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C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 1. We must examine the alternative possibility of Photograph 1 representing the spontaneous disintegration of a charged particle, coming up from below the chamber, into a charged and an uncharged particle. If we apply the argument which led to equation (4) to this process, it is readily seen that the incident particle ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | and less than that of a proton into an observed penetrating particle and a neutral particle. It may be noted that no neutral particle of mass 1,000m
has yet been observed; a charged particle of mass 990m
± 12 percent has, however, been observed by Leprince-Ringuet and L'héritier2
.
中文
Peculiar cloud-chamber photo... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 而图2中的另一条径迹(a
、b
径迹)代表了相似的转变过程:一种新的带电粒子转化为两种轻粒子,其中一种粒子带电,另一种粒子不带电。
英文
图1.立体照片显示了云室气体中一条不同寻常的叉状径迹(a b
)。磁场的方向使得向下运动带正电的粒子沿着逆时针方向发生偏转。
英文
图2.立体照片显示了云室气体中一个不同寻常的叉状径迹(ab
)。磁场的方向使得向下运动带正电的粒子沿着顺时针方向发生偏转。
英文
这两条叉状径迹的实验数据如表1所示。H
为磁场的强度值,α为叉状径迹的夹角,p
和Δp
为动量的测量值和估计的误差值。在表格的最后一列给出这些粒子的符号,其中正号表示如果粒子穿过云室向下运动,则粒子带正电... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 因此对于图1中观测到的每一种粒子,其电离情况与快粒子的电离情况是难以辨别的。因此,我们得出结论β=v
/c
≥0.7。既然入射粒子的动量可以由探测到的次级粒子的动量得出,我们就可以用公式(1)计算得出入射粒子的质量M
。按这种方法分析,我们得到M
/m
≤1,600。此外,由于图2中入射粒子的电离结果是轻粒子,β≥0.7,由此得到M
/m
≤1,200。然而,我们必须谨慎处理最后的结果,因为入射粒子动量的测量值具有不确定性。
英文
下面进行更深一步的全面讨论。即在这种少量的贯穿簇射中观测到的两个自发衰变表明,不稳定粒子的寿命要比普通介子的寿命短得多。下面的推导中将给出这个寿命的近似值。寿命为τ0
的不稳定粒子在... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | T is known that the spherical aberration of electron lenses sets a limit to the resolving power of electron microscopes at about 5 A. Suggestions for the correction of objectives have been made; but these are difficult in themselves, and the prospects of improvement are further aggravated by the fact that the resolutio... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | appreciable part of the primary wave. The photographic record is produced by the interference of the primary wave with the coherent part of the secondary wave emitted by the object. It can be shown that, at least in the outer parts of the diagram, interference maxima will arise very nearly where the phases of the prima... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | reconstruction are chiefly due to defects in the microscope objectives used for the production of the point focus, and for observation.
中文
It is a striking property of these diagrams that they constitute records of three-dimensional as well as of plane objects. One plane after another of extended objects can be obse... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | which may be called the “electron interference microscope”, will now be taken in hand.
中文
I wish to thank Mr. I. Williams for assistance in the experiments, and Mr. L. J. Davies, director of research of the British Thomson-Houston Company, for permission to publish this note.
中文
(161
, 777-778; 1948)
D. Gabor: R... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | (c
)干涉图,利用从一个焦点发散出来的射线束将显微图投影于照相干板上得到。字母由于衍射而变得模糊。(d
)利用光学合成从左侧图像得到的重现影像。以(b
)为参照,字母再度由模糊变得清晰。
编者注:图中所使用的三个人名Huygens(惠更斯)、Young(杨)、Fresnel(菲涅耳)代表证明光的波动性的三位重要科学家。
英文
将显微镜经过焦点向另一侧移动,我们会在相对于该焦点中心对称的位置发现原物体的第二个像。对此现象的简要解释是,照相图像无法区分初级波的正相移与负相移,这第二个像与原物体的相移相同,但是符号相反。
英文
如果将该原理应用于电子显微镜,那么在光学合成仪器中的尺度应该按光波对电子波的比值(即大约1... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | followed so closely on the Pan-African Congress of Prehistory, held in Nairobi in January of that year, when the implications of earlier finds first gained a wide recognition. The discoveries are due primarily to two men of science, Dr. Robert Broom in South Africa and Dr. L. S. B. Leakey in Kenya.
中文
The new discov... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | that of the foramen magnum, it should be noted, seemed to make it clear that the Australopithecinae were capable of assuming an erect posture closely approaching that of man.
中文
This accumulation of evidence was sufficient to convince most anatomists that the importance of the Australopithecinae had not been exagger... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | evidence that the canine was relatively small (compared with the premolars) and became worn down flat to the level of the adjacent teeth4
. In all these skulls the endocranial capacity seems to vary about 500 c.c.
中文
Dr. Broom, however, has not only found a number of skulls, but has also collected a considerable nu... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | It will naturally be some time before a detailed account of all this new material from Sterkfontein can be published, but private communications, together with unpublished photographs and drawings, make it clear that the information now available on the anatomy of the Australopithecinae is astonishingly complete. State... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | . Following the Pan-African Congress on Prehistory, some of the delegates had the opportunity of visiting the sites of these discoveries and were impressed with the possibilities of further excavation. A British-Kenya Miocene Expedition was therefore organised with the aid of a grant from the Royal Society, with Dr. Le... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | In all these specimens (which provisionally are regarded as constituting several species of the genus Proconsul
), there are certain characteristic features. The incisors are relatively small in comparison with modern apes, and the symphysial region of the jaw in narrow, the axis of the symphysis tending to be more ve... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Only a few limb-bones of the Early Miocene hominoids have so far been found, but these have provided information of unusual interest. The femur provisionally referred to Proconsul
is a long, slender and straight bone, very similar to the Eppelsheim femur, which is probably that of Dryopithecus
. The humerus is likewi... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Africa was populated with numerous species of primitive apes ranging in close gradations of size from small creatures no larger than Hylobates
to great apes of gorilloid dimensions.
中文
(161
, 667-669; 1948)
W. E. Le Gros Clark: F.R.S., Department of Human Anatomy, Oxford.
References:
Broom, R., and Schepers, G. ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 英文
这些证据的积累足以使大多数解剖学家相信南方古猿亚科的重要性并未被夸大。然而,一些评论家表示了怀疑,毫无疑问,这主要是因为他们没有机会亲自查看原始材料。另一个事实是,尽管这些材料很丰富,但是从某些方面看,它们是破碎的,因此要想正确理解其不寻常的特征,就需要对人猿超科的比较骨骼学有相当缜密的认识。1947年初,布鲁姆博士在斯泰克方丹重新开始了他的发掘工作,4月他宣布发现了一件非常完整的成年南方古猿头骨、另一个成年南方古猿的上颌骨、一个未成年南方古猿的上颌骨以及一些单个的牙齿[3]
。在斯泰克方丹化石材料中,该完整头骨被编为“5号头骨”。随后进一步的发掘工作表明在斯泰克方丹同一区域的石灰岩基质中埋藏了更多的南方古猿亚科化石,而且... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 英国–肯尼亚中新世探险队在松戈尔发现一个巨大下颌骨的残块,它代表了一种更大的物种,在某些方面这件颌骨比许多成年雄性大猩猩的颌骨还要粗大。
英文
在所有这些标本中(我们暂时把它们当作是原康修尔猿属下的几个不同物种),都存在几个典型特征。与现代猿类相比门齿较小;颌骨联合部狭窄,联合部轴线更加垂直;犬齿巨大,几乎没有明显的性别差异;相应地第一下臼齿有些小,上臼齿具有发育良好的内齿带,内齿带有时候呈现为精细的串珠状,下臼齿具有非常明显的外齿带痕迹。已发现的一些原康修尔猿的未成年颌骨对于了解这些原始猿类的牙齿更替情况很有帮助。鲁辛加岛及其周边地区发现的一些上牙与原康修尔猿的上牙大小相似,但是齿尖样式差异很大。这些表明它们与中新世中期的印... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | “osteodontokeratic” culture. These ideas have since fallen from favour for lack of evidence.
中文
D
URING 1947 the Bernard Price Foundation for Palaeontological Research in the University of the Witwatersrand maintained an archaeological party in the Makapansgat Valley, twelve miles north-east of Potgietersrust. Thei... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | occipitalis (or sutura mendosa) with subsidiary sulci forming a complex “Inca” bone (which has never been found hitherto in anthropoids).
中文
Australopithecine occiput from the Makapansgat Valley
中文
In all these features the Makapansgat Australopithecus
distinguishes itself from its smaller-brained contemporary ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | ). Thus apart from the elephant we have concrete evidence that these creatures drew upon every family of big game found in Southern Africa for their food supply. The dentitions of the big game specimens, however, show that these Australopithecines were more frequently successful in slaying juvenile and aged representat... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | agent is corroborated by their discoloration, disintegration and the chemical reports of free carbon made more than twenty years ago, and by the vesicular character of the adjacent glassy collophanites and clays recently discovered in the breccia by Dr. V. L. Bosazza and the comparative analysis he has made of ashy dep... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 然而,大型猎物标本的齿系显示,这些南方古猿亚科通常更善于猎杀各种哺乳动物科中的幼年和老年动物。而丰富的骨角砾岩表明它们有能力成功猎取到很大的猎物。
英文
1925年,南方古猿的存在尚未被意料到,因为这些骨太大并且它们的外观都是烧焦的,因此在马卡潘斯盖河谷石灰厂发现的骨角砾岩标本被送到了两位化学家(莫伊尔博士和福克斯博士)的手中,以分析这些骨是否曾受到过大火的灼烧。从角砾岩中发现的野兽个头之大、这些曾被故意折断或者拆分的骨、以及化学家们给出的关于碳存在的确证报告都表明,该沉积物在那时是作为原始人类的厨房内堆积物。现在,马卡潘斯盖河谷石灰厂遗址的所有这些“人类”的活动可能都是这些南方古猿亚科祖先们的行为。在马卡潘斯盖河谷石灰厂地层... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | different ages judging by the faunas. Almost all the animals at Kromdraai main deposit are quite different species from those at the main quarry at Sterkfontein. The jackals, the sabre-toothed tigers, the baboons, the dassies and the ape-men are quite different species.
中文
At the beginning of November we started wor... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | The mandible is very massive. The horizontal ramus is preserved from the 2nd premolar to the 2nd molar; the 1st premolar is also preserved but a little displaced. Most of the inner side of the symphysis resembles more closely that of the Heidelberg jaw than any other specimen of man or ape-man I know.
中文
But the tee... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 从克罗姆德拉伊主要沉积物中出土的几乎所有的动物都与在斯泰克方丹主采石场发现的物种有相当大的差异,如胡狼、剑齿虎、狒狒、蹄兔和猿人之间的差异非常大。
英文
11月初,我们和加利福尼亚大学探险队合作,在一新遗址处开始了发掘工作。尽管此处沉积物所在的斯瓦特克朗斯农场距离斯泰克方丹主采石场仅仅一英里,但是就我们发现的动物群而言,它们存在着很大差异,但是还不能断定二者谁的年代更久远。幸运的是,我们在10天之内就发现了一种新型猿人的牙齿,并在一星期后又发现了大半块下颌骨化石——具有完整的下前臼齿和臼齿。
英文
这件新型下颌骨与斯泰克方丹猿人(迩人)的下颌骨并无紧密的亲缘关系;而牙齿与克罗姆德拉伊猿人(傍人)的牙齿具有亲缘关系,但它们... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | -particle's mass by counting photographic grains, they found a value of roughly 1,080 times the electron mass. They interpret its decay as a process involving the creation of two particles called pions. These discoveries led towards the discovery, within a decade, that interactions involving the weak nuclear force do n... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | ; that it carried the elementary electronic charge and that it had reached, or was near, the end of its range at the point A
. We therefore assume that the particle k
initiated the train of events represented by the tracks radiating from A
and B
. It follows that the particle producing track t
originated in star A... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | , which gives a nearly uniform degree of development with depth.
中文
In the plates obtained by these methods, it is legitimate to compare the grain-density in the tracks of unrelated particles. Further, it is now known that at least the majority, and possibly all, the mesons which produce “stars” are π-
-particles6,... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | , and the measurements are represented in Fig. 10. This figure shows the mean values of the grain-density in the tracks of the four μ-mesons and four protons, together with the corresponding results for the particle k
. All the tracks under consideration occurred in the same plate.
中文
Fig. 10
中文
Table 1 shows t... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | lies between 700 and 1,800 m
e
, and we think it highly probable that it is substantially less than that of the proton. Thus every individual point representing the grain-density in the track k
, at a particular value of the residual range, lies below the corresponding points for each of the four protons.
中文
Disin... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | , we have calculated the variation with energy of the specific ionization of a particle of charge e
, from the formula of Halpern and Hall9
, assuming the atomic composition of the emulsion to be identical with that of the Ilford C
2 plates. This formula is a modification of that of Bloch10
; it applies to particle... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | -particle. It appears almost certain, however, that the release in a nucleus of such a large amount of energy would lead to the “evaporation” of many nucleons, a process commonly observed in plates exposed to the cosmic radiation; and that two protons of great energy would be only two components of a “many-pronged” sta... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | were mesons, we must assume, in order to conserve mass-energy, that their kinetic energies were 27 MeV. or 37 MeV., respectively, in the case of μ- or π-mesons (see Fig. 11). In either case, it appears to be very difficult to reconcile the observations with the assumption that the particles were emitted as a consequenc... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | were found to be coplanar. The departure of the direction of motion of any one particle from the plane defined by the other two is less than 4°. The error in this determination is largely due to the fact that track t
is of short range, and the particle producing it was of low velocity, and frequently scattered.
中文
... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | are assumed to be due to either electrons or protons. Further, the values of the momenta, as deduced from observations on the scattering of the particles, are inconsistent with those obtained from grain-counts, if the particles are assumed to have been either electrons or protons (see Table 2).
中文
The agreement betw... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | . The assumption of different particles, one π- and one μ-meson, gives an intermediate value of approximately 925 m
e
. In view of the error in the direct determination of m
k
, the results are not decisive.
中文
If the transmutation is to be interpreted in terms of particles of which the existence is already establ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | In the light of the analysis made in the preceding sections, we can now return to the original assumption that the event is not to be regarded as a fortuitous juxtaposition of tracks. The accuracy of the determination of the mass of the particle k
does not allow us to exclude the possibility that it has a mass as grea... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | shall be odd. From this point of view, the sign of the charge of the original particle can have been either positive or negative. If the particles producing tracks a
and b
form a pair of opposite sign, then the original k
-particle was negative. The only other alternative is that they were both positively charged, i... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | . It is a remarkable feature of their experiments that their τ-mesons give rise to no recorded secondary particles at the end of their range. It appears to be possible that these particles also decay with the emission of three fast mesons, but that the transmutation usually takes place with a more equal partition of ki... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 2 emulsions exposed at 90,000 feet, he and Dr. Bradt have observed three events with the following characteristics. A particle, which they judge to be similar in mass to their τ-mesons, appears to come to rest and to lead to the emission of a particle of smaller mass, which, at the end of its range, produces a nuclear ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Dilworth, Occhialini and Payne, Nature
, 162
, 102 (1948).
Occhialini and Powell, Nature
, 162
, 168 (1948).
Halpern and Hall, Phys. Rev
., 73
, 477 (1948).
Livingston and Bethe, Rev. Mod. Phys
., 9
, 263 (1937).
Camerini and Lattes (private communication); see also Powell and Occhialini, “Nuclear Physics in Ph... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 用这两类方法得到的结果分别为m
π
/m
μ
=1.65±0.11和m
π
/m
μ
=1.35±0.10
*
。最近在伯克利进行的实验[6]
表明,其真值为1.33±0.02,这个结果使人们对颗粒计数方法的可靠性产生了严重的怀疑。但是考虑到该方法的优点,以及据此得到的一些重要结论,我们进行了一些实验来确定在何种条件下才能获得可靠的结果。
英文
在首次实验中[5]
,两个最为严重的实验难点来自于潜影的褪色和显像度随深度的变化。若要对同一对π介子和μ介子径迹的颗粒数密度进行对比,就必须研究同时形成的径迹。然而这样一来,可以用于测量的π介子的径迹大多小于400微米。在后续的实验中,通过运用短期曝光的方法获得了更多良... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 在长径迹a
中,平均颗粒密度是每100微米49.0个颗粒,该密度是电荷为e
的粒子最小电离特征值的2.17倍。除非我们允许存在电荷的分数值,否则我们必然会得出,产生径迹a
和b
的粒子的带电量均为e
的量级。
英文
为了测定产生径迹a
和b
的粒子能量的可能值,我们假定乳胶的原子组分与伊尔福C
2胶片相同,根据哈尔彭和霍尔的公式[9]
计算了电荷为e
的粒子的比电离值随能量的变化。这个公式是布洛赫公式[10]
的修正形式;该公式适用于在固体介质中运动的粒子,并给出了与低能粒子的实验非常符合的结果。结果示于图11中,将比电离值作为量E
/m
的函数绘图,E
和m
分别为粒子的能量和质量,两个量均以兆... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 英文
如果我们将径迹t
归因于π-
粒子是正确的,则根据观测到45微米的射程可得,发射的动能是1.04兆电子伏。该粒子相应的动量值是17.5兆电子伏/光速。根据观测到的运动方向,可得产生径迹a
和b
的粒子的动量分别为98±5兆电子伏/光速和104±5兆电子伏/光速。这些值将与表2中列出的根据观测的径迹中颗粒密度而导出的相应的电子或介子的数值相比较。我们已看到表2中列出的两个粒子的动量值,如果假定它们是电子,则这些值显然已大出很多倍。因此如果假定径迹a
和b
是由电子或质子产生的,则与动量平衡存在很大的偏差。而且无论粒子是电子还是质子(见表2),根据粒子观测到的散射而导出的动量值与从颗粒密度得出的值也是不一致的。
... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 如果产生径迹a
和b
的粒子的电荷符号相反,则原始的k
粒子带负电。仅有的另一种可能是,它们两者都带正电荷,在这种情况下,k
粒子也是正的。因此可能的情况是,我们的观测对应于质量近似为900 m
e
的带正电粒子的衰变模式,而由勒普兰斯·兰盖[2]
的观测则表明了相应的负电粒子的情况,即核俘获产生“星”并发射π-
粒子。
英文
罗切斯特和布特勒[2]
已发表了一张膨胀室的照片,它记录的可能是一个质量近似为900 m
e
的中性粒子自发衰变形成了一对电荷相反的静止质量近似为300 m
e
的粒子。因此我们认为,该结果反映的衰变过程可能分为两个步骤:一个低能π-
粒子的发射和随后产生的中性粒子的自发衰变。然而... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | and more human. It was found in a lens of much more recent material than that which had yielded the australopithecines. Broom and Robinson compared the jaw with the famous Mauer mandible, exemplar of “Heidelberg Man” (now called Homo heidelbergensis
), calling it Telanthropus capensis
. This form was later reclassifi... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | The horizontal ramus is remarkably shallow. At the 1st molar it is only 29 mm. The base of the ramus is nearly level, and the angle is rounded and scarcely at all below the general level.
中文
The ascending ramus has apparently been fairly broad, but very shallow. Fortunately the cast of the side of the one condyle is... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | The new type of man represented by this fossil jaw we propose to call Telanthropus capensis
. We regard him as somewhat allied to Heidelberg man, and intermediate between one of the ape-men and true man.
中文
Fig. 1. Side view of lower jaw of Telanthropus capensis
B. and R. (half-size)
中文
Fig. 2. Occlusal view o... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 虽然在同一个洞穴中还发现了另一种类型的古人类颌骨化石,但是这个颌骨与傍人的不同而更像人类。它所在的沉积物的年代比发现南方古猿亚科所在的沉积物的年代晚很多。布鲁姆和鲁滨逊将此颌骨与作为“海德堡人”(现在称为人属海德堡种)标本的著名的毛尔下颌骨化石进行比较,并将其命名为开普远人。这种类型后来被归为直立人。
英文
在斯瓦特克朗斯一处洞穴中,已出土过一个巨型猿人傍人粗齿种的颌骨和头骨,1949年4月29日,鲁滨逊先生在其中发现了一个下颌骨,很明显,它是一个新型古人类的下颌骨。尽管这个下颌骨与早先发现的大型猿人是在同一个洞穴里发现的,但是很明显这种新型古人类所处的年代要晚得多。在洞穴主要骨角砾岩的沉积物中有一个被挖掘过的凹坑的痕迹,凹坑... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 英文
(刘皓芳 翻译;吴秀杰 审稿)
New Evidence on the Antiquity of Piltdown Man
K. P. Oakley and C. R. Hoskins
Editor's Note
The famous skull and jawbone of a fossil human excavated near Piltdown in southern England in 1912 had been the focus of much attention by anthropologists. By the 1940s, the combination of modern-looking sk... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | The Piltdown gravel is a thin remanié deposit in a terrace about 50 ft. above the River Ouse, containing fossil mammals of two distinct ages: a derived Villafranchian series (“Upper Pliocene” of earlier authors, now classed as Lower Pleistocene), and a later Pleistocence group, in part at least contemporary with the gr... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | argued that the skull should be assigned to the “Pliocene” group. He was influenced, he said, by the fact that in the Heidelberg jaw, of early Pleistocene date, the region of the chin was essentially human, whereas the Piltdown mandible showed simian characters. E. T. Newton5
said that the mineralized condition of the... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | ), undoubtedly a member of the derived group, was practically unrolled. The evidence then available, he said, justified the statement that “Piltdown Man is the oldest human fossil yet discovered” (ref. 6, p. 57).
中文
In recent years many anthropologists have held the view that, so long as its date remained uncertain,... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | After preliminary trials, Mr. R. H. Settle and one of us (C. R. H.), assisted by Mr. E. C. W. Maycock, adapted published methods of analysis to the exact determination of fluorine in very small samples of bone. A description of the analytical technique and a discussion on the limits of accuracy will be presented in a r... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Approximate estimations of the iron and phosphate contents of the bones were made on residues of the samples remaining after the fluorine determinations. Colorimetric methods were used in each case (thioglycollic acid for iron, and ammonium molybdate followed by reduction of phosphomolybdate with stannous chloride for ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | and associated mammalian bones and teeth. For the most part the samples were obtained by applying a dental drill to broken or worn edges of the specimens until a small but sufficient quantity of bone powder had been cored out. Where possible, powder from several drill holes in each specimen was mixed in order to ensure... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | sp., Cervus
sp.), than Villafranchian. Any such post-Villafranchian elements might theoretically be of first interglacial age (when according to Hopwood's terminology the “Middle Pleistocene” fauna began to appear); of great interglacial age (that is, Middle Pleistocene of all authors), or of last interglacial age (th... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | included a substantial proportion of dentine. The two exceptions were samples of enamel (P.
6, P.
24).
中文
On the evidence of their state of preservation, the molar and premolar of Hippopotamus
were placed by Hopwood (ref. 6, p. 49) with Eoanthropus
in the Lower Pleistocene group. He noted, however, that Hippopot... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | belonging to the Villafranchian group; but whether it is Middle Pleistocene or later is arguable. That the figures scarcely provide any differentiation between Eoanthropus
and recent bones requires some explanation; but at least it serves to emphasize the probably enormous time-gap separating the former from the Lower... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | From the palaeontological data alone, it is not possible to decide whether the final settlement of the Piltdown gravel took place during Middle or early Upper Pleistocene times.
中文
It was pointed out by Clement Reid11
that these gravels rest on a low plateau surface (100-120 ft. above O.D.) which was extensively de... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Marston, A. T., Geol. Assoc. London, Circular
, No. 483, 1 (1946).
Dawson, C., and Woodward, A. S., Quart. J. Geol. Soc. London
, 70
, 82 (1914).
Keith, A., Quart. J. Geol. Soc. London
, 69
, 148 (1913).
Newton, E. T., Quart, J. Geol. Soc. London
, 69
, 151 (1913).
Hopwood, A. T., Proc. Geol. Assoc. London
, 46... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 英文
在读到道森和伍德沃德的第一篇论文(参考文献1,第123页和第143页)时,他们在文中陈述了自己的观点,即实际上未被滚磨过的人类头骨和下颌骨与砾石层是同一时代的,因此可能是“更新世”时期的。然而在接下来的讨论中,阿瑟·基思[4]
爵士认为,头骨应该属于“上新世”时期,这是由于更新世早期的海德堡下颌骨的颏部本质上是人类的颏,而皮尔当人的下颌骨却显示出了猿的特征。牛顿[5]
认为头骨的矿化情况表明它们是“上新世”时期的生物。在对这一讨论进行回复时,道森承认了这一可能性,因为他指出(参考文献1,第151页):“......处于被显著滚磨过的状态的某些上新世时期标本的出现,提示了年代的差异,但是并不排除它们属于同时代生物的可能性。... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 简单地说,斯旺斯孔布的中更新世阶地砾石层中的本地的骨化石含有约2%的氟,而同一地区的上更新世沉积物化石骨的氟含量约为1%,晚更新世骨的氟含量则不高于0.3%。尽管伽力山骨架发现于中更新世时期的砾石层之中
,但是事实证明这些样本的氟含量只有约0.3%,因此很明显这是发生在更新世末的早期阶段的一处侵入型埋藏。另一方面,1935年~1936年间,马斯顿在这些砾石层发现的斯旺斯孔布头骨氟含量为2%,这与预期的结果一致。
英文
对其他遗址的一系列骨也进行了分析,结果表明尽管使用范围有局限性,但是当许多样本混合在一起同时出现、并且假如用来进行比较的样本具有相似的基质的话,那么用这种方法来区分不同年代的骨化石还是很有效的。这种方法不能用来... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 曙人的牙齿与该河马牙齿形成了鲜明的对比,实际上它与所有相关的动物牙齿化石都截然不同。非常出乎意料地是,曙人犬齿和臼齿上的钻孔揭示出,在非常薄的一层铁锈斑点表面之下,它们的牙本质是洁白的,这显然与从土壤中发现的近代牙齿的牙本质完全一样。
英文
对归于曙人的样本的氟值与地质学年代已确定的骨和牙齿的氟值进行的比较几乎可以确信:(1)包括两英里外发现的第二件头骨化石在内的所有曙人标本都是同一时代的;(2)曙人所处的年代最早是中更新世。
英文
任何关于曙人是否属于维拉方群的疑问都不复存在了,但是它属于中更新世还是更晚年代则还在争论之中。那些无法提供曙人和最近骨之间存在任何差异的数值尚需解释,但它至少强调了把曙人与下更新世材料分开的... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | . They admit that controversy still raged between those who saw the fossils as almost human, and those who regarded them more as apes, with the intermediate “ape-man” designation being seen by some as a kind of compromise. Broom and Robinson say that all those who had actually seen the fossils came away with the feelin... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Recently we have found five skulls with fair-sized brains. One is a child skull with a brain of perhaps 600 c.c., and one that of a child with a brain of about 700 or 750 c.c. Then we have two nearly complete female skulls with brain cases which we estimate at about 800 or 850 c.c. Each skull lacks the occiput, but is ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | We have a perfect female mandible with all the teeth in perfect condition and a number of other jaws in fairly good condition. One striking feature is that all the jaws have some indication of a chin, and one has a typical human chin with a well-marked mental prominence. If we did not have the whole symphysis, which is... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | , and a few still hold that they are all anthropoid apes. A considerable number of men of science from America and Europe have visited South Africa to examine our specimens, and we think all who have taken this trouble have gone back convinced that at least we have the remains of beings that were much more human in str... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Again, the teeth seem to solve our problem. Australopithecus
and Plesianthropus
have remarkable milk pre-molar teeth. Man has exactly the same type. But Paranthropus
has a more primitive type, so that it seems more probable that man (Homo
) has evolved from a Plesianthropus
-like type than from a Paranthropus
.
... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 当只知道我们所谓的“猿人”头骨的脑量在450毫升~650毫升之间时,那些说它们只是猿类并与人类没有任何密切亲缘关系的人似乎还有一些根据,但是现在我们发现了脑量达到750毫升、800毫升甚至可能为1,000毫升的头骨,那么我们正在讨论的生物似乎就是一些人声称的人类。
英文
最近,我们发现了5件具有较大脑量的头骨。一件是年幼个体的头骨,其脑量约为600毫升,另一件年幼个体头骨的脑量约为700毫升或750毫升。之后我们得到了两件几乎完整的女性头骨,我们估计其脑量约为800毫升或850毫升。每件头骨都缺少枕骨,但除此以外,尽管稍微有些破碎基本上还是完整的。复原出一件未破碎的头骨尚需一些时间,但是我们可以肯定地认为其脑量大于800毫升。... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 英文
现在问题产生了——脑量正好处于人类范围内的傍人粗齿种一定要称为“早期人类”吗?很明显,猿人有一个由于发生突变而发育形成的脑——在结构上可能是人类的脑,甚至有些人可能会认为它是一种早期人类的类型——或许是人类的祖先。
英文
那么,牙齿似乎能帮助我们解决问题。南方古猿和迩人具有显著的乳前臼齿。人类也拥有相同类型的牙齿。但是傍人的牙齿类型更为原始,因此人类(人属)似乎更可能是从一种类似迩人的类型进化而来的,而不是从傍人进化而来的。
英文
我们的以下推测可能是正确的:即一百万年或可能两百万年前在南非居住着高等灵长类动物家族,它们与现存的类人猿没有密切的亲缘关系,但有可能是从一种非常早的类人猿、或甚至是从一种不同世系的前类... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | pointed out the possibility that growth of crystals at low supersaturations, essential for good crystals, could take place because of the formation of dislocations in the crystal so that any real crystal should have a number of dislocations with a screw component, terminating on the face. When growth takes place on the... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | spirals shown in Fig. 1.
中文
Fig. 1-Fig. 4
中文
The dependence of the rate of advance of a growth front on the orientation of the step line should impose a characteristic distortion of the growth of spirals, exhibiting the crystal symmetry. In accordance with this, Fig. 2 shows a hexagonal spiral (crystal type II).... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | II, c
= 15.1 A. Thus it has been proved here that the step is a single unit-cell high.
中文
The observation of spiral markings on carborundum has already been reported6
. The observed shapes of these spirals are in accordance with the predictions of theory, and their step height is equal to that of a unit cell, show... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 英文
理论表明,对于气相条件下的生长,从位错出现的位置向晶体边界扩展的晶体阶壁具有一种独立于晶体学取向的推进速率,因此会形成一种简单的阿基米德螺线。这种螺线可由计算得出,并且其中各圈之间的间隔常数是可以预测的。这些预测已由图1所示的圆形螺线在数值上得到完全确证。
英文
图1~图4
英文
生长阵面的推进速率对阶梯线取向的依赖性会迫使螺线生长产生一种特征性的扭曲,体现出晶体的对称性。与此对应的就是图2显示的六方螺旋(类型II晶体)。作为阶梯线取向的函数,生长速率极小值与螺线的直线形边对应。
英文
对两个或更多终止于晶体表面并且依赖于生长阵面性质的复杂生长模式,如图1所示,此生长阵面在两个边缘相遇的位置相互抵消。因此... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | H. VAN'T HOFF extended the structural formulae of organic chemistry to include spatial configuration (“La chimie dans l'espace” (1874), the aliphatic carbon atom with hydrogen or other atoms at the corners of a tetrahedron surrounding it). X-ray analysis has determined the exact configurations and the interatomic dista... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | ) has been inverted. The path (phase) differences for each pair of atoms involved in the same direction of diffraction (p
) remains unchanged (except for sign); hence the resultant interference effect will be the same for both conditions. The removal of this equivalence is the essential point of the determination of a... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | . It enabled us, analogous to the case discussed above, to decide between the diffracting model and its inversion. The result is that Emil Fischer's convention
, which assigned the configuration of Fig. 2 to the dextrorotatory acid, appears to answer to reality.
中文
Fig. 2. Absolute configuration of natural dextror... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Bijvoet, J. M., Proc. Roy. Acad. Amsterdam
, 52
, 313 (1949). Peerdeman, A. F., van Bommel, A. J., and Bijvoet, J. M., ibid
., B, 54
, 16 (1951).
Cahn, R. S., and Ingold, C. K., J. Chem. Soc
., 612 (1951).
用X射线方法测定光学活性化合物的绝对构型
比沃特等
编者按
众所周知,自从19世纪以来,许多有机分子以“手性”形式或者对映异构体两两出现,除了互为镜像外,它们完全一致,就像人的左手和右手;但是没有方法能够确定给定... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 现在,命名法的问题涉及给定的构型,并且需要一套符号以一种清楚而且(如果可能的话)一目了然的方式表示这些构型。从后一角度来看,基于化学关系的常用符号,比如用D
s
或L
g
表示右旋酒石酸看起来相当地难以令人满意。关于此问题的一项近期研究可以参考有关文献[3]
。
英文
我们要感谢荷兰纯理论研究提升组织对本项研究的支持。
英文
(王耀杨 翻译;李芝芬 审稿)
Evidence for the Pauling-Corey α-Helix in Synthetic Polypeptides
W. Cochran and F. H. C. Crick
Editor's Note
In 1951 Linus Pauli... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | We quote here the value of the transform which applies when the axial distance between successive turns of the helix is P
, the axial distance between the successive atoms lying on the helix is p
, and the structure so formed is repeated exactly in an axial distance c
. (For the latter condition to be possible, P
/... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | is different. The basis of our prediction is that a reflexion will be absent if the contribution of all sets of atoms to it is very small, and that on the average it will be strong if all sets of atoms make a large contribution.
中文
It is a property of Bessel functions of higher order, illustrated in the graph, that ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | In addition, the theory predicts (as can also be shown by a simpler approach) that meridional reflexions can occur only on layer lines which involve Bessel functions of order zero; that is, at reciprocal spacings of multiples of 1/1.5 A.–1
. This had previously been pointed out by Perutz3
when reporting the strong me... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 尤其是,合成多肽聚–γ–甲基–L–谷氨酸酯所给出的X射线衍射图样,在上述理论基础上可以很容易地得到解释,该多肽中无疑存在鲍林–科里α螺旋或者某种与之极为类似的结构,这种高度晶态的多肽由位于梅登黑德的考陶尔兹有限公司研究实验室的班福德博士及其同事合成。鲍林和科里[2]
已经指出了在赤道平面上的这种对应关系;这里要说明的是,这种对应关系能够拓展到整个衍射图中。
英文
在这个变换中,我们设位于螺旋中相邻两圈之间的轴距为P
,位于螺旋中相邻原子之间的轴距为p
,而这样形成的结构精确地按轴距c
周期性重复排列。(为保证后一情况成立,P
/p
必须用整数比来表示。)在这种情况下,变换只限于与螺旋轴垂直的倒易空间中的平面,而且出... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 英文
(王耀杨 翻译;顾孝诚 审稿)
A Structure for Deoxyribose Nucleic Acid
J. D. Watson and F. H. C. Crick
Editor's Note
This short paper is probably the most famous Nature has ever published. By the early 1950s it was becoming clear that the genes responsible for inherited traits reside on the biochemical polymer DNA. Watson and... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | We wish to put forward a radically different structure for the salt of deoxyribose nucleic acid. This structure has two helical chains each coiled round the same axis (see diagram). We have made the usual chemical assumptions, namely, that each chain consists of phosphate diester groups joining β-D-deoxyribofuranose re... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | The novel feature of the structure is the manner in which the two chains are held together by the purine and pyrimidine bases. The planes of the bases are perpendicular to the fibre axis. They are joined together in pairs, a single base from one chain being hydrogen-bonded to a single base from the other chain, so that... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | on deoxyribose nucleic acid are insufficient for a rigorous test of our structure. So far as we can tell, it is roughly compatible with the experimental data, but it must be regarded as unproved until it has been checked against more exact results. Some of these are given in the following communications. We were not aw... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 编者按
这篇简短的文章可能是《自然》有史以来发表的最著名的文章。在20世纪50年代初期,人们越来越清楚地认识到,具有遗传特征的基因存在于生化多聚体DNA上。沃森和克里克利用X射线晶体学的测量结果和化学推理,提出了DNA的一种分子结构模型,即DNA分子是由两条聚合链缠绕而成的双螺旋结构。这一结果之所以令人震惊,不只是因为双螺旋结构的优雅和美丽,而且正如研究者所指出的,“我们提出的这种特定配对原则立即揭示了遗传物质一种可能的复制机制。”——也就是说,DNA复制的一种方式。它标志着现代基因组学的开端。
英文
我们希望提出脱氧核糖核酸(DNA)盐的一种结构。这种结构的新特性具有重要的生物学意义。
英文
鲍林和科里已经提出了核酸... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 我们还从伦敦国王学院的威尔金斯博士、富兰克林博士及其同事们未发表的实验结果与观点所包含的一般属性的知识中获得了启发。我们中的一员(沃森)由国家小儿麻痹症基金会资助。
英文
(王耀杨 翻译;王晓晨 审稿)
Molecular Structure of Deoxypentose Nucleic Acids
M. H. F. Wilkins et al
.
Editor's Note
James Watson and Francis Crick's famous paper describing the structure of DNA was accompanied by this contribution from th... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Oriented paracrystalline deoxypentose nucleic acid (“structure B
” in the following communication by Franklin and Gosling) gives a fibre diagram as shown in Fig. 1 (cf. ref. 4 ). Astbury suggested that the strong 3.4-A. reflexion corresponded to the internucleotide repeat along the fibre axis. The ~ 34 A. layer lines,... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Fig. 2. Diffraction pattern of system of helices corresponding to structure of deoxypentose nucleic acid. The squares of Bessel functions are plotted about 0 on the equator and on the first, second, third and fifth layer lines for half of the nucleotide mass at 20 A. diameter and remainder distributed along a radius, t... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | (Fig. 2). Hence this aspect of nucleotide shape affects the central and peripheral regions of each layer line differently.
中文
Interpretation of the X-Ray Photograph
It must first be decided whether the structure consists of essentially one helix giving an intensity distribution along the layer lines corresponding to... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | radius being proportional to the radius.
中文
On the zero layer line there appears to be a marked
, and on the first, second and third layer lines,
, etc., respectively. This means that, in projection on a plane at right-angles to the fibre axis, the outer part of the nucleotide is relatively concentrated, giving ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | The material is apparently not completely paracrystalline, as sharp spots appear in the central region of the second layer line, indicating a partial degree of order of the helical units relative to one another in the direction of the helix axis. Photographs similar to Fig. 1 have been obtained from sodium nucleate fro... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | phage photographed with X-rays while sealed in a cell with mica windows give a diffraction pattern containing the main features of paracrystalline sodium nucleate as distinct from that of crystalline nucleoprotein. This confirms current ideas of phage structure.
Transforming principle
(in collaboration with H. Ephrus... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 英文
尽管脱氧戊糖核酸的生物学性质暗示其分子结构极为复杂,但这里所描述的X射线衍射研究(参见阿斯特伯里的研究[1]
)却表明其基本分子构型非常简单。这篇通讯文章的目的是为了初步地描述一些实验证据,证明多核苷酸链的构型为螺形,并且以这种形式存在于自然状态中。对这一工作更完整的记述不久即将发表。
英文
不管是在提取的或者细胞内的核蛋白中,还是处于纯化的核酸盐状态下,所有物种中的脱氧戊糖核酸都具有相同的结构(尽管含氮碱基的比例有显著差异)。一组相同的线性的多核苷酸链能够以不同方式平行排列在一起,形成晶态[1-3]
、半晶态或类晶态物质。在所有情况下,X射线衍射照片都包含两个区域,其中一个区域很大程度上取决于沿着这条链排列规则的... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 英文
这种螺旋结构的直接结果就是在子午线处及其附近没有反射(图2中AAA
处的空白区域)。在照片上,赤道处及其附近也有一个相对空白的区域,对应于图2中的BBB
区域。如同上面讨论过的,核苷酸放射状分布的外形可以导致次级贝塞尔函数极大值的缺失。要使层线条纹变得足够窄,就必须把核苷酸的大部分质量置于直径为20Å处。图2中贝塞尔函数的平方是根据直径为20Å处的核苷酸质量的一半来作图的,其余部分则沿径向分布,在给定半径下的质量与该半径成正比。
英文
在第0层线,似乎出现了显著的
,而在第1、2和3层线则分别出现了显著的
等。这意味着,在与纤维轴垂直的平面上的投影图中,核苷酸外围部分相对比较浓缩,从而形成了与直径20Å的圆周相... | 400套付费套装书 |
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