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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 | called them “games of the underground”, because if not kept under restraint they would play havoc with the routines of disciplined thinking. But under exceptional conditions, when disciplined thinking is at the end of its tether, a temporary indulgence in these underground games may suddenly produce a solution which wa... | 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 | development to the point where it had gone wrong. Nor was the Keplerian edifice built on top of the Copernican structure. That ramshackle structure of epicycles he tore down and kept only its foundations. Nor did Copernicus continue to build where Ptolemy had left off. He went back two thousand years to Aristarchus. 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 | existence, and, when revealed, make us sometimes feel that we move like sleepwalkers in a world of untapped resources and unexplored possibilities.
中文
It could be objected that I have presented a reductionist view; that it is sacrilegious to call the creation of a Brahms symphony or of Maxwell's field equations an 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 | Thus to talk of goal-directedness or purpose in ontogeny has become respectable again. In phylogeny the monkey still seems to be hammering away at the typewriter, perhaps because the crude alternatives that had been offered—amorphous entelechies, or the Lysenko brand of Lamarckism—were even more repellent to the scient... | 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 phylogenetic self-repair: escapes from blind alleys and departures in new directions. On each level there is trial and error, but on each level it takes a more sophisticated form. Some twenty years ago, Tolman and Krechevsky20
created a stir by proclaiming that the rat learns to run a maze by forming hypotheses; so... | 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 | , London, November 2, 1961.
Lashley, K. S., Brain Mechanisms and Intelligence
(Chicago, 1929).
Kris, E., Psychoanalytic Explorations in Art
(New York, 1952).
Bruner, J. S., and Postman, L., J. of Personality
, XVIII (1949).
Wallas, G., The Art of Thought
(London, 1954).
Koestler, A., The Act of Creation
(New York,... | 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
逃离迷宫的一条路线可以用进化学习者所熟知的一种现象来说明,这一现象有一个难听的名字叫做幼稚形态,是加斯唐[2]
在大约四十年前提出的一个概念。已经明确证实该现象是存在的;但是在教科书中却很少被提及,这也许是因为它违背了时代精神
。该概念指出,在特定环境下进化可以重演,犹如沿着一条通往死胡同的道路,转入一个更有希望的方向重新开始一样。简单说来,幼稚形态就是指动物祖先的幼体或胚胎期出现的一些进化的新表型可能在成熟期到来前就消失了,但却又会重新出现在成体的后代当中。这种令人不可思议的进化可能是由人们熟知的幼态持续机制导致的,也就是说,越过了正常的性成熟年龄之后,身体发育逐步延迟,以至于在它开始出现繁殖行为时仍表现出幼体的形态特... | 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 | 再生可以被称为是挑战中受创伤后的一种超适应性,这种超适应性只有当其受到的挑战超过一定的临界点才会表现出来,且只有具备胚胎期遗传可塑性的生命有机体才会表现出来。我们刚才已经了解到系统发生的主要变化是在成体退回到胚胎形式时产生的。事实上,发展到我们人类物种的主要线路可以被形容为是一系列系统发生的自我修复的结果,通过对适应不良的机体结构进行淘汰和重塑来避开进化过程中的死胡同。
英文
显然,个体的自我修复并没有产生进化上的新事物,它只是恢复了原状。然而,这却是所有个体在静态环境中重获正常适应性平衡所必须经历的过程(假定损伤干扰只是暂时的)。另外,系统发生的“自我修复”也暗示着在变化的环境中基因型的改变能够修复适应性平衡。
英文
... | 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 | 只有当大脑回复到更为流畅的、较少教条化和特化的构思状态时,这种任务才得以完成,而这种构思状态通常在黎明时分运作,因为此时集中意识水平较低。现在,无意识过程对创造性行为的干涉作用甚至被带有较强实证主义偏见的行为主义者所普遍接受,虽然他们有时并不十分情愿。因此,请允许我理所当然地认为,在潜伏期(用格雷厄姆·沃拉斯[11]
的术语来说),创造性个体经历了思维模式暂时性的退行,这种思维模式通常在理性的成年期被抑制。
英文
但是,有时用弗洛伊德的所谓的“初级过程”来鉴别这些模式总显得高度单纯化。一般说来初级过程是缺乏逻辑性的,是被快乐原则所支配的,是易于混淆感知与幻觉的,是由自发行为所表达出来的,并且伴随着大量的情感释放。我认为,在这... | 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,我的看法却刚好相反,因为它试探性地指出了目的形成因素的共同特性,而没有当作是任意的巧合。不能否定尝试与错误在所有发展进程中是固有存在的。但是,猴子在打字机上的随机尝试与我所称之为以退为进的过程完全不是一回事。前者指的是在有机体所有可能的反应库中随意抽取,直到偶然地做出了一次正确的输入为止,之后通过强化而铭刻于心;而后者可能仍然被称为尝试和错误,但是却是有目的性地通过利用更为复杂的方法,如探索和搜寻,向着目标迂回前进。引用赫伯特·马勒[15]
的话来讲,“目的不是被输入到自然界的,是不应该像陌生的或神圣的事情一样让人迷惑的,......它只是简单地暗含在事实或组织之中”。重要过程的发展趋向性是确定的,沿着从有意识的行为到尼达姆... | 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 | Biological Systems at the Molecular Level
B. Askonas et al
.
Editor's Note
This report of a meeting of the International Union of Pure and Applied Biophysics in Naples offers a snapshot of what biophysics meant in the 1960s. By this time the key characteristics of the molecular structures of proteins were known, alt... | 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 remaining papers were more closely concerned with the investigation of specific conformations and the limitations imposed on them by interactions between non-bonded atoms. Given that the conformation of the peptide group is generally trans
and planar, the most important variables determining the conformation 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 | is close to 110°. On the other hand, right- and left-handed π-helices (1-5 hydrogen bonded) are allowed only when the angle at Cα
is 115°, and the 2.27
ribbon structure (1-2 bonded) is permitted only with hydrogen-bond-angles greater than 20°. The triple helix structure for collagen with two inter-chain hydrogen bond... | 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 an unbranched side-chain does not limit the range of allowed conformations any more, but the presence of more than one δ-atom, as in leu, reduces the allowed conformations to 11 percent of the possible, and branching at Cβ
, as in val, ile or thr, reduces this total to only 4.5 percent.
中文
From all these analyse... | 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 | proportions.
中文
Unfortunately there are very few reliable data from which the conformational potential energy of a polypeptide can be calculated. Prof. Liquori presented some evidence to suggest that the general features of the ψ, φ potential energy diagram for helices do not depend very sensitively on the exact sha... | 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 | A preliminary calculation of the dihedral angles ψ, φ in lysozyme had shown them to be nearly all in allowed regions of a potential energy diagram calculated for a peptide unit by the use of Lennard-Jones type interaction potentials. This diagram, which was similar to that calculated by Brant and Flory, differed from 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 | conformation. There was general agreement that models based only on α-helices and “random coils” must be considered inadequate. In view of the present very large number of investigations in which peptide conformations are described in terms of ψ, φ-diagrams, a plea was made for the general adoption of the standard conv... | 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 | constant and variable regions of the antibody molecules.
中文
Next, Prof. Jerne (Pittsburg) discussed the cellular kinetics of the antibody response when antigen is injected into the whole animal. Studying haemolytic antibody formation by individual spleen cells, using his plaque assay technique, he observed the event... | 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 | class of immunoglobulin and one type of light or heavy chain. In an investigation testing for genetic markers on heavy chains less than 5 percent of the cells had a potential to express both alleles. Therefore, only one structural gene appears to be expressed by the majority of cells. The significance of the low percen... | 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 question of how antigen stimulates the potential antibody-forming cell is still a vital problem. Whether it does so by direct interaction with the reactive cell or has to go through an intermediary cell needs further clarification. Since the phagocytic cells, the macrophages, take up the antigen they have been impl... | 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 second speaker, Dr. J. Monod (Paris), described a model which aims at explaining both the interactions between similar and between different ligands, in terms of quaternary structures of proteins. In this model an allosteric protein is considered to be a polymer with an axis of symmetry, which can exist under at 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 the final session on “Molecular Aspects of Differentiation”, with Prof. J. Brachet (Brussels) as chairman, the main topic discussed was the synthesis of nucleic acids and proteins during early development. Prof. Monroy (Palermo) described in detail the significance of the events following the process of fertilizatio... | 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 | studies on the mechanism of carcinogenesis by polyoma virus and by carcinogenic hydrocarbons. In the experiments with polyoma it was shown that virus infection can induce the synthesis of cellular DNA after normal cell DNA synthesis has been repressed by contact inhibition or by X-irradiation, that each cell is induced... | 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 | 他接下来描述了一份当允许角NCα
C1
发生偏离四面体值±5°(当Cα
的其他角偏离110°的值最小时)以内时所产生的影响的研究报告。这表明通过引入这种灵活性,ψ、φ图中的允许区域增加了,以接受先前禁止的多数观察到的构象。
英文
拉马钱德兰教授接下来考虑螺旋多肽链的特征,其每个α碳原子的键角ψ和φ都保持一致(特别参考了主链中的
氢键)。他指出右手螺旋家族和左手螺旋家族的3.613
或α型,以及3.010
型(其肽1与肽4,以及肽1与肽3分别形成氢键)在空间上都是允许的,倘若Cα
的键角接近110°,其氢键长度位于可接受的范围并且距离共线性最大不超过30°。另一方面,只有在Cα
的键角为115°时才允许存在右手和... | 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
初步计算溶菌酶中的二面角ψ、φ,结果表明它们几乎都落在了运用伦纳德–琼斯型相互作用势计算得到的多肽单元势能图中的允许区域。此图与布兰特和弗洛里的计算结果相似,而与最初利用限制接触法获得的图不同,主要区别在于它允许更大范围的接近于3.010
和左手α螺旋的构象。这可能是因为在这些区域中发生了少量短接触,这在限制接触法分析中是不允许的,在大量有利接触存在的情况下,它们在势能的计算中被高估了。这对ψ、φ图的影响与拉马钱德兰教授所报道的在允许NCα
C1
角偏离110°时所得到的结论非常相似。
英文
这些报告引发了活跃的讨论,在此期间,克里克博士(剑桥)评论道,除了多诺霍从对模型的仔细测量中所获得的结果外,对于被允许的螺... | 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 | 放射性抗原被遍布于淋巴腺内的吞噬细胞吸收;在二级应答中,放射性抗原特别集中在树突状细胞的生发中心。尽管被吸收抗原的主要部分很快就被降解了,但是抗原的剩余部分仍能维持几周,并且只能从细胞中逐渐消失。诺萨尔、汉弗莱和他们的同事们未能在抗体生成细胞中检测到放射性标记的抗原,这表明在抗体生成细胞中只会有极少量抗原决定簇出现。
英文
抗原如何刺激潜在的抗体生成细胞仍是一个关键问题。它是直接与反应细胞作用还是必须通过中间细胞,这一点尚需进一步明确。因为吞噬细胞,如巨噬细胞吸收抗原,所以它们已经被认为可能是中间细胞。从巨噬细胞中可以提取出包含抗原的RNA制剂,它们在诱导抗体的过程中有很高的活性,但是这是否是抗体诱导中的必需步骤仍不清楚。有人... | 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 | 致癌烃的实验表明,在体外,这些化学物质能够直接且迅速地引发正常细胞向肿瘤细胞的高频转变。这种体外研究为这两类致癌作用间的相似性提供了证据。
英文
(孙玉诚 翻译;崔巍 审稿)
Globin Synthesis in Thalassaemia: an in vitro
Study
D. J. Weatherall et al
.
Editor's Note
Thalassaemia is an inherited disease of the blood which takes several forma, each corresponding to an abnormal configuration of the h... | 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 | . Furthermore, the genetic determinant for this type of thalassaemia behaves as though it were allelic or closely linked to the β-chain locus and also interacts with the sickle-cell (βs
-chain) gene5
. These observations suggest that this form of thalassaemia results from an inherited defect in β-chain synthesis, 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 | and the nature of the apparent defect in synthesis remains quite obscure. The experiments to be described here were carried out in an attempt to clarify some of these problems by comparing the in vitro
incorporation of radioactive amino-acids into α-, β-, and δ-chains in the reticulocytes of thalassemic and non-thalas... | 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 some experiments, chain separation was also achieved by hybridization with canine haemoglobin or by counter-current distribution17
. The purity of each chain was checked by fingerprinting16
and the radioactivity measured, after plating out about 0.5 mg of protein on aluminium planchets, using a low-background ga... | 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 | periods of incubation, implies that a small pool of α-chain exists on the ribosomes. The existence of only a small peak of radioactivity associated with the β-chain from the ribosomes indicates that release of β-chains from the ribosomes is much more rapid than that of α-chains, but is not instantaneous. These observat... | 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 | synthesis in reticulocytes is retarded before that of haemoglobin A. This observation cannot, however, explain the ratio of specific activity of α-chain to δ-chain of 5/1 in haemoglobin A2
. It has recently been suggested that one reason for the relatively slow rate of δ-chain synthesis might lie in the presence of on... | 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 findings in the experiments utilizing cells from persons with β-thalassaemia, which were quite different from those in non-thalassaemic samples, are summarized in Table 2. The specific activity of the α-chain of purified haemoglobin A always exceeded that of the β-chain, the ratios α/β ranging from 1.5/1 to 7/1. 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 | subsequent dilution of newly labelled chains, as a basis for the observed differences in specific activity in α- and β-chains.
中文
Fig. 2. Incorporation of radioactivity into the α- and β-chains of haemoglobin A prepared from the cells of a patient with β-thalassaemia major. Incubation time 60 min. ●—●, O.D.
(0.280 ... | 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 | homozygous for β-thalassaemia, after incubation of the cells with 14
C-leucine for 45 min. After addition of carrier globin to the ribosome pellet, the chains were separated by column chromatography. No peak of radioactivity corresponding to the β-chain was observed, while a large peak was seen in the α-chain region 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 | C-leucine incubation experiments performed on the cells of persons with haemoglobin H thalassaemia are shown in Table 2. At incubation times of 30 min-5 h the specific activity of the α-chain of purified haemoglobin A was 1.5-15 times that of the β-chain (Fig. 5). This difference became less marked with more prolonged ... | 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 striking difference between the specific activities of the α- and β-chains of haemoglobin A in haemoglobin H disease. Newly-made labelled α-chains will combine with unlabelled β-chains which were already present in this pool. Whether the excess β-chains exist as haemoglobin H (β4
) in the red cell is uncertain, bu... | 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 seems likely that at least one mechanism whereby δ-chain synthesis occurs at a slower rate than α- and β-chain synthesis is the slow ribosomal release of δ-chains. This slow release may well be due to the presence of one or more “slow points” during assembly of the δ-chain.
中文
In both forms of thalassaemia 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 | differences in the specific activities of the α- and β-chains noted here, and yet at the same time leave the rate of assembly of the β-chain unaltered. If, for example, the defect were simply in the number of ribosomes active in β-chain synthesis, there would be a deficit in β-chains but those which were made would hav... | 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 | nevertheless, alter the rates of translation by requiring recognition of the altered codons by other s
RNA anti-codons. It is conceivable that if synthesis of the α- or β-chains is dependent on a polycistronic messenger RNA, then changes in messenger RNA at a site remote from the α- or β-chain cistron might in some wa... | 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
遗传性血红蛋白病有两种主要类型,一些能被证明的血红蛋白病(如镰状细胞贫血病)在其珠蛋白部分的一条肽链上发生了结构改变,而另一些血红蛋白病,尽管有证据表明,在珠蛋白合成时发生了遗传性缺陷,但珠蛋白部分未发现结构改变。在具有地中海贫血的临床和血液学表现的患者中,经常可以见到第二种类型的血红蛋白合成异常,因此被称为“地中海贫血综合征”[1]
。
英文
成年人血红蛋白有一种主要组分和一种次要组分,分别被称为血红蛋白A和血红蛋白A2
[2]
。血红蛋白A有两条α肽链和两条β肽链(α2
β2
),血红蛋白A2
有两条α肽链和两条δ肽链(α2
δ2
)(参考文献3)。通常到一岁时消失的胎儿血红蛋白,有两条α肽链和两条γ... | 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
非地中海贫血的网织红细胞
表1总结了从各种非地中海贫血病症纯化的血红蛋白A的单独的α链和β链的比活,图1则给出了一种典型的分离链在温育30分钟后放射性的分布情况。在研究的所有病症中,当温育时间为5分钟~5小时,α链和β链的比活非常相似。但是,当温育时间较短时,β链的比活总是显著大于α链的比活。在这一组,向核糖体沉淀物中加入载体珠蛋白,所得到的单独的α链和β链的放射性模式总是相同的。这样,α链峰的放射性总是超过β链峰的放射性,α链和β链的比值在1.5∶1~2.1∶l的范围内。在各例中都可见到两条链的清晰的放射性峰,放射性峰通常略偏离蛋白质峰。这些结果表明,由于α链和β链中亮氨酸残基的数目相同,所以α链和β链的合成通常是同步的。... | 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 | 因此,这些结果排除了在细胞内存在大的β链库的可能性,也不存在随后新标记的链被稀释,以及由此可能导致的α链和β链比活的差异。
英文
图2.掺入到由一位重型β–地中海贫血患者细胞制备的血红蛋白A中α链和β链的放射性。温育时间为60分钟。●—●,O.D.
(0.280纳米);○---○,放射性。
英文
图3.在一位重型β–地中海贫血患者红细胞制备的洗涤过的全细胞裂解物中蛋白质与放射性分布的比较情况。温育时间为60分钟。●—●,O.D.
(0.280纳米);○---○,放射性。
英文
然而,如果在β链组装或从核糖体上释放的过程中的某个点存在大的阻塞(即限速步骤),与在任何给定的时间核糖体上存在大量已合成或部分合成的... | 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 | ●—●,O.D.
(0.280纳米);○---○,放射性。
英文
图6.由一位血红蛋白H病患者的红细胞制备的洗涤过的全细胞裂解物的蛋白质与放射性分布的比较。温育时间为45分钟。●—●,O.D.
(0.280纳米);○---○,放射性。
英文
当然,必须慎重解释这些实验结果,因为体外系统中细胞的行为也许不能完全反映其在体内的特性。此外,这类使用外周血的实验仅测定了网织红细胞中蛋白质合成的最后痕迹。不过,我们仍然可以得出一些初步的结论。在非地中海贫血的个体内,α链和β链的合成似乎是同步的,并且如前所述[18]
,从核糖体中释放α链需要已合成的β链,这也许会导致在任何给定的时间里,少量的已合成的α链会停留在核糖体上。... | 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
本研究得到了:美国公共卫生署,国立心脏病研究所编号为HE
-02799的研究经费的支持;美国国立关节炎和代谢病研究所编号为T
1-AM
-5260的研究经费的支持;美国国立卫生研究院编号为AM
-06006-03的研究经费的支持;以及美国国家自然科学基金会编号为CB
-2630的研究经费的支持。
英文
(周志华 翻译;杨茂君 审稿)
Reconstruction of Phase Objects by Holography
D. Gabor et al
.
Editor's Note
In 1948, Hungarian physicist Dennis Gabor reported in 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 | As holograms are recorded on photographic emulsions which register only intensities, not phases, one might easily believe that a hologram is not a full substitute for a real object. Indeed, the total wave-front which issues from a hologram in the reconstruction cannot be the same as the original wave-front emitted by 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 | a photographic film. In essence, the image-forming wave-fronts reconstructed from holograms are indistinguishable from the wave-front which would be obtained from an ideal lens or mirror looking directly at the object, when it is possible to form an image in the ordinary “one-step” imaging, for example, in microscopy. ... | 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 phase object was recorded by projecting an image on to the plate deliberately slightly out of focus, in order to avoid steep gradients at the edges of the letters. (The amount of shrinkage shown in Fig. 2b
was achieved in a 20-sec exposure, with a 75 W bulb, at f
/11, in 1:1 imaging in the enlarger, and suitab... | 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 with four different exposures (in ratios ×1, ×2, ×3, ×4), and suitable bleaching with Kodak chromium image intensifier, used to obtain almost pure “phase objects”, with minimum residual absorption
中文
The hologram of the phase object was recorded in the “lensless Fourier-transform” hologram recording arrang... | 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 | imperfectly clean reconstructing optics). It may be noted that excellent imaging is obtained under similar conditions when the original objects are amplitude or intensity objects12,13
, rather than pure phase objects
中文
Fig. 4a
. Reconstructed image of phase object, obtained with “phase-contrast” enhancement by d... | 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 visible-light laser domain)
中文
Figs. 4 and 5 show well-contrasted images of the phase object, obtained by a number of the well-known phase filtering or phase-contrast methods, in which the phase variations are made visible in the form of amplitude (that is, intensity) variations in the image.
中文
Figs. 4a
... | 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 | interferometry of various types. We may note that there is some indication that holograms of phase objects, recorded with a 1/1 ratio of reference/diffracted field intensity (rather than the about 5/1 used here), appear to display some noticeable “phase-contrast” enhancement simply in the focus of the “conventional” Fo... | 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 | 匈牙利物理学家丹尼斯·盖伯于1948年在《自然》上发表了一篇关于一种三维成像过程的报道,他把这种过程称作全息术。他提出的这个想法最初与电子束光学有关,但是后来他将其推广至光学。全息术依赖于反射光线相位的相互作用,但是正如盖伯及其同事们在本文中所说,在利用照相术得到的影像中相位信息似乎会丢失,这些影像记录到的只是光束的亮度。然而他们展示了一种能够通过光学全息术同时重建光束相位和振幅的方法,并通过这种方法获得了有关散射光线的物体的全部有效信息。
英文
1948年,笔者之一首次描述了波前重建成像的原理(参考文献1~3),最近这个原理产生了惊人的进展,在宏观和微观物体的三维“无透镜”照相术和成像中尤其明显[3-8]
。通过对基本方法... | 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 | 在本文中,f
1
= 415毫米,f
2
= 600毫米,λ
2
=λ
1
= 6,328埃。)
英文
图2a
.在本研究工作中使用的相位物体的直接(不是全息的)图像,这是用柯达649F
感光乳胶(见正文和图2b
)进行适当漂白得到的“纯”相位物体的程度。该物体是单词“phase”和字母“φ”(单词“phase”长20毫米)。可以检测到的微弱衬度是由于轻微的散焦以及干板上一些剩余吸收而产生的。
英文
图2b
.本研究工作中所使用的相位物体的双光束单通干涉图(6,328埃)。这个相位物体的全息图是用参考文献12中记录的“无透镜”傅里叶变换全息图记录装置进行记录的。
英文
图2c
.双光束单通干... | 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
图5是一幅重建空间像的双光束干涉图,它由空间像与一个平面波(通过适当的光束分束装置)的干涉所形成:通过比较相位物体的干涉图(图2b
),可以很容易地对相位保持的程度和“相位保持”重建的保真度进行评估。
英文
将图4和图5的像和像的干涉图与图2的相位物体和物体–干涉图对比,可以清晰地看出,记录在全息图内相位物体的相位分布不仅可以获取,而且相位物体中像的相位也能容易地借助于相衬法或其他图像–滤波方法,包括各种类型的干涉测量方法,以重建图像的振幅(各自强度)来表示。我们可能会注意到一些迹象,就是以1/1的参考/衍射场强比(而不是本文中所用的大约5/1的场强比)记录的相位物体的全息图,似乎可简单地在“传统的”傅里叶变换重建装... | 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 | , show that the angular diameter of the source is approximately 3.5 arc min, and demonstrate that, adjacent to Sagittarius A
, there is an irregular emission region, which is apparently thermal in nature. The relation between radio data concerning the galactic centre and optical information about the centres of nearby... | 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 | (Left), galactic centre region at 8.25 Gc/s. Contours represent antenna temperature in ̊K, corrected by 4 percent for extinction. b
(Right), galactic centre region at 15.50 Gc/s. Contours represent antenna temperature in ̊K, corrected by 8 percent for extinction
中文
Estimates of the flux densities of Sagittarius 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 | . at 5 Gc/s suggests that the sources are both thermal in nature and that they may therefore be H II regions. There is, however, no evidence to indicate that the sources are physically associated with Sagittarius A
.
中文
In considering the structure of the centre of our own galaxy, it is instructive to compare the 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 | 中文
We thank Mr. A. B. Hull and Dr. S. Weinreb of Lincoln Laboratory, and Mr. R. Rinehart and Mr. J. H. Taylor of Harvard University, for their assistance in making the observations. Lincoln Laboratory is a centre for research and development operated by the Massachusetts Institute of Technology with the support 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 | 采用漂移扫描进行观测,在赤纬上8.25千兆周/秒处的间隔为2角分,15.50千兆周/秒处间隔为1角分。这个方法使散射或衍射进天线的地面辐射效应减到最小。当银河系中心区域位于中天附近±2小时的时候进行扫描,在这段时间中介于视界上的仰角范围为18弧度到13弧度。
英文
图1a
显示了8.25千兆周/秒频率下银河系中心区域的射电强度等亮度线图,图1b
显示了15.50千兆周/秒频率下银河系中心区域的射电强度等亮度线图。其中亮源是人马座A
。在人马座A
的北边有一个和它部分重叠并且很复杂的辐射区域,由不规则的弯曲的隆起组成。也可以在其他频率的等亮度线图上辨别出这个区域[3,4]
。在这些源之下有一个延展达几弧度的著名辐射区域... | 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
(钱磊 翻译;王有刚 审稿)
Formation of Hydroxyl Molecules in Interstellar Space
J. L. Symonds
Editor's Note
In the mid-1960s radio astronomers were beginning the process of finding emission from molecules in space. J. L. Symonds here proposes a particular way in which the OH (hydroxyl) radical might be formed, which he cra... | 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 process of association of two atoms to form a molecule normally has a low probability. Since atomic recombination is known to proceed more rapidly in the presence of a third body, “dust” grains in space have been suggested as a suitable medium. The tenuous nature of the gas would seem to rule out a three-body proce... | 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 H+
essentially may be a transition from the coulomb potential energy curve to the 2
∑+
or, more probably, the 2
Π8/2
state curve, involving charge transfer. The interaction cross-section should have a maximum value when the relative velocity of the two ions produces kinetic energy close to the differences 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 | ions and protons, or for that matter any similar process between other ions, does not appear to have received great attention. The study of recombination rates in flames6
shows evidence of a non-equilibrium condition in the excitation of molecules and atoms in the flame. Unexplained concentrations and intensity ratios... | 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 | since the movement of hydrogen appears to be radially outward and the axis of rotation of the OH molecules will tend to be in a plane normal to the proton direction.
中文
The known presence of OH molecules must also lead to the assumption that OH–
molecular ions are also present. The electron affinity of the OH molec... | 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 summary, the association mechanism appears to offer some prospect of success in accounting for the anomalous intensity ratios; the emitted radiation may well be linearly polarized if a magnetic field is present; some suggestions can be made as to kinds of molecules that might be formed. More theoretical and experime... | 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 | 随后麦吉等人[4]
将观测对象扩展到其他射电源,发现不论是发射还是吸收,4个频率的强度比都出现了极为反常的现象。
英文
具有如此反常强度分布的发射谱线和吸收谱线,意味着OH分子的能级布居不同寻常。所观测到的布居似乎更有可能是发生了某种化学反应机制(以及随后的辐射退激发),而不是由热激发引起的。因为产生这些信号的区域中的气体非常稀薄,碰撞之间所具有的长时标将使在激发态形成的分子更有可能发生辐射退激发而不是碰撞退激发。
英文
一般通过两个原子结合而形成一个分子的过程的可能性很低。因为原子复合需要一个第三体作为媒介才能加快进程,太空中的“尘埃”颗粒被认为是一种适当的媒介。但是太空内的气体非常稀薄,发生三体过程似乎是不可能的。... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\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 | 观测来自电离区的OH辐射时,上述机制意味着辐射将会是线偏振的[10]
,因为氢原子的运动表现为沿径向向外,而OH分子的旋转轴则倾向于垂直质子方向的平面内。
英文
已知OH分子的存在就势必产生OH–
分子离子也存在的假定。OH分子的电子亲和能比氧原子的电子亲和能大,这使得两个我们感兴趣的反应成为可能。第一个反应类似于形成OH分子的反应,只是再形成H2
O分子。第二个反应是电荷转移过程,将会产生一个氢原子和一个激发态的OH分子。除去离子化和其他一些消除OH分子的过程外,很明显,还有另外一些通过离子、原子和分子间碰撞来形成OH的方式,这些也是必须加以考虑的。
英文
最后,上述机制为我们提供了一些关于其他分子形成方面的诱人... | 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 | 中文
Although they are not alone in their importance to psychiatry1
, the biological sciences have a significance which is not attenuated by community with the social and psychological sciences, nor is their power less real by having been only partially demonstrated. It is the area, tentative as yet, between biology an... | 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 | normal values representing, in fact, the average of the first investigations of healthy volunteers of about twenty-five years of age2
. Measurement of glucose consumption followed later, confirming the thesis that the major substrate for oxidative energy in the brain is glucose, the utilization of which represented an... | 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 interaction between neurons at the synapses, which once inhibited, depressed both the functional activity and the energy requirements of the system. This interesting problem of the coupling between function and metabolism must await clarification by the work of those like McIlwain, Rodnight, Larrabee and Chance, am... | 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 | force the rejection of a simple cerebral ischaemic theory for sleep which dated back to Alcmaeon; they challenged as well the generally accepted “Sherringtonian” notion which equated sleep with neuronal inactivity. More recent neurophysiological findings are more consonant with what we learned about the nature of sleep... | 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 | . If the tracer is radioactive, one can measure its uptake during a standard time interval in the various structures of the brain by autoradiography. In the autoradiogram, density is related to the concentration of tracer which in turn can be related to the blood flow during the physiological state just prior to the ab... | 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 | . These results demonstrated that the effects of thyroid hormone were not uniformly applied to the metabolism of all cells in the body. A finding such as this requires an explanation and Sokoloff set about to find one. Using radioactive thyroxine he learned that the hormone crossed the blood-brain barrier and was avail... | 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 | . Thyroxine in the presence of mitochondria and an oxidizable substrate apparently produces a soluble factor that can be isolated and which will in itself stimulate protein synthesis. The evidence indicates that this factor stimulates the transfer of s
RNA-bound amino-acids into microsomal protein16,17
. Much remains... | 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 1956, soon after the Laboratory of Clinical Science, National Institute of Mental Health, was organized, some of us became interested in the cluster of thought disorders which is called schizophrenia, and gave attention to the hypothesis which attempted to explain many of the mental symptoms of schizophrenia 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 | In 1957, Armstrong, McMillan and Shaw identified the first major metabolite of epinephrine (vanillylmandelic acid, VMA, or 3-methoxy-4-hydroxymandelic acid) in the urine of a patient with phaeochromocytoma and in normal urine20
.
中文
A few years before, Julius Axelrod had joined the Laboratory, bringing with him gre... | 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 background of information on the normal degradation of the hormone which was thus provided, it was then possible to examine the metabolism of epinephrine in schizophrenic patients and normal volunteers using the tritium-labelled substance24,25
. We were unable to find any evidence for a significant abnormalit... | 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 | interesting behavioural effects, could possibly be formed by transmethylation in vivo
. In 1961, Pollin, Cardon and I28
tested this hypothesis by observing the mental effects of methionine given orally to a small number of chronic schizophrenic patients who had been maintained on a monoamine oxidase inhibitor. We rea... | 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 | , lends further support to the hypothesis of Osmond, Smythies and Harley-Mason, especially since it was that compound to which Harley-Mason had directed attention ten years previously.
中文
Our observations of the effect of methionine in schizophrenic patients, as well as the findings of Friedhoff and Van Winkle, are ... | 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, Kopin was able to demonstrate, in the isolated, perfused heart, a differential metabolism of tritiated noradrenaline released under different circumstances39
. When the catecholamine was liberated in a manner which did not provoke its characteristic effects on the heart, that is, by reserpine, it appeared la... | 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 convincing evidence that they were studying the metabolism of endogenous norepinephrine in the brain, they examined the effects of a number of psychoactive drugs. Reserpine caused a rapid depletion and the predominant formation of deaminated products as it did in the heart. On the other hand, monoamine oxidase inh... | 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 | , who presented evidence for the normal synthesis and accumulation of octopamine, the β-hydroxylated derivative of tyramine, in the region of the sympathetic nerve endings, its enhancement by monoamine oxidase inhibitors and its release by sympathetic stimulation. Their hypothesis that this relatively inactive amine ma... | 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 not difficult to predict what would have resulted had Thudichum spent those years and the funds made available to him by the Privy Council in a premature search for the toxins of insanity. With the tools, techniques and knowledge available to him at that time, it is extremely unlikely that he would have found any... | 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 | Sokoloff, L., and Kaufman, S., Science
, 129
, 569 (1959).
Sokoloff, L., and Kaufman, S., J. Biol. Chem
., 236
, 795 (1961).
Sokoloff, L., Kaufman, S., Campbell, P. L., Francis, C. M., and Gelboin, H. V., J. Biol. Chem
., 238
, 1432 (1963).
Sokoloff, L.: The action of thyroid hormones on protein synthesis, as stu... | 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 | , edit. by Himwich, H. E., Smythies, J. R., and Kety, S. S. (to be published).
Shore, P. A., Pletscher, A., Tomich, E. G., Carlsson, A., Kuntzman, R., and Brodie, B. B., Ann, N. Y. Acad. Sci.
, 66
, 609 (1957).
Kopin, I. J., and Gordon, E., J. Pharmacol
., 140
, 207 (1963).
Glowinski, J., Kopin, I. J., and Axelrod,... | 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
表1.正常人脑的总血流量和能量代谢
血流量 毫升/100克/分钟
54
耗氧量 毫升/100克/分钟
3.3
呼吸商(CO2
/O2
)
0.99
葡萄糖消耗量 毫克/100克/分钟
4.9
英文
我们期望对那些在功能水平上与正常状态具有显著差别的状态进行检查,并选择了一些意识改变的状态(表2)。非常明显的是,在意识水平和人脑的总氧气与能量利用之间存在着一种粗略的相关性[3]
。例如,在麻醉时,脑的耗氧量会减少40%,体内实验结果似乎支持夸斯特尔早期进行的体外研究[4]
,他曾经指出,麻醉会影响脑切片的耗氧量。但是所有这些数据只能告诉我们,在意识处于受抑制状态时,脑的耗氧量与能量水平会下降;他们并没有... | 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 | 这些结果证明,甲状腺激素的作用并非对生物体内所有细胞的新陈代谢都一样适用。诸如这样的发现需要一个解释,索科洛夫便开始寻找原因。通过使用放射性甲状腺素,他认识到激素可以穿过血–脑屏障从而为脑细胞所利用。他还发现,脑是非常特殊的,因为脑中的氧化过程几乎只局限于葡萄糖这一种底物。尽管里克特、韦尔施和其他一些人曾证明过在成熟的脑中有一种活性蛋白质的合成,但是与在肝脏中相比,该过程在脑中还是要慢很多,而且它几乎不能对脑耗氧量的主要部分给出解释。基于上述考虑,他做出了如下假设,即甲状腺素既不直接刺激氧化代谢也不参与磷酸化作用的解耦联(这是普遍流行的看法),而是作用于一些特殊的过程,如蛋白质合成。
英文
1954年,他来到国家心理健康研究所... | 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 | 他描述了负责这一转化过程的酶及其特征(儿茶酚氧位甲基转移酶),而且需要S
–腺苷甲硫氨酸作为甲基供体[22]
。他提出,在涉及循环肾上腺素失活的主要酶促过程中,涉及的是氧位甲基化作用而非脱氨基作用,后来他又进一步表明,去甲肾上腺素是借助同一种酶通过完全类似的途径产生代谢变化的[23]
。图1显示出目前我们对这两种儿茶酚胺代谢过程的认识情况,其中一些是由阿克塞尔罗德等人鉴别的一些额外的次要代谢产物。所有的这些代谢产物可以解释给予的肾上腺素或去甲肾上腺素中约98%的部分,据推测,当这些物质在各种生理条件下释放到循环中,可以得到相似程度的解释。
英文
图1.目前认识的肾上腺素和去甲肾上腺素代谢过程(继阿克塞尔罗德和科平之后)
... | 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,随着证据的积累,我们认识到这些药物也会影响脑内去甲肾上腺素和多巴胺的水平,并且儿茶酚胺前体多巴会快速而有效地逆转利血平在动物体内的抑制作用,表明儿茶酚胺在这些药物的作用中和可能在情感状态中起着某些同等重要的作用。但是,始终难以从主要的生物胺的角度来解释两种有效的抗抑郁药物的作用机制。安非他明和丙咪嗪这些药剂作为单胺氧化酶抑制剂不是特别有效,也还未曾表现出能够提高脑内去甲肾上腺素或5–羟色胺的水平。
英文
最近,科平能够论证分离的、灌注后心脏在不同条件下释放的氚标记的去甲肾上腺素的代谢[39]
。当儿茶酚胺以不引发其对心脏的特征性作用的方式释放时,即通过利血平的方式,那么它作为脱氨基产物就会在灌注液中大量出现。另一方面,... | 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 | Malaria and the Opening-Up of Central Africa
R.Weatherall
Editor's Note
In the nineteenth century, the British government was much occupied with the exploration of tropical Africa, partly because of the government's decision to do what it could to suppress the slave trade. This paper, based on a book by Michael Gelfa... | 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 legend that cinchona bark was introduced to Europe by the Countess of Chinchon, wife of the Viceroy of Peru, has been convincingly disproved. What is clear is that Jesuit missionaries were in contact with Indians who were aware of the medical properties of cinchona bark, at Loxa, in Brazil, and in Peru, about the 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 | established a monopoly in its supply, mainly based on Java.
中文
In comparison with the Portuguese, the British were slow in making attempts to trade with or settle in Central Africa. One of the earliest schemes for settlement was made by William Bolts; it was sponsored by Maria Theresa of Austria. The expedition set ... | 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 | An expedition financed by the Navy and led by Captain James Kingston Tuckey set out from England in 1816. The party entered the mouth of the Congo, and some members worked their way up the River as far as Soondy Nsanga, 280 miles from Cape Padron, where, stricken by disease, they had to abandon all hope of progressing ... | 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 | At about the same time, a further expedition set out to reach the Niger by way of Tripoli and Timbuktu. It was led by Major Alexander Gordon, who was the first known European to reach Timbuktu, but he was murdered by Arabs soon afterwards. In 1827, a Frenchman, René Caillié, starting from Freetown, reached the Niger an... | 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 | , reached Raba and then turned round. At the end of two years, of the total European complement of the three ships, numbering 82, 64 were dead.
中文
By this time the British Navy was active along the west coast of Africa, attempting to suppress the slave trade. Some indication of the health risks to which the crews we... | 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 | By this time it was obvious that Africans were much less susceptible to malaria than Europeans, although these too became more resistant if they lived in the country for long periods. This realization, along with a better appreciation of the value of quinine, marked the turning-point in the opening-up of Central Africa... | 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 | By then a national hero, Livingstone had no difficulty in persuading the Foreign Office to sponsor an expedition to ascend the Zambesi as far as Chobe and plant a mission somewhere near the Batoka plateau. When the party reached Africa the members took two grains of quinine every day. Livingstone doubted if that was en... | 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 next steps in the conquest of malaria are more widely known. In 1880, Laveran, a French Army doctor, discovered the cyst-like bodies of the protozoon in the red corpuscles of human blood. This observation was only slowly taken up, but it was confirmed by Marchiafava in 1884; and in 1889, the tertian, quartan and ma... | 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 conquest of malaria has also been greatly assisted through the use of insecticides, such as pyrethrum, Paris green, benzene hexachloride (BHC) and DDT. In the case of some of these there was long delay between their first discovery and exploitation. BHC, for example, was isolated by Faraday in 1825, yet its insecti... | 400套付费套装书 |
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