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C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | inoculation of the kuru virus. Histopathological examination of the brain of this rhesus monkey has confirmed this first successful transmission of kuru to an old-world monkey. Previously the chimpanzee and four species of new-world monkeys (spider, Ateles; capuchin, Cebus; squirrel, Saimiri; and woolly, Lagothrix) hav... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | At necropsy the animal was thin with scant subcutaneous and omental fat. The brain was firm and, on cutting, a blanching of the grey matter was noted. There were no other gross pathological changes. 中文
Preliminary histological examination of the brain by light and electron microscopy revealed extensive neuropathologica... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | in hosts not yet demonstrated to be susceptible. 中文
We thank Drs. Peter Rampert and Reid Heffner for electron microscopy. 中文
(240, 351; 1972)
D. C. Gajdusek and C. J. Gibbs, jun.: National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, Maryland.
Received June 26; revised July 31... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 英文
值得关注的是,最近有两种动物海绵状脑病传染到了旧大陆猴中:羊瘙痒症传染到食蟹猴中[1];水貂脑病传染到恒河猴中[2]。鉴于库鲁病在黑猩猩和一些新大陆猴中连续传代的潜伏期迅速缩短,可以猜测在不同寄主内的连续传代也许会改变寄主范围,甚至在寄主中盲传时也有可能是易感的,尽管现在没有证据能证明这一点。 英文
感谢彼得·兰伯特博士和里德·赫夫纳博士为我们提供了电子显微镜。 英文
(李梅 翻译;袁峥 审稿)
Inhibition of Prostaglandin Synthetase in Brain Explains the Antipyretic Activity of Paracetamol (4-Acetamidophenol)... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Prostaglandins are themselves pyrogenic13 and occur in the central nervous system14. Feldberg et al.15 found that a prostaglandin-like substance appeared in the cerebrospinal fluid (CSF) at the same time as the fever produced by intravenous injections of pyrogen. Paracetamol produced a prompt defervescence, accompanied... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Prostaglandin was routinely bioassayed using the rat fundic strip16, but the identity of the biologically active reaction products was verified by parallel bioassay using the rat fundic strip, rat colon and chick rectum, superfused in series with Krebs solution containing antagonists17 and by thin layer chromatography ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | There is a remarkable correlation between the clinical actions of these drugs and their potency against one or other of the enzymes. All three compounds are antipyretic (a central action) and all have an inhibitory effect on the brain enzyme in concentrations found in the plasma after therapeutic doses6. Both as antipy... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | R. J. Flower and J. R. Vane: Department of Pharmacology, Institute of Basic Medical Sciences, Royal College of Surgeons of England, Lincoln’s Inn Fields, London WC2A 3PN.
Received September 14, 1972.
References:
Vane, J. R., Nature New Biology, 231, 232 (1971).
Smith, J. B., and Willis, A. L., Nature New Biology, 231... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 在本文中,文及其同事罗德·弗劳尔对上述观点给予了支持,他们指出:扑热息痛之所以具有退热能力是因为大脑中合成前列腺素所需的酶受到了抑制。因为前列腺素存在于大多数组织和器官中,所以该发现支持了以下观点,即通过以特定组织中前列腺素释放为靶向的阿司匹林类药物可能得到一类新的特异性更强的抗炎化合物。这篇文章也有助于我们解释以前发现的一个令人困惑的现象:扑热息痛对狗脾的前列腺素合成酶无效——身体不同部位的组织对阿司匹林类药物的敏感性不同。 英文
目前,已有多个系统的研究[4-7]证实,阿司匹林类药物[1-3]可以抑制前列腺素的生物合成。近来亦有文献[8-11]详细综述了有关理论[1],即对前列腺素合成酶的拮抗作用是阿司匹林类药物临床功效的基础。... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 消炎痛在狗脾[6]和牛精囊[5]中表现为更强的合成酶抑制剂,这种更强的效能同样体现在其对动物模型[5,19]和人体[12]的抗炎作用上。而扑热息痛没有抗炎作用,在治疗浓度下也没有抑制狗脾酶的活性。 英文
除了能为文氏理论[1,8]提供进一步的支持以外,我们认为我们的结果还阐明了一种机制,即阿司匹林类药物的临床功效取决于其对“靶”组织前列腺素合成酶系统的敏感性差异。因此也支持了这样一个观点[1,8],即对不同组织前列腺素合成酶系统的研究将会促使我们研发出特异性更强的阿司匹林类药物。 英文
感谢美国卡拉马祖市普强制药公司的派克博士为我们提供了前列腺素,还要感谢英国维康信托基金会和英国医学研究理事会为我们提供资金上的援助。 英文
(周志华... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | our data indicate that when the synthesis of protein is inhibited, the synthesis of DNA proceeds normally except that the rate of chain elongation is slower. This applies to each replicon in each S phase cell. Here I present evidence that the proteins, termed chain elongation proteins (CEP), involved in this fine contr... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Fig. 1. Resistance of histone synthesis to cycloheximide. Four day old erythroblasts were incubated in vitro1 in L-leucine-4, 5-3H (20 μCi ml.–1; 35 Ci mM–1) or 3H-methyl-TdR (20 μCi ml.–1; 15 Ci m M–1) for 30 min in the presence and absence of the stated concentrations of cycloheximide. The various protein fractions w... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | their corresponding amino-acids as equimolar concentrations can markedly depress uptake of labelled amino-acid into TCA precipitable material. Addition of cycloheximide with canavanine results in only a light potentiation. This indicates that both drugs are probably affecting the same step in DNA synthesis, made more l... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Fig. 2a shows the dose response for DNA synthesis and the synthesis of the various protein fractions after a 90 min pre-incubation with actinomycin D5-7. Both histone and DNA synthesis are again comparatively resistant to low concentrations of inhibitor, both follow curves compatible with those obtained using cyclohexi... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Incorporation of 3H-TdR (10 μg ml.–1), 3H-5-uridine (10 μCi ml. –1 20 Ci mM–1), and 3H-leucine (20 μCi ml.–1) into histone was measured as a rate percentage of controls after addition of actinomycin D (2.5 μg ml.–1). ×—×, 3H-TdR; ●—●, 3H-leucine in histone; ○---○, 3H-U.
中文
Relation to DNA Synthesis
It was previously ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Fig. 3. Leaky coupling of histone synthesis to DNA synthesis. After 90 min in the stated concentrations of cytosine arabinoside, control and treated cells were labelled with 3H-TdR (20 μCi ml.–1) and 3H-leucine (25 μCi ml.–1) for 30 min. The inhibition of DNA (●—●) and histone (×—×) synthesis as a function of dose was ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | into alkali stable, TCA precipitable material, a high concentration (10 μg ml.–1) of deoxyadenosine in the medium was used to diminish effects from small fluctuations in the internal pool size. The acid soluble pool was monitored for all time points, and the precipitable incorporation adjusted accordingly. Similar conc... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | it sedimented to a higher density than native DNA on CsCl and that both of these characteristics were unaffectled by shear, alpha-amylase, phospholipase C, or sonication and denaturation. It is therefore unlikely that the behaviour of pulse-labelled DNA in erythroblasts results only from some single-stranded property. ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | ×—×, Control; ●—●, cycloheximide. b, The SDS treated nuclei were sedimented to equilibrium on CsCl1 after a 30 s agitation on a “Vortex” mixer. Elimination of SDS fails to affect either the extraction or the sedimentation results. LL, Native DNA. ×—×, 5’ pulse; ○—○, 10’ chase; ▲—▲, 40’ chase.
中文
Histones Remove Nasce... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | during the course of experiments similar to those in Fig. 5, and that this histone can protect the nascent DNA from degradation by pancreatic DNAase. Similar experiments to be presented in more detail at a later date have shown that compared to chase DNA, pulse DNA is relatively resistant to DNAase and that this resist... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | I conclude that in vitro the proper concentration of whole calf thymus histone can remove nascent DNA from a replication complex. How this activity might relate to DNA synthesis in the intact cell remains to be seen. Other basic proteins have activity in this assay but the histones are much more active at lower molar c... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | are some 3,000 growing points in the average S phase cell1. Inhibiton of DNA synthesis by cycloheximide probably occurs within 10 s. The rapidity of inhibition, the linear kinetics after inhibition, and the fact that low levels of cycloheximide give low levels of DNA inhibition indicate that the CEP is probably used st... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Received June 12; revised October 12, 1972.
References:
Weintraub, H., and Holtzer, H., J. Mol. Biol., 65, 13 (1972).
Weintraub, H., Campbell, G., and Holtzer, H., J. Mol. Biol. (in the press).
Spalding, J., Kajiwara, K., and Mueller, G. C., Proc. US Nat. Acad. Sci., 56, 1535 (1966).
Malpoix, P., Zampetti, F., and Fi... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 这也许可以说明CEP的合成对于低浓度的抑制剂有相当的抗性,或者在细胞内存在着一定量的CEP库存。后一种可能性不大,因为高浓度抑制剂可以在25 s之内达到对DNA合成的最大抑制。放线菌酮对DNA合成及多种蛋白质合成的量效曲线示于图1。在至少30 min内,DNA合成的抑制率与放线菌酮的浓度呈线性关系。本文还给出了归一化为最大DNA合成抑制量的DNA合成曲线。这些数据表明:组蛋白的合成对于放线菌酮具有相当大的抗性[3,4],并且组蛋白的量效曲线与对DNA合成进行归一化后的量效曲线是一致的。在放线菌酮浓度为1 μM、5 μM和20 μM时对细胞质组分以及酸性核蛋白组分进行十二烷基硫酸钠(SDS)–丙烯酰胺凝胶电泳分析的结果显示:通过双标记... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 对组蛋白、DNA以及RNA合成的抑制随时间变化的曲线如图2b所示,在滞后大约30 min之后,组蛋白和DNA合成都降至一个恒定的水平。除了都存在这种滞后期以外,DNA合成和组蛋白合成的动力学曲线均类似于用次最大量(5 μM)放线菌酮抑制培养物时得到的结果。当放线菌素的浓度为2.5 μg/ml时,细胞中RNA的合成量约为对照组的18%,并且在5 min后就能达到这种抑制效果。如果放线菌素直接影响DNA合成,假如是通过与DNA结合,那么其对DNA和RNA合成的抑制作用就应该遵循相同的时间进程。显然实际情况并非如此。另有一些实验表明,用放线菌素(2.5 μg/ml)对细胞进行预孵育并不能增加放线菌酮对DNA合成的抑制作用。这说明放线菌素和... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 利用这些实验可以检测3H–脱氧腺苷掺入到碱性条件下稳定且TCA可沉淀的物质中的比例,在培养基中加入高浓度(10 μg/ml)的脱氧腺苷以消除因内部积存量微小波动而造成的影响。我们在各个时间点都监测了酸溶性库存,沉淀中放射性标记的含量会随之变化。由使用放射性标记的胸腺嘧啶脱氧核苷和脱氧胞苷的类似实验也可以得到相近的结论。我认为DNA链在体内的延伸过程至少可以分为两个步骤,并且对CEP浓度下降敏感的步骤与插入核苷酸的步骤是两个不同的步骤。 英文
一个假定的复制复合物
成红细胞中的脉冲标记DNA呈现出与HeLa细胞(译者注:是指源自一名美国妇女的子宫颈癌细胞的细胞。这名美国妇女名叫Henrietta Lacks,于1951年死于癌症)中脉... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 在加入SDS增溶之前使用组蛋白处理细胞核也会把新生DNA从处于某个CsCl密度梯度顶层的复合物中去除(图5中的小插图)。高浓度的组蛋白通常会抑制与复制复合物的反应。在上述实验中,高浓度的精蛋白和细胞色素c都是有活性的。两者活性都只有低分子浓度全组蛋白或富含赖氨酸组蛋白作用时的20%左右。浓度高至10–3 M的精胺、亚精胺和腐胺并不能引起复制复合物的解离,也不能降低放线菌酮对完整细胞中DNA合成的抑制作用。组蛋白在上述实验中发挥作用的有效浓度与它们在细胞中的浓度大致相等,但因为细胞中的组蛋白大多与DNA结合在一起,所以很难进行比较。初步结果显示:在类似于图5的实验中,超过50%的外源性组蛋白会出现在细胞核组分中,而且这类组蛋白可以保护... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 英文
放线菌酮对DNA合成的抑制作用的最有趣特征是大约50%的DNA可以被复制。如果复制前染色质中的组蛋白可以源源不断地为复制生长点提供组蛋白,那么这种活性的持续存在就可以得到解释。这种被循环利用的组蛋白与新合成的组蛋白一起与新生DNA及复制复合物发生反应,使得复制叉能够以正常的速度向前推移。当不存在新合成的组蛋白时,链延伸速率有所减慢,但不会为0,因为还能使用可循环利用的组蛋白。 英文
由于所有已知的聚合酶都具有延长新生DNA链的固有特性,因此DNA合成过程对组蛋白的需要很可能反映的是更高级的机制,在这种机制中,新DNA的合成与一种固定不变的染色体结构的生成相关联。 英文
感谢霍尔泽、弗拉克斯和科津斯基对我的帮助及批评。这项工作的... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | We adapted to E. coli the method with which Weintraub20 demonstrated that DNA replication in developing chick erythroblasts is bidirectional rather than unidirectional. The technique allows one to analyse the way in which the segments of DNA made immediately after initiation of replication are synthesized. 中文
Cells of ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Fig. 1. Diagrammatic representation of the predicted behaviour of unidirectionally (A) as opposed to bidirectionally (B) replicating origin DNA after the following treatment. Synchronized cells are pulse for 15 s with 5-bromouraci (~~~BU-DNA) and then with 3H-thymine for 100 s (- - -, 3H-DNA; ——, unlabelled DNA). Lysat... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | if it were incorporated at its end (Fig. 1A). 中文
Fig. 2. Centrifugation of irradiated (○—○) and unirradiated (●—●) DNA in which initiation was allowed to take place in bromouracil. 50 ml. cultures at densities of 5×108 cells ml.–1 were synchronized with regard to DNA replication by 100 min of amino acid starvation fol... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | in one of the ways set out below. 中文
BU Found Only in Daughter DNA
The results obtained above, that BU present during the initiation of replication is incorporated internally into a DNA fragment, could have been generated in ways other than that set out in Fig. 1B. According to the model presented there, BU is flanked ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Another source of error could be the retention of an internal pool of thymine after termination of rounds of replication or some leakiness in the thymine requirement of the strain used in these experiments. Initiation of synthesis could then occur during the thymine starvation period and the BU, when added, incorporate... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | but would not be doubly labelled. 中文
Fig. 3. Separation of daughter and parental DNA on CsCl gradients. E. coli B/r (L6) was grown in M9 medium +0.2% glucose +10 μg ml.–1 thymine, 20 μg ml.–1 each of leucine, histidine and cysteine (aa) with rotary shaking at 37°C. The cells were labelled with 14C-thymine (10–2 μCi μg... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | nor is linked to, light DNA containing thymine. It should be noted that this experiment does not eliminate the possibility that daughter DNA is linked to parental DNA for a period of less than 100 s. Because, however, this is shorter than the labelling period used in the experiment reported above, we conclude that link... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Fig. 4. Thymine incorporation after initiation of replication in BU. Cells were synchronized, labelled with BU and resuspended in 3H-thymine as described in the legend to Fig. 2. Samples are taken every 10 s for 2 min and then every 30 s for another 6 min into ice cold 7% TCA. TCA precipitates are collected on “Millipo... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Caro, L. C., and Berg, C. M., J. Mol. Biol., 45, 325 (1969).
Berg, C. M., and Caro, L. C., J. Mol. Biol., 29, 419 (1967).
Donachie, W. D., and Masters, M., Genet. Res., 8, 119 (1966).
Donachie, W. D., and Masters, M., in The Cell Cycle: Gene-Enzyme Interactions (edit. by Padilla, Whitson and Cameron), 37 (Academic Pres... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 大肠杆菌DNA的复制从一个固定位点开始连续进行,在本文中麦克纳和米莉森特·马斯特斯提出生物化学证据证明其复制是从起始点开始朝两个方向同时进行的。大约在同一时间,戴维·普雷斯科特和彼得·金佩尔发表了细菌DNA双向复制的放射自显影照片,从而证实了上述假设。目前,DNA双向复制的现象已经被人们广为接受,该过程分三步进行:起始、延伸和终止,这些步骤都受到一套复杂而高效的、有催化活性的蛋白质的调节。 英文
大肠杆菌的染色体是一个单一的环状DNA分子,其连续复制[1-3]始于一个固定的起始点[4-14,15]。尽管起初认为其复制是沿单一方向进行的,但马斯特斯、布罗达[16]和随后的伯德等人[17]以及霍尔菲尔德、菲尔梅特[18]提出的遗传学证据... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 此时,0.2毫升的粗裂解样品可根据需要选择用紫外线照射(剂量为3×105尔格)或者不用紫外线照射,然后使其在5毫升5%~20%线性梯度碱性蔗糖溶液(0.1摩尔/升NaOH,0.9摩尔/升NaCl)中分层,方法是在转子为SW50.1的“贝克曼L2-65B”型离心机中以20,000转/分的转速离心分离12小时。10滴分离出来的级分被收集于“沃特曼 3 MM”滤纸上,先用5%冷TCA后用80%乙醇溶液冲洗。样品用PPO–POPOP闪烁体计数(图3)。
英文
利用分子量已知的小鼠卫星DNA组分作为标准,我们计算出了新合成的、3H–标记的单链DNA片段的分子量为2×107。假设大肠杆菌染色体的分子量是1×109~2×109,并且假设其合成... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 将细胞和碎冰加进缓冲剂B中以便终止50毫升等分试样(5×108个细胞/毫升)中的DNA复制[28]。细胞用1×SSC(译者注:氯化钠–柠檬酸钠缓冲液)洗涤两次,然后悬浮于2毫升0.1×SSC + 10–3摩尔/升EDTA中,最后在1%十二烷基硫酸钠(SDS)+1毫克/毫升链霉蛋白酶中裂解(参考文献29)。用过量的88%苯酚—12%间甲酚—0.1% 8–羟基喹啉对DNA裂解物进行两次抽提,然后在氯仿∶辛醇为24∶1的混合物中轻轻振荡以除去SDS。利用斯坦和哈纳沃特的方法[26]使DNA变性并离心,不同之处是我们使用了“英国药品所的分析纯”CsCl,并将DNA在10–3摩尔/升的EDTA中稀释。10滴分离出来的级分被收集到冷的5% TC... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 英文
(董培智 翻译;孙军 审稿)
Appendix: Index by Subject
附录:学科分类目录
Physics
物理学
Synchrotron Radiation as a Source for X-Ray Diffraction
作为X射线衍射光源的同步辐射
Estimation of Nuclear Explosion Energies from Microbarograph Records
根据微压计记录估计出的核爆炸能量
Statistical Mechanics and Quantum Mechanics
统计力学和量子力学
The Macroscopic Level of Quantum Mec... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 对青霉素不敏感的肺炎双球菌
Mitochondrion as a Multifunctional Organelle
线粒体是一个多功能的细胞器
Transmission of Two Subacute Spongiform Encephalopathies of Man (Kuru and Creutzfeldt–Jakob Disease) to New World Monkeys
两种人类亚急性海绵状脑病(库鲁病和克雅氏病)传染给了新大陆猴
Inhibition of Prostaglandin Synthesis as a Mechanism of Action for Aspirin-like Drugs
抑制前列腺... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | On the Mechanism of Action of lac Repressor
关于乳糖操纵子阻遏物的作用机理
Functional Organization of Genetic Material as a Product of Molecular Evolution
功能性遗传物质是分子进化过程中的产物
Covalently Linked RNA–DNA Molecule as Initial Product of RNA Tumour Virus DNA Polymerase
RNA肿瘤病毒DNA聚合酶的初产物是通过共价键连接的RNA–DNA分子
Titration of Oral Nicotine Intake... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 旋转中子星作为脉动射电源的起源
Evidence in Support of a Rotational Model for the Pulsar PSR 0833–45
支持脉冲星PSR 0833–45的旋转模型的证据
Detection of Water in Interstellar Regions by Its Microwave Radiation
通过微波辐射探测到星际空间中存在水分子
Galactic Nuclei as Collapsed Old Quasars
星系核是塌缩的老年类星体
Superfluidity in Neutron Stars
中子星内部的超流
Implications of the “W... | 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 | 目录
《自然》百年科学经典(英汉对照版)
Significance of the Australopithecinae
南方古猿亚科发现的意义
Australopithecinae or Dartians
南方古猿亚科或达特猿
Discovery of a New Skull of the South African Ape-Man, Plesianthropus
一件新的南非猿人——迩人头骨的发现
Processes Involving Charged Mesons
涉及带电介子的过程
Jaw of the Male Sterkfontein Ape-Man
斯泰克方丹男性猿人的颌骨
A Floating ... | 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 | Correlation between Photons in Two Coherent Beams of Light
两个相干光束中光子间的相关性
Chinese Astronomical Clockwork
中国的天文钟
Structure of Vitamin B12
维生素B12
的结构
The Neutrino
中微子
A Test of a New Type of Stellar Interferometer on Sirius
一种新型恒星光干涉法对天狼星的测试
Production of High Temperatures and Nuclear Reactions in a Gas Discha... | 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 | Experimental Evidence of a Twinkling Layer in the Earth's Atmosphere
地球大气闪烁层存在的实验证据
Opening Electrical Contact: Boiling Metal or High-Density Plasma?
断电接触:沸腾的金属还是高密度等离子体?
Abnormal Haemoglobins and the Genetic Code
异常的血红蛋白及其遗传密码
A New Class of Faults and Their Bearing on Continental Drift
一类新断层及其与大陆漂移的关系
A Physi... | 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 | Propagation and Properties of Hepatitis Virus
肝炎病毒的繁殖及其特性
Three Haemoglobins K: Woolwich, an Abnormal, Cameroon and Ibadan, Two Unusual Variants of Human Haemoglobin A
三种血红蛋白K:一种异常的伍力奇血红蛋白、两种人血红蛋白A的稀有变体——喀麦隆和伊巴丹血红蛋白
A Dense Packing of Hard Spheres with Five-Fold Symmetry
具有五重对称性的硬球的密堆积
Antimatter and Tree Rings
... | 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 | I.1自... II.1马...2坎...3路... III.1自然科学—文集—英、汉 IV.1N53
中国版本图书馆CIP数据核字(2010)第260858号
出 版 人:
蔡剑峰
项目负责:
王勇 章思英
责任编辑:
何铭 蔡迪
装帧设计:
孙莉明
出版发行:
外语教学与研究出版社
社 址:
北京市西三环北路19号(100089)
网 址:
http://www.fltrp.com
印 刷:
北京华联印刷有限公司
开 本:
787×1092 1/16
印 张:
78.5
版 次:
2011年4月第1版 2011年4月第1次印刷
书 号:
ISBN 978-7-5135-0494-2... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | N 1924, the immature skull of a large ape-like primate was discovered in some lime workings at Taungs in the valley of the Harts River, South Africa. It was briefly described by Prof. R. A. Dart, who regarded it as representing an extinct race of apes intermediate between living anthropoid apes and man. To this extinct... | 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 this monograph, which is abundantly illustrated and incorporates numerous comparative studies, Broom deals in considerable detail with the osteological material, while Schepers discusses the endocranial casts. Apart from the obvious fact that access to the original material is really necessary to complete the evid... | 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 | resembles in its general proportions those of anthropoid apes; and in a number of details, for example, the great facial extension of the premaxilla, the contour of the mandibular symphysis, and the apparent absence of a foramen spinosum, it is entirely simian and departs widely from the human condition.
中文
So far, ... | 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 | ). Compared with the humeral fragment (which presumably belongs to the same individual) the size of the talus indicates a disproportionately small tarsus—more so, indeed, than would be expected if Paranthropus
used its hind-limbs for the bipedal mode of progression characteristic of man. Further, the unusual medial ex... | 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 | talus, although stated to be natural size, actually represents the bone as somewhat larger than the cast. So much depends on this limb material for a proper assessment of the Australopithecinae. Thus, when Broom states at the conclusion of his section that “at Sterkfontein there are deposits of breccia probably as exte... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | , but also to delineate no less than twenty-six separate cyto-architectural areas and to compare them in their relative extent with those of modern apes and man. Cortical physiologists may likewise feel inclined to demur at some of the inferences regarding functions such as speech, abstract thought and motor skill whic... | 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 judged to be as high as 650 c.c.; but since this estimate is based on little more than the left temporal region of the skull, it is not easy to accept it without qualification. For the same reason, the contours of the reconstructed endocranial cast of Paranthropus
, which are used for graphic comparison with casts ... | 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 of two species of sabre-tooth tigers, in the deposits at Sterkfontein signifies a date not later than Upper Pliocene, and that the Taungs site is probably still older, perhaps Middle Pliocene. But he specifically states that, as with the deposits at Kromdraai, it is quite impossible at present to determine the ge... | 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 | Such a divergence of opinion among recognized experts only serves to emphasize the need for still more fossil material. In this connexion we would quote a remarkable statement by Dr. Broom: “When some wealthy man or corporation undertakes the systematic exploration of our deposits...I think one can safely affirm that w... | 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 | Morton, D. J., Amer. J. Phys. Anthrop
., 7
, 1 (1924).
See Kaufmann, H., and Sauter, M., Arch. Suisses d' Anthrop. gén
., 8
, 161 (1939).
See, for example, the most recent monograph on the subject, “Anthropoid and Human Endocranial Casts”. By Pierre Hirschler. Pp. ix+150+11 plates. (Amsterdam: N. V. Noord-Hollandsc... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 但是布鲁姆博士经过坚持不懈的搜寻,也发现了一些十分重要的肢骨破片,例如,傍人的肱骨下端、尺骨上端以及距骨,利用这些破片可对上述化石做出更加令人吃惊的解释。从模型以及布鲁姆博士的插图来判断,傍人的肱骨与尺骨破片与智人的非常相似。的确,在获得这些充分证据之前,如果解剖学家对其与傍人头骨存在联系表示怀疑,那是可以理解的。但是布鲁姆博士明确声明头骨、颌骨、肱骨破片与尺骨破片以及距骨都是从一堆小于一立方英尺的骨头角砾岩中获得的,而其他任何地方的相同堆积物中都没有发现人属的化石。因此似乎可以确定,该灭绝的类似猿类的动物的上肢与人类的上肢大小一致(至少就肘部而言),并且很明显它不是用来在树枝间游荡的。另一方面,距骨是一块尺寸非常小的骨,就对模型进... | 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 | 出于同样的原因,用来与其他灵长类动物颅内模作图样比较的复原傍人颅内模轮廓也因过于依赖推测而使其可信度大打折扣。因此,就脑的绝对容量而言,南方古猿亚科似乎正好在类人猿的范围之内。另一方面,因为舍佩尔斯博士的猜测可能就是事实,如果迄今获得的颅内模刚好代表了变化值的下限,那么南方古猿亚科颅容量的上限值就很可能超出了已发现的现代大型猿类的颅容量变化范围。只有获取更进一步的化石材料后才能确定这一点。但是还有一点相当重要,相应于体型大小
(其体型大小大体上能从肢骨破片中推断出来),南方古猿亚科的脑量似乎确实比现代大型猿类的脑量大一些。
英文
这篇评述充分论证了南方古猿亚科介于猿类和人类之间,其许多解剖学特征混合了猿类和人类的特点。以形态... | 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 | compensation. Keith's apology did not save his reputation. Less than five years later, the Piltdown Man remains, by which Keith had set such store in his own conception of human evolution, were exposed as forgeries.
中文
W
HEN Prof. Raymond Dart, of the University of the Witwatersrand, Johannesburg, announced in Natu... | 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
南非约翰内斯堡威特沃特斯兰德大学的雷蒙德·达特教授在《自然》[1]
上宣布他发现了幼年南方古猿,并声称它同人类具有亲缘关系。当时我和其他一些人持有以下观点,即如若人们发现的是成年个体时,也许将能够证实它拥有和现存非洲类人猿——大猩猩和黑猩猩有更加接近的亲缘关系[2]
。和克拉克教授[3]
一样,依据罗伯特·布鲁姆博士[4]
提出的证据,现在我深信达特教授是正确的,而我是错误的;南方古猿亚科位于或者靠近这条最终进化为人类的线。现在我唯一不满的是这个已经灭绝的南非类人猿命名的长度。鉴于达特教授不仅发现了它们,而且正确地认识到了它们真正的本质,我冒险地提议在写南方古猿亚科时使用通俗的名字“达特猿”,这样能节省大量的油墨和印... | 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 | In 1946, a book was published on all we know of the South African ape-man; and the world awoke to the possibilities of the wonderful results that might be achieved by the further study of our caves. The United States has come to realize that South Africa is a more promising centre for the solution of the problem than e... | 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 | , with the brain case broken across. In ten days we had found the remains of five—possibly six—individuals of the Sterkfontein ape-man, Plesianthropus
, and one of them represented by a complete skull.
中文
Fig. 2. Front view of skull of old female Sterkfontein ape-man, Plesianthropus transvaalensis
(Broom).
natur... | 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 | Of course, it will take many weeks before the skull is completely worked up and a full account can be published, but it seems well that the world should know that such a valuable skull has been discovered.
中文
(159
, 672; 1947)
R. Broom: Transvaal Museum, Pretoria, April 2.
一件新的南非猿人——迩人头骨的发现
布鲁姆
编者按
由于第二次世界大战,从19... | 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
当然,将这个头骨完全整理出来并发表一份完整的报告,还需要花费几个星期的时间,但是世界应该知道这样一件有价值的头骨已经被发现了,这一点看起来很好。
英文
(刘皓芳 田晓阳 张立召 翻译;赵凌霞 审稿)
Processes Involving Charged Mesons
C. M. G. Lattes et al
.
Editor's Note
César Lattes and colleagues from the University of Bristol here report recent results from cosmic-ray experiments suggesting the existen... | 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 | , to determine the mass of a particle which comes to the end of its range in the emulsion, provided that we are correct in assuming that its charge is of magnitude |e
|. We define the “grain-density” in a track as the number of grains per unit length of the trajectory. Knowing the range-energy curve for the emulsion4
... | 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 | than those used in making the calibration, the individual values are subject to wide variations. In no case, however, have mass determinations by grain-counts of particles, judged to be protons from the frequency of the small-angle scattering, given values exceeding 2,400 m
e
or less than 1,300 m
e
.
中文
In these c... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Fig. 1 is a reproduction of a mosaic of photomicrographs which shows that a particle, m
1
, has come to the end of its range in the emulsion. The frequent points of scattering and the rapid change of grain-density towards the end of the range show that the track was produced by a meson. It will be seen from the figure... | 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 | measurements indicate that if there is a difference in mass between a primary and a secondary meson, it is unlikely that it is of magnitude greater than 100 m
e
. The evidence provided by Fig. 2 is not so complete because the secondary particle passes out of the emulsion, but the variation in the grain density in 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 | The only meson theory, to our knowledge, which assumes the existence of mesons of different mass is that of Schwinger8
. It is visualized9
that a negative vector meson should have a very short life and should lead to the production of a pseudo-scalar meson of the same charge but lower mass, together with a quantum of... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Fig. 3 shows a mosaic of photomicrographs of a disintegration in which six tracks can be distinguished radiating from a common centre. The letters at the edge of the mosaic indicate whether a particular track passes out of the surface of the emulsion, s
, into the glass, g
, or ends in the emulsion, e
. The grain-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 | emulsion, the grain-density in the track of a meson becomes very small at energies greater than 2 MeV., and we must anticipate a similar result in the C
2
emulsion at higher energies. Our observations are therefore not inconsistent with the view that the ejection of mesons is a common feature of the disintegration of ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | . In attempting to apply the method, we meet the difficulty of identifying the particular type of nucleus undergoing disintegration and of taking account of any ejected neutrons which will not be recorded by the emulsion. A photograph of such a disintegration which, at first sight, appears to allow us to draw definite ... | 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 more probable. When a sufficient number of observations with loaded plates has been accumulated, it may be possible to draw more definite conclusions from observed regularities in the modes of disintegration of particular types of nuclei.
中文
A detailed account of the experiments will be published elsewhere.
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 | 知道了对于乳胶的射程–能量曲线[4]
,我们就可以观测快质子的径迹,以测定描述径迹的颗粒密度与粒子能量损失率间关系的标定曲线。利用这条曲线,所观测到的沿着介子径迹的颗粒分布能够使我们推导出乳胶中粒子的总能量损失。利用粒子被带走的能量以及观测到的粒子射程可以对粒子的质量进行测量。
英文
在测试实验中,对受粒子辐射后立即显影的照片进行观测,并用上述方法对质子质量进行测定,我们发现上述方法给出了令人满意的结果。各条径迹颗粒计数观测值的误差,只是略大于一条径迹中有限的颗粒数的统计波动对应的误差。然而,正如我们先前所强调的那样,在将这种方法用于被宇宙射线[2]
辐射数周的照片时,会产生严重的误差。这些误差主要是由于在粒子穿过照片和照... | 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
第二个过程用以下方程表示
式中X
和Y
表示电荷数近似相等的两个核,这个反应按能量守恒可能发生,但在两个反冲核的总能量仅为几百万电子伏特量级的条件下发生的可能性很小。因此我们的照片显示的可能是不同质量的介子[5,6,7]
的存在。由颗粒计数提供的证据与这个猜想不矛盾。除了知道在乳胶中到达射程末端的一个次级介子并不引发伴随重粒子发射的嬗变外,我们还没有两个介子带电荷符号的直接证据。然而,如果我们假设,嬗变对应于初级介子与轻核的相互作用用方程(3)表示,
那么,根据对铍核的质量估计,2个介子的质量差一定是60 m
e
的量级。
英文
我们所知道的,认为存在不同质量介子的唯一介子理论是施温格模型[8]
。该模型... | 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
穿透乳胶的长程粒子径迹d
的颗粒计数表明,如果它是由质子产生的,那么粒子的初始能量约为15兆电子伏。如果粒子是氘,那么其能量为30兆电子伏;或者,如果是氚核,则能量为45兆电子伏。无论如何,在嬗变中如果动量守恒,我们可以确定来自发射的中子的最小能量。结果,我们发现初级介子质量的最小值为240 m
e
。颗粒计数测定的值也是240±50 m
e
。
英文
鉴于最近的关于延迟符合的实验结果,并参考以前的结果[12,13]
,目前而言,必须以相当保留的态度采纳上述结论。我们可以预测,在任何核中释放出100兆电子伏量级的能量将导致若干个粒子的发射,其中有些可能是中子。因此,认为图4中所示的衰变是氮核嬗变而不是银或溴的嬗... | 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 front of the jaw is remarkably interesting. It does not slope rapidly backwards as in the living anthropoids but more downwards than backwards, giving an appearance not unlike that of the Heidelberg jaw. The front of the Sterkfontein jaw is narrower owing to the incisors being smaller. The symphysis, so far as can ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | This jaw is much too large to have fitted the elderly female skull recently discovered; and the skull that belonged to this jaw must have been remarkably large. If a restoration of the skull is made from the known female skull, but large enough to have fitted this jaw, it is seen that we have a skull that is nearly hum... | 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
女性头骨的脑量只有450毫升左右,估计这具颌骨所属的男性头骨的脑量可达到600毫升,甚至700毫升。
英文
另一个有趣的发现是,颌骨前方的下部有一点骨质增厚,被认为可能是下巴的雏形。
英文
这个颌骨对我们研究人类起源问题可能具有相当重要的意义。
英文
(刘皓芳 田晓阳 翻译;吴秀杰 审稿)
A Floating Magnet
V. Arkadiev
Editor's Note
Russian physicist V. Arkadiev here reports his observation of a levitation phenomenon achieved with the aid of a s... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Computation shows that in space a straight magnet keeps at a certain distance from a large diamagnetic body. Thus a magnet 1 cm. long will take up a position at a distance of 1 cm. from the surface of a copper sphere about 20 m. in diameter. Diameters of 300 m. and 3,000 m. respectively would be necessary for bismuth 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 | The lower the coercive force of the magnet, the smaller the magnet itself must be. Carbon steel magnets, for example, can “float” when they have the dimensions of 0.5 mm. × 9 mm. By scattering microscopically small magnets over the surface of a body, it is possible to reveal superconductive inclusions directly, since 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 | 英文
(沈乃澂 翻译;赵见高 审稿)
Observations on the Tracks of Slow Mesons in Photographic Emulsions
*
C. M. G. Lattes et al.
Editor's Note
Physicists in the late 1940s had adopted the term “meson” to refer to any particle having mass between that of an electron and a proton. Here the Brazilian physicist Cesar Lattes and collea... | 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 | Part 1. Existence of Mesons of Different Mass
As in the previous communications1
, we refer to any particle with a mass intermediate between that of a proton and an electron as a meson. It may be emphasized that, in using this term, we do not imply that the corresponding particle necessarily has a strong interaction w... | 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 | being the range of a secondary meson, and
the mean value for n
particles of this type.
中文
Fig. 1. Observation by Mrs. I. Powell. Cooke × 95 achromatic objective; C
2 Ilford Nuclear Research emulsion loaded with boron. The track of the μ-meson is given in two parts, the point of junction being indicated by a
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 | mesons in the Nuclear Research emulsions will, in fact, increase the probability of “escape”. The six events which we observe in plates exposed at 2,800 m., in which the secondary particle remains in the emulsion for a distance greater than 500 μ, therefore correspond to the occurrence in the emulsion of 120±50 events ... | 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 | energy. This strongly suggests a fundamental process, and not one involving an interaction of a primary meson with a particular type of nucleus in the emulsion. It is convenient to refer to this process in what follows as the μ-decay. We represent the primary mesons by the symbol π, and the secondary by μ. Up to the pr... | 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 | analysis shows that it is very difficult to account for our observations, either in terms of a nuclear disintegration, or of a “building-up” process in which, through an assumed combination of a negative meson with a hydrogen nucleus, protons are enabled to enter stable nuclei of the light elements with the release of ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | for different particles of the same type can be attributed to the different degrees of fading associated with the different times of passage of the particles through the emulsion during an exposure of six weeks.
中文
Fig. 4. N is total number of grains in track of residual range R
(scale-divisions).
1 scale-division=... | 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 | =2.0. Similar measurements on event No. VIII give the value 1.8. In considering the significance which can be attached to this result, it must be noticed that in addition to the standard deviations in the number of grains counted, there are other possible sources of error. Difficulties arise, for example, from the fact... | 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 | being the mass of the electron (see Table 3). A similar result is obtained if it is assumed that a particle of low mass, such as an electron or a neutrino, is ejected in the opposite direction to the μ-meson.
中文
Table 3
中文
On the other hand, if it is assumed that the momentum balance in the μ-decay is obtained b... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 第二部分中(编者注:本书未收录第二部分),我们进一步证明了介子的产生,这使得我们可以得出,许多可观测到的介子是以“爆炸”式的核嬗变在局部区域产生的,同时也使我们可以对威尔逊云室和计数器实验中研究的宇宙射线的穿透成分与受照的感光底片中观测到的不同类型介子之间的关系进行探讨。
英文
第一部分.不同质量介子的存在
如之前的报道[1]
所述,我们把所有质量介于电子与质子之间的粒子称为介子。在这里需要强调的是,使用这个术语并不意味着我们认为相应的粒子必然与核子有强相互作用,或是与核的凝聚力密切相关。
英文
我们现已观测到终止于底片乳胶中的介子径迹总共为644条,其中451条发现于比利牛斯山脉的米迪山峰海拔2,800米处天文台受照... | 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 | 在粒子射程末端终止于乳胶中的事例中,粒子停止时似乎并未进入核并产生发射重粒子的嬗变。
英文
知道了乳胶中质子的射程–能量关系后,如果设定了粒子的某个质量值,次级介子的发射能量便可以根据其观测到的射程导出。据此,表2列出了不同质量对应的介子能量的计算值。
英文
表2
对于能量大于13兆电子伏的质子尚未确立射程–能量关系,因此必须依靠已经确立的低能关系外推。我们估计,表2中给出的能量在10%以内是正确的。
英文
π介子和μ介子质量差的证据
我们已指出[1]
,用初级介子与乳胶中原子核的相互作用导致一个与初级介子质量相同的高能介子的产生难以解释μ衰变。因此可以认为,已有的观测表明存在不同质量的介子。由于支持这个观点的... | 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 | 据此可以确定发射光子的动量和能量;π介子的质量遵从以下关系:
c
2
m
π
= c
2
m
μ
+ E
μ
+ hv
英文
因此可以表明,对质量m
μ
在100 m
e
~300 m
e
区间内的任意假定值,m
π
/m
μ
比值都小于1.45,其中m
e
是电子质量(见表3)。如果假定一个小质量粒子,例如电子或中微子,与μ介子以相反方向射出,亦会得到类似结果。
英文
表3
英文
另一方面,如果假定在μ衰变中的动量平衡是通过发射一个与μ介子质量相等的中性粒子而达到的,则计算出的比值约为2.1:1。
英文
因此,我们的初步测量表明,不能将次级介子的发射归因于初级粒子的自发衰变,其中一个... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | ), represents the spontaneous transformation in the gas of the chamber of a new type of uncharged elementary particle into lighter charged particles, and that the other, shown in Fig. 2 (tracks a
and b
), represents similarly the transformation of a new type of charged particle into two light particles, one of which ... | 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 | tracks cannot be due to a collision process but must be due to some type of spontaneous process for which the probability depends on the distance travelled and not on the amount of matter traversed.
中文
This conclusion can be supported by detailed arguments. For example, if either forked track were due to the deflexi... | 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 | must be greater than that obtained by taking the rest masses of the secondary particles as small compared with their momenta; thus the minimum value M
min
is given by the following equation:
中文
Applying this equation to the forked track of Fig. 1, after calculating P
from the observed values of p
1
and p
2
, it... | 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 | Upper values of the masses of the incident particles may also be obtained from the values of the ionization and the momenta. Thus for each of the observed particles in Fig. 1, the ionization is indistinguishable from that of a very fast particle. We conclude, therefore, that β=v
/c
≥ 0.7. Since the momentum of the in... | 400套付费套装书 |
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