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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 | The combination of these two isolating mechanisms permits sympatric coexistence of two, or even three, semispecies. Thus, the Central American semispecies occurs alone from Guatemala to Costa Rica and western Panama, but in central Panama it meets the Amazonian and Orinocan semispecies, The distribution of the Amazonia... | 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 | might have resulted from accidental contamination was ruled out on two grounds. First, a cytological study of the Llanos strain in 1959 showed two polymorphic chromosomal inversions which were, at that time, found in no other strain. Llanos still carries these chromosomal polymorphisms. Second, in 1963, Llanos was syst... | 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 tests of this kind, the “choice” is actually exercised by the females who accept some males in preference to others. Table 1 shows that Llanos males are accepted by females of their own kind more easily than by Orinocan females; Orinocan males are accepted equally by both kinds of females. In 1969, the experiments 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 | acquire ethological isolation from the Orinocan. But can ethological isolation be superimposed on the hybrid sterility by means of artificial selection? 中文
Selection for Isolation
Several workers14-16 have induced or intensified ethological isolation between strains of the same or of different species. The techniques u... | 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 exposed to a mixture of the same Orinocan mutant males and of Llanos rough eyed males. Among the progeny, the hybrid females, coming from matings of unlike parents, are distinguishable by being wild type in phenotype. Non-hybrid females, coming from matings of like parents, show the traits of the respective mutants... | 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 | The selection for ethological isolation was successful in all six populations, although in none has anything like complete isolation been achieved. It can be stated that, as a rule, the proportions of hybrids among the progenies have decreased from early generations to the later ones. The progress of the selection seem... | 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 | The designation Llanos unselected refers to the wild type Llanos strain which had not been exposed to challenges of hybridization with Orinocan strains; rough selected is the rough-eyed mutant which had been so exposed for fifty generations by October 1969, and fifty-eight generations by March 1970; Orinocan unselected... | 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 | between, or even a hybrid of, Orinocan and Interior semispecies12. Another possibility is that the change was brought about by an alteration in the population of mycoplasma-like intracellular symbionts, which seem to be different in the different semispecies17,18. 中文
At any rate, no appreciable reproductive isolation a... | 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 | semispecies capable of sympatric coexistence with the Orinocan semispecies is to free it from the rough-eye mutant, without disturbing the rest of its genotype responsible for the ethological isolation. This may not be easy to achieve, but it can be attempted. 中文
This work was supported by grants from the US Atomic Ene... | 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 | 多布赞斯基是20世纪30年代的杰出遗传学家之一,他在奠立现代遗传学的理论基础方面作出过重要贡献。 英文
利用异源多倍性——使物种间杂种的染色体组加倍——通过实验创建新生物学物种在几十年前就已经为人们所知。卡尔佩琴科的研究堪称该领域中的经典之作之一[1];他从萝卜和甘蓝的杂交种获得了四倍体萝卜甘蓝。萝卜甘蓝的种内交配几乎是完全可育的,但与其亲本物种的杂交种是高度不育的。一些存在于自然界中的异源多倍体物种已经通过实验重新合成,例如薄荷、野芝麻[2]、普通小麦[3]等等。虽然通过异源多倍性形成物种在某些植物科属中广泛存在,并且还十分重要,但在整个生物界中并不算常见。物种起源的另一种不同模式在有性繁殖和远系繁殖的生物中是普遍存在的,即随着遗... | 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 | 我们是否可以由此得出结论——亚诺斯品系已经从典型的奥里诺科半分化种转变为内陆半分化种?这样一个结论是没有道理的,尽管我们显然并不知道在1958年或1959年期间,亚诺斯品系的果蝇是否已经能跟内陆半分化种产生可育的雄性杂交种。我们所知道的是:虽然亚诺斯品系至少与一些内陆品系果蝇之间存在着明显的性隔离,但它却可以跟奥里诺科果蝇进行自由交配;而内陆品系和奥里诺科品系之间的性隔离是相当强的。 英文
亚诺斯品系和奥里诺科品系果蝇之间不存在性隔离这一事实已经在1964年通过“雄性挑选”测验而得到证实[10]。来自两个品系的未交配过的雌蝇,包括亚诺斯品系和在圭亚那乔治敦发现的奥里诺科品系的橙眼突变体,被限制只能与其中一个品系的雄蝇进行交配。在半数... | 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 | 由于橙眼是常染色体遗传的,因此它使我们既可以区分雄性杂交子代和非杂交子代也可以区分雌性杂交子代和非杂交子代。总共有如下6对实验种群:
1A:糙眼♀♀ + 糙眼♂♂ + 橙眼♂♂
1B:橙眼♀♀ + 橙眼♂♂ + 糙眼♂♂
2A:糙眼♀♀ + 糙眼♂♂ + 无脉翅♂♂
2B:无脉翅♀♀ + 无脉翅♂♂ + 糙眼♂♂
3A:糙眼♀♀ + 糙眼♂♂ + 黄体色♂♂
3B:黄体色♀♀ + 黄体色♂♂ + 糙眼♂♂ 英文
目前(1970年12月)已经对种群1A和1B进行了73代的选择。种群2A和2B在选择了65代之后及种群3A和3B在选择了60代之后都没有再继续。雌蝇所面对的同品系和不同品系雄蝇的比例在不同的世代都被调整到足以对雌蝇的辨别能力... | 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 | 表4中列出的隔离系数大多低于平均值,不过都稳稳地落在实验得到的、自然界中半分化种的隔离系数的范围之内——从0.28±0.10到0.94±0.03(参考文献12)。我们有合适的理由认为,自然界中的行为隔离很可能会强于在实验室条件下发生的行为隔离。这使得一些半分化种可以在同一个区域内共存,即分布区域重叠但并不发生混交。奥里诺科半分化种和内陆半分化种是个例外——它们并不同域。室内实验检测到这些半分化种的品系之间的隔离系数为0.28±0.10~0.65±0.08(参考文献12),低于我们得到的数值(表4)。 英文
我们的结论是:经过选择的亚诺斯品系与自然条件下存在的半分化种之间具有可比性。然而,当它与奥里诺科半分化种同域共存时,就无法维持自... | 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 | chromosomes5. The inactive X is detected cytologically as the heterochromatic Barr body or sex chromatin in interphase nuclei and because it synthesizes its DNA late, that is, it labels late5. Once established the inactivation is very stable. In abnormal individuals with more than two sex chromosomes all X chromosomes ... | 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 | purpose of this article is to examine the adequacy with which the model accounts for data at present available and to propose new investigations which should test it more critically. 中文
Maize Controlling Elements
Controlling elements may be exemplified by the activator–dissociator (Ac–Ds) system of maize18. This system... | 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 | Ac by promoting the formation of dicentric chromatid bridges (a property from which Ds derives its name). In further responses, these were chiefly absent and only activity of adjacent genes was affected. 中文
Controlling Element of Mouse X
Several workers have studied a region of the mouse X called the inactivation centr... | 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 | purposes of this paper that there is only one.) 中文
Fig. 1. Diagram of portion of the mouse X linkage group, showing position of sex linked genes discussed in the text. The diagram is from ref. 48. Bn, Bent tail; Str, striated; sla, sex linked anaemia; Tfm, testicular feminization; Gs, greasy; Ta, tabby; Blo, blotchy; ... | 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 | is unlike all other mouse X autosome reciprocal translocations, which by contrast show random inactivation of either the normal or rearranged chromosome. 中文
It is particularly significant that the break in Searle’s translocation maps is the same region of the X as the controlling element. The break in the X is given as... | 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 are other examples of apparent or possible paternal X inactivation in eutherians. Studies on the G6PD of mules indicate that in most tissues there is preferential inactivation of the paternal donkey chromosomes32,33. This is interpreted here to mean that the lack of homology between the two distantly related X ch... | 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 | Retention of the controlling element cannot occur in the mouse, however; Searle’s translocation gives normal segregation ratios for genes near the controlling element locus31, which it would not do if the chromosome with the controlling element was preferentially included in a polar body. The only report of multiple X ... | 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 | while hypoxanthine guanine phosphoribosyl transferase was essentially the same in both sexes at these stages. The structural loci for both enzymes are sex linked. In this instance induction of greater activity of the one active X seems more likely than switching on of the second X. 中文
Possible Experimental Tests
Althou... | 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 | example, G6PD46 and PGK47, a procedure which is now being followed in this laboratory. 中文
I thank Professor R. A. Brink, Drs. B. M. Cattanach and D. L. Hayman and Professor G. B. Sharman for helpful comments. My experimental work on X inactivation in marsupials is supported by grants from the Australian Research Grants... | 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 | Cattanach, B. M., Genetics, 60, 168 (1968).
Cattanach, B. M., Pollard, C. E., and Perez, J. N., Genet. Res., 14, 223 (1969).
Cattanach, B. M., and Isaacson, J. H., Genetics, 57, 331 (1967).
Cattanach, B. M., Genet. Res., 8, 253 (1966).
Cattanach, B. M., and Perez, J. N., Genet. Res., 15, 43 (1970).
Searle, A. G., Hered... | 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 | 文中指出:在早期雌性动物的胚胎发育过程中,父源X染色体中的遗传控制元件会随机地跳到两条X染色体中的一条上,这种跳跃方式类似于芭芭拉·麦克林托克所发现的玉米中的遗传因子在染色体上的位置转移行为。虽然库珀的假说已经被后人修正,但从本文仍可以看出麦克林托克赖以获得诺贝尔奖的成果有多么大的影响力。 英文
1961年,莱昂提出了单一活性X染色体假说,用来解释雌性真兽亚纲哺乳动物的性染色体基因的剂量补偿效应[1]。她在假说里提出:在成年生物体的每一个细胞中,不是来自母本就是来自父本的那条X染色体会具有活性,但永远不可能两者都具有活性。到底哪条X染色体会失活这一问题在胚胎的早期就已经决定了[2-4]。在雌性二倍体个体中,母源X染色体有活性的细胞与... | 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 | 卡塔纳克将这段失活中心称作控制元件,因为他在研究X染色体–常染色体斑点易位(XT, T(1X), Ct)时发现,失活中心的行为与玉米控制元件类似[19,24]。发生这种易位时,连锁群1的常染色体组分插入到X染色体中,使X染色体增大了约20%[19,25]。插入部分包含从白化基因(c)到红眼基因(ru-2)的片段。插入位点靠近吉皮基因(jp)(图1),但还不能确定插入位点是远离还是靠近陀螺基因(Gy)。卡塔纳克早期的实验数据表明,XT染色体中失活的常染色体物质的量在每一代中都有所不同,仅仅用控制不同失活水平的XT染色体在减数分裂中的交叉互换来解释这些变化并不能完全令人满意[24]。对此,他提出这些控制元件发生了“状态改变”。在一项近期... | 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
尚未解决的问题
这个模型解释了X染色体随机失活是如何形成的、染色体选择性失活是如何做到的、一旦形成后的稳定性和许多至今尚未解决的关于X染色体失活的问题,尤其是解释了瑟尔易位和卡塔纳克易位的现象。然而,它并不能解释所有的现象,因为还有几个难题仍未解决。 英文
对于人和小鼠中的XO个体,如果X染色体与通常情况下一样来自父本,那么这些个体是怎么存活的[35-37]?如果这个模型正确,显然控制元件在发展的早期就必然会以一定方式被抛弃或者失活。但是为什么这种现象发生在XO个体的父源X染色体上,而不会发生在正常的雌性个体中? 英文
具有多条X染色体的女性和男性中只有一条X染色体是有活性的[6]。如果多余的染色体来自母亲[37],那么多出的... | 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 | 英文
(郑建全 翻译;梁前进 审稿)
Pneumococci Insensitive to Penicillin
D. Hansman et al.
Editor’s Note
Since the introduction of penicillin to treat human infections three decades earlier, capsular pneumococci bacteria were thought highly sensitive to the antibiotic. And although penicillin-insensitive mutants had been selected in ... | 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 | These penicillin-insensitive pneumococci were isolated from an aboriginal child at Ernabella, South Australia, in 1967, and from fifteen New Guineans at Anguganak in the West Sepik district during a fourteen week period in 1969. Pneumococci were typed by the specific capsular reaction, using typing sera from the Staten... | 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 | strains, including the Ernabella strain, were tested. The results (Table 1) indicated that the Ernabella and Anguganak isolates were uniformly insensitive to penicillin G, methicillin and cephalosporin antibiotics. Penicillin sensitive pneumococci of 16 different types (including types 1, 2, 3, 4 and 6) tested as 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 | It may seem surprising that antibiotic-insensitive pneumococci should appear in a remote area such as the Sepik district, but much penicillin is used because respiratory and other infections are common in New Guinea. During the preceding 10 yr, the 507 inhabitants of the two villages at Anguganak had received 1,357 cou... | 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 thank Dr. Phyllis Rountree of the Royal Prince Alfred Hospital, Sydney, for the pneumococcus isolated at Ernabella. These investigations were supported in part by a grant from the Wellcome Trust. 中文
(230, 407; 1971)
David Hansman: Department of Bacteriology, The Adelaide Children’s Hospital, North Adelaide 5006.
H. ... | 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
这些对青霉素不敏感的肺炎双球菌是1967年从居住在南澳大利亚厄纳贝拉的一个土著小孩和1969年在安古干纳克的西塞皮克区逗留14周期间从15个新几内亚人体内分离得到的。用来自哥本哈根丹麦国立血清研究所的分型血清进行特异荚膜反应将肺炎双球菌分型,并按照丹麦命名系统对其命名。从土著小孩的上呼吸道中分离得到的肺炎双球菌菌株被确认为6型。大多数来自塞皮克区的肺炎双球菌菌株是从带菌者体内分离出来的,但有两个是从因呼吸道感染而接受过青霉素治疗的患者体内分离得到的,它们都被确认为4型。 英文
青霉素不敏感菌株是具有肺炎双球菌形态的革兰氏阳性球菌;其培养特征和在马血琼脂中的α溶血反应也很典型;实验证实它可溶于胆汁并对盐酸乙基氢化叩卟林(“奥普托... | 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 | 英国维康基金会为上述研究提供了一部分资金。 英文
(董培智 翻译;王昕 审稿)
Synchrotron Radiation as a Source for X-Ray Diffraction
G. Rosenbaum et al.
Editor’s Note
The new DESY synchrotron accelerator in Hamburg, Germany, had recently become operational. Here biologist Gerd Rosenbaum of the Max Planck Institute for Medical Research and his colleagues ... | 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 have evaluated the spectral luminance (that is, the power in photons per second radiated per unit area, solid angle, and wavelength interval) of both the synchrotron and a fine-focus rotating anode X-ray tube (see Table 2). The values are 2×1022 (time averaged) and 3×1020 photons s–1 sterad–1 cm–2 Å–1 respectively a... | 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 | Because of its large mosaic spread (300 times greater than that of quartz) a graphite monochromator might seem advantageous for our application. When used with the white radiation from the synchrotron, however, the mosaic spread of graphite would produce a highly divergent reflected beam with considerable wavelength in... | 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 | final position of the focus was determined by through-focal photographs. The best focal line had a width of 180 μm and represented the image of the radiating electron beam in the synchrotron. (The total effective source size, including the betatron and synchrotron oscillations, was about 4 mm.) Photographs were also ta... | 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 | used to bend the quartz. Fortunately, the camera entrance-slits were not symmetrically positioned, so that a clear view of one side of the diffraction pattern was obtained. The substantially greater width of the “20” line on the photograph made with synchrotron radiation, compared with that made using a conventional X-... | 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 | The experimental conditions and data are summarized in Table 1. 中文
Table 1. Data for Quartz Monochromator in Synchrotron Radiation Beam
中文
The ratio of the intensity at 1.5 Å, evaluated as indicated above, to the calculated incident intensity per unit wavelength interval is an “integrated band pass” which was found t... | 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 | although it has a considerable influence on the actual shape and height of the reflectivity curve14,15. 中文
Estimated Intensities for Various Configurations
We intend to set up a Berreman monochromator6 to give a point-focused beam from a quartz crystal ground so as to give the required curvature in one plane and bent t... | 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 | Some possible methods of obtaining higher intensities and utilizing the continuous spectrum are as follows. (a) According to current plans, the DESY synchrotron current will be raised from 10 mA to 50 mA. Also the electrons will be kept at the maximum energy for 1 or 2 ms, giving overall a six-fold improvement. (b) Sak... | 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 | Haensel, R., and Kunz, C., Z. Angew. Phys., 23, 276 (1967).
Bathow, G., Freytag, E., and Haensel, R., J. Appl. Phys., 37, 3449 (1966).
Witz, J., Acta Cryst., A25, 30 (1969).
Berreman, D. W., Rev. Sci. Inst., 26, 1048 (1955).
Pringle, J. W. S., Prog. Biophys. Mol. Biol., 17, 3 (edit. by Huxley, H. E., and Butler, J. A. ... | 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 | 因为焦距小,所以通量密度,这个在使用胶片进行测量时的一个重要参数,比起其他X射线源还会更高一些。 英文
由于石墨有很大的嵌镶度(是石英的300倍),因而石墨单色器或许会有利于我们的应用。然而,当我们使用来自同步加速器的白辐射时,石墨的嵌镶度将导致产生波长相当不均匀的高度发散反射束,因此为了在胶片上形成一个大小合适的光斑,单色器–胶片的距离必须非常短。对于这么短的距离,通过聚焦来收集来自大面积石墨的辐射是不可能的。另一方面,在单色器–胶片距离较大的情况下,反射束需要准直,这也将降低强度的预期值。因此,我们不认为石墨能给出比石英更高的强度。此外,石墨的光学和力学性质在使用上也很不方便。 英文
实验的详细过程
全部实验都是在汉堡DESY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 | 英文
表1.同步辐射束中石英单色器的数据
英文
由上述方法估计得到的在1.5 Å处的强度与单位波长间隔入射强度的计算值之比是一个“积分带通”,可由下式表示:
∫R(λ)dλ = 0.7 ×10−4 Å
用布拉格定律将波长转换为角度,我们得到了以相对1011面8 ̊30′夹角切割的石英晶体的积分反射率:
∫R(θ)dθ = Rint = 1.0×10–5 rad
英文
石英在本质上是个理想的动态衍射器[10]。伦宁格[11]已经计算出了一个理想石英晶体的反射率(未作吸收校正):
Rint = 4.4×10−5 rad
布罗格伦[12]通过测量得到了一个经平行于面切割的抛光石英晶体的积分反射率:
Rint = 3.9×10−5 r... | 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
(沈乃澂 翻译;尚仁成 审稿)
Mitochondrion as a Multifunctional Organelle
R. B. Flavell
Editor’s Note
Mitochondria—membrane-enclosed organelles found in most eukaryotic cells—are commonly described as the powerhouses of the cell, since their primary function is the manufacture of the molecular energy source ATP (which, as Richa... | 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 | Many of these enzymes or sequences of enzymes are biosynthetic or catabolic and consequently have end products not directly involved in energy metabolism, so that the mitochondrion has a biosynthetic and catabolic as well as an energetic role, which would suggest that unless all mitochondrial end products—biosynthetic,... | 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 | anaerobic cells possess similar percentages of extracted protein to those in extracts from aerobic cells9, giving unequivocal biochemical evidence that mitochondria exist in anaerobic yeast cells, as would be expected from knowledge of their diverse functions. 中文
In spite of this demonstration of the similarities betwe... | 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 | Changes that occur in mitochondria after the transfer of yeast cells from an anaerobic to an aerobic environment, or from high glucose repression to low glucose repression, have been studied14,15. In these conditions a number of mitochondrial components, particularly those concerned with energy production, are preferen... | 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 has been suggested (refs. 22 and 23 and article in preparation by Flavell and Raven) that mitochondria have evolved from a prokaryote, able to catalyse oxidative phosphorylation, which sheltered in a primitive amoeboid-like cell and became stabilized there in a symbiotic relationship. At some time before the presume... | 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 | mitochondrion, to facilitate cytophasmic organization, substrate and product channelling and metabolic pathway isolation. 中文
Recently, great research emphasis has been placed on the electron transport system, oxidative phosphorylation, mitochondrial DNA and mitochondrial protein synthesis, which together with the endos... | 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 | Kun, E., and Volfin, P., Biochem. Biophys. Res. Commun., 23, 696 (1966).
Clark-Walker, G. D., and Linnane, A. W., J. Cell. Biol., 34, 1 (1967).
Roodyn, D. B., and Wilkie, D., The Biogenesis of Mitochondria (Methuen, London, 1968).
Beattie, D. S., J. Biol. Chem., 243, 4027 (1968).
Kroon, A. M., and De Vries, H., FEBS Le... | 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
虽然林纳内等人并没有在厌氧酵母细胞的电子显微镜照片中观察到线粒体[8],但是他们确实看到了“网状膜”,该网状膜在有氧条件下似乎可以分化成线粒体(参见参考文献5和7),而且详细的生化研究[9,10]也证实了它们与线粒体的同源性。尽管这些网状膜不含有氧化磷酸化反应所需要的酶和细胞色素,但是它们确实含有线粒体DNA、线粒体腺苷三磷酸酶和琥珀酸脱氢酶。这些线粒体的“结构蛋白”部分与从有氧细胞中分离出来的部分即使不完全相同,至少也比较相近。厌氧细胞提取物中的这些膜结构与有氧细胞提取物中的膜结构具有同样百分比的蛋白提取物[9],这一生物化学证据确凿无疑地证明,在厌氧酵母细胞中存在线粒体,此论点与我们根据对线粒体具有多种功能的认识所料想到的... | 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 | 不能把现在的线粒体看作是一种共生的原核生物,或者从任何意义上来说认为它们可以像原核生物那样自给自足,而只能认为它们具有类似于其他细胞区室或细胞器(如高尔基体、乙醛酸循环体和微体等)的结构。尽管其他细胞区室或细胞器并不具有原核生物的起源,但它们和线粒体一样,都是朝着有利于细胞质组织架构、底物和产物疏导以及代谢路径分隔的方向而演化。 英文
最近,人们把大部分的研究重点放在了电子传递系统、氧化磷酸化、线粒体DNA和线粒体蛋白质的合成上。我认为上述研究重点与线粒体起源的内共生理论都未能认识到:线粒体是具有多种功能和可变组分的细胞质中的一个特定区域,线粒体的存在并不依赖于线粒体DNA,而且即便在无氧条件下,线粒体对真核生物的生存来说也是必需的... | 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 | Both diseases have been transmitted to the squirrel monkey and to the spider monkey using 10% suspensions of human brain, inoculated intracerebrally, with incubation periods of about 2 yr. Human kuru brain suspension has caused the same disease in the capuchin monkey 45 months after intracerebral inoculation (Fig. 1). ... | 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 | infectious units per ml. Infectious virus is present in tissue pools of spleen, liver and kidney, as well as in the brains of chimpanzees affected with kuru, but so far intracerebral inoculation into chimpanzees of urine, blood, serum and cerebrospinal fluid from similarly affected humans and chimpanzees has not produc... | 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. Spongiform changes in the cerebral cortex of two squirrel monkeys: on the left (squirrel monkey SSC-1 in Fig. 1) inoculated with brain suspension from a kuru patient, and, on the right (squirrel monkey SCC-5 in Fig. 1), inoculated with brain suspension from a patient with Creutzfeldt–Jakob disease.
中文
The squ... | 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 | The squirrel, spider and capuchin monkeys and the chimpanzee are the only species out of twenty-three sub-human primates to develop kuru after inoculation with tissues from human kuru victims. Creutzfeldt–Jakob disease has been transmitted directly with human tissues to the squirrel and spider monkeys, as it was transm... | 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 | Eckroade et al6. have successfully transmitted mink encephalopathy to the squirrel and stump-tailed monkey. This disease and scrapie are the two naturally occurring diseases which we have grouped with kuru and Creutzfeldt–Jakob disease and called subacute spongiform virus encephalopathies7. Scrapie virus has not yet pr... | 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 | Gibbs, jun., C. J., and Gajdusek, D. C., Science, 165, 1023 (1969).
Marsh, R. F., thesis, Univ. Wisconsin (1968).
Zlotnik, I., and Barlow, R. M., Vet. Rec., 81, 55 (1967).
Barlow, R. M., and Rennie, J. C., J. Comp. Pathol., 80, 75 (1970).
* Species used in transmission attempts were six New World monkeys: squirrel mon... | 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 | 现在我们正处于第五个从黑猩猩到黑猩猩的传染过程之中,并且潜伏期已经降到了10~18个月。通过脑内或者外周(包括静脉内、皮下、腹腔内和肌肉内)接种经由孔径为220纳米的“密理博”滤膜过滤的无菌滤液就有可能导致感染。感染库鲁病的人脑和黑猩猩脑中的病毒含量都在106黑猩猩感染单位/毫升以上。传染性病毒除了存在于患库鲁病黑猩猩的脑内之外,还存在于脾、肝和肾的组织液中,但迄今为止通过给黑猩猩脑内接种同样感染库鲁病的人和黑猩猩的尿液、血液、血清和脑脊液均未使其染病。用一位在库鲁病晚期还分娩婴儿的女性患者的胎盘和羊膜组织悬液也不能使黑猩猩发病。 英文
图3.库鲁病首次从11位人类患者的脑组织传染给18只黑猩猩。
英文
克雅氏病首次从人传染给... | 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 | 到底是其中一种还是两种都与这两种病理相似的动物疾病病毒相关,至今仍没有定论。 英文
(李梅 翻译;袁峥 审稿)
* 尝试用于传染的物种是6种新大陆猴:蜘蛛猴、卷尾猴、松鼠猴、绒毛猴、猫头鹰猴和绒猴;15种旧大陆猴:恒河猴、食蟹猴、短尾猴、帽猴、地中海猕猴、豚尾猴、非洲绿猴、狒狒、叶猴、乌白眉猴、赤猴、懒猴、侏长尾猴、树鼩和灌丛婴猴;两种猿:黑猩猩和长臂猿。
Inhibition of Prostaglandin Synthesis as a Mechanism of Action for Aspirin-like Drugs
J. R. Vane
Editor’s Note
Aspirin is one of the most ... | 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 | bronchoconstriction. Because RCS has a short half-life (<5 min) it has not been isolated and its chemical nature is unknown. However, the finding that arachidonic acid, a prostaglandin precursor which induces bronchoconstriction, also releases RCS from perfused lungs12 makes it possible that RCS is a prostaglandin or h... | 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 | Arachidonic acid was dissolved in ethanol (0.1 ml./mg) and diluted with a 0.2% (w/v) sodium carbonate solution (0.9 ml./mg), thus giving a solution of arachidonic acid of 1 mg/ml. This was further diluted to 200 μg/ml. with the modified Bucher medium. 中文
Flasks containing 10 μg of arachidonic acid (0.05 ml.) and lung h... | 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 | developed chromatograms corresponding to the marker spots were separated, as was the area in between them. The rest of the chromatogram was divided into 1–3 cm strips. Each section was scraped into a test tube and shaken with 2 ml. Krebs solution. The supernatant was assayed on the rat colons and stomach strips. 中文
The... | 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 | inhibitor of synthesis of PGF2α, and on a molar basis forty-seven times more potent. Sodium salicylate was less potent than aspirin as an inhibitor of synthesis of PGF2α-like activity and there was much more variation in the results (Fig. 1). Similar results were obtained when the activity of the samples was assayed on... | 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 the second experiment, lower concentrations of indomethacin (1 μg/ml.) and aspirin (20 μg/ml.) were used. As Fig. 2 shows, indomethacin reduced the generation of activity in the PGF2α zone to 25% of that in the control incubation but the activity in the PGE2 zone was only reduced to 78%. With aspirin (20 μg/ml.) act... | 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 | Anti-inflammatory acids have three principal actions; antipyretic, anti-inflammatory and analgesic. They also antagonize bronchoconstriction and some other smooth muscle contractions induced by substances such as bradykinin1 and have a tendency to induce gastro-intestinal irritation. Can any of these actions be explain... | 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 | Analgesic action is less easily explained. Although PGE1 and PGE2 and larger doses of PGF1α and PGF2α induce a weal and flare response similar to that caused by histamine release when injected intradermally in man26, the only subjective effect reported was a sensation of warmth and a slight itching. It is unlikely, the... | 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 | tracings from these experiments shows that aspirin-like drugs not only prevented RCS release but also reduced activity on chick rectum and rat colon, indicative of a reduced output of PGE2 and PGF2α (see, for instance, Fig. 7 in Piper and Vane10). 中文
Prostaglandin F2α is bronchoconstrictor5,29, so the antagonism of bro... | 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 | One fact that needs explanation is the apparent lack of activity of sodium salicylate as an inhibitor of prostaglandin synthesis, for this substance has about the same potency as aspirin in antipyretic and antiinflammatory tests1. One possibility is that salicylate is more potent as an inhibitor of synthesis of PGE1 fr... | 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 also the possibility that use of anti-inflammatory acids could be extended to ameliorate conditions thought to be brought about by prostaglandin release. For example, some evidence33 suggests that release of PGF2α occurs during labour. It may therefore be worthwhile testing an anti-inflammatory acid as an inhi... | 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 | Piper, P. J., and Vane, J. R., in Prostaglandins, Peptides and Amines (edit. by Mantegazza, P., and Horton, E. W.), 15 (Academic Press, London, 1969).
Vargaftig, B. B., and Dao, N., Pharmacology (in the press).
Piper, P. J., and Vane, J. R., in Prostaglandins (edit. by Ramwell, P., and Shaw, J.) (NY Acad. Sci., in the ... | 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 | Ferreira, S. H., Moncada, S., and Vane, J. R., Nature New Biology, 231, 237 (1971).
抑制前列腺素合成是阿司匹林样药物的一种作用机制
文
编者按
阿司匹林是应用最广泛的合成药物之一。早在20世纪初,阿司匹林就已经得到了普遍的应用,但在那个时候的大部分时间里,人们并不了解阿司匹林治疗疼痛、发烧和其他一些病症的机理。1971年,生理学家约翰·文提出了阿司匹林和阿司匹林样药物的一种作用机制,即认为这种药物的效用是通过抑制前列腺素的合成来实现的。前列腺素是活细胞产生的激素,过量时会引起炎症和疼痛。文因为这项工作在1982年获得了诺贝尔奖,并在同一年被授予英国... | 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 | 混合抽提物在减压条件下蒸发至干。残留物用0.2 ml乙醇溶解后,以5 μg明确的前列腺素E2和F2α为标准物在A I系统[20]的薄层色谱板上进行层析分离[21]。在所得的层析图上,对应于标准物位置的条带以及它们之间的区域都被分离出去。将层析图的其余部分分成1 cm~3 cm的小条带。将每一部分分别刮到一个试管中,然后加入2 ml克雷布斯溶液并摇匀。用上清液进行大鼠结肠和胃条的分析。 英文
零时间点的样品含有(每ml)60 ng~150 ngPGF2α样活性和120 ng~750 ng PGE2样活性。同批次酶制剂不同样品之间的活性差异小于5%;将酶在无花生四烯酸的条件下孵育30 min后,活性并没有增加。在有花生四烯酸的条件下孵育... | 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(1 μg/ml)和阿司匹林(20 μg/ml)抑制了PGF2α和PGE2的合成。a, 对照;b, 消炎痛;c, 阿司匹林。
英文
结果表明:这三种消炎酸都能抑制前列腺素的合成。但目前尚不清楚这种抑制作用是如何产生的。如果作用机制是通过与花生四烯酸竞争酶的活性位点,那么就有可能解释为什么这些消炎物质都含有一个酸性基团,并且还可以解释为什么另一类消炎物质——氢化可的松就几乎或者完全不具有竞争前列腺素合成酶的能力。 英文
与治疗作用的关系
消炎酸有三种基本功能:退热、消炎和止痛。它们也可以抑制支气管收缩以及其他一些由血管舒缓激肽[1]等物质诱导的平滑肌收缩,并有可能刺激胃肠。这些效应是否都能用直接抑制前列腺素的合成来解释呢? ... | 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 | 因此,与黏膜相关联的机械刺激可能会导致壁内前列腺素的合成,从而在某种程度上保护了黏膜使其免受伤害。而阿司匹林样药物对前列腺素合成的抑制会使这种保护机制失效。 英文
用抑制前列腺素的合成能否解释消炎酸的所有功效还有待于进一步阐明。显然,在成人口服200 mg消炎痛之后,即使将消炎痛与血浆蛋白的结合率[31]放宽至90%,人体血液中的消炎痛浓度[31](峰值为7.5 μg/ml;4 h后为3.2 μg/ml)依然高于实验中抑制前列腺素合成所需的浓度。 英文
需要解释的一个事实是:虽然水杨酸钠所具有的退热和消炎功效[1]与阿司匹林相差无几,但它对前列腺素合成的抑制作用非常有限。一种可能性是,水杨酸盐对合成二高–γ–亚麻酸来源的PGE1的抑... | 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 | ASPIRIN reduces the adhesiveness to glass of platelets in citrated plasma1, reduces platelet aggregation by washed connective tissue fragments2, and inhibits the second wave of aggregation induced by ADP, adrenaline and thrombin3-5. Aspirin also inhibits the release from washed pig or human platelets of permeability fa... | 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 | D-glucose; 15 mM Tris-HCl, pH 7.4). Portions (6 ml.) of this suspension, containing 5–20×108 platelets/ml., were shaken at 37°C for 5 min with 0.06 ml. thrombin (bovine thrombin, Leo Laboratories, Hayes, Middlesex; 500 NIH units/ml. buffered saline), 2 min after the addition of solutions of various drugs (0.001–0.120 m... | 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 | The effects of aspirin given to three volunteers were then examined. Blood was taken before and 1 h after taking two tablets (600 mg) of aspirin. Platelets were washed and re-suspended as soon as the second sample of platelet-rich plasma had been obtained. The two suspensions from each donor were incubated simultaneous... | 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 | that aspirin inhibits the synthesis of prostaglandins from arachidonic acid in guinea-pig lung homogenates. 中文
In these experiments, prostaglandin production in human platelets was inhibited by sodium salicylate, aspirin and indomethacin and this effect occurred after oral administration of the latter two drugs. Prosta... | 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 | Holmsen, H., Day, H. J., and Stormorken, H., Scand. J. Haematol., Suppl., 8 (1969).
Smith, A. D., and Winkler, M., Biochem. J., 108, 867 (1968).
Bartels, J., Kunze, H., Vogt, W., and Wille, G., Naunyn-Schmiedeberg’s Arch. Pharmak. Exp. Pathol., 266, 199 (1970).
Bergström, S., Danielsson, H., and Samuelsson, B., Biochim... | 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 | 一般认为,组织中的PGE2和PGF2α是在磷脂酶A作用下(参考文献15)释放的花生四烯酸发生环化并结合分子氧而形成的[16,17],因此我们检测了溶酶体磷脂酶A的释放情况(参考文献14)。 英文
取数天内未服用过阿司匹林的健康供者的血液,在18°C~20°C、相对离心力为900ɡ下将含5.8 mM乙二胺四乙酸的这些血液离心15 min,即得到富含血小板的血浆。在体外实验中,将血浆和0.5 μM 31–14C–5–羟色胺肌酐硫酸盐(58 Ci/mol)于18°C~20°C下孵育1 h从而使放射性掺入到血小板中[18]。对血小板进行一次清洗[19],然后使其重新悬浮于缓冲盐溶液(134 mM NaCl;5 mM D–葡萄糖;15 mM三... | 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 | 在由角叉菜胶诱导的大鼠炎症的第二阶段渗出物中[20]以及在过敏性接触性湿疹患者的发炎皮肤中[25]均发现了前列腺素。给人皮下注射低浓度PGE1或PGE2会使人出现非常明显的红斑[5,26]。如果前列腺素确实是炎症的重要介质[27],那么作为消炎药的阿司匹林和消炎痛的治疗作用就可以用抑制前列腺素的合成来解释。 英文
感谢韦伯斯特教授在磷脂酶A的检测方面为我们提出了宝贵的建议,还要感谢医学研究理事会为我们提供了经费上的支持。 英文
(彭丽霞 翻译;莫韫 孙军 审稿)
Indomethacin and Aspirin Abolish Prostaglandin Release from the Spleen
S. H. Ferreira... | 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 | an experimental model in which anti-inflammatory drugs can be tested as inhibitors of prostaglandin synthesis when the organ and cell integrity are preserved and prostaglandin synthesis is promoted by a naturally occurring mediator. 中文
Spleens were perfused with Krebs-dextran solution by the method described earlier6,7... | 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 | The spleen was supported on a plastic tray hanging from a strain gauge, the output from which was displayed on one channel of a pen recorder. Thus, contractions of the spleen were recorded as decreases in weight. The splenic perfusion pressure and the reactions of the assay tissues were displayed on other channels of t... | 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 | infusions of prostaglandins directly to the assay tissues. Repetition of the adrenaline infusion at 20–40 min intervals had similar effects on perfusion pressure, splenic weight, and prostaglandin output, even though there was a gradual increase in perfusion pressure throughout the experiment. After 3–5 h of perfusion ... | 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 | after the indomethacin infusion was stopped, there was a gradual return of prostaglandin output induced by adrenaline infusion, which reached at least 60% of the initial output within 1–3 h and sometimes 100%. 中文
Fig. 1 illustrates one of these experiments. The first panel shows the reaction of the assay tissues to pro... | 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 release was abolished. In two experiments there was also a potentiation of the pressor response to adrenaline during the abolition of prostaglandin release but in only one of these did the rise in perfusion pressure return to the previous levels when the indomethacin infusion to the spleen was stopped. 中文... | 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 | Aspirin was much less effective as an inhibitor of prostaglandin release. At 15 μg/ml. (one experiment) there was 60% inhibition and at 40 μg/ml. (two experiments) there was 75% and 100% inhibition. Sodium salicylate (20 and 40 μg/ml.; two experiments) did not change the prostaglandin output induced by adrenaline infus... | 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 | Hedqvist17 has shown that prostaglandin E2 release in the spleen may be a feedback mechanism, controlling the output of noradrenaline from sympathetic nerves. He measured the effects of PGE2 on the increase in perfusion pressure induced by injections of noradrenaline; they ranged from potentiation to inhibition, depend... | 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 | Ambache, N., Kavanagh, L., and Whiting, J., J. Physiol., 176, 378 (1965).
Smith, J. B., and Willis, A. L., Brit. J. Pharmacol., 40, 545P (1970).
Hucker, H. B., Zacchei, A. G., Cox, S. V., Brodie, D. A., and Cantwell, N. H. R., J. Pharmacol. Exp. Ther., 153, 237 (1960).
Milton, A. S., and Wendlandt, S. J., J. Physiol., ... | 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 | 为了确保拮抗剂不会对受试组织的敏感性造成影响,在实验一开始,我们就将拮抗剂注入脾脏流出液。为了检测拮抗剂对脾脏的影响,药液先加入脾脏流出液,再加入脾脏流入液。 英文
当开始用脾脏流出液浇盖受试组织时,由受试组织的收缩可以看出:脾脏通常会有一个基础的前列腺素输出。通过三次用脾脏流出液不连续地灌注受试组织长达3 min的实验估算出了这个基础输出量,如果以PGE2衡量,则脾脏流出液中的输出量可以达到10 ng/ml~20 ng/ml。由受试组织的相对收缩情况可知:上述输出物是前列腺素E和F的混合物。 英文
当在动脉内注入肾上腺素(200 ng/min或6 ng/ml~10 ng/ml持续3 min)时,脾灌注压就会升高。脾脏重量减轻和脾脏... | 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 | 最下面的两条曲线(底部)表示的是灌注压的变化(∆PP)和脾重量的变化(ΔSP. wt.)。除了灌注脾脏时之外,消炎痛以0.37 μg/ml的浓度被加入到脾脏流出液中。第一列数据表示由前列腺素E2(20 ng/ml 直接作用)诱导的CR收缩和RSS收缩。第二列是由在脾脏中注入肾上腺素(ADR 10 ng/ml 注入脾脏)所诱导的灌注压上升、脾重量下降和前列腺素输出(以PGE2计算,约为20 ng/ml)。随后将消炎痛(0.37 μg/ml)注入脾脏。在接下来的25 min时间里,受试组织变得松弛(未显示),并且对PGE2(10 ng/ml 直接作用)的敏感性更高。这时,肾上腺素(加入消炎痛40 min后)会使灌注压的升高更加明显,而脾... | 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 | to one or other of the two alleles. They found that verrucal tissue from such donors contained just one phenotype, a result consistent with a clonal origin. Although human papilloma virus had yet to be identified as the causative agent of warts, researchers were aware of the links between certain viruses and cancers, m... | 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 | Verrucal tissue was obtained in a dermatology clinic from Negro females. Lesions were diagnosed as typical verruca vulgaris by J. H. The study included only lesions with typical appearance11, and measuring 2–8 mm in diameter. They were excised surgically without removing adjacent normal tissue. The root of the wart 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 | Tissue and blood from twelve Afro-American females were tested. On starch gel electrophoresis wart tissue showed a single principal zone of G6PD activity and a slower minor zone. The former zone has the same mobility as that visible in mammalian liver and epidermal tissue and was found to have substrate specificity for... | 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 | Viral infection would be expected to involve a rather large target with spread to thousands of adjacent cells assuming a reasonable titre of the virus. If the proliferative process involves the spread of the virus, this should result in a lesion of multicellular origin, showing both G6PD phenotypes. On the other hand, ... | 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 | DeMars, R., and Nance, W. E., Wistar Inst. Symp. Monog., No. 1, 35 (Wistar Institute Press, Philadelphia, 1964).
Boyer, S. H., Porter, I. H., and Weilbacher, R. G., Proc. US Nat. Acad. Sci., 48, 1868 (1962).
Linder, D., and Gartler, S. M., Science, 150, 67 (1965).
Fialkow, P. J., Gartler, S. M., and Yoshida, A., Proc. ... | 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 | 而另一方面,人们对结肠恶性肿瘤的转移性病变[7]和宫颈表皮样癌的研究结果表明[8]两种G6PD表型均存在,这间接说明了一种多克隆起源。 英文
我们将这项技术应用于对寻常疣的研究——寻常疣指的是表皮的增厚或突起,它被归为皮肤的良性肿瘤,是由一种直径为50 μm[9]的球形病毒引起的,这种病毒在结构上类似于多瘤病毒[10]。 英文
疣组织是从一个皮肤病诊所的多位黑人女性患者身上获得的。詹姆斯·霍布斯将这种病诊断为典型的寻常疣。本研究所涉及的仅仅是具有典型表现[11]且直径为2 mm~8 mm的病变区。把它们用手术切除的时候没有触及邻近的正常组织。用冷冻法破坏掉疣的根部,然后将样本置于一个含有约2 ml TC 199组织培养基的无菌试管里... | 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
(毛晨晖 翻译;袁峥 审稿)
Carbon Compounds in Apollo 12 Lunar Samples
B. Nagy et al.
Editor’s Note
Samples of lunar “soil” (mineral powder, or regolith) were brought back by Apollo 11, the first manned mission to the Moon’s surface. The Apollo 12 mission was more systematic in collecting rocks and regolith. Here geochemist Ba... | 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 | the organic molecules and to shed some light on their possible origin(s) and history. It is difficult to interpret the results unequivocally, which is not surprising in view of the difficulties encountered with the explanations of the Apollo 11 and 12 findings. This is illustrated by the apparent disparity in age of lu... | 400套付费套装书 |
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