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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 | above the glabella than on either side. In such parts as are preserved the frontal bone rises from this valley in a low curve towards bregma. There is sufficient of the frontal bone to be reasonably certain of the glabella–bregma length, which is approximately 90 mm. 中文
On the right side of the cranium the region immed... | 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 | asterion to the midline of the occipital it is also possible to estimate the bi-asterionic width, which is approximately 99 mm. The occipital index (Martin’s index 129) is approximately 72.0. 中文
Viewed in profile, when the skull is orientated in the Frankfurt plane, the occipital region is seen to project far beyond 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 | (6) The face and palate. (a) The nasal bones. Both nasal bones are preserved with only the tips of the lateral processes on either side slightly damaged. The contact of the two bones in the midline is marked by a distinct keel which continues almost to the end of the nasal area. The margins of the pyriform aperture are... | 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 | areas of their contact with the maxillary tuberosities and with the sphenoid are well preserved. 中文
中文
(7) The teeth (see Table 2) present in the cranium as now reconstructed are as follows; (a) The crown of the left M3. This is slightly broken on the distal aspect. The occlusal surface is undamaged and is very wrink... | 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 frontal bone does not exhibit the marked post-orbital constriction that is seen in the australopithecines from South and East Africa, nor does the supra-orbital element of the frontal bone curve backwards to the same extent. Seen in both lateral and vertical views the supra-orbital torus and glabellar region form 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 | lower Bed II, Maiko Gully, although differing in some respects. The problem therefore is whether or not there are two forms of Homo in Beds I and II or whether the differences between the two groups can be accounted for on the basis of individual variation and sexual dimorphism. 中文
Although only part of the upper denti... | 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 teeth of Olduvai H. 7 and H. 16 are megadont and within the size range of Australopithecus africanus; yet, in other respects, they display a number of morphological differences, especially in the premolars. 中文
Distinct differences from the australopithecines are also evident in the cranial morphology, particularly ... | 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 | Curtis, G. H., and Hay, R. L., in Calibration of Hominoid Evolution (edit. by Bishop, W. W., and Miller, J.) (Scottish Academic Press for Wenner Gren Foundation for Anthropological Research, in the press).
Leakey, L. S. B., and Leakey, M. D., Nature, 202, 3 (1964).
Leakey, M. D., in Background to Evolution in Africa (e... | 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
共生的石器业
除了一些石英岩片和碎屑之外,没有发现任何人工制品,但早先在DK挖掘出的居住地面——所包含的熔岩块围成的圈被认为是一种人造结构——曾出土过一系列代表当时石器工业的人工制品[4]。该遗址由一个居住地面构成,和DK东部的遗址一样都处于同样的凝灰质黏土中,而且也同样被凝灰岩IB所覆盖。在有些地方,人类活动留下的生活垃圾积聚在熔岩的表面,所以居住地面所在的层位略微低于人们认为头骨曾在此被侵蚀出来的石灰岩结核层。从居住地面以及覆盖于其上的黏土中发现的人工制品总计达到了1,198件,包括154件工具、187件使用器具和857件废片。这种工业是奥杜威文化的典型特征,它广泛分布于第I层之中。包括通常由用水磨蚀的熔岩卵石制造而成的各... | 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
(2)顶骨。尽管两块顶骨都不完整,但是整条矢状缝被保存了下来,因此可以相当准确地测量出前后囟索和前后囟弓来:它们分别是76.5 mm和81.0 mm。在矢状缝的两侧,顶骨以一条稍微有一点向下弯曲的曲线向侧面横向延伸了约50 mm。尽管两块顶骨的侧面部分都丢失了,但是如果这些骨头与颞骨的鳞状部分会合的话,那么它们的走向肯定是突然向下的。从该头骨保存得比较完整的右侧部位可以清楚地看到这一点。大部分矢状缝融合在了一起,但仍然可以看到它的痕迹。在第三臼齿几乎没有萌出且尚不能咬合的个体中出现这种情况的确有点令人吃惊。这说明按照与现代人相似的方法用第三臼齿的萌出来推断早期原始人类的年龄可能是不太可靠的。 英文
(3)枕骨。大部分枕骨保存完... | 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
额骨并未表现出向眶后明显收缩的现象,在南非和东非的南方古猿类中可以看到这种现象,额骨的眶上区部分也没有发生同等程度的向后弯曲。从侧面和垂直角度来看,眶上圆枕和眉间区域几乎形成了一条直线;但在所有已知的南方古猿种中,眉间都倾向于更加向前突出,而眶上圆枕的侧面边缘则向后摆动。顶骨从矢状缝处向外延伸,起初只是稍微有一点儿向下弯曲,而后则急剧地向下弯曲而与颞骨的鳞部会合。因此,第24号奥杜威原始人类脑子的顶骨区比南方古猿的要大,南方古猿的顶骨通常在接近中线处开始向下弯曲。当头骨位于法兰克福平面时,即便考虑到枕骨区的向后变形,第24号奥杜威原始人类头骨的这部分区域也比南方古猿类在更大程度上延伸到了穿过外耳道的垂直线之后。下颌窝很深,在形... | 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
(刘皓芳 翻译;林圣龙 审稿)
Non-Random X Chromosome Expression in Female Mules and Hinnies
J. L. Hamerton et al.
Editor’s Note
Equine hybrids, such as mules (produced from a male donkey and a female horse) and hinnies (produced from a male horse and a female donkey), have proved useful in the study of developmental genetics. 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 | culture plates. (Each plate contains ninety-six wells of 0.5 ml. capacity. For each experiment five or six plates were seeded.) Then 0.2 ml. of McFC15 was added to each well and the plates were covered and incubated in a 100% humidity incubator in an atmosphere of 5% CO2 in air. They were examined after 3 and 5 days an... | 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 three hybrids that were cloned are included in this table and show the expected Gd patterns. The interrelationship of the various hybrids which we have studied in detail is shown in Fig. 1. The hybrids, with one exception, develop a strong GdH band and either a faint or no GdD band. The exception (animal 192) has 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 | A number of conclusions can be drawn from these results. First, the mixed expression seen in the hybrids and some of the original cultures derived from them can be accounted for by the expression of one X chromosome only in any given cell and its descendants, as postulated by Lyon9,10, and not from partial activity of ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | by Sharman and his co-workers12-14 on X-inactivation in marsupial hybrids in which they demonstrated preferential late replication of the paternal X chromosome and inactivation of the paternal Gd and phosphoglycerokinase (PGK) loci. Finally, the results obtained here agree with other data showing that the proportion of... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Finally, the close agreement between the autoradiographic data2,4-6 and the genetic data presented here adds further support to the hypothesis that late replication is the cytological manifestation of genetic inactivity. A final proof of this would be provided by autoradiographic studies on the two clonal types derived... | 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 | Cooper, J. E. K., Texas Rep. Biol. Med., 28, 29 (1970).
Trujillo, J. M., Walden, B., O’Niel, P., and Anstall, H. B., Science, 148, 1603 (1965).
Lyon, M. F., Ann. Rev. Genet., 2, 31 (1968).
Lyon, M. F., Phil. Trans. Roy. Soc., B, 259, 41 (1970).
Grüneberg, H., J. Embryol. Exp. Morphol., 22, 145 (1969).
Sharman, G. B., N... | 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
在两个亲代物种中都只能看到一条单一的Gd电泳条带,并且GdH比GdD移动得要慢(参考文献2和8)。经过淀粉凝胶电泳之后,在亲代物种和杂交体中都能看到一些移动较慢的微弱条带,它们代表的是裂解的产物。我们对来自100号至196号实验动物的早期样品进行了淀粉凝胶电泳分析结果的归类,这已在以前发表的文章中描述过[2]。现在我们用未经克隆的红细胞和成纤维细胞对其他许多物种进行研究——不仅研究了其亲代,而且研究了包括雌雄两性的杂种。Gd类型总结于表1中,由此显然可以证明马科动物中Gd的X连锁特性。三只被克隆的杂交动物的亲本都包括在这张表中,其结果都与预期的Gd类型一致。我们曾经仔细研究过的各个杂交动物之间的相互关系示于图1。除一只以外,其... | 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 | 不幸的是,我们在对马和驴的其他X连锁酶系——PGK系和α–半乳糖苷酶系进行测试时,并没有发现它们的迁移率有何不同,因而无法进行验证。此外,这些数据还表明:体外的细胞选择倾向于那些带有一个活性染色体XH的细胞。我们对这些动物中未克隆的成纤维细胞和红细胞进行检测的结果也表明,占主导地位的是GdH基因的表达(表1),这意味着体内带有一个活性染色体XH的细胞比例与我们在体外的测试结果相符,因而在体外得到的结果不能用培养板对这两种细胞类型具有不同的接种效率来解释。进一步研究所需的、能等量表达这两种基因类型的单个动物是很难得到的。莱昂[9,10]曾提出,用体内细胞的选择可以解释小鼠和人类性别连锁基因位点在表达上的变化。发现由单一X染色体的活性或... | 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 | Cambridge5, three of the mules (Nos. 27, 33, 100), subject of a preliminary communication2, were obtained from various sources in Great Britain, while the remainder of the hybrids were from Portugal. 中文
Lymphocyte and fibroblast cultures were established by standard methods7,8. Mixed lymphocyte cultures, using female d... | 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 | Twenty-one suitable metaphase plates from each of two hinnies and one mule (Nos. 100, 188, 203) were selected for quantitative autoradiographic studies, and karyotypes prepared. The total autoradiographic grains for each cell and for each of the five longest medium sized submetacentric and metacentric chromosomes were ... | 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 sample of twenty cells selected at random from a mule and each of two hinnies (Table 4) the grain counts over the most densely labelled medium sized submetacentric and metacentric chromosomes showed the same regression line on the total cell grain counts, but the former chromosome had clearly higher grain counts... | 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 | Scatter diagrams were made before these analyses. These have shown a linear relationship between the presumptive X chromosome grain counts and the counts over the rest of the complement. The variance of Y was fairly constant over the range of total grain counts used and this was similar in the two samples compared. 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 | In our opinion, this definition is too strict because of the difficulty of counting fifty grains or more over an X-like chromosome, which means that all cells with a total grain count of 100 or more over the remainder of the complement would have to be rejected. To see whether a more strict definition of DLX could affe... | 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 | quantitatively (Table 4). Furthermore, an analysis of lymphocyte cultures from the hybrids shows that with an increase in labelling time the proportion of labelled cells increases and that of cells with a DLX decreases, while the relative frequency of DLXD and DLXH remains the same (Tables 1 and 6). 中文
Table 6. Analys... | 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 | expectations. In the study described here our intention was to investigate the relationship between differential labelling and genetic inactivity of one X chromosome, and it was expected that a 1:1 relationship would be found between the DLXH and DLXD in accordance with earlier findings1. Preliminary observations on di... | 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 | kidney and parotid gland) GdH is preferentially expressed. In thyroid and lung there appeared to be random expression while in the liver GdD seemed to be preferentially expressed. 中文
The excellent correlation observed in our studies and those of Cohen and Rattazzi6 between differential labelling and the expression of 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 | Our finding of one animal (No. 192)5 with a preponderance of GdD, on which unfortunately autoradiographic studies were not possible, suggests that there may be inter-animal variation in the expression of Gd. Inter-animal variation could perhaps account also for the discrepancy between our autoradiographic results and 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 | Moorhead, P. S., Howell, P. C., Mellman, W. J., Battips, D. M., and Hungerford, D. A., Exp. Cell Res., 20, 613 (1960).
Giannelli, F., Human Chromosomes DNA Synthesis, Monographs in Human Genetics, 5 (edit. by Beckman, L., and Hauge, M.) (Karger, Basel and New York, 1970).
Hook, E. B., and Brustman, L. D., Genetics, 64,... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 这并不影响含一个差异标记染色体XD或者XH的细胞的相对频率。在每一只有足够多细胞可供分析的杂交动物中都出现了相对频率明显偏离0.5的情况,并且每次都是DLXD过量(表4)。而另一方面,在混合的白细胞培养物中,含有一个DLX的马细胞数量要多于含有一个DLX的驴细胞数量(表2)。 英文
表1.6匹马骡和8匹驴骡的放射自显影数据
* 用3H–Tdr孵育3 h。
† 用3H–Tdr孵育4 h。
‡ 显影颗粒数量至少是任何其他相似大小染色体的2.2倍的DLX染色体。 英文
表2.混合淋巴细胞培养物的放射自显影数据
英文
DLXD和DLXH在每匹马骡或者驴骡细胞培养物中的相对频率与其在马骡或者驴骡所属群体中的总体频率并没有明显的差异(表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 | 混合淋巴细胞培养物的结果显示:马的淋巴细胞具有与驴的淋巴细胞相似的G2期,并且至少经常会含有一条差异标记的X染色体。诚然,混合淋巴细胞培养物并不是杂交体培养物的最佳对照物,因为我们需要将杂交体中的每一条染色体与来自两个亲本物种的单倍体组进行对比。但是对混合淋巴细胞培养物中DLX染色体的颗粒计数的协方差分析结果显示:在考虑了剩余标记物对标记的影响后,染色体DLXD和DLXH在S期的部分阶段表现出相似的标记方式。这一观点得到了以下事实的证实:在我们用于定量研究的3匹杂交骡子上,对类XD和类XH染色体的颗粒计数进行基于全部标记物颗粒计数(TGC)的回归分析,所得的结果是相似的(表4)。此外,关于杂交体的淋巴细胞培养物的一项分析结果显示:随... | 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 | 从异染色质化机制的角度来看,至少有两种解释可以说明染色体XD和XH之间的差异。第一,染色体XD更容易发生异染色质化;或第二,异染色质化发生在驴身上比发生在马身上更早,并在杂交体上保留下来,于是就产生了染色体XD发生异染色质化要早于XH的结果。我们在以前文章[5]中报道的关于成纤维细胞克隆体的研究结果表明:体外细胞的选择偏向于含活性染色体XH的细胞;胡克和布鲁斯特曼的研究结果[10]表明:体内的细胞选择会发生在各种器官中。 英文
我们发现有一只动物(编号为192)[5]中GdD占多数,这表明Gd的表达也许存在动物的个体间差异,可惜我们无法对其进行放射自显影研究。动物的个体间差异或许还可以用于解释我们的放射自显影结果与慕克吉及其同事的结... | 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 | Studies of the DNA replication patterns of the chromosomes of two female mules by Mukherjee et al.3,4 have shown that, in about half the cells investigated in each animal, the X chromosome derived from the female parent (the horse X) was late replicating and the X chromosome derived from the male parent (the donkey 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 | that the horse band was the usual predominant one here also. Mixing experiments with variable proportions of donkey and horse blood samples with known activity indicated that, when the bands of approximately equal intensity were observed, there was at least 35% activity of the major component in the mixture. In a mule ... | 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 were two organ types: those in which the horse phenotype was usually predominant, and those in which expression was not significantly different from what would be expected on a random basis. In none of the organs studied was the donkey phenotype the usual predominant one. If X inactivation were non-random, and oc... | 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 | Ernest B. Hook and Loretta D. Brustman: Birth Defects Institute, New York State Department of Health, and Department of Pediatrics, Albany Medical College of Union University, Albany, New York 12208.
Received February 18, 1971.
References:
Trujillo, J. M., Walden, B., O’Neil, P., and Anstall, H. B., Science, 148, 160... | 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 | 表型结果(见图1)是由欧内斯特·胡克和洛蕾塔·布鲁斯特曼分别得到的,如果两个人的结果之间存在不一致或者不确定的情况,那么样品实验就需要重复进行。对血液样品的检测结果显示:在这里马的显带仍然是普遍显著的。对已知活性的驴和马的血液样品进行不同比例混合实验,结果表明,当观察到显带的强度大致相同时,混合物中主要成分的活性至少可达35%。在一匹驴和马的表型接近相等的马骡中,并没有观察到在富含和缺乏网织红细胞的培养物之间存在亲本表型比例上的差异,尽管在后者中活性会更低一些。同样地,在新鲜的细胞和储存的细胞之间也没有观测到亲本表型比例上的差别,尽管在储存的细胞中活性更低。在一匹幼驴和一匹幼马的外周血中,两者的G6PD比活性相差不到10%。我们早先... | 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 | Strikingly, this increase is very short-lived, because the bomb 14C is rapidly diluted by carbon dioxide released from fossil-fuel burning—today considered a much greater hazard. 中文
IN the atmosphere 14C occurs principally as 14CO2 and is usually produced by nuclear reactions between cosmic ray neutrons and the nitroge... | 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 model for CO2 exchange between the various reservoirs is shown in Fig. 2, in which the CO2 in the troposphere is in exchange with CO2 in the stratosphere, the land biosphere and the ocean. For CO2 exchange between the troposphere and the biosphere we share the view of Münnich (for discussion, see ref. 17), who divi... | 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 amount of bomb-produced 14C in the atmosphere has increased the total natural amount of 14C in nature by about 3%. According to Harkness et al.8, the production of CO2 from fossil fuel would lower the natural 14C concentration in the atmosphere to about 16% below normal at the end of this century. It is thus reason... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | At our laboratory the transfer of 14C into the human body was studied by following the time-variation of δ14C in blood and hair for three persons5,27 (Tables 1–3). No separation between blood plasma and erythrocyte protein was performed, and the measured 14C activity is thus a mean value for the total blood samples. Fi... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | last 2 yr to correspond with the upper limit of the shaded area in Fig. 1. Function (2) was simplified by assuming that all previous nuclear tests occurred within a short time interval, and that the 14C increase in the human population started in about January 1963. 中文
The first term in the brackets of equation (2) ind... | 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 amount of artificial 14C in the human body at about the year AD 2000 will constitute about 3% of the total amount of 14C. This isotope has a half-life of 5,700 yr, and several scientists2,3,9,28 think that it would therefore cause a most serious genetic threat. The long term radiation dose can be calculated from th... | 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 | Harkness, D. D., and Walton, A., Nature, 223, 1216 (1969).
Rep. UN Sci. Comm. Effect of Atomic Radiation, No. 14 (A/5814) (United Nations, New York, 1964).
Münnich, K. O., and Roether, W., Proc. Monaco Symp., 93 (Vienna, 1967).
Bien, G., and Suess, H., Proc. Monaco Symp., 105 (Vienna, 1967).
Rafter, T. A., NZ J. Sci., ... | 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 | 14C在产生和衰变之间的自然平衡决定了人类所受到的一部分天然本底辐射的大小。由于核试验的原因,从1955年起,大气层、陆地生物圈和海洋中的14C开始逐步增加。虽然起初人们并不认为14C会对人类造成重大危害[1],但后来有人指出[2-4]:由于14C的半衰期很长(5,700年),因而它对人类基因造成一定程度危害的可能性还是存在的。 英文
在本实验室中,我们研究了人体内的14C浓度[5]。经过6年时间的测试,我们已证实大气中的14C与人体中的14C是相互关联的,它们之间的媒介是光合作用[6-8]。 英文
自1955年起到现在,从核试验中释放出来的全部核能的2/3左右来自于1961年和1962年人们在北纬高纬度地区大气层中所进行的试验(参... | 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 | 因为南半球对流层的δ14C值比北半球对流层滞后大约1年,所以居住在两个半球的人体内的δ14C值也应该存在类似的滞后。大致到1970年之后,14C在南北半球的人体内的浓度将会趋于持平,并等于对流层中的14C浓度。从图1中可以看出:人体内部的δ14C(xH)值就像一个落后于大气中δ14C值的脉冲。用以下这个包含两项指数函数的式子可以很好地拟合xH的观测值:
xH = 108 (e–0.1t – e–0.75t)
(2)
函数式中的系数是通过最小均方法得到的,用到了在1963年~1970年间测得的人体中14C的上限值,以及将对流层的数据外推到1970年~2000年时的数据。选择上限值是因为还应当考虑到1963年以前的一些14C过量。在最近... | 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 | of a generally apparent frontier of science—separating the known from the unknown—is mostly a romantic illusion. Instead, he suggests, there are always many frontiers, and they usually become identified whenever there is an advance, not the other way around. 中文
ARE the problems of statistical mechanics truly fundamenta... | 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 | Quantum mechanics on the other hand provided a foundation from which everything should follow, including the behaviour of gases, liquids and solids. This seemed to be confirmed by the success of the electron theory of metals. Pauli and Sommerfeld (both recipients of the Lorentz Medal) showed how all difficulties disapp... | 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 | My opinion about the fundamental character of statistical mechanics began to change in 1937 to 1938 when I, together with Boris Kahn, became involved in the so called condensation theory. The question why a gas condenses below a sharply determined critical temperature at a sharply determined density has never been call... | 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 | short, I hoped that we could discover the “structure” of statistical mechanics. 中文
We worked hard on it but did not get very far and the sudden death of Ted Berlin in 1962 makes it doubtful that our plan will ever be realized. I have learned a lot from it, however, and I have the feeling that I more or less understand ... | 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 | my ideas. They seem to me to show that the existing theories of superconductivity and superfluidity do not provide a complete explanation and that the true macroscopic description of the superfluids has not yet been found. It would be no surprise to me that this is so because the foundations of quantum statistical mech... | 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 seems better to me to view progress in science as the expansion of different circles of investigation, each autonomous and often apparently entirely independent of the others. The deep problems are to determine how these areas hang together, and how one can arrive at a larger unity. Biology and physical–chemical res... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 对于一位量子力学代的物理学家(我也属于这一代)来说,20世纪30年代的基本问题是正电子理论、量子电动力学和正在发展的核结构理论、β放射性理论;这些才是当务之急。 英文
在这个关键时刻,我想说:把科学进步看成是对有清楚“前沿”并能不断被“突破”的未知领域的一种征服,对我来说越来越像一个浪漫的幻象。这个图景显然是由量子力学的伟大突破激发产生的,它在很长一段时间里影响了我的判断。我甚至可以说它曾折磨着我。 英文
在1937年到1938年间我对统计力学基本特征的看法开始改变,那时候我和鲍里斯·卡恩在合伙研究所谓的凝聚理论。为什么一种气体在严格确定的临界温度之下以严格确定的密度凝聚,这个问题自范德瓦尔斯之后从未引起过人们的注意,而我们要想正确... | 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 | 在我看来,它们之间的相互关系是人类能够提出的最有深度的问题之一,是一个真正令人敬畏的奥秘。在小得多的尺度上,宏观物理和分子物理组成了两个这样的领域,统计力学则试图去探究它们之间的关系。 英文
(何钧 翻译;李军刚 审稿)
Lithium in Psychiatry
I. B. Pearson and F. A. Jenner
Editor’s Note
The medicinal uses of lithium salts far predate their current application to treat the psychiatric illness manic depression (bipolar disorder... | 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 | observation of a sedative effect on guinea-pigs, lithium was found to be helpful in controlling mania. The modern psychotropic use of lithium dates from that time, but dissemination has been slow and probably reflects a natural caution after the earlier fatalities, combined with the introduction of many new and effecti... | 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 effectiveness of lithium in the treatment of mania is now well recognized, and has been confirmed by controlled studies. But this treatment requires daily doses of the order of 1.5–2 g of lithium carbonate, when therapeutic and toxic levels closely approximate. In recent years the prophylactic use of lithium has be... | 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 | Lithium belongs to the group of alkali metals which includes sodium and potassium and it shares several properties with the other members of this group, but Birch has pointed out that in certain respects it resembles magnesium and calcium to which it bears a diagonal relationship in the periodic table7. It is absorbed ... | 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 | possible patients should be treated by forced diuresis. Long term treatment may give rise to small goitres and hypothyroidism but these usually respond to modest doses of thyroxine. Teratogenic effects have now been reported in two out of forty patients who received lithium during pregnancy8. Clearly lithium should be ... | 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 kidney. Conceivably the consequences of this inhibition are relevant to the therapeutic effects. 中文
Further work on this particular action has demonstrated that lithium probably blocks the action of the cyclic AMP released by vasopressin10. This raises the possibility that inhibition of the effect of vasopressin is... | 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 | way, but the significance of these observations in relation to the therapeutic actions of lithium is not entirely clear. 中文
Lithium does, however, have very clear effects on the electroencephalogram in man. In particular, it increases the amplitude of the alpha rhythm and causes slow waves to appear. After quite usual ... | 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 pharmacological actions of lithium salts are curiously complex, and knowledge about them is far from complete, Indeed, there is ample room for further research designed to increase our understanding of the effects of lithium, which may in turn shed more light on the biological mechanisms possibly involved in manic-... | 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 | Coppen, A., and Shaw, D. M., Lancet, ii, 805 (1967).
锂在精神病学中的应用
皮尔逊,詹纳
编者按
锂盐在被人们用于治疗躁狂抑郁症类精神病(双向障碍)之前早已作为药物使用。但正如精神病学家皮尔逊和詹纳在这篇综述中所指出的,人们过去对锂的应用总是过于乐观,毫不在意副作用。1949年,澳大利亚医生约翰·凯德偶然发现了锂在改变情绪上的作用,从此开创了锂在现代精神类药物中的应用。也许20年的使用时间还不足以让人们认识锂的作用机制,但直到现在我们也几乎不比那个时候知道得更多。皮尔逊和詹纳指出锂可能干扰了脑内部分新陈代谢;现在看来它也可能控制着一种重要神经递质的产生,但具体细节尚不清楚。 英文... | 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 | 从肾排出的锂在很宽的范围内正比于血浆浓度,肾清除率的数量级为15毫升/分钟~30毫升/分钟,但会随着年龄的增长而下降,在老年人中低至10毫升/分钟~15毫升/分钟的情况并不少见。当钠的摄入量受限时,锂的排泄也会下降。 英文
锂作为治疗药物的主要缺点在于治疗剂量和中毒剂量之间的安全范围太窄。一般认为血浆治疗的浓度在0.8毫当量/升~1.6毫当量/升之间,在这样的浓度范围内,只会出现很有限的副作用。其中最常见的是胃肠道障碍、肌肉无力、颤抖、嗜睡和晕眩。当血浆中的药物浓度更高时,很可能会随即出现严重的中毒反应,中毒的后果是昏迷、反射亢进、肌肉颤动、肢体伸展过度发作和痉挛,以至于致命。如果有条件,血液透析是最有效的治疗手段;但在条件不允许的... | 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 | 随着去甲肾上腺素被破坏程度的增加,去甲肾上腺素代谢从O–甲基化转变到神经细胞内的脱氨基作用;突触体对去甲肾上腺素的摄取也在增加,而突触神经递质的释放可能会减少。不幸的是,这些发现不太容易适用于那些解释神经药物作用机制的模型,因为这些药物只在一个方向上改变了情绪,而锂对情绪波动的限制是双向的。然而,有一个学派认为可以把躁狂症看作是抑郁症的一种深度发展的形式[21]。 英文
锂盐的药理作用极其复杂,目前人们在这方面的知识还远远不够。确实,为了增加对锂作用机制的了解,我们还需要进行广泛的研究,这也许会有助于揭开隐藏在躁狂抑郁症背后的生物学机制。 英文
(刘霞 翻译;陈建国 审稿)
Formation of New Connexions ... | 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 | of division, growth and differentiation: following destruction of nerve cells, non-neural elements divide and migrate into the region of damage, phagocytosing the wreckage and replacing it with an impenetrable scar. Even if the cell bodies are intact but their axons are severed, there is no evidence of successful regen... | 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 | response of VPL cells to leg and body stimulation. Here we concentrate on those cells whose receptive fields switched from leg to arm. 中文
Fig. 1. Diagram of the representation in rat thalamus of the contralateral body surface. The region in which arm, trunk, leg and tail is represented in nucleus ventralis-posterior-l... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | anaesthetized with “Equithesin”. With the head fully flexed and the cisterna magna open, nucleus gracilis can be observed directly without further dissection. The nucleus was destroyed by repeated maceration with honed jeweller’s forceps. At various times after this lesion, thalamus or cortex was mapped and then the ex... | 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 limbs. Ventral to the arm area these cells respond to arm movements and the cutaneous leg zone has leg movement cells ventral to it. 中文
Cross-sectional maps were made first of one side and then continued across the midline to investigate the opposite nucleus. Fifty-seven pairs of maps were made in twenty animals at... | 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 sites increased by an average of 132%. The change was most marked at the rostral pole where the zone normally monopolized by leg cells was now occupied by arm cells. Arm cells now lay dorsal to cells which responded to leg movement. The 16 and 17 week survival animals showed no greater expansion than the 3 week s... | 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 | 2. The thalamus on the medial side of the line contains a similar map on both the intact and deafferented side. But the region representing the arm, especially the lower arm, has expanded on the operated side to invade a region which responds to leg on the intact side. At the lateral edge of the nucleus four cells were... | 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 | them at at least the frequency of normally connected cells showing that the deafferented cells themselves do not go through a period of lowered excitability. 中文
To postulate the formation of new connexions, it is necessary first to discover the time course of their development. Eleven animals were examined 1–7 days aft... | 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 | A possible explanation for the newly effective connexion is that a background of ineffective fibres from the cuneate nucleus lie scattered through the area normally innervated by n. gracilis and that these fibres mature and successfully stimulate the cells vacated by degenerating axons. The change could be either presy... | 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 | explain the small receptive fields of the newly connected cells. The distance over which the sprouts would have to extend is not known, because although the cell bodies of the switched cells can be as much as 400 μm from the intact area it may be that the dendritic fields of the denervated cells overlap with those 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 | References:
Wall, P. D., Brain, 93, 505 (1970).
Edds, jun., Mac V., Quart. Rev. Biol., 28, 260 (1953).
Guth, L., and Bernstein, J., J. Exp. Neurol., 4, 59 (1961).
Liu, C. N., and Chambers, W. W., Arch. Neurol., 79, 46 (1958).
Goodman, D. C., and Horel, J. A., J. Comp. Neurol., 127, 71 (1966).
Raisman, G., Brain. Res.,... | 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 | 当电极位点需要标记时,先用镀银的钢微电极记录信号,接下来进行铁电解沉积,稍后用普鲁士蓝反应定位。皮层单元信号用充满3 M KCl的电阻为2 MΩ~4 MΩ的玻璃微电极记录。当需要测量反应时间时,可以用30号皮内针对与该单元对应的皮肤感受野进行电刺激。腹腔注射“Equithesin”(译者注:0.6%戊巴比妥钠和水合氯醛混合物)麻醉动物,在无菌条件下慢性损坏薄束核或背柱。使头部充分弯曲,打开小脑延髓池,不用进一步解剖就能直接观察到薄束核。用精巧珠宝镊反复浸离,破坏该神经核。在这种损伤后的不同时间点,绘制丘脑或皮层映射图,接下来用达罗红–罗克沙尔固蓝对连续冷冻切片进行染色,以确定损伤范围。我们只报道了那些损伤限制在薄束核内的动物的实验结... | 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
图3.未受损伤的丘脑腹后外侧核中感受野的分布横断面图(上图);在投射到这一核团的薄束核被破坏7周后进行研究,将断面继续绘至越过中线到对侧丘脑腹后外侧核,得到对应的映射图(下图)。垂线标出了电极轨迹,距离中线2.8 mm,在丘脑未受损一侧垂线上的取样与图2中的垂线相同。垂线内侧的丘脑在未受损一侧和传入神经阻滞一侧的映射图类似。但是代表前肢的区域,尤其是代表前肢下部的区域,在手术一侧发生扩展,侵入到未受损一侧对后肢产生反应的区域。在该神经核侧面边缘找到4个对来自躯干或后肢的刺激产生反应的细胞,但这一区域中的大多数细胞对外周刺激不产生反应。
英文
变化的时间进程和本质
对于这种扩展,最简单的解释可能是:传入阻滞的细胞发生萎缩,... | 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 | 但是,在侧索生芽的例子中,还需要解释新联系起来的细胞的小感受野。芽不得不延伸跨越的距离仍属未知,因为虽然已转换细胞的细胞体距离未受损区域可达400 μm,但是去神经细胞的树突野也有可能和那些未受损细胞的树突野发生重叠。如果一个芽为了占领新细胞,只需长几μm,那么一个先导芽可能会铺好一条通路,它邻近的细胞可以沿着这条通路生长。形成受限感受野的另外一种可能方式是,同时产生神经冲动的纤维一起生长。这就要求有一种机制能使终端有几乎同时产生的神经冲动发生,这会促进能感受到自身和相邻细胞冲动的终端的生长。 英文
显然,要想给出此现象的一个解释,还需要等待用电子显微镜对反应发生改变区域中的形态学变化的检查结果。在评价新联系现象的意义时,必须给出某... | 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 | Kasugamycin also inhibits the binding of fMet-tRNA to the mRNA-ribosome initiation complex in the presence of β,γ-methylene-guanosine triphosphate (GMPPcP), which indicates a different mode of action from the other aminoglycosides11,13. In this article we show that resistance to kasugamycin is determined by the propert... | 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 | Analysis of CsCl “split” and “core” fractions for ksg sensitivity and resistance. 30S subunits were reconstituted from the appropriate split protein and core particle preparations using the methods of Traub and Nomura16 and assayed for poly UG-directed 14C-valine incorporation. In a volume of 100 μl., the reactions con... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Fig. 1. RNAase T1 plus phosphatase fingerprints of 32P-labelled 16S RNA isolated from ksg sensitive (a) and resistant (b) E. coli. The arrows in b indicate the positions of oligonucleotides which are present in only one or the other digest. The strains were labelled by growth in 1% “Bactotryptone”, 0.5% yeast extract, ... | 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 | This inference was confirmed by fingerprint analysis of 14C-methyl-labelled 16S RNAs. These fingerprints (Fig. 2) show that an oligonucleotide with the mobility of (No. 71) is present only in the RNA from the sensitive cells (2a). It is clear that no other methylation changes in the 16S RNA fragments can be detected (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 | source of the 16S RNA in reconstitution experiments. The change from kasugamycin-sensitivity to resistance is apparently associated with a failure to methylate a specific sequence in this RNA. We have yet to establish, however, a direct cause and effect relationship between the presence of the sequence and the sensitiv... | 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 | Fingerprinting of the 23S RNA and total soluble RNA fractions (unpublished observations) has provided two other points of interest. First is the fact that, in the kasugamycin-resistant strain in which dimethylation of adenine does not occur, monomethylation of the N-6 position of adenine in 23S RNA does occur. Thus it ... | 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 | Ozaki, M., Mizushima, S., and Nomura, M., Nature, 222, 333 (1969).
Bollen, A., Davies, J., Ozaki, M., and Mizushima, S., Science, 165, 85 (1969).
Takata, R., Osawa, S., Tanaka, K., Teraoka, H., and Tamaki, M., Mol. Gen. Genet., 109, 123 (1970).
Bernardi, A., and Leder, P., J. Biol. Chem., 245, 4263 (1970).
Kuwano, 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 | Grossman, L., in Methods in Enzymology (edit. by Grossman, L., and Moldave, K.), 12A, 700 (Academic Press, New York, 1967).
大肠杆菌中春日霉素抗性突变与16S核糖体RNA的甲基化变化相关
赫尔泽等
编者按
核糖体在所有细胞中都是蛋白质合成体系中的核心成分,它由一大一小两个亚基构成。在这篇论文中,詹姆斯·达尔伯格和他的同事们指出,小亚基中成分(16S核糖体RNA)的化学修饰的变化(甲基化)会引起大肠杆菌对一种抗生素——春日霉素的抗性。他们还指出,突变是与靠近16S核糖体RNA一端的某一特定核苷酸序列的甲基化变化... | 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 | 图b中箭头指示存在只被一种(或另一种)酶消化的寡核苷酸的位置。配制含1%“细菌用胰蛋白胨”、0.5%酵母提取物和0.3%葡萄糖的培养基,灭菌前在pH 9条件下用MgCl2沉淀除去无机磷酸盐。用这种培养基培养大肠杆菌品系,从而标记它。加入32P标记的磷酸盐(1 mCi),使上述培养基(pH 7.8)的体积达到25 ml。细胞在这种培养基中生长到对数期后期,收集,用离心法洗涤,再用溶菌酶/ EDTA溶液处理以溶解细胞。用苯酚提取全RNA,并经5%~20%蔗糖梯度纯化。在16S RNA峰值收集,并用乙醇沉淀除去EDTA。每20 μg(~106 c.p.m.)RNA在2 μl pH值为7.7的0.05 M Tris-HCl和0.0001 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 | 由于我们未能检测到春日霉素敏感性和春日霉素抗性品系的核糖体蛋白间的任何区别,我们提议,ksgA基因座是对RNA甲基化酶产生反应的基因。对这一提议的支持将来自于下述证据:在体外能够通过甲基化将来自春日霉素抗性品系的16S RNA转化为“敏感性”RNA。这样的实验正在进行中。 英文
23S RNA和全部可溶RNA片段的指纹图(尚未发表的观察结果)提供了另外两点值得关注之处。第一点,在没有发生腺嘌呤二甲基化的春日霉素抗性品系中,的确存在23S RNA中腺嘌呤的N–6位置被单甲基化的现象。因此非常有可能由不同的酶负责RNA中腺嘌呤残基的单甲基化和二甲基化。第二,在抗性品系中发现,小分子量(大约4S)RNA经T1核糖核酸酶和磷酸酶消化后得到的... | 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 | clinical and scientific problems associated with the study of human fertilization and cleavage. The opening came with the discovery that human oocytes would undergo their final stages of maturation—those occurring just before ovulation—when removed from their follicles and placed in a suitable culture medium. These sta... | 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 surgical methods for collecting human oocytes are perhaps almost as refined by now as they ever will be. Laparoscopy has proved to be a simple and very safe procedure permitting the necessary manipulations to be carried out on the ovary3. Oocytes are collected from more than one-half of the available Graafian folli... | 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 | most patients. Alternatively, the use of compounds such as clomiphene, to induce the release of endogenous hormones, might prove superior, cheaper, and more acceptable than the injection of gonadotrophins. Clomiphene is widely used in the treatment of female hypopituitarism, and should work well with cyclic patients. 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 | Media suitable for fertilization and for cleavage are rarely identical. The development of media to support the cleavage of human ova has not relied on experiments with mammalian ova to nearly the same degree. Simple defined media had been developed for the cleavage of mouse ova, following the recognition of the import... | 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 | embryos in culture augurs well for their continued development. Conditions in the mother also seem to be satisfactory: most patients have had a secretory endometrium, excreted suitable amounts of pregnanediol, and their induced cycle has resembled a natural cycle3. 中文
What is known of the capacity of the embryos for no... | 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 | secondary sex ratio had been controlled in any mammal. Most efforts in this direction had been devoted to the attempted separation of X and Y spermatozoa, so far without any convincing success. 中文
Improvements are now needed in the methods for sexing blastocysts. Two approaches are currently feasible: the identificatio... | 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 | Studies on human conception open new approaches to human problems including preventive medicine and family planning. More knowledge about the growth of ovulatory follicles, the secretions of the blastocyst or the components of capacitation could lead to the development of novel methods of contraception. Rational discus... | 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 | Lappe, O. O., and Schalk, M. J., Transplantation, 11, 491 (1971).
关于人工受精的几个难题
爱德华兹
编者按
在本文中,体外受精技术(IVF)的先驱者罗伯特·爱德华兹描述了与这项技术相关的实际操作问题和社会问题,那时他已经能够运用该项技术获得6天大的人类胚胎。他强调了使用排卵前卵子的必要性,并指出可诱导排卵的化合物如克罗米酚等可能比注射促性腺激素更有效而且更便宜——关于两者效用对比的讨论至今仍在继续。他指出,体外受精技术的成功可使一些不孕夫妇拥有自己的孩子,所以“和这些生育能力低下的少数群体谈论人口过剩问题似乎是很不公平的”。迄今为止,那些不断提及核克隆和家庭维持问题... | 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 | 根据主要基于兔卵子的实验结果,人们曾认为在实验中必须使用从子宫内取出的精子,这一结论几乎成了金科玉律。即使发现仓鼠卵子可与附睾精子在体外受精[6]这样的证据也几乎没能动摇这一固有的观念。在使仓鼠受精所需的培养基条件确定之后,研究工作随即扩展到包括体外成熟的卵母细胞和清洗过的射出精子在内的人类材料。在设定人类体外受精条件时采用了从动物卵子的研究中得到的标准[7]。此外,类似的研究如今已经扩展到了其他物种,如小鼠和牛,现在甚至发现兔精子也可以穿透卵子的细胞膜。所用的培养基非常简单:在一种碱性台罗德氏溶液中加入牛血清白蛋白、丙酮酸和碳酸氢盐并将pH值调至7.6。丙酮酸显然是一种能量来源,而白蛋白可能作为氮源或者起稳定细胞膜的作用。现在我们... | 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 | 目前仅有一篇文献与性连锁抗原有关,该文指出,小鼠后代的性别比例可以通过干扰怀孕时的自然免疫过程来改变[16]。囊胚性别鉴定将是一种通过避免患病男婴出生从而控制性连锁突变基因的绝好方法。如果有证据表明父母们的普遍意愿会严重干扰人口的性别比例,那么就必须对性别鉴定进行严格的控制。 英文
人类受孕研究开辟了解决包括预防医学和计划生育在内的人类问题的新途径。更多地了解关于排卵卵泡生长、囊胚分泌以及精子获能成分方面的知识也许会使我们找到避孕的新方法。关于由这些研究引发的社会问题尚需要通过理性的讨论来解决。迄今为止的讨论大多因为远远脱离了实际临床问题而显得毫无意义:经常被引用的核克隆就是一个例子。当怀孕四个月或者更大的胎儿因社会原因而被流产时,... | 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 | verify the absence of the usual nucleotide modifications from this molecule; (b) that a mutation7 (A2P) that increases the amount of mature tRNA produced by tyrosine tRNA-mutant A2 is located in the precursor segment close to the usual 5 ́ end of the tRNA sequence, and (c) that a nuclease activity, present in crude ext... | 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 | differences: (1) those bases which are normally modified were almost completely unmodified, and (2) the T1 and pancreatic digestion products derived from the 5 ́ and 3 ́ termini of mature tRNA were absent in digests of precursor. 中文
Table 1. Additional Products of Enzymatic Digestion of Precursor tRNA
All products are... | 400套付费套装书 |
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