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C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | <σv> Bremsstrahlung≃<σv> Spallation
(9)
from which it follows that an appreciable fraction of the α particles must be fragmented by the time they pass downstream of the shock. 中文
At this stage we have to distinguish two cases according to whether the gas density is high enough for neutrons from spallation to be capture... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | The first question to be asked is: what will be the order of the depth of the shock zone? Taking ~3×10–7 g cm–3 as the average density within the shock zone, and noting that <σv>Bremsstrahlung≃3×10–16, we see that the electrons lose their energy in a time ~2×10–2 s. In this time material flowing at a mean speed of say ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | Deuterium produced within the shock zone will itself be subject to spallation, as will be 3He and T. Consequently we shall not regard D production as being due to the immediate spallation of 4He, but as arising from neutrons released in the breakup of 4He. The lifetime of the neutrons against weak decay (~103 s) is ver... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | could be the origin of all the deuterium in the Galaxy. Accompanying the production of D in the shock front will be that of a smaller amount of 3He, perhaps enough to yield the proto-solar values (~10–5) taken by Black3 as typical. Further, because the explosion which produces the shock wave may well be due to nuclear ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | Audouze, J., Epherre, M., and Reeves, H., High Energy Nuclear Reactions in Astrophysics, chap. 9 (Benjamin, New York, 1967).
Fowler, W. A., Greenstein, J. L., and Hoyle, F., Geophys. J. Roy. Astron. Soc., 6, 148 (1962).
Colgate, S. A., and White, R. H., Astrophys. J., 143, 626 (1966).
Appenzeller, I., and Fricke, K., A... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | 另一方面,无论在局部天区还是从天空的一个区域到遥远的其他区域,2.7K的背景辐射值都非常均匀。这种均匀性,虽然没有完全排除很小尺度上不均匀性的存在,但似乎预示着并不支持这一论点。 英文
在新的困局下,重新考虑氘起源的可能的天体物理模式也是重要的。如果证明局部D/H具有变化,那么天体物理过程比原初核合成更为合理,但如果D/H比值具有均一性,则原初合成模式较合理。 英文
自20世纪50年代中期开始的研究已经不断地表明,在天体物理中D在非热力学条件下最容易产生。我们想象α粒子以高速射入一团主要由氢组成的电离气体中。如果气体具有某一适中温度,比如确切的105 K,导致D形成的核反应就可以发生。D可以通过散裂反应从一个α粒子中被击出,从4He... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | 如果我们现在把物质想象为一些单独的粒子,而不是从连续介质力学的观点来看,这些粒子在从冲击波的上游到下游的过程中,其速度变化了2c/7。我们必须认为波前具有有限深度,并且来自上游的粒子在通过有限冲击区时经历了碰撞。由于2c/7的速度等效于每个核子约40 MeV的轰击能量,我们得到了与上面讨论过的α粒子射入静止气体类似的情景。因此,冲击波上游物质中的4He在通过波前的时候会碎裂。 英文
事实上,由于冲击区中的所有粒子都来自上游并经历了碰撞,当前情形比α粒子射入周围气体的情形更有利于碎裂。虽然大约一半的轰击能量将被转移给电子,但除此之外的轰击能量将以冲击区内无规则运动的质子和α粒子形式存在,这些α粒子在冲击区内的整个时间段内都易发生分裂。... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | 英文
总结起来说:由氢产生4He的一般热核过程几乎不生成氘。但是,如果在异常情况下,如在一个高速冲击波的前沿,4He能够被震动分解为组成它的中子和质子,在这种情况下,只要气体密度不小到中子在被俘获前就完全衰变,将会有利于D产生。随后的条件同样有利于D的形成,这是由于波前后面的温度为T≃7.6×106 K,导致D(p, γ)3He的寿命约1010 s,这比一个局域爆炸天体消散所需时间长得多。局部的D/H比可以比地球上的值高102,但是和其他外部物质平均后,D/H值会降低。如果总体上原初太阳的估计值3×10–5是星际介质的特征值,那么这里描述的过程可能是银河系中所有氘的来源。伴随冲击波前锋中D的产生,将有少量的3He形成,这可能足以产生... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | THE origin of the Afar Triangle, the locus or near locus of the triple junction formed by the Red Sea–Gulf of Aden and East African Rift, has been debated in detail recently1,2. It is particularly important to determine whether the Afar Triangle has controlled the evolution of the three lines of plate divergence or vic... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | Afar—Iceland Mantle Plume Analogue: Rare Earth Evidence
I reinterpret rare earth abundance data from submarine tholeiitic basalts erupted along the Red Sea Trough, the Gulf of Aden, and tholeiites from Jebel-Teir Island, reported earlier, by first drawing analogy with similar but more extensive evidence obtained from t... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | Fig. 1. La/Sm enrichment factors relative to chondritic meteorites13 in tholeiitic basalts erupted along the post-glacial Reykjanes Ridge Axis and its extension over Iceland (see map insert).
中文
A [La/Sm]E.F.>1 generally indicates light rare earth enriched fractionation patterns, such as for alkali basalts or island ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | composition, again judging from the CIPW norm and Yoder and Tilley’s classification19-22. 中文
Thus a similar phenomenon seems to occur away from the Afar hotspot as in the case of the Iceland hotspot. The rate of progressive light RE depletion is smaller for the Afar. No data are available in tholeiitic basalt erupted f... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | PHMP-tholeiites. 中文
The second mantle source (DLVL), of more global extent, is the low velocity layer. This layer is characteristically depleted in large ionic lithophile elements (K, Rb, Cs, Ba, U, Th, light rare earths, and so on)13,31, and low in radiogenic Pb and Sr (refs. 32, 33). Usually, away from any hot plume ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | In considering the evidence for the Iceland–Reykjanes system in detail14-15, I have proposed two mechanisms for the mixing of the two primary lava types to occur, both probably operating simultaneously. One mechanism calls for elongated magma chambers beneath the zones of rifting, and the other requires horizontal dike... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | state is approached or reached, zones of plate divergence in the upper asthenosphere should be characteristically hotter and mass deficient because of diapiric and magmatic injection, and therefore should favour mantle flows. Further, the overflow can be affected by damming effects caused by remanent continental blocks... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | Fig. 3. Afar Triangle showing the three main zones of crustal attenuation also corresponding to preferred mantle plume flow direction about its centre in the upper asthenosphere. Length of arrows roughly proportional to intensity of flow. Estimate of the plume diameter cannot be made for lack of data on the Danakil Dep... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | crust is very strongly attenuated and partly oceanized; along the Wonji Fault Belt toward the Ethiopian Rift, the crust is slightly attenuated and most probably continental. This evidence is in excellent agreement with the prediction based on rare earth consideration. Unfortunately no gravity data are available from th... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | reached from Fig. 3. Later, I found that this point coincides with the shaded area of Fig. 3 of Barberi et al.23, characterized by centres of thermal activity, and where evidence for earlier submarine volcanism exists47-48. It also corresponds to the area where the Wonji Fault Belt seems to die out and lose its identit... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | It is important to carry out geochemical, petrological and geophysical characterization of both the PHMP and the DLVL mantles. The trace element and isotopic composition of the DLVL have been indirectly but extensively inferred from the so-called low-K2O mid-ocean ridge tholeiites13,32,33,50,51 erupting sufficiently fa... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | further complicates direct isotopic comparisons and inferences on the depth location of plume sources. 中文
I thank Mrs M. Osti and M. Zajac for help with typing and drawings. This work has been supported by the US Office of Naval Research and the National Science Foundation. 中文
(Nature Physical Science, 242, 2-5; 1973)
... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | Barberi, F., Borsi, S., Ferrara, G., Marinelli, G., and Varet, J., Phil. Trans. Roy. Soc., 267, 293 (1970).
Tatsumoto, M., J. Geophys. Res., 71, 1721 (1966).
Peterman, Z. E., and Hedge, C. E., Geol. Soc. Amer. Bull., 82, 493 (1971).
Welke, H., Moorbath, S., Cumming, G. L., and Sigurdsson, H., Earth Planet. Sci. Lett., ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | Gast, P. W., Geochim. Cosmochim. Acta, 32, 1057 (1968).
Philpotts, J. A., and Schnetzler, C. C., Can. Mineralogist, 10, 375 (1970).
Vogt, P. R., Nature, 240, 338 (1972).
阿法尔地幔柱:稀土元素证据
席林
编者按
冰岛具有异常的地球物理背景,它处于两种不同的火山源之上:一个是洋中脊,即热物质从两个离散的构造板块之间上涌的部位;另一个是热点或地幔柱,即从地幔深处呈柱状上升的岩浆流。让–居伊·席林的这篇文章是最早证实上述情景的文章之一。由于两个火山源在冰岛地区有重叠,因... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | 英文
当[La/Sm]E.F.<1,通常指示轻稀土元素亏损的海底洋中脊拉斑玄武岩(按照我的模型,洋中脊拉斑玄武岩来源于不受热点影响的亏损低速层(DLVL))。 英文
图2. 沿红海海槽和亚丁湾喷出的拉斑玄武岩中相对于球粒陨石[13]的La/Sm富集因子,与到阿法尔三角中心的(不计方向,见插图)径向距离的相关关系。
英文
最后[La/Sm]E.F.~1,指示的是海底洋中脊拉斑玄武岩。一般见于摩根提出的热地幔柱或三联点附近,这一点当时还无法解释[13](按照我的模型,这种混合型拉斑玄武岩是由来源于PHMP和DLVL来源的拉斑玄武岩浆混合形成)。 英文
上述结果并不仅限于雷恰内斯海岭和冰岛地区。与图1相似,对阿法尔地区的稀土元素数据... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | 英文
阿法尔地幔柱中心的流动模式:稀土元素证据
过渡带沿线的混合比例取决于PHMP的流动模式以及热柱进入周围LVL的强度。热柱的溢流模式各不相同,且随时间不断变化(参考文献37;让–居伊·席林,完稿中)。它取决于区域环境,如PHMP垂直通量、扩张脊的局部地形以及其他构造因素、相关岩石圈扩张速率与主应力场和热场等等。另外,在上部的200~300 km深处,两种幔源在不同程度上均由部分熔融的岩石组成。我们并未直接采用德费耶新近提出的热柱模型[38]。我认为,这里的涌流是相互渗透的多孔介质流,即表现为熔体渗透和渗透对流。此类体系被称为岩热体系[39],且该概念已被引入对阿法尔地区的研究中[8]。 英文
在冰岛,PHMP溢流似乎主要是沿两个... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | 英文
其他地球物理和构造资料也显示,该处为三向浅层软流圈流动模式,而这正是磁异常线性构造[4,5]及所谓大型构造的方向和类型[46]。 英文
那么如何确定热柱中心的位置呢?图2中用于测定径向距离的参考中心(11°15′N,41°25′E),是人为选定的,在阿贝湖西北部,大致处于阿法尔三角的中心位置。这个位置是三个走向的三联点,即亚丁湾的西—南西走向,达纳基勒凹陷(以埃尔塔阿勒火山和阿莱塔山脉的拉斑玄武岩喷出形成雁列裂缝为特征)的南—南东走向[23]以及埃塞俄比亚非州大裂谷沿翁吉断裂带(图3)的大致延伸方向。当然,我并不是说该点一定就是热柱的中心。坐标的确切位置对于本文的论证并不是特别重要。热柱中心发生100 km左右的位移是很容易的... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | 英文
(齐红艳 翻译;徐义刚 审稿)
T and B Lymphocytes and Immune Responses
M. C. Raff
Editor’s note
In this paper, Canadian-born cell biologist Martin C. Raff sums up what was then known about T and B lymphocytes. The two white blood cell types are found in peripheral lymphoid organs where they look identical, and Raff had previousl... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | cells) and/or phagocytosed by cells of the reticuloendothelial system. On the other hand, in some cases, such immune responses may have deleterious effects on the host, such as in hypersensitivity reactions (hayfever and drug allergy, for example), where antigen reacting with antibody fixed to basophils and mast cells ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | and rodents5 it was found that removing the thymus from an embryo or newborn markedly impaired the cell-mediated immune responses of the animals when they grew up, but had much less effect on humoral immunity. On the other hand, removal at hatching of the bursa of Fabricius3,4, a cloacal lymphoid organ unique to birds,... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | Until recently it was thought that specific immune responses were confined to vertebrates. There is now evidence, however, that some invertebrates, such as annelids and tunicates, can reject foreign tissues and that these primitive immunological responses can display specificity and possibly short-term memory8 (that is... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | In most animals, lymphocytes first appear in the foetal thymus. The thymus anlage is composed of epithelial cells and is derived from the third and fourth pharyngeal pouches. Although in the past it had been suggested that thymus lymphocytes (thymocytes) develop from thymus epithelial cells, experiments in chickens and... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | lymphocytes9,12,13. This suggests that the second differentiation step may occur within the thymus and that T cell development may be visualized as stem cell→thymocyte→“mature” thymus lymphocyte→peripheral T lymphocyte (Fig. 1). This scheme is almost certainly an oversimplification, however, for there is some evidence ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | anti-μ antibody (that is, specific for the heavy chains of IgM) before hatching, combined with neonatal bursectomy, suppresses later production of IgG as well as IgM15. This suggests that even B cells that will eventually produce IgG initially express IgM on their surface, and is strong evidence for an IgM→IgG switch w... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | As resting T and B lymphocytes are morphologically indistinguishable and are found together in all peripheral lymphoid tissue, it has been essential to find ways of distinguishing and separating them in order to study their individual properties. The demonstration of important surface differences between them has been ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | Most T lymphocytes continuously recirculate between blood and lymph, passing out of the blood through specialized post-capillary venules in lymph nodes and Peyer’s patches, passing through the substance of the lymphoid tissues and entering the efferent lymph; they then re-enter the bloodstream by way of the thoracic du... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | concanavallin A (Con A), phytohaemag-glutinin (PHA) and lentil stimulate only T cells, and lipopolysaccharides (for example, E. coli endotoxin) and anti-Ig sera stimulate only B cells35. It is of interest that although soluble Con A and PHA selectively activate T cells, they bind equally well to B cells, and if covalen... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | coated with the antigen and can thus be specifically removed from a cell suspension38. Although T cells tend not to adhere under these conditions38 for reasons that are unclear, T cells responsive to cell surface alloantigens can be selectively removed in cell monolayers bearing the specific alloantigens39. 中文
In 1900,... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | Germ-line theories, which suggest that one is born with a large number of variable region Ig genes, are competing with various somatic theories, which postulate that one is born with few variable region Ig genes and that some somatic process (for example, mutation or recombination) creates a large number. 中文
The chemic... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | When an antigen combines with its corresponding receptors on a T or B lymphocyte, one of at least three things can happen to the lymphocyte: first, it may be stimulated to divide and differentiate to become an effector cell in some type of immune response (that is, it is induced to respond immunologically); second, it ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | B cells, and although T cells may be paralysed at very low and very high concentrations of antigen (low and high zones of tolerance respectively) B cells seem to be paralysed only at high antigen concentrations49. The way in which the antigen-receptor interaction signals a lymphocyte is unknown, although it probably in... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | antigen-antibody ± complement complexes adhering to Fc or complement receptors on B cells) and/or in killing target cells with coated antibody52. 中文
When T cells are activated by antigen, they proliferate and differentiate to become blast cells, but they do not develop significant amounts of endoplasmic reticulum and d... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | Although T cells do not themselves secrete antibody in the usual sense, it is now known that they play an important role in helping B cells to make antibody responses to most immunogens. Thus, in these responses T cells are referred to as “helper” cells, and B cells as “antibody-forming precursor” cells. The first dire... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | antigen-specific IgM-like factors (?receptors) complexed with antigen, which are subsequently taken up on macrophages60. 中文
Fig. 2. Possible mechanisms of T-B cell collaboration in humoral antibody responses. The “antigen bridge”(→) between T and B cell receptors could serve to : (i) present antigen to B cells on the ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | With the recognition that there are two distinct classes of lymphocytes with different origins, properties and immunological functions which modulate each other’s activities, the door has opened to a new era of immunology. The resulting insight into the functioning of the immune system in health and disease has paved t... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | Owen, J. J. T., in Ontogeny of Acquired Immunity, a Ciba Foundation Symposium, 35 (Associated Science Publishers, Amsterdam, 1972).
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Raff, M. C., and Cantor, H.,... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | Cunningham, A. J., and Sercarz, E. E., Eur, J. Immunol., 1, 413 (1972).
Greaves, M. F., and Janossy, G., Transplant. Rev., 11 (1972).
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Basten, A., Miller, J. F. A. P., Warner, N. L., and Pye, J., Nature New Biology, 231, 104 (1971).
Wigzell, H., Transplant. Rev., 5, 76 ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | Mitchison, N. A., Rajewsky, K., and Taylor, R. B., in Developmental Aspects of Antibody Formation and Structure (edit. by Sterzl, J., and Riha, I.), 2, 547 (Academia, Prague, 1970).
Schimpl, A., and Wecker, E., Nature New Biology, 237, 15 (1972).
Feldmann, M., J. Exp. Med., 136, 737 (1972).
Jacobson, E. D., Herzenberg,... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | 对免疫缺陷病患者的研究也表明,体液免疫和细胞免疫分别受到不同因素的影响(见参考文献6):由于缺乏产生抗体的淋巴细胞,患有布鲁顿型先天性丙种球蛋白缺乏症的病人不能产生抗体,但是细胞免疫正常;而先天性胸腺发育不全的儿童(如迪乔治综合征患者)则表现为细胞免疫功能显著受损,但对某些抗原产生免疫应答时可以产生相对正常量的抗体。 英文
在过去的几年中,免疫的双淋巴细胞模型(至少在鸟类和哺乳动物中)已经确立。在这个模型中,有两个“中枢”淋巴器官——法氏囊或在哺乳动物中具有的同功能器官(目前尚不明确)和胸腺——产生不依赖于抗原的淋巴细胞,并将它们运送到“外周”淋巴器官(淋巴结、脾脏和肠道相关淋巴组织),淋巴细胞在那里等候与抗原接触从而诱导其进一步分... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | 然后这些细胞的一部分迁移到外周淋巴组织中,分别成为T淋巴细胞和B淋巴细胞。
英文
B淋巴细胞的发育
在鸟类中,B细胞的发育依赖于法氏囊。法氏囊是在胚胎发育第五天由泄殖腔背壁外翻所形成的一个囊状结构。染色体标记研究显示,在胚胎发育第12天到第13天时便有干细胞(与胎儿胸腺中检出的干细胞形态一致)从卵黄囊迁移到法氏囊中,并且在1~2天内在那里分化成淋巴细胞[9]。到第14天可以观察到表面有IgM的法氏囊淋巴细胞,几天后可以观察到产生IgG的法氏囊淋巴细胞[15]。同位素标记实验证明法氏囊淋巴细胞可以迁移到外周淋巴组织。在胚胎时期摘除法氏囊会导致外周B淋巴细胞的显著缺失和抗体(即免疫球蛋白)产量的显著减少[15]。最近人们发现,向孵化... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | 此外,T细胞更容易被抗淋巴细胞的血清清除[31](主要针对反复循环的细胞),但通常对细胞毒性药物(如环磷酰胺[32])、皮质类固醇[33]和辐射[34]的敏感性较低。另外它们在体外对于各种“有丝分裂原”的反应也是不同的,比如植物提取物(如植物有丝分裂原)、细菌代谢产物(如内毒素)或淋巴细胞表面抗原的抗体,其均可刺激很大一部分T和(或)B淋巴细胞分裂、分化为母细胞。尽管美洲商陆可以同时刺激T细胞和B细胞增殖,但是伴刀豆球蛋白A(Con A)、植物凝集素(PHA)和扁豆素只能刺激T细胞增殖,而脂多糖(如大肠杆菌内毒素)和抗免疫球蛋白血清则只能刺激B细胞增殖[35]。有意思的是,尽管可溶的ConA和PHA只能选择性地激活T细胞,但它们同样... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | T细胞应答的精准特异性非常类似于抗体的特异性和B细胞识别的特异性[47];再加上种种(尽管存有争议)实证表明T细胞上有免疫球蛋白(有关综述见参考文献1),使得人们不愿放弃T细胞表面具有免疫球蛋白受体的观点。也许T细胞(可能也包括B细胞)表面至少具有两套“识别”系统,其中一套包含免疫球蛋白,另一套通过Ir基因编码的产物介导,对于不同的抗原、不同的免疫应答和(或)不同的T细胞亚型来说,这两套识别系统可能具有不同的重要性。此外,这种假定的非免疫球蛋白识别系统可能与无脊椎动物对外源性物质的简单识别类似。 英文
T细胞和B细胞的功能
当抗原与T淋巴细胞或B淋巴细胞表面相应的受体结合时,淋巴细胞至少会发生下列三个事件中的一种:第一种是在某些免疫... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | 尽管越来越多的证据表明,在某些环境下T细胞可以成为“杀手细胞”[55],但是关于T细胞自身是否可以直接杀伤靶细胞还是必须通过激活其他细胞(如巨噬细胞)杀伤靶细胞目前尚有争论。 英文
尽管T细胞本身一般不分泌抗体,但现在已经知道它们在帮助B细胞对免疫原作出应答方面发挥着重要的作用。因此,在这类免疫应答中,T细胞被称为“辅助”细胞,而B细胞则被称为“抗体–形成前体”细胞。关于T-B细胞协作的首例直接证据是在1966年发现的。研究人员发现,向经放射照射的小鼠同时移植胸腺细胞和骨髓细胞,其产生抗绵羊红细胞(SRBC)抗体的能力比那些只移植胸腺细胞或骨髓细胞的小鼠产生抗体的能力强的多[56]。后来人们发现,在这类实验中,所有抗体分泌细胞(也就... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | 英文
(张锦彬 翻译;秦志海 审稿)
Cometary Collisions and Geological Periods
H. C. Urey
Editor’s Note
The idea that comet impacts on Earth could have caused mass extinctions in the geological past is usually attributed to geologist Walter Alvarez and his father Luis, who proposed in 1980 that such a catastrophic collision at the end... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | leading surface it is 71.9 km s–1; and if with intermediate positions and directions the relative velocities are intermediate. Of course, the escape velocity of the Earth, 11.2 km s–1, must be added, and is considerable for trailing type collisions. The two velocities, including this correction, are 16.6 and 72.8 km s–... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | Table 1. Energetic Effects a Cometary Collison with Earth Could Produce
中文
The scattering of ocean water over land areas would destroy land plants and animals, though probably such water would not fall uniformly and some would not be killed by this method. The earthquake effect would be great in the immediate neighbou... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | Were the ages of Tertiary times determined by the fall of comets which produced the tektite fields? Table 2 lists the ages of these recent geologic periods and the ages of tektites. Rough agreement exists. Errors are probably present in both the geological estimates and the physical measurements of the tektite ages whi... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | Urey, H. C., Science, 137, 746 (1962).
Durrani, S. A., Nature, 235, 383 (1972).
Russell, H. N., Dugan, R. S., and Stewart, J. Q., Astronomy, 446 (Ginn and Co., New York, 1945).
Whipple, F. L., in Moon, Meteorites and Comets (edit. by Middlehurst, B. M., and Kuiper, G. P.), chapter 19 (Chicago Univ. Press, 1963).
Lin, S... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | 由彗星上的氨和其他化合物引起的雾效应可能会比较小。由于碰撞的总能量相当于一年中地球得到的来自太阳能量的0.29倍,所以如果所有的热量都被大气吸收,大气温度可升高到190°C,因此温度看起来将会出现明显的上升。短期高温对于动植物来说是极具灾难性的,并且在高湿度条件下,适当的温度上升就会导致大量生物死亡。对于海洋动植物来说,倘若处于离碰撞点较远、震动不强烈的地方,它们似乎就不会受到很大影响。但是对于呼吸空气的海洋恐龙来说,情况会是这样吗?由于体内温度较低,吸入的高湿度空气会在它们体内冷凝产生大量的水。当然,其他一些陆栖爬行动物,例如短吻鳄以及一些原始的哺乳动物和鸟类则从白垩纪幸存下来,并一直延续到古新世。它们的幸存可能由于“好运”,因为... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | MANY recent studies have been concerned with the construction of biological model systems to describe adequately regulation of gene action during development of eukaryotes1-5. The number of genes in mammals and Drosophila has been suggested to be 1 to 2 orders of magnitude less than the amount of available DNA per hapl... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | complementation groups or genes to 5,000 chromosome bands. There are also estimates available on the total number of lethal loci in the Drosophila genome. By screening for large numbers of lethal chromosomes either in natural populations or following irradiation, it is possible to relate the frequency of allelism to th... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | cross reacting material (CRM) was measured (Acph-1 and ry) it was also negligible. 中文
Null alleles of at least two of the loci were induced in a crossing scheme that would have recovered lethal alleles (αGpdh-1 and Acph-1). A lethal “null” allele would also be detected as an exceptional heterozygote with normal alleles... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | In two cases double “null” mutants of alkaline and acid phosphatase (R. S. MacIntyre, personal communication) and of Zw and 6-Pgd (W. J. Young, personal communication) were constructed and proved viable, fertile, and morphologically normal. Also, in two of the five cases where there is an observable phenotype, bb and α... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | A second widely used argument which suggests a minimum of informational DNA in the eukaryote genome (less than 10% of the available DNA) states that the mutational genetic load would be inordinate if mammals used all their DNA to carry and transmit biological information. Ohno4 states that with a mutation rate of 10-5 ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | multiplicative fitness is an unrealistic assumption, then besides questioning selective neutrality as a major force, it also removes the restrictions imposed by the mutational and substitutional load on the number of functional genes. 中文
There are a number of ways, suggested by myself and others, that a population can ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | In the cellular slime mould, Dictyostelium discoideum, 28% of the nonrepetitive nuclear genome is represented in the cellular RNA during the 26 h developmental cycle33. If only one of the complementary strands of DNA of any gene is transcribed, the estimate represents 56% of the single copy DNA. Because the nonrepetiti... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | tissues33,35. 中文
The major arguments supporting the contention that much of eukaryotic DNA is neither transcribed nor functional are based essentially on the response of the functioning genes to natural selection. The tremendous amounts of physiological and/or genetic compensatory mechanisms which defer the presumed de... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | O’Brien, S. J., and MacIntyre, R. J., Drosophila Information Service, 46, 89 (1971).
Lindsley, D., and Grell, E. H., Genetics Variations of Drosophila melanogaster (Carnegie Inst. Publ. No. 627, 1967).
O’Brien, S. J., and MacIntyre, R. J., Genetics, 71, 127 (1972).
Ritossa, F., Malva, C., Boncinelli, E., Graziani, F., ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | Sofer, W., and Hatkoff, M. A., Genetics, 72, 545 (1972).
Tobari, Y., and Kojima, K., Genetics, 70, 347 (1972).
Ritossa, F. M., Atwood, K. C., and Spiegelman, S., Genetics, 54, 819 (1966).
Baglioni, C., Nature, 184, 1084 (1959).
Ghosh, D., and Forrest, H. S., Genetics, 55, 423 (1967).
真核生物功能基因数的估计
奥布赖恩
编者按
在人类基因组计划定位了数... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | 在自然或实验室群体中发现的“无效”等位基因中(Est-C、Est-6、Aph、Aldox和Idh),也能检测到一种致死性“无效”等位基因,这种等位基因与有着不同电泳迁移率的正常等位基因形成一个异常杂合子。 英文
14个基因座中有5个具有能够产生可见的隐性表型的等位基因,其中ry,cn和v影响眼睛的颜色,bb影响刚毛,而αGdph-1“无效”突变使果蝇尽管在形态学上表现正常,但丧失了持续飞行的能力。但是5/14这个比例并不能作为产生可见表型的“无效”等位基因在基因座中所占比例的估算值。因为所研究的5个基因座中的4个(除了αGdph-1)最初就是作为形态学的突变而被发现的,其基因产物已经从它们的可见表型中推断和鉴定出来,所以这个数值很可... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | 英文
真核细胞中的信使RNA一般连有很长的(150~300个核苷酸)多聚腺苷酸序列[26-28]。尽管人们假设多聚腺苷酸添加到信使RNA末端发生在转录后[29-31],细胞核DNA中存在类似长度的多聚胸苷酸提示转录时添加也是可能的[32]。RNA-DNA杂交动力学显示高达0.55%的哺乳动物核DNA退火后结合多聚腺苷酸,对应于1.1%的多聚脱氧腺苷酸–脱氧胸苷酸序列[32]。这提示至少有5×104个多聚脱氧腺苷酸–脱氧胸苷酸位点。如果这些序列的每一个都与邻近的结构基因一起转录,再加上转录后加入的多聚腺苷酸序列、非信使RNA基因以及所有的非转录性调节基因,那么功能基因数肯定会超过5×104。这个数目可能是相当可观的。 英文
在细胞型黏... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | below 700 km, owing to a “discontinuity” in the mantle that subsequently became a major focus of geophysical studies. 中文
Study of seismic wave propagation in the mantle beneath the New Hebrides island arc shows that the remarkable gap in seismic activity between deep and intermediate depth earthquakes at the northern p... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | earthquakes and recorded at stations along island arcs where large gaps in seismic activity exist provides evidence for determining which of these models is correct. Observation of attenuated, low frequency waves for the appropriate paths indicates a gap in the descending lithosphere. But if high frequency shear waves ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | Fig. 1. Map showing the Tonga-Fiji-New Hebrides region of the southwest Pacific. ●, Historically active volcanoes; ▲, seismic stations; ■, locations of deep earthquakes used in Figs. 2 and 3. Water depths are in km.
中文
The inclined seismic zones of South America also have remarkable gaps in seismic activity between a... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | Fig. 2. Cross-section of the New Hebrides arc showing J-B ray paths to NOU, PVC and LNR stations and the corresponding records [E-W component at PVC, N-S component at NOU, and Z component at LNR] and the locations of seismic activity (vertical lines). Only low frequency S waves are recorded at the stations.
中文
Deep e... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | first direct evidence that the attenuating, asthenospheric layer is deeper than about 300 km in the upper mantle. 中文
New Hebrides deep earthquakes always produce low frequency S waves at NOU (Fig. 2). This is most probably due to attenuation in the upper mantle (the asthenospheric layer), because the ray paths to NOU c... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | We will present a detailed study of the travel times of P waves of the New Hebrides deep earthquakes later. The travel time residuals of P waves of the New Hebrides deep earthquakes at PVC and LNR stations along the arc are close to normal (about 1 to 2 s earlier). This is in contrast to P residuals of about 4 to 5 s e... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | different explanations can be made for this. One is that the slab beneath New Zealand is continuous and reaches depths of at least 600 km, and thereby provides a path for high frequency S waves. The second is that although the slab may have a gap beneath about 300 km, the portion above 300 km is sufficient to provide a... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | An interesting observation is that New Zealand deep shocks produce high frequency S waves at stations in the South Island. Fig. 4 shows an example recorded at Gebbies Pass (GPZ), a station located along the aseismic13 east coast of the South Island. This observation suggests that beneath at least the northern part of t... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | Fig. 5. Map showing contours of earthquake depths for Tonga and New Hebrides arcs, the deep seismic zone of New Hebrides, and well located deep earthquakes beneath the Fiji islands and the Fiji plateau. ▲, Events with depth range between 525 and 575 km; ●, events with 576 to 625 km depth; ■, events with 626 to 675 km d... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | Barazangi, M., Isacks, B., and Oliver, J., J. Geophys. Res., 77, 952 (1972).
Mitronovas, W., and Isacks, B., J. Geophys. Res., 76, 7154 (1971).
Adams, R., N. Z. J. Geol. Geophys., 6, 209 (1963).
Le Pichon, X., J. Geophys. Res., 73, 3661 (1968).
Chase, C., Bull. Geol. Soc. Amer., 82, 3087 (1971).
Mooney, H., J. Geophys.... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | 沿南美洲西海岸的观测站记录了过去10年该区发生的几乎所有的深源地震,目前我们正在对其进行详细研究,具体将另文发表。 英文
新赫布里底岛弧下的岩石圈空区
图1所示为本研究采用的新喀里多尼亚和新赫布里底的观测站位置。我们利用新赫布里底的深源地震对这些站位上记录到的所有数据进行了检验。最令人吃惊的一项观测结果是,PVC和LNR站上均从15°S以北的深源地震记录到了低频(约0.5 Hz)S波占主导地位。 英文
图2所示为穿过新赫布里底岛弧与NOU、LNR相交的一个横剖面,该剖面也通过PVC附近。新赫布里底深源地震位于深部地震带的西部(距中层深度带向下的投影很近),它在PVC站形成衰减的低频S波。地震波列的路径恰好穿过下倾地震带的下方。频率均... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | 从新喀里多尼亚的NOU站和位于新赫布里底岛弧的北部各站(至北部约16°S处,LNR和LUG站)得到的上述地震的记录均表现为衰减的低频S波。但在PVC站得到的最近一次发生在18°S,173°E附近的地震记录则表现为大振幅、高频率的S波。这是在PVC站记录到的三次地震中唯一一个质量较好的记录。不过该观测结果非常清晰,而且很可能意味着新赫布里底岛弧南部存在连续的下降板片。要对南部深源地震带作出实质性解释,还需要更多数据的支持。 英文
新西兰下部存在拆沉的岩石圈碎片?
在新西兰,北岛地区地震发生于约300 km深处,而在南岛的最北部大约为200 km。另外,1953年和1960年在北岛有三次地震发生在约600 km深处[9]。图4所示为新西... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | 英文
(齐红艳 翻译;李三忠 审稿)
Fusion of Rat and Mouse Morulae and Formation of Chimaeric Blastocysts
G. H. Zeilmaker
Editor’s Note
Over ten years earlier, Polish embryologist Andrzej Tarkowski made chimaeric mice by fusing together eggs taken from different mouse strains. Here, Gerard H. Zeilmaker manages to fuse early mouse emb... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | Fig. 1. a, Mouse (left) and rat morulae in apposition, shortly after withdrawal of egg holders. Developmental stages after 2 (b), 4 (c), 6 (d), 8 (e), 11 ( f) and 12.5 h (g). In d the blastocoelic cavity is formed.
中文
Fig. 2. Mouse (left) and rat (upper right) morulae in the process of fusion. Pictures taken after 3... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | in the other partner (Fig. 2g). In one experiment one of the aggregate partners formed a cavity before the cell mass had become round (Fig. 3b); this disappeared and a final one was formed after aggregation (Fig. 3d). The pictures and analysis of the time-lapse photographs show that both rat and mouse cells contribute ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | 英文
通过将不同种系小鼠的囊胚细胞融合诱导产生嵌合体是近期实验胚胎学领域最卓越的成就之一[1,2]。 英文
去年,有人(麦克拉伦博士,私人交流)指出,将不同物种的桑葚胚融合在一起的可能性,这种可能性还没有得到充分的研究[3]。因此我用与融合小鼠桑葚胚基本相同的技术[3,4]进行了一系列的实验,来研究能否诱导大鼠和小鼠桑葚胚的聚集。 英文
在妊娠第2天的21:00,用培养液将小鼠桑葚胚(C3Hf×瑞士种,8细胞至16细胞阶段)从子宫–输卵管区域洗脱出来,未经历栓塞,见光14小时,置于暗处10小时,并使黑暗阶段的中期处于午夜。在妊娠第3天的21:30,洗脱出大鼠桑葚胚(R,阿姆斯特丹大鼠,8细胞至16细胞阶段)。分离出来的桑葚胚分别储存... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | cell, enabled researchers to effectively isolate and identify chromosome fragments and assign genes to chromosomes. The technique correctly assigned many genes to their chromosomes, but was “unacceptably slow”. Somatic cell recombination and gene transfer, Ruddle prophetically muses, could provide the way forwards. 中文
... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | chromosomes from both parental genomes. In many parental cell combinations, the hybrids have an infinite life expectancy and can be grown into large clonal cell populations. In man–mouse and man–Chinese hamster hybrids there is a unilateral loss or segregation of human chromosomes. The segregation of human chromosomes ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | that adenine phosphoribosyltransferase (APRT) deficiency mutations can be used similarly for hybrid cell selection9. Conditional lethal mutants other than those based on drug resistance can also be used for hybrid selection. Puck et al. have used nutritional auxotrophs with good results10,11, and it is likely that temp... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | agents in permissive medium to select against hybrid cells which have retained human chromosomes 17, 16 and X. 中文
Table 1. Conditional Drug Resistance and Nutritional Auxotrophic Genetic Markers
中文
Rodent–Human Hybrids
In rodent–human hybrids, the human chromosomes are unilaterally segregated, both homologous human a... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | overall frequency of human chromosome retention (29%). It has been reported that hybrids with two rodent genomes (2 s hybrids) retain more human chromosomes than 1 s hybrids15. The relationship between rodent and human chromosome number is significant and should be resolved, because it is fundamental to the problem of ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | but which do not express detectable levels of mannose-phosphate isomerase (MPI) activity. Linkage analysis in other cell hybrids shows a strong correlation between C-7 and MPI. I have concluded that MPI may represent a partially constitutive phenotype. Such phenotypes pose problems for linkage analysis, but they also p... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | detection of human–mouse chromosome translocations27 (see below). Several laboratories have reported evidence indicating that the centromeric constitutive heterochromatin in man has different physical properties unique for several of the human chromosomes28. 中文
Assigning Genes to Chromosomes
Linkage of enzyme phenotype... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | It is frequently possible to strengthen the assignment of a gene to a particular chromosome by correlating the frequency of a particular chromosome within a clone with the intensity of expression of an assigned phenotype(s). Discrepant clones of two classes can occur, however. In the first, presuming a valid assignment... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | It is also possible to make use of spontaneous, sporadic chromosome rearrangements which occur in hybrid cells to fix the location of genes within subregions of particular chromosome. Human chromosomes within hybrids may undergo rearrangement and even translocation to mouse chromosomes29 and it has been possible to mak... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | Chinese hamster–human hybrids. If the findings based on cell hybrids are combined with linkages known from human pedigree analysis, the following additional gene markers can be assigned to chromosome 1: zonular pulverulent cataract, Duffy blood group, auriculo-osteodysplasia, salivary amylase, pancreatic amylase, ellip... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | There are no assignments to chromosomes 8 or 9. There is evidence from mouse–human hybrids for the assignment of the cytoplasmic form of glutamate oxaloacetate transaminase (GOT) to chromosome 10 (unpublished work of R. P. Creagan, J. A. Tischfield, F. A. McMorris, M. Hirschi, T. R. Chen and F. H. R.) 中文
Boone et al.29... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | No assignments have been made to chromosome 13. For chromosome 14, Ricciuti and Ruddle (ref. 46 and F. Ricciuti and F. H. R., unpublished) using a 14/X translocation in a human diploid fibroblastic cell strain (KOP) hybridized to a mouse cell line have demonstrated a segregation of nucleoside phosphorylase (NP) with th... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | adenovirus 12 infection induces host TK activity, and concurrently a secondary constriction in the proximal segment of the long arm of 17. These findings suggest that the TK gene may be located near the adeno-12 induced gap region. 中文
Creagan et al. (unpublished) using mouse–human cell hybrids have provided evidence fo... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | chromosome 21. No assignments have yet been made to chromosome 22. 中文
Glucose-6-phosphate dehydrogenase (GPD), hypoxanthine-guanine phosphoribosyltransferase (HGPRT), and phosphoglycerate kinase (PGK) have all been assigned to the X chromosome by segregation analysis in families59. Nabholz et al.17 using mouse–human hy... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0304. 《自然》百年科学经典(英汉对照版)(第六卷)(1973-1984).epub | .epub | 45,637,976 | 2025-09-26T19:07:36.672222 | proposed by Ricciuti and Ruddle46. It also confirms the assignment of GPI to 19. 中文
No assignments have been made to the Y chromosome. 中文
Possibilities for New Approaches
The development of a detailed human genetic map is certain to provide insight into the evolutionary origins of man and the primates. LDH-A and LDH-B ... | 400套付费套装书 |
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