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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 | The ratio of the observed numbers of single positives compared with the pairs is also of great importance in this connexion. Whether a positive is always formed paired with a negative, or whether a positive not accompanied by a negative can in some cases be produced, is a question difficult to answer from the data so 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 | only a million or two electron volts, ejected from plates of lead by the impact of non-ionising particles. These low energy ejections are in all respects identical with those produced by the thorium C′′ γ-rays and are undoubtedly due to low energy photons. These electron effects cannot be ascribed to ordinary neutrons ... | 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 | negative electrons and only in rare cases of positrons.
中文
Because of the powerful magnetic field we are using, it is possible to deflect all but a very small number of the electrons projected in the showers by the photon impacts. In general, in a shower a pronounced asymmetry is noted in the numbers of positive as ... | 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 annihilation is in general greater than the range of the positron, so that such annihilation should be evidenced by the appearance of quanta of about half a million electron-volts energy and a very small number of quanta of about one million electron-volts energy when positrons pass through matter20
. The experime... | 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 | , 432; 1933.
Anderson and Neddermeyer, Phys. Rev.
, 43
, 1034; 1933.
Curie and Joliot, C.R.
, 196
, 1581; 1933.
Meitner and Philipp, Naturwiss.
, 24
, 468; 1933.
Curie and Joliot, C.R.
, 197
, 237; 1933.
Oppenheimer and Plesset, Phys. Rev.
, 44
, 53; 1933. Beck, Z. Phys.
, 83
, 498; 1933.
Anderson, Phys. Re... | 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 | 因此除非我们允许电荷的基本单位为分数值,否则我们可以断定自由正电子和负电子的电荷大小是完全相同的。根据这个事实,连同在磁场中正电子穿透铅板前后测量到的曲率一起,就可以确定出其质量不会比自由负电子的质量高出20倍。
英文
上述结论得出之后[4]
,对发生在云室气体中的一个运动正电子和一个自由负电子间的碰撞的观测表明,根据守恒定律,正电子的质量和自由负电子的质量是相等的,其误差不超过30%。通过在磁场中的径迹上进行真实离子计数,得到的与高速和低速的正负电子的比电离有关的更多最新测量结果[15]
表明,正电子和负电子的比电离差别不会超过20%。这样就确定了对于电荷和质量,正电子和负电子的最大差值分别为10%和20%。有关这个发现... | 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1MV
是产生一个电子对所需要的能量,那么来自铅和铝的正电子和电子对的最大能量1.6 MV
就能与狄拉克图像的预期很好地吻合。然而,产生一个电子对所需的总能量是2.9 MV
;虽然不太可能,但可以想到的是,它也许已经由宇宙线产生,再或许是它表示了一个电子对铅板下表面的反弹。
英文
与能量分布同等重要的是,与单个负电子相比,单个正电子及电子对的数目分布。放射性钍通过2.5 cm厚的铅板过滤得到的γ射线照射0.25 mm厚的铅板,总共可发射出1,542个电子,其中有1,387个单个负电子、96个单个正电子和59个电子对。用相同的γ射线照射0.5 mm厚的铝板,总共有943个电子径迹,其中916个单个负电子、20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 | 英文
由于我们所用的磁场很强,因此除了由光子碰撞产生的簇射中发射出的极少量的电子没有发生偏转外,可能所有的电子都发生了偏转。通常在一个簇射中可注意到,从铅板发射出的正电子数目与负电子数目明显不对称。其中一个簇射中,有7个正电子和15个负电子,而在另一个簇射中,则有15个正电子和10个负电子。这些效应遭遇的唯一困难是,很难与入射光子产生电子对的狄拉克理论取得一致。很可能这些效应表明存在一类核反应,其中核的作用不仅是催化剂而是比之更加活跃,例如,正电荷和负电荷从核中发射出来,然后作为自由正电子和负电子出现在簇射中。然而,这两种观点本质上的区别可能只不过是,其中一个认为核是可以改变其电荷的,而另一种观点则认为其电荷不会改变。
英文
... | 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 | have reported that a number of new radioactive isotopes can be produced by the bombardment of various elements with α-particles, these isotopes emitting positive electrons. In particular, they showed that boron when bombarded by α-particles was transformed to the isotope N13
, radio-nitrogen, this isotope having a hal... | 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 also taken about 250 Wilson chamber photographs in a field of 2,000 gauss, placing the activated source against the outside of the chamber wall, which was about 3 mm. thick. Under these conditions, we observed only two electrons of positive curvature which could possibly have come from the source, these electro... | 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 | 考克饶夫等
编者按
直到20世纪30年代中期,物理学家通常使用α粒子和质子轰击多种元素以产生新的放射性同位素。这篇文章中考克饶夫和他的合作者们描述了一种使用高能质子轰击石墨的实验,该实验产生了以半衰期约为10分钟的速率衰减的放射性。这表明质子束产生了某种数量可观的放射性核,有可能是13
N。发射出来的粒子中有一些是正电子,当然,大部分是高能的普通电子,普通电子可以解释为是由γ射线引起的“反冲”造成的。反之γ射线可能是由于正电子在云室壁上湮灭产生的。这是首次观察到的电子–正电子湮灭现象之一,而这一过程直到20世纪40年代才被人们很好地理解。
英文
居里和约里奥[1]
曾经报道,许多新的放射性同位素可以用α粒子轰击各种元素... | 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 | have been hoping that, following Lord Rutherford's proposal of a name for the heavy isotope of hydrogen, someone would suggest a more satisfactory word than “positron” for the positive electron. Since, however, no better qualified reformer has appeared, may I raise the question before it is too late? “Positron” is ugly... | 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 | 然而,我并不会进一步要求大家非要接受这一命名。事实上,本文的主要目的是想消除“positron”这一命名,并顺便推荐我的命名。
英文
(金世超 翻译;朱永生 审稿)
Hormones of the Anterior Lobe of the Pituitary Gland
Editor's Note
In the 1930s, biochemists spent much effort in identifying the vitamins necessary for healthy human life and which are not produced in the body, and also the hormon... | 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 | . Although the association of overfunction of the pituitary with body overgrowth (gigantism or acromegaly) and of its underfunction with dwarfism has been frequently confirmed, it was not until 1921 that Evans and Long succeeded in preparing an extract of ox anterior lobes which stimulated growth in mammals. This was 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 | H8 with sulphuric acid and again centrifuged. The solution is then acidified and poured into excess of acetone; the precipitate is filtered off and dried. This powder is stable but still contains the gonad stimulating hormone. On extraction with 95-98 percent acetic acid, the latter is destroyed and the growth hormone ... | 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 | gigantism and acromegaly in human beings are due to over-secretion by the anterior lobe of the pituitary gland.
中文
The gonad stimulating hormone (or hormones) is responsible for the normal development and maintenance in a state of functional activity of the sex glands, with the accessory organs and secondary sex cha... | 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 | purest preparations was about 0.05 mgm.
中文
Although preparations from these different sources all stimulate the gonads, yet they show differences in their chemical properties and biological effects. Prolan, for example, is more sensitive to both acid and alkali than preparations from pregnant mare serum; the latter,... | 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 | Substitution therapy failed to induce the rhythmic changes in the vagina characteristic of the oestrous cycle, a continuous oestrous reaction only being obtained. Pregnancy was not observed owing to failure of implantation, but it could be maintained in animals, hypophysectomised after implantation, by injection of mix... | 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 | tests, which only further work with a standardised technique can clarify.
中文
In immature male rats, doses of gonad stimulating hormone sufficient to produce enlargement of the ovaries in immature females produced little or no increase in the weight of the testes, although the accessory organs grew markedly and attai... | 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 Growth and Gonad-Stimulating Hormones of the Anterior Hypophysis. By H. M. Evans, K. Meyer and M. E. Simpson, in collaboration with A. J. Szarka, R. I. Pencharz, R. E. Cornish and F. L. Reichert. Memoirs of the University of California. Vol. 11. pp. 446. (University of California Press Berkeley, California, 1933.)
... | 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
促性腺激素负责性腺的正常发育,并通过附属器官及第二性征使性腺功能活性维持在某个水平上。在雌性个体中,卵巢本身容易对该激素产生反应;在雄性个体中,附属器官表现出最显著的反应。埃文斯及其同事用未成熟的雌性大鼠来检验他们的促性腺激素制剂;连续注射3天,在第四天和第五天时检查阴道口,阴道口一打开就立刻进行涂片,在开始处理之后大约96~100小时杀死这些大鼠并进行检查。
英文
激素可由牛垂体前叶(比较差的来源)、怀孕母马的血清(比较好的来源)以及孕妇的尿液制备。将来自垂体前叶碱性萃取物的丙酮粉末溶解在水中,调节溶液中发生的反应使其能够产生最大量的沉淀物:大部分激素存留在溶液中,然后用黄胺酸使其沉淀,随后用乙醇–氨的混合溶液清除黄... | 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 | 对于垂体被切除的雄鼠,注射激素能使萎缩睾丸再生,精囊增大并充满精液,精子发生过程重新开始;替代治疗获得了成功,因为已经能够生育出正常的幼崽,而且睾丸在组织学检查上也表现正常。
英文
垂体被切除后,注射促性腺激素不能修复甲状腺和肾上腺的萎缩,但是含有生长激素的提取物则可以保持或者恢复这些器官的重量,尽管它们在组织学上不能完全恢复正常结构。埃文斯的结果没有揭示产生这些效应的到底是生长激素还是提取物中的其他活性物质。注射生长激素还能缓解垂体被切除后的大鼠中非常常见的恶病质。
英文
加州大学的研究者们得出上述结论所依据的具体数据可以在那本受人瞩目的专著中查到。书中介绍的方法对于其他研究者来说应该是有价值的,而他们得到的结果则将成... | 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 | followed by our amplifier and oscillograph. The proton group has a definite range of 14.3 cm., corresponding to an energy of emission of 3 million volts. In addition to this, we have observed a short range group of singly charged particles of range about 1.6 cm., in number equal to that of the 14 cm. group. Other weak ... | 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 | leading to the production of a helium isotope of mass 3 and a neutron. In a previous paper we suggested that a helium isotope of mass 3 is produced as a result of the transmutation of Li6
under proton bombardment into two doubly charged particles. If this last reaction be correct, the mass of
is 3.0165, and using 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 | 从质能关系计算得到这种新的氢同位素的质量为3.0151。
英文
另一种可能发生的反应是:
其产生一个质量为3的氦同位素和一个中子。在之前的一篇文章中,我们指出,6
Li被质子轰击后会转变为两个带双电荷的粒子,这样就产生了质量为3的氦同位素。如果最后的这个反应是正确的,那么
的质量应为3.0165,利用这个质量和查德威克给出的中子质量进行计算,得出中子的能量约为3百万电子伏。根据动量关系,反冲的
粒子的射程应该约为5毫米。由于存在很多干扰因素,观测并记录这样短射程的粒子是困难的,但是正在进行中的实验正试图去探测这样的粒子群。在探测所需的短时间内,
原子核似乎是稳定的,它们的持久性问题还需要更进一步地探讨。
英文
... | 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 | The first to give any full and clear account of the properties of liquid crystals was O. Lehmann1
. Following him, a number of investigators have attacked the general problem from various sides, Vorländer, Schenck, Friedel, Grandjean, Mauguin, Oseen and others. Quite a large literature has grown up round the subject. ... | 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 optical effects possess in many cases a singular beauty, in respect both to colour and to form (see
Figs. 1, 12 and 13
†
). Most of them, but not all, can be explained in comparatively simple terms which, however, are rarely described in treatises on optics. Writers have confined themselves to true crystals 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 | Let us suppose now that such layers are formed in the substance ethyl azoxybenzoate, which shows the smectic phenomena very well. Each sheet is very flexible. If such a sheet could be suspended in space, free from gravity, it would take the form of a perfectly flat surface because the molecules would tend to lie parall... | 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 | beam shall be perpendicular to the layers. The experiment shows that the substance behaves like a positive crystal, such as quartz. In other words, the frequency of the light vibrations perpendicular to the layers (and parallel to the molecules) is less than the frequency when the vibrations are not perpendicular there... | 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 optical peculiarities of the smectic state are caused by these contortions of the strata. We have therefore to consider in the first place the forms which the strata assume, and in the second their effect upon the transmission of light.
中文
From direct observation it can be inferred, as will be seen presently, 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 | to any point on the axial circle of the ring meets every layer at right angles. In this figure emphasis is laid on those parts of the layers which lie within the cone of which the upper point A
is the vertex and the axial circle is the circumference of the flat base. Within the cone the layers are in equilibrium 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 | Fig. 4. A drawing of a model made to illustrate the structure of the interior of an oblique cone containing the smectic substance. The two sheets of zinc are cut into the form of an ellipse and part of a hyperbola, and are fastened together so that their planes are perpendicular to each other and each curve goes throug... | 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 | If two such conical regions are made to touch along a common generator, the cyclides in one region may be looked on as continuations of the cyclides in the other, though they come into contact only at the common generator. Any pyramidal space can be divided into cones, large ones in the centre, smaller cones partially ... | 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 | point on the lower, they are all normal to the set of cyclides which divide the space inside the wedge into layers of uniform thickness. Thus the whole of a solid block can be divided into uniformly thick contorted layers by Dupin cyclides belonging to a number of different sets which, however, fit on to each other per... | 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 ratio of the refractive index of the extraordinary to that of the ordinary ray, and a
(=OA
) is a constant. If n
=1, the curve becomes a straight line, as it ought to do, since the substance would then behave as if isotropic, and a ray of light would go straight through. The curve in the figure has the two 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 | A particular case is alone of importance to us here. In cases with which we are dealing, the wave-length λ is very small compared to p
, the pitch of the screw. As Mauguin showed in the case of the nematic substances which we shall examine later, it is not possible to twist the medium so much as to make λ/p
anything ... | 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 | Any axial direction can be brought into coincidence with any other axial direction by a rotation in the plane containing the direction of the ray combined with a rotation about the ray. Thus we are able to say, as the result of the two cases considered, that the ordinary ray goes through the liquid crystal without any ... | 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 | Fig. 8. The arrangement of a set of cones within a pyramid. It follows closely the actual arrangement within a polygon near the bottom and on the left of the left hand photograph in Fig. 1. It is to be remembered that the apparent cones in the photographs of Figs. 1 and 12 are not the cones of this figure though connec... | 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 | converge melts into a point where a number of edges of polygons meet. This is illustrated in Figs. 10 and 12.
中文
Fig. 10. This shows the disposition of polygon edges in one face of the lower left hand portion of
Fig. 12 with respect to polygon edges in the other face.
中文
The polygon edges of Fig. 1 vary in shade... | 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 | From the general and close agreement between theory and observation, we may surely conclude that the smectic substance is indeed arranged in strata which take the form of Dupin's cyclides. There are, however, any number of other geometrical arrangements of sheets of uniform thickness. There must be a reason why the cyc... | 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 | If strata, originally plane and parallel to each other, are forced out of this arrangement, which is the simplest of all, they must tend to take the cylindrical form which comes next in simplicity. If the disturbing influences are complicated, the various attempts to adopt the cylindrical form must in some way be accom... | 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
Nematic Crystals
The second of the three chasses of liquid crystals outlined by Friedel, was called by him “nematic”, from the singular appearance of mobile threads, either free in the interior of the substance or attached more or less to the bounding plates. These have none of the focal conic structures of the sme... | 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 | Another striking characteristic of the nematic state is the tendency for the molecules to be attached sideways to the slide or the coverslip. If once a solid crystal has formed between the two glass surfaces, it is difficult to remove all traces of its having done so. The substance may be completely melted and allowed ... | 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 | Suppose now that the cover slip is moved, either by translation or by rotation with respect to the slide. In many places it must consequently happen that the orientation of the molecules on the top face is different from the corresponding orientation on the face below. The angle between them is α, let us say. It then 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 | corresponding to a vortex ring, which is either complete or anchored at two ends. The molecules and the optic axes are then tangential to circles having the line as axis. Sometimes a line marks the boundary between two portions in which the axial directions are different.
中文
In these cases, the ordinary ray is not 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 | -azoxyphenetole in the nematic phase, at two moments separated by as short an interval as possible. The only difference is that the position of the analyser in one case is approximately at right angles to its position in the other. No polariser. The clearer portion of each photograph is seen by ordinary rays; and the 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 | The whole effect depends on the compelling power of the pellicle, setting an arrangement at the surface to which the internal arrangement, whatever it may be at a distance from the surface, must gradually conform as the distance from the surface diminishes. The vibrations have been orientated in a different direction 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 | are coalescing and are attaching themselves to the glass above and below. The connexions are irregular but there are traces of the original simple arrangements of the groups. On the border between the liquid crystal phase are larger groups formed by the coalescence of smaller groups.
中文
Fig. 14. Para
-azoxyanisole ... | 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 substances, when in their characteristic state, are optically active to an extraordinary degree, represented sometimes by as much as a whole turn in the hundredth of a millimetre.
中文
This short account of the chief properties of “liquid crystals” is very far from complete. Nothing has been said of the influenc... | 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 | 后一性质意味着其组分分子必定存在某种程度的规则排布,而前一性质则意味着这种排布很容易被打乱,尽管它也可能很容易恢复。一般将这种物质称为“液晶”。有人——特别是夫里德耳,我们所知道的关于这类物质性质的很多知识都归功于他——认为这个称呼很糟,因为它们既不是完美的晶体也不是完美的液体。既然该状态被描述为我们所熟知的两种状态的中间状态,夫里德耳想称其为中间态,这个称呼更合乎逻辑。不过,“液晶”这个词既简单又有启发性,不会对使用者造成误导。
英文
最早对液晶的性质给出完整、清晰描述的人是莱曼[1]
。在他之后,很多研究者从多个方面研究了相关的基本问题,其中包括福伦德、申克、夫里德耳、格朗让、莫甘、奥森和其他一些研究者。围绕这一主题的文... | 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 | 这是可以预期的,因为我们经常发现沿着分子伸展方向的振动比穿过分子的慢。
英文
这种简单分层还使其适合于通过X射线进行研究,层的厚度看起来与我们已知的该分子的长度相当一致——分子长度基于对其他有机分子精确的X射线测量。夫里德耳[4]
给出的值为19.9Å。在固态晶体中发现层的厚度为16.2Å。二者的差异归因于下列事实:在固体的层中分子是倾斜的,不像在液晶中是竖直的。
英文
但是一般来说,将这种物质置于玻璃之间时(如同在显微镜下检验常常做的那样),当温度升高到适当范围,或者从熔融态冷却时,它都不会呈现简单的形式。层变皱了。物质与玻璃之间的附着作用很强,在各个点上,附着作用会迫使分子以不同的方向进行排布。整体排布不得不进行自... | 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
如果令两个这样的圆锥形区域沿着一条公共母线接触,一个区域内的圆纹曲面就可以看成是另一区域中圆纹曲面的延续,不过它们只在公共母线处发生接触。任何锥形空间都可以分隔成圆锥,较大的一些在中心,较小的圆锥部分地填充遗留空隙,更小的则填充剩下的遗留空隙,以此类推。那么,锥形空间就可以用若干组圆纹曲面进一步细分为同样厚度的层,每个圆锥对应一组,所有的圆纹曲面组合在一起,并且都与从顶点到构成底面的多边形上的所有点所做的直线以直角相交。在每个圆锥中,顶点和构成其底面的椭圆的焦点是属于这一圆锥的双曲线上的两个端点。由于所有的双曲线都位于垂直于圆锥底面(这些底是共面的)的平面上,并且都经过锥体的顶点,因此椭圆的长轴全都经过顶点在底面上的投影。
... | 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 | 那么,
英文
由此看来,两个各自具有特定速度的椭圆振动可以从盘曲的介质中通过而不发生形式变化。当盘曲很小时,我们可以假定入射光分解为两个线性振动,椭圆率可以忽略。不过,这些振动随着盘曲而变化,因而任一点处的振动总是分别沿着和垂直于该点处的晶轴线方向。如果必须考虑精确性的话,我们就不得不认为,入射光总是分解成两个以不同速度行进的具有不同椭圆率的椭圆振动。例如,一条振动与表面晶轴方向平行的极化射线分解为以不同速率行进的两个椭圆振动。较大振动的长轴位于入射振动的方向上,较小的则与其垂直并且等于较大振动的短轴。两个振动以相反的方向旋转。在介质中规则分布深度位置,它们再次结合为线性振动。
英文
我们可以观测到,这种效应实际上与波... | 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
从理论与观测结果之间普遍且极好的一致性来看,我们可以确定地得出以下结论:近晶态物质确实采取迪潘圆纹曲面形式排列成层状。但是,还存在任意多种相同厚度的层的其他几何排布。圆纹曲面具有优势必然有一个原因,而这个原因必是基于能量的考虑。从一个框架上拉伸出的肥皂膜一定呈现具有最小能量的形状;如果其两边的压力相同,则总曲率处处为零,而其边则满足强制的边界条件。同样的道理,近晶态中的层必定也会在遵循边界条件的前提下进行排布,以使势能取最小值。
英文
相对于不必要的复杂性和对称性缺失而言,简单性和对称性意味着储存较少的能量。让我们按照对称性逐渐减弱的顺序考虑各种可能的排布方法。
英文
图12.某种近晶态制剂同一部分的两张照片,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 | 但是该物质是液态的(夫里德耳,见上述引文)。如果有灰尘颗粒或其他侵入物质通过,它们可以自由移动,同时光学效应不变。分子的指向是受表面上的分子所支配的,即使有某种流量存在,分子也不会偏离其所在部分中的共同指向。但是,如果它们进入另一部分,原有的指向就会发生改变。
英文
现在假定将盖玻片相对于载玻片移动,或平移或旋转。在很多情况下,这必定会导致上表面分子的指向不同于下表面分子相应的指向。两者之间的夹角我们不妨称为α。接着就可以看到,沿途径会出现一种指向向另一种逐渐过渡;物质采取一种螺旋形或盘曲形的排布方式。如果将起偏器置于与下表面分子平行的方向,那么为了获得消光,就必定不能将检偏器置于垂直方向,而是要与垂直方向成α角。我们已经考虑... | 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
将对–氧化偶氮基苯甲醚从液态进行冷却时,首先出现的相变化现象是独立分子团的形成,图14显示了位于交叉尼科尔棱镜之间的物质所呈现出的效应。暂不考虑更具体的细节,每个分子团都呈十字形交叉,其两臂平行于尼科尔棱镜的主平面。在某些固体中可以观测到类似的效应,例如在碳酸锶和水杨苷中,有时也可以在熔岩和玻璃中,还可以在诸如胆甾醇乙酸酯等有机物中看到。这预示了每个分子团中存在一个核心,微小晶体的轴从这个点均匀地向所有方向辐射。在这些方向中的两个彼此垂直的方向上,晶体的轴分别平行于交叉尼科尔棱镜的两个主平面。当试剂相对于尼科尔棱镜旋转时,交叉结构并不移动,因而分子团独立于任何薄膜;它在各向同性液体的中心自由地漂流。分子或者从位于中心的核向外... | 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 | effect applies only to sufficiently thin superconducting films, less than a micrometre or so thick.
中文
E
XPERIMENTS on the relation of high frequency currents to the phenomenon of superconductivity led to work at Toronto with films of superconducting metals. The films (of tin) were produced by “tinning” the surface... | 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 seen that as the film of tin increases in thickness, a point is reached at which the superconducting property of the tin film is not lost by surface plating. This phenomenon will undoubtedly be of importance in framing a satisfactory theory of superconductivity—a consideration of utmost importance in dealing 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 | it even if the external magnetic field were removed. Yet the experiments reported here showed that the flux expulsion wasn't perfect: some magnetisation remains inside superconducting tin. This was the first evidence of persistent “supercurrents”, although their value was only one-sixth of that predicted earlier.
中文
... | 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 | (1) A solid tin sphere of 1.5 cm. radius was cooled from 4.2°K. to 2.5°K. (the liquid helium was produced in a liquefaction apparatus utilising the expansion method of Simon) in a field of 70 gauss. When the field was switched off, the magnetic moment of the sphere was observed with a test coil. Its magnitude was about... | 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 all these experiments the magnetic field was produced by a cylindrical coil in the middle of which the sphere was placed, all iron being excluded. Although the field near the sphere was thus fairly homogeneous, we think it possible that the observed phenomena may be influenced by slight inhomogeneities of the extern... | 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 | 如果事实确实如此,那么超导体中的感应磁通量应为零,而且我们也可以推断出与旧观点相反的结论:关闭外磁场并不会在超导体中产生持续的电流或有效的感生偶极。
英文
下列实验似乎表明,超导体虽然并不符合旧的理论,但也没有表现出磁导率为零的性质。
英文
(1)在70高斯的磁场中,将一个半径为1.5厘米的固体锡球的温度从4.2K冷却到2.5K(液氦是在一个液化装置中利用西蒙膨胀法产生的)。当关闭磁场时,我们用实验线圈测量固体球的磁矩。测量得出的磁矩大小约为根据洛仑兹方程计算所得值的1/6。
英文
当球的温度从2.5K上升到2.9K时,磁矩几乎保持恒定;而在温度进一步上升时,磁矩稳步减少,且在3.7K时变为零,这个临界温度就是锡的... | 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 | a table of all the determinations of the velocity of light which I compiled from the original memoirs, together with a discussion, and I pointed out that except a pair of practically simultaneous values obtained in 1882 the final values (printed in heavy type) indicate a secular decrease of velocity. The last (and lowe... | 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 | . Even “die-hards”, however, may fruitfully meditate over the 2nd and the 4th values in the above table.
中文
(133
, 464; 1934)
M. E. J. Gheury de Bray: 40 Westmount Road, Eltham, S.E.9.
References:
Nature
, 120
, 603, Oct. 22, 1927.
Phys. Z
., 698-702; 165-167; 1929.
Engineer
, Sept. 13, 1912.
Proc. Phys. 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 | reports on a failed attempt by Chadwick and colleagues to detect it. If such particles do exist, they found, they must have very small mass. Indeed they do, and because they interact so weakly with other particles, neutrinos are enormous difficult to detect. This was finally achieved in 1956. Physicists later discovere... | 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 | 对这种中性粒子可能的性质考虑得到的结果是,如果它们存在的话,其质量一定很小且磁矩为零。
英文
(王耀杨 翻译;朱永生 审稿)
The New Hydrogen
*
Rutherford
Editor's Note
Scientists had believed for more than a century that pure water is a well-defined chemical substance with molecular weight 18. That confidence was disturbed four years ago, Rutherford remarks in this lectur... | 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 | not appear to have any practical importance.
中文
As a result of investigations during the last two years, there has been a revolutionary change in our ideas of the constancy of the constitution of water. This has resulted from the discovery that a hydrogen isotope of twice the normal mass is always present in prepara... | 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 the relative abundance of the isotopes of oxygen was first measured, Birge and Mendel showed that there was a slight discrepancy—only about 1 in 5,000—between the ratio of the masses of the atoms of hydrogen and oxygen measured by Aston by the method of positive rays and the ratio deduced by direct chemical method... | 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 | isotope by fractional distillation of liquid hydrogen; and with some success. Another important observation was made by Urey and Washbourn, who found that the water in old electrolytic cells contained a larger proportion of heavy hydrogen than the normal. The concentration of H2
was found to be rapidly enriched by con... | 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 | indebted to Prof. Lewis for a sample of this heavy water with which we were able to make a number of experiments on the transformation of matter to which I shall refer later.
中文
We are all aware of the important part that hydrogen plays in many chemical compounds and particularly in organic molecules. When reasonabl... | 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 widely recognised that the new hydrogen will prove of so much general importance to chemistry and physics that it is desirable to give it a definite name and symbol. Prof. Urey, its discoverer, has suggested that the isotope of mass 1 should be called “protium” and the isotope of mass 2 “deuterium” while the nucl... | 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 | between the four units, the electron, positron, neutron and proton. If we assume, as seems not unlikely, that the D nucleus consists of a close combination of a proton with a neutron, it can be shown from the masses concerned that its binding energy should be somewhat less than 1 million volts if we take the value 1.00... | 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 discovery of heavy hydrogen has provided us with a new form of projectile which has proved markedly efficient in disintegrating a number of light elements in novel ways. It was a very fortunate coincidence that, when Prof. Lewis had prepared some concentrated diplogen, his colleague in the same University, Prof. La... | 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 | Still another interesting type of complex transformation occurs in this element. Oliphant and Rutherford observed that lithium when bombarded by diplons gave, in addition to the group of fast α-particles first observed by Lawrence, a distribution of α-particles of all ranges from 7.8 cm. to 1cm. in air. It is believed ... | 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 groups contain equal numbers of particles.
中文
In order to account for these observations, it seems likely that, as the result of a close collision, the diplon occasionally unites with the struck diplon to form a helium nucleus of mass 4 and charge 2, but containing a large excess of energy over the normal heli... | 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 of interest to speculate why the heavy isotope of hydrogen appears in many cases far more effective, for equal energies, in producing transformations than the lighter isotope. On the general theory of transformation proposed some years ago by Gamow, it is to be anticipated that, for equal energies of motion, 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 | 比如现在我们在水的制备过程中,可以将质量为1的氢同位素完全用质量为2的同位素代替。重水的密度比普通水约大10%;其凝固点是3.8°C,沸点也比普通水高1.42°C。虽然在表观上重水与普通水类似,但在物理性质和化学性质方面它们却有明显的差异。与普通水相比,重水不仅有明显不同的蒸汽压,而且潜热也相当高。其表面张力和介电常数都较低,黏度则相对较高。
英文
在这里我很乐意简要地指出这段发生在知识领域飞速进步的近乎浪漫的历史,并且非常有意思的是重氢的发现与已故的瑞利爵士对大气中氩气的发现存在某些相似之处。这两个“发现”的线索都缘于对在密度的精确测量中观测到的微小差异的重要性的重视。
英文
首次对氧同位素的相对丰度进行测定后,伯奇和... | 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 | 其发现者尤里教授提议质量为1的同位素应称为“protium”,质量为2的同位素称为“deuterium”;而重氢的核应称为“deuteron”或“deuton”,后者已被认为可在物质变换过程中用作非常有效的轰击粒子。合适的命名对科技工作者具有普遍的重要性,并且值得慎重地思考。另一种命名似乎在英国获得青睐,即将2
H命名为“diplogen”(διπλουs
,意思为“双”),将其原子核命名为“diplon”。以D作为重同位素的符号似乎是非常合适的。
英文
尽管重氢(或氘)可以从接近于纯态的重水中大量分离出来,不过我还是很乐意提一下赫兹所使用的另一种分离方法。他所发明的这种特殊的扩散法,使他已经能够从普通氢气中分离出体积约1... | 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,射出的粒子数远大于在同样电压下任何其他嬗变中观测到的粒子数。发射出的主要质子群在空气中的射程为14厘米,其相当于3百万电子伏的能量。除此之外,我们还观测到另一组很强的带单位电荷的带电粒子群,其在空气中的射程仅为1.6厘米。这两组粒子群中包含了相同数量的粒子。
英文
为了解释这些观测,似乎可以认为其是近距碰撞产生的结果。入射氘核有时会与被击中的氘核一起形成质量为4、电荷数为2的氦核,但其能量大大超过正常氦核的能量。新的原子核继续爆炸并分裂为两部分,一部分是快质子,另一部分是质量为3的氢的新同位素
。如果这种情况的确存在,那么质子和3
H核应分别向相反方向飞出。这时可以简单计算出反冲3
H核的射程应是1.7厘米,这与... | 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 | N application of science has enabled a chairman of a company to become a historic figure. At the annual general meeting of Baird Television, Ltd., held in a theatre in the west end of London on March 20, the shareholders heard and saw distinctly the chairman address them from a studio at the Crystal Palace, nearly eigh... | 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 | high definition television service for the whole of the Greater London area, which includes a population of about eight millions. Capt. A. G. D. West, who joined the board of the Baird Company last June to direct its technical development, is to be warmly congratulated on his achievement; and the Company on the first 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 | 在1933年9月30日的《自然》上丘奇少校曾描述过该方法,通过这种方法,时事新闻的电视图像能够在事件发生后的几秒内显示在电影院屏幕或者家用接收机上。在贝尔德先生发明的新“扫描”系统上进行的另一系列实验也快要完成了。这些实验的目的是确保演播室有足够的照明度,以使“拥挤”的镜头能直接高保真地在电视上播放。
英文
(刘霞 翻译;赵见高 审稿)
A Rapid Test for the Diagnosis of Pregnancy
C. W. Bellerby
Editor's Note
In the 1930s, biologists were occupied with two important and novel sea... | 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 | can be obtained easily and cheaply in large numbers. Several hundreds can be kept without difficulty at the sole cost of a few handfuls of raw meat once a week, provided that they are kept in a warm well-lit room and that their water is changed after feeding. Ovulation does not occur spontaneously in captivity. Ova she... | 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 | (2) If less than one month has elapsed, a sample of 100 ml. of urine is precipitated with acetone and centrifuged. The residue is suspended in 10 ml. of distilled water and 1 ml. of the suspension injected into each of 10 toads. A positive result is indicated as before. This procedure is necessary owing to the facts 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 | 在10只爪蟾的淋巴囊内分别注射1 ml尿液。如果在9小时内,10只爪蟾中至少有5只出现了排卵,那么结果就是阳性的。将装有爪蟾的容器放置在20°C~25°C的房间里,通过电热装置来保证温度的准确性。
(2)如果时间还未到1个月,那么就取100 ml尿样,用丙酮使其沉淀并离心。将沉淀物溶解于10 ml蒸馏水中。在10只爪蟾的淋巴囊内分别注射1 ml这种悬浮液。阳性结果的判断方法同前。这个操作过程是必需的,因为在怀孕后最初的时期,1 ml尿液中所含有的卵巢刺激物质的量不足以引起排卵反应,而且为了保证吸收,不能向淋巴囊内注射2 ml以上的体液。
英文
我们随后将详细叙述这项工作的过程。目前为止还没有出现错误的诊断。考虑到这种检测方法的... | 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 | and one would expect that positive electrons could also sometimes be created together with a neutrino in nuclear transformations. Therefore the experiments of Curie and Joliot5
on an artificial positive β-decay give strong support to method (b
), as one can scarcely assume the existence of positive electrons in the n... | 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 possibility of creating neutrinos necessarily implies the existence of annihilation processes. The most interesting amongst them would be the following: a neutrino hits a nucleus and a positive or negative electron is created while the neutrino disappears and the charge of the nucleus changes by 1.
中文
The cross ... | 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 point of view was first put forward by I. Curie and F. Joliot at the Conseil Solvay, 1933.
I. Curie and F. Joliot, Nature
, 133
, 201, Feb. 10, 1934.
“中微子”
贝特,佩尔斯
编者按
泡利认为放射性β衰变的过程中涉及了一种未知粒子——中微子,汉斯·贝特和鲁道夫·佩尔斯在这篇文章中对沃尔夫冈·泡利这一提议的含义进行了讨论。如果这种粒子质量很小且自旋为1/2,那么β衰变中放出的电子能谱的连续性就是可以理解的,而且核反应过程也因此而能满足能量和动量守恒。他们认为衰变发生... | 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
(沈乃澂 翻译;刘纯 审稿)
Disintegration of the Diplon
P. I. Dee
Editor's Note
The recent experiments of Oliphant, Harteck and Rutherford with “diplons” (nuclei of the hydrogen isotope deuterium) suggested that they might react in pairs to form 3
He and 3
H. A colleague at the Cavendish Laboratory, Philip Ivor Dee, here ... | 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 14.3 cm. range emerging through the thick window and the particles of 1.6 cm. range emerging through the thin window end in the chamber and the usual reprojection permits precise determination as to whether the two tracks are co-planar and of the ranges. Owing to the fine structure of the grid supporting the thin wi... | 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 the first to be made with a new discharge tube constructed following a design due to Dr. Oliphant. I should like to acknowledge the much valuable advice which Dr. Oliphant has always so readily given me in the course of construction of this tube. I am also indebted to him for preparing the diploge... | 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;张焕乔 审稿)
Apparent Clustering of Galaxies
B. J. Bok
Editor's Note
Recent surveys of the placement of distant galaxies made it possible to begin describing their distribution. Here Bart Bok of the Harvard Observatory reviews evidence that galaxies are clustered, not distributed at random. This is particular... | 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 | exhibits conspicuous deviations from a random distribution. Both galactic polar caps were divided into a number of equal areas (well-known clusters being excluded), and the number of galaxies was counted in each area. The observed frequency curve had a much larger dispersion than the theoretical curve, computed on 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 | . For the south galactic polar cap the discrepancy is even greater. We should in addition consider Shapley's elegant and definite proof for the presence of clustering in nine regions4
.
中文
We can scarcely escape the conclusion that a widespread tendency towards clustering among galaxies is one of the chief characte... | 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
(周杰 翻译;邓祖淦 审稿)
The Inheritance of Acquired Habits
E. W. MacBride
Editor's Note
By the mid-twentieth century, Lamarckism—the idea that organisms can pass on traits developed in response to their environments—was out of favour. Paul Kammerer, whose work William MacBride cites here, killed himself in 1926, shortly ... | 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 | , an eastern and a western. In the latter, which inhabits the Jura and the Vosges, the yellow pigment is arranged in two longitudinal bands on the back, over a general body colour of black. Miss Sladden has reared animals of this race from birth to an age of three years in boxes painted inside with bright yellow 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 | about three months to develop: there is no metamorphosis and as there are no wings the nymph is morphologically similar to the adult.
中文
The plan adopted was to isolate the just hatched young, keeping each one in a separate box. These boxes were made of metal: they were circular and had glass covers. In each box was... | 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 with these insects, we reached exactly the same conclusions as those arrived at by Prof. McDougall with regard to induced habits in rats, namely, that when members of one generation are compelled to adopt a new habit, a residual effect of this habit is carried over to the next generation, so that the young insects... | 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 | reviewed in Nature
of December 17, 1932, removed Cladoceran Crustacea from northern lakes to Lake Nemi in Italy. When he examined the transported stock after twenty years he found them much altered in shape: when he again re-transferred some of this stock to the post-glacial lakes of their ancestry they reverted to 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 | original constitution reasserts itself. In 1790 Capt. Cook introduced the English domestic pig into New Zealand in order to induce the Maoris to abstain from cannibalism. The animals escaped into the woods, and by 1840 had increased to herds of at least 40,000 in number and had assumed all the characters of the ancestr... | 400套付费套装书 |
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