc
相比拟时,表示相互作用的(58a
)式中的一些项就会变得非常大。即使在质子运动可能被认为是非相对论性的极限情况下,这些可引发爆炸的项也是一样由横向介子波和纵向介子波
引起的。此外,爆炸开始出现时的临界动量在mc
变小时也会变小,当mc
趋于0时,临界动量会变得几乎为0。
英文
另一方面,由哈密顿量
(A(14)和(15),并在中性介子的假设下作适当简化)导出的严格介子场量子化运动方程
... | 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 editorial comments on the possibility of deriving energy, perhaps in explosive form, from nuclear transmutation. The likelihood, it suggests, is remote. Meanwhile, recent experiments had demonstrated the artificial transmutation of most elements, including gold, though without any repercussions for world financial... | 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 | only go into atoms other than uranium. There need be little fear of an explosion in Nature due to uranium. The very heavy elements, in which such an energy release can be secured, occur only in very small amounts in the Earth's crust. The release of atomic energy can only be achieved by direct experiment with this end ... | 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 | When Dido landed at the site of the citadel of Carthage, she opened negotiations with the inhabitants for some land and was offered for her money only as much as she could surround with a bull's hide. But the astute woman cut the bull's hide into narrow strips, joined them end-to-end and with this long string encompass... | 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 | +QP
2
as short as possible. The light behaves as if each beam had a tendency to contract, and the French philosopher, Fermat, has shown that all the laws of geometrical optics can be reduced to the same principle. Light moves like a tired messenger boy who has to reach definite destinations and carefully chooses the s... | 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 dualism between “local” and “total” laws appears not only in this simple geometrical problem, but also has a much wider application in physics. It lies at the root of the old controversy whether forces act directly at a distance (as assumed in Newton's theory of gravitation and the older forms of the electric 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 | rise.
中文
Fig. 1
中文
Fig. 1 illustrates an example where gravity competes with another force, elasticity. A steel tape is clamped at one end and carries a weight at the other. This weight is pulled downwards by gravity, while the tape tries to resist bending in virtue of its elasticity. This elastic force also has... | 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 experiments are not merely pretty toys without serious background. They have been chosen only for the sake of illustration. The real importance of the principle of minimum energy can scarcely be exaggerated. All engineering constructions are based on it, and also all structural problems in physics and chemistry.
... | 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 | spread out over the whole box and attain a configuration of lower order. If I throw some marbles into the box one after the other so that their position is purely accidental, it is very improbable that they will all fall in the right-hand half. One can easily calculate the probability of a uniform distribution over 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 | The determination of this brachistochronic property of the cycloid was a very satisfactory piece of mathematics. It attracted much attention, and there is no philosopher of this period who did not test his analytical powers by solving similar extremal problems. Another member of the Bernoulli family, Daniel Bernoulli, ... | 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 | quite correct, behaved rather strangely; he did not claim his own rights, but even expressed his admiration for Maupertuis's principle, which he declared to be more general. The reasons for this attitude are difficult to trace. One of them seems to have been the publication by König of a fragment of an alleged letter 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 | For there is, by a kind of fortunate mathematical coincidence, a statical problem for which the statical minimum principle for the potential energy coincides formally with Hamilton's principle of least action for the pendulum; this statical problem is the loaded steel tape considered before. The curves representing 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 | The importance of Hamilton's principle lies in a different direction altogether. It is not Nature that is economical, but science. All our knowledge starts with collecting facts; but proceeds by summarizing numerous facts by simple laws and these again by more general laws. This process is very obvious in physics. We m... | 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 | law of gravitation, which contains Newton's law as a limiting case, can also be derived from an extremum principle in which the quantity that is an extremum can be interpreted as the total curvature of the space-time world.
中文
We call this period of physics which ends with the theory of relativity the classical peri... | 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 | 从以上对同一个问题的两种表述方式中我们看到,求极大值与极小值的问题之间并没有本质的区别;我们可以简单地称之为“极值”或“极值函数”问题。
英文
在17世纪末的艾萨克·牛顿时代,极值函数的几何问题和力学问题开始引起数学家们的兴趣,在牛顿去世(1727年)后不久,自然界的意义或经济性等形而上学的思想逐渐与这些极值问题联系起来了。
英文
最简单的一个例子是光学中的“反射定律”,这个定律可以表述成极小原理:从某一点P
1
传播到另一点P
2
的光束所选择的反射点Q
要满足总路程P
1
Q
+ QP
2
为最短。光的行为性质表现为每束光都具有缩短路程的趋势,法国哲学家费马已经指出,几何光学的所有规律都可以归纳为这一原理。... | 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
图2
英文
另一个证明极小能量静态原理的例子是肥皂泡。肥皂泡具有尽可能收缩变小的性质;其势能与表面面积成正比。因此,肥皂泡具有最小范围的表面,或者说极小的表面。自然界是一位专业的数学家,它很快就找到了这个问题的解决办法。
英文
这些实验并不是不能应用于实际的玩具模型。选择它们只是为了便于说明。我们绝对没有夸大极小能量原理的实际重要性。它是所有工程建筑的基础,也是物理学和化学中所有结构问题的基础。
英文
晶格模型提供了这类例子。晶体是确定种类的原子在空间中规则排列形成的。由两种化学性质类似的化合物即普通的盐(NaCl)和氯化铯(CsCl)各自组成的晶格的模型在结构上是不同的。为什么二者会存在这样的差别呢?因... | 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 | 他受到了巴黎的达西爵士、伯尔尼的塞缪尔·柯尼希和其他人的猛烈攻击,他们指出,如果莫佩尔蒂的主张是正确的话,那么一向经济节俭的自然在某些情况下将被迫做最大的而不是最小的功!欧拉提出的原理是正确的,但他的行为颇为奇怪;他非但没有声明自己发现该原理的优先权,反而对莫佩尔蒂的原理表示赞赏,并宣称这个原理是更普遍的。我们很难找到欧拉持这种态度的原因。其中的一个原因似乎是由于柯尼希公开了所谓的莱布尼茨信件的一部分,该部分对最小作用量原理也进行了阐述。这封信的真实性从未得到证实,似乎很有可能是伪造的,目的是用来削弱莫佩尔蒂的地位。这也许是使欧拉站在莫佩尔蒂这一边的原因,当时的莫佩尔蒂是柏林学院的院长并且特别受当时的国王弗雷德里克二世,也就是后来所... | 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
如果我们选择合适的势能表达式,哈密顿原理就可以描述几乎所有的现象,不仅包括刚体、弹性体的动力学,也包括流体、气体的动力学以及电学、磁学、电子学和光学。爱因斯坦的相对论是这个理论发展的极致,其中抽象的作用量原理又可以用简单的几何学进行解释了。在通常的空间中加入时间这个维度后,则我们可以认为行星的运动轨迹是这种四维空间中的“测地线”。牛顿运动定律作为一种极限情况被包含在爱因斯坦的引力定律当中,而我们也可以从极值原理导出后者,其中,极值原理中的极值这个量可以被解释为时空世界总的曲率。
英文
我们把相对论出现之前的时期称为经典物理学的时期。与之相对的是最近以量子理论为主导的时期。新的量子力学假定所有的物理规律都具有统计特性。其... | 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 | I have developed a tentative theory of the magnetic field based on the assumption that this field is caused by thermo-electric
currents in the core which owe their existence to the conditions created by the turbulent convection. The thermo-electric current density is
I
= σ
grad ω
– B
grad T
, (1)
where σ
is 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 | in the Earth's core. Since any particle of the mass undergoes large pressure changes during vertical displacements, the inhomogeneities are best accounted for by phase transformations induced by the pressure changes which are a frequent occurrence at high pressures3
. Perhaps there are also considerable chemical inhom... | 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 | 热电流的密度为:
I
= σ
grad ω
– B
grad T
(1)
式中σ
为电导率,ω
为电荷内部和表面的电势,B
为物质的热电常数,T
为温度。σ
、B
、T
为坐标函数。如果它们已经给定,则ω
将是微分方程div I
=0在适当边界条件下的解。
英文
有些令人吃惊的是,方程(1)中电流的局部起伏加起来可以形成一个近似与地轴平行的磁矩。这是因为流体的机械运动受到了地转偏向力
的作用。看一下流体力学方程就会发现当黏度值较小时,相对于其他动力学因素,地转偏向力占绝对优势。在给定情况下,这就会引起一个明显的东西不对称温差。这种温差通常是由对流运动的垂直分量引起的。
英文
为了深入分析,... | 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 | to suggest that an unnecessary mystery is being made of what is really an elementary point of relativity theory. In short, we know why the present theory has got into difficulties, and we know what must be taken into account if it is to get out of them.
中文
Relativity theory begins with a denial of absolute motion. E... | 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 | of one relative to the other is observable independently of any origin of co-ordinates, being the original observable called “x
” in our second paragraph. This must not be confused with the co-ordinate difference ξ = x
2
– x
1
, which introduces twice over the uncertainty of the physical origin from which x
1
and x... | 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 | that an observable object
has an uncertainty relation to the geometrical space-time frame, and the relativity principle that an observable quantity
relates to two observable objects. Current theory recognizes these principles separately but not in combination; and in dealing with co-ordinates and momenta it pays atte... | 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 10/136 of the mass of a hydrogen atom; and ε, which is very simply related to certain magnitudes calculated in cosmological theory2
, has the value 1.10×10–13
cm. (For technical reasons, the constant more usually given is k
0
= 2ε =2.20×10–13
cm.)
中文
That the virtual particle of mass m
0
, originally studied... | 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
相对论以否认绝对运动为出发点。每一个我们观测到的速度dx
/dt
都是两个物理对象的相对速度。同样地,“x
”是两个物理对象之间的相对位移,而速度是“x
”对时间的一阶导数。两个物体都与海森堡所指出的时空框架相联系;即它们并不是像三维空间中的点(或四维时空中的世界线)那样有确定的位置,它们的位置和动量具有不确定性。
英文
通常,dx
/dt
和x
赋予其中一个物体(本文称之为实物粒子),另一个则被视为是参照物。显然,在精确的公式中,参照物必须是一个粒子。这个参照粒子即为物理“原点”,我们可以由此测量实物粒子的可观测坐标x
。目前的量子理论已重复了相对论前时期的错误,即对精确公式所对应的物理参考系的定义不... | 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m
0
与ε是共轭的,因此选择哪个作为基本量是任意的;但我要指出的是,由介子的质量出发确定核力的作用范围是一种不直接的方式,因为此范围是原点位置不确定性的直接表现。在两个质子之间的核力来自两个质子重合时产生的能量奇点——一个下陷,它(在均匀分布中)刚好可以补偿两个质子不重合时产生的库仑能。在刚好符合ξ=0的条件时,有
,这(在ξ的计算值方面)与布莱特、康登和普雷森特在他们对质子散射的论述中建立的力的范围精确地一致。
英文
(沈乃澂 翻译;鲍重光 李军刚 审稿)
A Living Fish of Mesozoic Type
J. L. B. Smith
Editor's Note
Imagine discoveri... | 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 | redemption, and the fish had been mounted by the local taxidermist.
中文
Since the fish was unquestionably alive when caught, there is at least a possibility that this zoological tragedy may be ameliorated by the capture of another specimen. This is not so remote as might appear. After careful inspection of the mounte... | 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 skeleton was cartilaginous, the vertebral column apparently tubular, and the whole fish extraordinarily oily. The fish has small spiracles situated as shown in the accompanying illustration, and a definite though not very obvious lateral line, which continues uninterrupted to the end of the supplementary caudal. 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 | 鉴于1938年圣诞节期间在南非的东伦敦海岸发现了腔棘鱼(人们原以为这种鱼在8,000万年前的恐龙时代就已经灭绝了),上述想法也就不像看上去那么荒诞了。当鱼类学者詹姆斯·里奥纳多·布莱尔利·史密斯到达现场进行本次观察时,这一标本已经腐烂得很厉害了,但是残余的躯体足以使他确信,这个被他命名为拉蒂迈鱼的奇怪鱼类确实与白垩纪大盖鱼属的腔棘鱼非常相似。史密斯希望能够捕获另一个标本的愿望最终得到了满足,但那已是十几年后了。
英文
“在非洲总是可以发现新东西”。我很荣幸地宣布,我们发现了一种被认为在中生代末期就已经灭绝的总鳍鱼。它是在1938年12月22日于东伦敦以西几英里的深约40英尺的水中用拖网捕到的。刚被捕获时它还是活的,死后不久它就... | 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 | Thanks to the diligence of chemists in the early decades of the twentieth century, most of the elements predicted by Mendeleev's table (Mendeléeff's table) had been discovered, but there remained gaps, one of which was element 43—predicted to be closely similar to the known element rhenium. Emilio Segrè was one 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 | Artificial radioactivity has supplied chemistry with a powerful new instrument, and from the point of view of the discovery of new elements its most striking feature is that one is able now to create, by transmutation from other elements, the element one wants to study. The first achievement in this type of investigati... | 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 | of radioactive detection, as worked out by Curie, Rutherford, Soddy and others in their classical work on the natural radioactive elements, have been employed throughout and satisfactory methods of separation have been worked out. The fundamentals of the analytical chemistry of this element have thus been secured and 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 | , 712 (1937); and in the Press.
Cacciapuoti, B., and Segrè, E., Phys. Rev.
, 52
, 1252 (1937); and unpublished results.
Segrè, E., Seaborg, G. T., Phys. Rev.
, 54
, 772 (1938).
Abelson, P., unpublished results.
43号元素
塞格雷
编者按
20世纪前几十年,由于化学家的不懈努力,门捷列夫周期表所预言的绝大多数元素均已被发现,但是还有一些位置空缺,其中之一就是43号元素,人们预测它非常类似于已知元素铼。埃米利奥·... | 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;郝项 审稿)
Liberation of Neutrons in the Nuclear Explosion of Uranium
H. von Halban, jun. et al.
Editor's Note
Recent experiments had shown that considerable energy was released in the explosion of uranium or thorium nuclei, triggered by impacting neutrons. The possibility of an energy-releasing chain reacti... | 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 | products have been observed to be β-active and several periods have been recorded, so that a part, at least, of the neutron excess is certainly disposed of in this way. Another possible process is the direct liberation of neutrons, taking place either as a part of the explosion itself, or as an “evaporation” from the r... | 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 | that the introduction of nuclei which act merely by capture or by increasing the hydrogen content of the solution can affect the shape of the density curve only in a characteristic way: the modified curve can always be brought to coincide with the primitive curve by multiplying all abscissae by a suitable factor and al... | 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 | = 25 cm.; this limit, certainly inferior to the actual value, is 6×10–25
cm.2
.
中文
Our measurements yield no information on the energy of the neutrons produced. If, among these neutrons, some possess and energy superior to 2 Mev., one might hope to detect them by a (n
,p
) process, for example, by the 32
S
(n,p... | 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,至少有一部分过剩的中子必定是通过这种方式去除的。另一种可能的过程是中子以部分爆炸产物的形式被直接释放,或从处于激发态的生成核中“蒸发”掉。
英文
为了找到这类次级现象的某些证据,我们研究了Raγ-Be光中子在1.6摩尔硝酸双氧铀溶液和1.6摩尔硝酸铵溶液中的减速所产生的热中子的密度分布(这两种溶液中的氢含量只相差2%)。将Ir
2
作为r
的函数绘图(其中r
是源点与给定点之间的距离,I
是热中子在相同点的局部密度,通过镝探测器中感生到的放射性进行测量),图中所得曲线的面积与Q·τ
成正比,Q
是每秒由中子源发射出的或在溶液中形成的中子数,τ是中子被俘获之前在溶液中度过的平均时间[3,4]
。将任何其他不产... | 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 | that the mere absorption of a neutron could give a uranium nucleus enough kinetic energy to reach their collecting surfaces. This new technique offered a route to the more detailed examination of the nuclear fragments created in fission processes.
中文
O
Hahn and F. Strassmann1
have discovered a new type of 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 | found a well-measurable activity which decayed first quickly (about two minutes half-value period) and then more slowly. No attempt was made to analyse the slow decay in view of the large number of periods to be expected.
中文
The considerable intensity, however, of the collected activity encouraged us to try to get 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 | irradiation) of the precipitate and of the evaporated sample showed that the precipitate contained about two thirds of the total activity collected in the water. After about two hours, however, the evaporated sample was found to decay considerably more slowly than the precipitate, presumably on account of the more long... | 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
哈恩和施特拉斯曼[1]
发现了一种新型核反应,即在中子轰击下,铀核和钍核分裂为两个更小的核。以此他们证明了钡核、镧核、锶核、钇核以及最近又发现的氙核和铯核等裂变产物。
英文
可以简单的以一种本质上经典的方式,比如类似于液滴分裂的形式来描述这类核反应,并且分裂的产物必定以上百兆电子伏的动能飞离[2]
。弗里施[3]
首先给出这些高能反应的证明,几乎是在同一时间其他多位研究者也给出了证明[4]
。
英文
迈特纳已经指出(见参考文献3),像人们从α反冲中收集放射性沉积物那样,利用这些高能量来收集裂变产物是可能的。在此期间,约里奥已独立地进行了这类实验[5]
。我们利用哥本哈根理论物理研究所最近制成的高压装置,... | 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 all circumstantial, but they are a reminder of how difficult it was to say anything definite about protein structure until X-ray crystallography began, over a decade later, to reveal it in earnest.
中文
O
N recent occasions a number of objections to the cyclol theory have been raised, to many of which replies hav... | 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 | . Proteins are so different from other substances that it is surprising that there is a reluctance to accept for them a structure for which no analogue in organic chemistry can be found. Globular proteins have not yet been synthesized in the laboratory. The fact that it has not proved possible to form ring structures 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 | , need to make the assumption that proteolytic enzymes open cyclol bonds. We know of no evidence which conflicts with the view that the enzyme can take advantage of the situation arising from the opening of these bonds, so that, if it is a fact that proteolytic enzymes act only on CO–NH bonds, there is no incompatibili... | 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 | . When few bonds are open they may re-form because of the multiple paths of binding holding the parts in position. Reversible denaturation (of either type) is thus not excluded by the cyclol theory. In the case of the fibrous proteins in which some cyclol bonds may be present,13
the first and second stabilizing factor... | 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 spontaneous formation of monolayers from solution represents a very mild type of degradation, presumably involving no hydrolysis. It seems likely that much could be learnt about protein structure by studying the structure of the constituents of these protein monolayers. On the cyclol theory, fragments of fabric 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 | that many of the arguments in favour of the cyclol hypothesis could be used equally well in favour of any “regular geometrical structure which joins peptide chains to form a globular molecule”, a theme which has already been developed in considerable detail23,24
. This remark, in focusing attention on the fundamental ... | 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 should, however, be recognized that there are broad deductions to be drawn from this point of view, irrespective of the particular form of the atomic pattern. Chief among these is the suggestion that the molecules of the globular proteins are cage-like structures, consisting of a characteristic fabric folded round 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 | 针对批评,好斗的多萝西·林奇在本文中捍卫了她关于蛋白质分子结构的(不正确的)理论。林奇坚持认为蛋白质不是由氨基酸通过肽键连接形成的简单的链,而是由六边形的环状结构连接成为笼状的形式。这个理论面临的严重问题非常明显——特别是一些氨基酸上的“侧链”显然不能与这一理论吻合,但这一问题在本文中并未被提及。林奇在这里的辩解都是根据情况推测的,但是它提醒我们,要对蛋白质结构作出任何确定的描述有多么困难。直到十年之后X射线晶体学兴起,这一情况才得以改观。
英文
最近在一些场合中,出现了一些反对环醇理论的意见;对于其中很多反对意见,已经有人在许多出版刊物上发表文章作出或明白或含蓄的答复,特别值得一提的是,1938年12月20日朗缪尔在对物理学... | 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 | 肌球蛋白的变性(这被认为是环醇理论不能解决的一个难题[4]
)由此变得很容易解释。
英文
第一个稳定性因素似乎也可以解释至今不能使多肽的羟基实现甲基化或者乙酰化这一事实。在目前的假说下,这种情况应当在卵清白蛋白和血红蛋白中存在[14]
。
英文
需要强调的是,尽管前三种稳定性因素对于所有的球蛋白是等同的,但第四种稳定性因素的强度会随着每种蛋白的特定氨基酸组成的变化而变化。这一点可以通过胰岛素的例子得到证明,它的异常行为(耐受热和酸的能力,晶体在干燥状态下的稳定性等)可能与其含有的疏水基团异常多有关。胰岛素“不会发生通常意义上的变性”[4]
这一事实并不能作为反驳关于变性的环醇理论的证据:它只是进一步说明第四种稳定性... | 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 | 无论原子的排列方式如何,事实仍然是天然蛋白质的定义性特征不仅符合分子笼状结构的理念,甚至似乎还要求蛋白质的分子具有这样的结构。在这一点上,似乎达成共识的意见真的越来越多[2,4]
。无论如何,核心问题就是去解释那些非常大但是化学和物理上定义明确的分子的存在。作为这个引人关注事实的解释,笼状结构的理念已经被提出来供人们考虑。有没有可能在我们看到一个笼状结构的时候通过已经可用的实验技术手段把它识别出来呢?
英文
(刘振明 翻译;顾孝诚 审稿)
New Products of the Fission of the Thorium Nucleus
L. Meitner
Editor's Note
In 1939, physic... | 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 | protactinium isotope resulting from pure neutron capture) only products which, on the basis of their chemical properties, had originally to be assigned to radium and actinium isotopes3
and which have more recently been identified with barium and lanthanum isotopes4
.
中文
A “thick” layer of thorium oxide on a glass ... | 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 | . Analysis of the decay of the sulphide precipitate showed again the presence of a substance of half-period about 40 minutes and of one of 14.5 hours, which was followed for nearly three days and found to decay to zero. The initial intensities of the two periods were about equal, in spite of the short duration of bomba... | 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 | 1939年,物理学家接近于发现放热核裂变——大原子核(例如铀)分裂为稍小的碎片,并释放出巨大的能量。近期的一些实验用中子轰击铀核,结果似乎使之分裂成了两份大致相等的碎片,本文中奥地利物理学家莉泽·迈特纳对这些实验进行了拓展。迈特纳描述了用钍核进行类似的实验显示,类似的核反应分裂生成了大碎片,并发现钍核和铀核裂变都产生相似的最终产物。迈特纳是犹太人,最近她在德国同事奥托·哈恩帮助下被迫逃离德国。五年后哈恩因为发现核裂变而获得了诺贝尔物理学奖。
英文
在此前的一篇通讯[1]
中我们曾指出,在中子轰击下产生的铀的裂变产物中,发现了“超铀”元素。因此它们一定是序数较小的元素,可能部分位于碲附近[2]
,部分(互补的裂变碎片)则位于... | 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 | built of hundreds or thousands of atoms. Bernal was still baffled by the apparent complexity of the process by which the chain-like molecules fold into a compact form (this is still not fully understood), but the important role of “hydrophobic” interactions between insoluble regions was already emerging.
中文
T
HE st... | 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 | weights, but rather a scattering of weights concentrated in certain regions. There is no doubt that in closely related proteins there are simple relationships. Both haemoglobins and haemocyanins can, for example, be split reversibly into 2, 4, or 8 parts. But whether these relationships hold for all proteins is more do... | 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 third line of attack is that of X-ray study. The beautiful crystalline forms exhibited by proteins, which have been known for at least a hundred years, were always a powerful attraction to X-ray crystallographers, but until the last five years the instability of protein crystals and their small size had defeated 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 | . Thus the X-ray method furnishes an extremely accurate measure for the basic molecular weight of proteins though it cannot determine its multiplicity. It may well be that many proteins are built of sub-units, which though of approximately equal weight are not chemically identical, and are more properly to be called 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 | H and salt concentrations, varying, for example, between 320 A. at p
H 7, and 206 at p
H 3.4. It should be possible to find a quantitative theory to explain these changes and, indeed, the beginning of such a theory has been made by Langmuir4
and Levine5
.
中文
The general picture of the external character of prote... | 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 | backbone spacing between the main chains themselves, which are held together by the CO and NH groups. In the shorter α form, the 10 A. spacing remains, while the 4.5 A. disappears, and this indicates that the chains are folded, but folded definitely in a plane and not as in rubber in two dimensions. What the precise me... | 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 | introduced in this way can only be removed by some physical artifice, such as the introduction of a heavy atom, or the observation of intensity changes on dehydration, which have not hitherto been carried out in practice. For all but one of the proteins examined, the task is made still more difficult by the presence 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 | none of these will at the same time fit the sections. The claims to have done so10
are based on the arbitrary selection of a certain number of vectors, and the agreement disappears if all the vectors are taken11
. The failure to find a point solution suggests that we are dealing with groups of size of the same order ... | 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 question of the unitary nature of the protein molecule arises whether the inter-residue linkage is peptide or not. With a multiple link it is easy to construct models either of the cage or solid type, but as has already been pointed out, it is difficult to reconcile such continuous structures with the definite 10 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 | The question of the structure of the sub-unit would seem to raise at first sight the same difficulties as the structure of the molecule itself. Actually, however, with the smaller number of residues the difficulties and the improbabilities of the coiling become much less, particularly if we postulate—which is not unrea... | 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 | however, the behaviour of the hydrophobe groups of the protein must be such as to hold it together. As Danielli13
and Langmuir14
have pointed out, on the basis of surface-film work, the protein molecule in solution must have its hydrophobe groups out of contact with water, that is, in contact with each other, whereas... | 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 | attack would probably save much effort which is now wasted, and lead to an immediate clarifying of the problem.
中文
(143
, 663-667; 1939)
References:
Svedberg, T., Proc. Roy. Soc.
, A, 170
, 40 (1939).
Bernal, J. D., and Crowfoot, D., Nature
, 133
, 794 (1934).
Bernal, J. D., et al., Nature
, 141
, 521 (1938... | 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 | 但是是否所有的蛋白质都有这种关系还存在着更多的质疑;特别是通过测定物质黏度的研究发现,属于相同分子量量级的蛋白质,例如胰岛素和麦醇溶蛋白,可能在形状上差别非常大;前者是一个扁平球体,而后者是伸长的棒状结构,很难看出它们具有什么共同的物理结构。
英文
曾经有人认为属于同一个斯韦德贝里等级的蛋白质分子量的变化,可以被归结为已知的氨基酸成分之间的差异。然而,在现有分析数据的基础之上,至今都不可能说这是否就能充分地解释观察到的差异。因此,认为分子量在35,000这个等级的蛋白质是由288个氨基酸残基组成,这在目前只不过是个猜测而已。
英文
研究蛋白质结构的第二类方法是基于这些分子的带电性质。科恩、蒂塞利乌斯以及其他一些研究者的工... | 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 | 任何蛋白质结构的有效图像都必须同时提供对于所有蛋白质而言的共同特性,因为已确证它们不仅具有诸多化学的和物理学的相似性,每一类蛋白质还具有高度的特异性。尽管无法证实,我们仍有理由相信这其中首要一点依赖于氨基酸的某种基本排布。关于这一点的最初线索来自于对纤维蛋白的研究。由于这类蛋白在技术上的重要性以及它们具有的便于操作和处理的特性,此方面的研究已经取得了相当大的进展,这主要归功于阿斯特伯里等人的精心设计以及坚持不懈的研究[6]
。
英文
全伸展的β–角蛋白纤维每隔3.5Å就会有一次重复,这个长度与一个氨基酸残基的长度相一致;另外两种重复的间隔分别是10Å和4.5Å,与链长度的直角周期相一致。阿斯特伯里最为重大的发现之一是这两种周... | 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
关于蛋白质分子的结构,真正重要的问题主要有:
(a
)氨基酸残基之间的连接的本质是什么?
(b
)这种连接贯穿于整个分子中还是仅仅存在于分子的某些部分?换句话说,是蛋白质作为一个整体依靠基本的价键力量结合在一起,抑或是它由亚单位构成,以另外的某种方式结合在一起?
(c
)如果这些亚单位存在的话,那么存在于它们之间的连接的本质又是什么?
英文
对于第一个问题,解释由线性多肽链形成球形分子结构所面临的困难引出了交替式连接的概念,其中每一个氨基酸残基都可与其他四个或者不少于两个氨基酸残基连接起来。尽管这种假设初看上去具有理论上的吸引力,但是它仍然缺乏任何化学方面证据的支持,在化学领域[12]
备受争议。即便不引入不确... | 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 | 需要阐明的至关重要的问题是肽链折叠或者卷曲的精细模型,为此我们可能不得不等待相当长的时间,直到X射线技术以及其他方法获得比现在更进一步的发展。蛋白质结构的问题目前是一个明确而且并非不可实现的目标,但是为了获得成功,它需要研究者之间某种程度的协作,然而现在的协作远未达到所需要的程度。目前绝大多数的蛋白质研究工作之间都是不协调的,不同的研究者采用不同的技术观测不同的蛋白质,也许集中而又有计划的研究可能会节省许多现在这种状态下浪费掉的时间和精力,从而有助于对问题的直接阐明。
英文
(刘振明 翻译;周筠梅 审稿)
*
来自1月27日在英国皇家研究院星期五晚间演讲的内容。
Number of Neutrons Liberated ... | 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 | being the number of neutrons per second emitted by the source or formed in the solution, and τ
the mean time a neutron spends in the solution before being captured. Assuming that the solution contains only nuclei which absorb neutrons according to the 1/υ
law (the only exception to this rule will presently be dealt w... | 400套付费套装书 |
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