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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 | Because the power law is near E–2 except close to Emax, we expect the γ of synchrotron radiation theory to be close to two, and the corresponding spectrum to be close to Sv∝v–a with . It is possible to work out a better approximation using the δ function approximation to the frequency spectrum of a single electron9. Fo... | 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 Magellanic clouds have no nucleus. M31 has a strong radio source rather larger but weaker than that found in the Galaxy11. Code has discovered strong ultraviolet emission from the nucleus, which Kinman finds to have a large mass-to-light ratio and to contain some 108 solar masses. This suggests a small mass flux in... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | When F–3 achieves large values ~106 or 107 (that is, 103–4 M⊙ yr–1) the mass of the Schwarzschild throat rapidly build up to 109–1010 M⊙. When galaxies first formed there was this amount of gaseous material in them. Large proto-galaxies rapidly achieved large Schwarzschild throats and greedily swallowed gas. It is clea... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | D. Lynden-Bell: Royal Greenwich Observatory, Herstmonceux Castle, Sussex.
Received July 8, 1969.
References:
Ryle, M., Highlights of Astronomy (edit. by Perek, L.) (D. Reidel, 1968).
Hoyle, F., Fowler, W. A., Burbidge, G., and Burbidge, E. M., Astrophys. J., 139, 909 (1964).
Greenstein, J. L., and Schmidt, M., Astrop... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 我将假设在最初的一个持续109年的时期里类星体是常见的,但是每个类星体只能在106年内保持明亮,采用桑德奇的估计(见参考文献4中的引述),天空中应有107个亮于22星等的类似类星体的天体。这应该代表了类星体时期的一个快照,因此只有千分之一会是明亮的。如果这些代表了所有类似于类星体的天体,那么死亡类星体的密度应为每哈勃体积107个×103=1010个。于是两个相邻的死亡类星体之间的平均距离就是10–3哈勃距离(1010光年)或者3兆秒差距(Mpc)。从这些统计结果看来,很可能有一个死去的类似类星体的天体存在于本星系群中,并且我们必然可以预期有很多这样的天体距我们比室女座星系团和M87还近。如果我们仅限于研究那些在射电波段明亮的老年类星... | 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 | 详细地考虑当一团气体云在星系核中聚集时将发生什么会有力地支持这一说法。(上述说法由萨尔皮特最先提出,他也推导出了0.057 F c2的功率输出[5],这正是现在所描述的结果。) 英文
气体吞噬
一个星系中,所有恒星的总质量损失大约是1 M⊙/年。其中的一部分质量积聚在引力中心的星系核中。在气体云碰撞时,由于激波辐射了碰撞的能量,因此会产生耗散。对于给定的角动量,最小能量的轨道是圆形轨道,因此我们只能期望气体将形成一个扁平的盘,靠圆周运动来维持与中心的距离。这样一个较差自转系统会由于“摩擦”而不断演化,正如人们早期对一个正在死去的类星体所描述的那样。因为在没有摩擦的情况下什么都不会发生,所以能量是通过摩擦释放的。在宇宙环境中,分子的黏... | 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 | 磁力线不是物质的线,因而以无限快的速度移动并没有什么不妥;甚至表征磁力线速度的标准公式v = c (E×B/B2)也会在| E×B | > B2(即,在高斯单位制中满足|E| > |B|时,假设两者是垂直的)时给出视超光速的速度。粒子会一直绕着磁力线旋转直到磁力线的运动速度达到光速;随后电场开始起主导作用,而磁场变得很弱以至于不能使任何物理量发生显著的变化,这时粒子是通过静电场加速的。电位降可以直接由法拉第定律给出:
其中dN/dt是磁通的重联速率。为了计算这个电动势,我们可以根据在时间(2A)–1内重联的磁通为2b2B估算出重联速率。由此得到的电动势为4b2AB/c(式(11))。我们将会看到,这些电动势的量级为1012 V。因... | 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 | 由式(7)得到:b/r = 0.05x; ρ0 = (2π)–1/2∑/b=4.6×10–19r0–3/2x–3F–3M7–1/2 =1.4×10–9 m0–3/2x–3F–3M7–2 g cm–3 (m0 ≫ 6)。由式(13),B = 3×10–3 r0–5/4 x–1/2 F–31/2M71/4 = 2.7×105 m0–5/4 x–1/2 F–31/2M7–1 G (m0 ≫ 6)。根据式(18),p(r) ≈ 0.22r0–3F–3M7 erg cm–2 s–1(r ≫ 6m)。可以看出:功率具有向中心区高度聚集的趋势,在那里我们需要使用精确的相对论公式(17):
英文
总功率
P = 0.057 F c2 = 3.2... | 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 | 更准确地说,我们预期会在m = 22处发生时标为2r/Vr(120天)的光变,因为这刚好是物质流能够在其发射大部分流量的区域内发生变化的时标。应用我们的理论所得到的一个最直接的结果显然是:更多的能量被用于加速质子而不是电子。质子被加速所要求的密度是电子被加速所需密度的918倍。在我们的模型中,密度的变化如同r–3/2,而总功率在3/2 r和1/2 r之间的变化如同r–1。我们推测质子的功率大约是电子功率的102倍。稳态的谱容易被确定。从我们的加速器来看,我们期望能量与电位降成比例。因为粒子是从各个点开始运动的,所以被加速器喷射出的能谱在直到最高能量eΦ~1013eV的范围内都是均匀的。 英文
图1.标准模型中盘和同步辐射的发射谱。... | 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 | 巨大的原初星系很快形成巨大的史瓦西喉并贪婪地吞噬着气体。显然该过程可以产生足够的能量,并且通过使M接近于1010 M⊙,我们可以降低史瓦西喉附近的密度。这使得射电现象能够发生在更靠近奇点的地方,那里也是有更高功率的地方。 英文
附加说明。洛最近在100 μm波段对银河系中心进行了观测(报告于1969年的剑桥红外天文学会议),结果表明银河系的F–3更接近于10–2而不是1。瑞斯提出的尘埃模型可以在假设存在单一的可见光或紫外光中心源的前提下来解释这些红外观测结果。来自这些源的光压将把含尘埃的物质从塞弗特星系的星系核中排出,导致观测到的外流,正如魏曼所提出的一样。这样一种机制可以截断质量流F–3并因此产生辐射流量的变化。光压可能会驱使尘埃... | 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 | chondrites (up to 70 percent)4 is insoluble and the soluble matter is frequently of a very minor nature. In addition, the soluble, and so potentially more mobile, organic chemicals are more likely to have moved in total or in part from their point of origin, and problems of rock contamination with such substances, eith... | 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 | non-oxidative chemical reagents including those used to separate microfossil or insoluble organic material from their inorganic environment. (b) They are highly unsaturated and readily oxidized—the oxidation (especially ozonization) products from both modern6 and fossil7 spore exines are very similar both qualitatively... | 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. Infrared spectra of some sporopollenins. a, Lycopodium clavatum spore exine after heat treatment; b, Tasmanites punctatus spore exine (a fossil planktonic alga); c, insoluble organic matter form the Orgueil meteorite; d, insoluble organic matter from the Murray meteorite; e, oxidative polymer of ß-carotene; f, ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | To our objective results must be added the earlier recorded subjective evidence which claimed the presence of spore-like bodies in both carbonaceous chondrites9 and early terrestrial Pre-Cambrian sediments10. 中文
Our experimental results on the two meteorites, which are completely objective and readily repeatable on qui... | 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 | Hayes, J. M., Geochim. Cosmochim. Acta, 31, 1395 (1967).
Han, J., Simoneit, B. R., Burlingame, A. L., and Calvin, M., Nature, 222, 364 (1969).
Brooks, J., and Shaw, G., Nature, 219, 532 (1968); Grana Palynologica, 8 (2-3), 227 (1968).
Brooks, J., and Shaw, G., Nature, 220, 678 (1968).
Shaw, G., Sporopollenin, in Phytoc... | 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 | 它们的共性主要体现在以下几个方面:(a)它们对于非氧化性化学试剂具有稳定性,其中包括用于分离微化石或从无机环境中提取不溶有机质的非氧化性试剂。(b)它们都是高度不饱和的并且很容易被氧化——无论从定性角度还是从定量角度来看,现代孢子外膜[6]和化石孢子外膜[7]的氧化(尤其是臭氧化)产物都极其相似,同时源自若干碳质球粒陨石相关实验的有限证据也证明形成物具有孢粉素降解产物的典型特征[1]。(c)它们在乙酸的作用下不发生水解。(d)它们与氢氧化钾发生熔合后,给出的特征谱类似于酚酸(参考文献6和一些我们尚未发表的结果)(间羟基苯甲酸、对羟基苯甲酸和原儿茶酸,或者是它们的混合物)。(e)它们具有相似的红外光谱(图1中给出了几个例子)。(f)它... | 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 | Remains of Hominidae from Pliocene/Pleistocene Formations in the Lower Omo Basin, Ethiopia
F. C. Howell
Editor’s Note
The search for fossil hominids moved from Olduvai Gorge in the Rift Valley of East Africa to the Omo valley in Ethiopia—further north, and back in time. This is Clark Howell’s field report on work by 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 | Hominid remains have now been recovered from twelve localities in the lower Omo Valley. The temporal relationships of the hominid localities are set out in Table 1 and their positions keyed to a succession of volcanic tuffs which are useful and important marker horizons within the >500 m thick Omo Beds series. Radiomet... | 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 | Except for several milk teeth and an upper incisor (from Brown Sands) the teeth from these two localities represent exclusively the permanent premolar and molar dentition. The complete dm1 (W-753) is larger than the few known (and reported) specimens referred to either Australopithecus africanus (four specimens from tw... | 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 | Only two complete upper molars are known, an M1 (B-23b) from Brown Sands and an M2 (W-749) from White Sands. The M1 is within the known size range of homologues referred to A. africanus; it is shorter than known homologues referred to A. robustus (or to A. boisei), though barely within the known lower range in breadth ... | 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 | Localities below Omo Beds Tuff D and Tuff C
Arambourg and Coppens2,3 have already reported a hominid mandible, without tooth crowns preserved, from a locality (their Omo 18) below Tuff D. Two K/Ar determinations on this tuff indicate an age of 2.37–2.56 m.y. (ref. 1). This fossiliferous zone thus seems to postdate 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 | particularly details of their fissure pattern and occlusal surface morphology these lower molars, and the incomplete specimens from Locality 2 (L2–79) and Locality 51 (L51–7) as well, have resemblances to lower molars from South African sites referred to A. africanus. 中文
The first upper molars from Locality 51 are with... | 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 upper and lower third molars from Locality 9 probably represent only one individual. Both teeth are large. The M3 is in the range of samples referred to either A. africanus or A. robustus, though it is smaller than Olduvai hominid 5 referred to A. boisei. Its shape index and occlusal morphology agree best with spec... | 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 | incomplete M1, which lacks small parts of the mesio-buccal and disto-lingual margins of the crown, is clearly australopithecine in its morphology. Both specimens are reasonably assigned to A. cf. africanus. 中文
Locality below Omo Beds Tuff G
Three hominid teeth have been recovered from one locality (Locality 28) between... | 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 | Hominid mandibles of australopithecine type have been recovered from two localities above Tuff G (and below Tuff H, although this tuff is hardly exposed in the northern sector of the main Omo Beds). Locality 7 (specimen No. L7–125) has yielded a complete mandibular corpus, lacking both ascending rami, with all permanen... | 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 known range of homologues referred to A. robustus. Its length (13.0 mm) exceeds that of specimens referred to A. africanus, and its breadth (13.75 mm) is barely within that range. It has a higher shape index (94.4) than the range recorded for such homologues. The crown is strongly molarized, with expanded talonid, ... | 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 | thickening of their upper portion (comparable with the alveolar prominence) beginning just distal of the level of the second molar and continuous anteriorly as the alveolar planum. 中文
Fig. 8. Right lateral view of hominid mandible (L7–125) from Locality 7, above Tuff G, main Omo Beds.
中文
Fig. 9. Left lateral view o... | 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 crowns of the premolar and molar teeth are substantially worn. Dentine is exposed across the full width of P3, and on the buccal side of P4. The occlusal surfaces of M1 and of M2 have extensive dentine exposure except for the marginal rims of enamel. The surface of M2 is worn deeply concave, even more so than that ... | 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 | well as other localities worked by the French contingent of the expedition (Y. Coppens, personal communication), also have robust australopithecine resemblances. This suggests that antecedents of robust australopithecines extend back at least another half million, and probably more, years. The series of isolated teeth ... | 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 | Arambourg, C., and Coppens, Y., CR Acad. Sci. Paris, 265, 589 (1967).
Arambourg, C., and Coppens, Y., S. Afr. J. Sci., 64, 58 (1968).
Patterson, B., and Howells, W. W., Science, 156, 64 (1967).
Martyn, J., and Tobias, P. V., Nature, 215, 476 (1967).
在埃塞俄比亚奥莫下游盆地的上新世/更新世地层中发现的人科化石
豪厄尔
编者按
对原始人类化石的搜寻从位于东非大裂谷的奥杜威峡谷转移到了奥莫... | 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 | 在褐沙滩发现的5枚完整P4中,有2枚与其余牙齿有关联(见前面的列表)。所有这些牙齿的尺寸都处于南方古猿非洲种标本的已知尺寸范围之内(由11枚牙齿得到的范围),但是比南方古猿粗壮种(或南方古猿鲍氏种)的已知P4标本要窄一些。它们与南方古猿粗壮种的最小已知标本(20枚牙齿中的一个标本)一样短,甚至更短。在从褐沙滩发掘出来的两个关联标本中,P3比P4小,不如粗壮南方古猿中那么明显,而与南方古猿非洲种中常见的情况更相似。这些牙齿的整体形态,尤其是最初裂隙系统的模式以及爪部发育的欠缺,都与在斯泰克方丹发现的南方古猿非洲种标本非常吻合。 英文
现在人们只知道两枚完整的上臼齿,其中一枚是来自于褐沙滩的M1(B-23b),另一枚是来自于白沙滩的M2... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 因此从该地层得到的这一标本被归入南方古猿非洲种。 英文
奥莫组凝灰岩E层之下的地点
仅在凝灰岩D层和E层之间的两处地点发现了原始人类的化石。这些标本只包括3枚单独的牙齿(图4)。它们是:
英文
图4.在主奥莫组凝灰岩E层之下地点(第9号、64号)发现的原始人类牙齿。上排:左M3(9–12),右M3(9–11);下排:左dm2(64–2)。
英文
无论是与来自奥莫层序列的其他乳齿相比,还是与已知的南方古猿相比,这个dm2都格外大。它同斯瓦特克朗斯南方古猿粗壮种标本(13枚牙齿)中最大的那些dm2一样大,比来自克罗姆德拉伊的两个标本要大一些。其大小与南方古猿非洲种标本(6枚牙齿,两两分别来自斯泰克方丹、马卡潘石灰厂和汤恩,来自... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 英文
该半侧下颌骨(L74–21)具有一个很深且强壮的下颌体(图6和图7)。该下颌体的高度超过了除斯瓦特克朗斯的大型成年SK12标本之外其他所有之前已知的粗壮南方古猿的对应值。该下颌体的厚度只在一个方向上没有SK12标本和佩宁伊标本(纳特龙盆地)的大。其联合部高度很大,处于(或超过)已知粗壮南方古猿对应范围的上限;这一区域的厚度值也是如此。C和P4都是大齿冠牙齿。C的长度(8.8 毫米)和宽度(9.7毫米)均超过斯瓦特克朗斯南方古猿粗壮种标本的已知数值,但是落在了来自斯泰克方丹和马卡潘石灰厂的南方古猿非洲种标本的范围之内。然而,这枚牙齿的形态与粗壮南方古猿非常相像。虽然P3只有根部被保存了下来,但是可以通过其与C和P4的接触面来估计... | 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 | 从这一个体的下颌骨和齿系可以看出:它代表的是一种非常粗壮的南方古猿类型,在很多方面类似于来自奥杜威第I层FLK I遗址的5号原始人类,并且被认为属于南方古猿鲍氏种。 英文
现在人们已经知道奥莫下游盆地的奥莫组跨越了上新世/更新世时期的一段相当长的时间。现在已经从这组地层里的一系列化石层中发现了迄今为止鲜为人知的一段时期的人科化石。到目前为止,有理由认为肯定来自于新生代晚期这一大致范围的原始人类化石包括:来自图尔卡纳东南卡纳波伊的左肱骨远端[4]以及来自巴林戈盆地科莫龙地层序列的上菲什组的右颞骨[5]。在每个例子中,来自动物群的证据都表明,其与奥莫层序列最古老沉积物所代表的最早的时间范围基本一致,也就是说,这些化石的年代可能介于300... | 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 | SIR,—Dr. Donahoe’s unduly alarmist and misleading letter concerning anomalous water (Nature, 224, 198; 1969) has come to our attention. As one of the groups currently trying to sort out the chaos surrounding this phenomenon, we feel a reply is called for, especially considering the alarming newspaper reports to which 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 | There is still no adequate explanation of the phenomenon, and no coherent picture of its properties. One of the greatest difficulties in even accepting the existence of a more stable phase is its apparent absence in nature. Indeed, this is the most persuasive evidence of its inability to grow at ordinary water’s expens... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Because of the difficulty of making precise measurements on such small samples, some of the physical properties of “anomalous” water are still subject to some uncertainty. In particular, those listed by Donahoe cannot all be accepted without question. “Anomalous” water does not have negligible vapour pressure for it ca... | 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 | Robert Burns’s affections were guaranteed to remain constant “till all the seas run dry”. While he may not have envisaged the possibility that the oceans might instead become anomalous, we feel that his shade may derive some consolation from the fact that they have not already done so.
Yours faithfully,
D. H. Everett
... | 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 | 首先,必须要强调的是:无论正确的解释可能是什么,杰里亚金的若干实验观测结果已经被几个实验室的最新研究工作所证实,其中也包括我们的实验室。将饱和水蒸气于直径不足50微米的石英(或“派莱克斯玻璃”)毛细管中液化,通过将蒸汽压降低约5%除去大量正常的水,这时就很容易观测到反常的性质。甚至在有空气存在和常压条件下进行实验也会出现这种现象。 英文
由于用如此少量的样品难于进行精确的测定,“反常”水的某些物理性质到目前为止仍是不确定的。尤其是不能不加怀疑地全盘接受多纳霍列出的所有性质。“反常”水并不具有小到可以忽略不计的蒸汽压,因为它是可以蒸馏的;尽管有人报道说它的密度是1.4 g/cm3,但最近曼斯菲尔德对此提出了质疑[1]。而且目前也没有得... | 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 | MATTER in the interior of a typical neutron star is a mixture of three degenerate interacting quantum liquids—neutrons, protons and electrons, the latter two having a density at most a few percent that of the neutrons1. The mixture, bounded on the inside by a superdense core of hadrons, muons and so on, and most likely... | 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 characteristic time, τD, for flux diffusion in normal, that is, non-superconducting, neutron star matter is ~ 4πσR2/c2, where σ is the electrical conductivity of the normal state, R is the scale of variation of the magnetic field, typically the radius of the star, and c is the speed of light. Electrical conduction ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | There are two possible ways in which magnetic flux can penetrate superconductors9: in the mixed state in which one has a periodic array of quantified vortices of supercurrents, aligned parallel to the field; or in the intermediate state, where one has, on a fine scale, alternating regions of normal material containing ... | 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 conditions of constant B, the transition from the normal to the superconducting state is first order. The maximum B for which the superconducting state is thermodynamically preferable to the normal state is that for which the free energy density of the vortices (=BHc1/4π for B≪Hc1) is equal to the superconducting co... | 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 | where εn= ħ2kn2/2mn. Taking R ~10 km, kn~1.4×1013 cm and ∆n=1 MeV, one finds ξn~1.6×10–12 cm, Ωc1~10–14 s–1 and Ωc2 ~1020 s–1. The angular momentum per neutron pair per vortex is ħ, and thus the density of vortices per unit area is ~ 2mnΩ/πħ ~ 2×105 cm–2 for Ω ~ 2 ×102 s–1, appropriate for the Crab pulsar NP 0532. 中文
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 | must occur via the creation or destruction of vortices, either in the bulk of the superfluid or at the interface of the superfluid and normal regions. Estimating the rates for these processes remains, as in the case of laboratory superfluid helium, an unsolved problem. The observed decrease in the slow-down rate of 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 | 物理学家们逐渐认识到中子星内部的物质密度必须达到1015 g/cm3。有人认为,这类恒星的内部有可能会处于超流(无黏滞性流动)状态。戈登·贝姆和他的同事们在本文中讨论了超流对这些恒星的性质可能产生的影响。他们注意到超流体有将磁场排除出其内部的倾向,但他们通过分析表明这个过程是非常缓慢的,以至于对恒星而言并不重要。这几位研究者指出:超流中子与这类恒星周围磁层之间的相互作用也许能解释为什么会观测到若干脉冲星(被认为是中子星)的转速在减慢,尽管为确认这一点尚需要更详细的计算。 英文
典型中子星的内部物质是三种相互作用的简并量子液体的混合物——中子、质子和电子。后两者的密度至多是中子密度的百分之几[1]。该混合物被约束在由强子和μ介子等组成... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 当B~1012 G(参考文献10)时,涡旋晶格呈三角形,晶格常数约为5×10–10 cm,比粒子间隔要大。这种涡旋具有半径为ξp的正常核,同时磁感应强度在距离核中心λp处迅速降低。 英文
涡旋态在两个临界磁场强度(H,而非B)之间是热力学稳定的,它们分别是Hc1≈ (φ0/4πλp2) ln λp/ξp和Hc2 ≈ φ0/2πξp2;当εp/∆p~20和kf = 0.7×1013 cm–1时,可得出Hc1~1015 G及Hc2~3×1016 G。我们还注意到,把磁通量排斥出涡旋态的时间要比排斥出正常态区域的时间τD长很多。 英文
对于B保持不变的情况,从正常态到超导态的转变是一阶相变。使超导态在热力学上比正常态更稳定的B有一个上限,... | 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
(岳友岭 翻译;蒋世仰 审稿)
New Finds at the Swartkrans Australopithecine Site
C. K. Brain
Editor’s Note
The site of Swartkrans, near Sterkfontein, had been opened up by Broom and Robinson, who had discovered abundant remains of a robust australopithecine as well as a more advanced hominid, at first called Telanthropus, later ... | 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 | remains of carnivores, especially of leopards. 中文
Swartkrans is situated in the Sterkfontein valley, approximately 8 miles north of Krugersdorp, Transvaal. It was first scientifically investigated in 1948 by the late Dr. Robert Broom and By Dr. J. T. Robinson, who transferred the Transvaal Museum’s operations to the ca... | 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 | palaeontological exploration. 中文
After working through the hillside dump, rubble was removed from the excavation and hand-sorted. This work is now almost complete and, after a grid over the excavation area has been erected, selected blocks of breccia from different stratigraphic levels will be removed for detailed comp... | 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 1958 (ref. 8), the entrance to the outer cave was interpreted as an incline, opening obliquely into the hillside. The walls of the cave can now be seen, however, on all sides except the south-east, where extensive decalcification has occurred. On the evidence of the new exposures, it seems very likely that the origi... | 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 | site. Stratigraphy in a talus cone is difficult to follow because it is steeply inclined close to the apex, but becomes progressively flatter in those parts of the cave further from the shaft (see Fig. 1). Today, erosion has removed the overlying hillside with its shaft and rock shelter. The original form of these miss... | 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 | SK 1585 A natural endocranial cast from a hominid, presumably Paranthropus (see Fig. 3). The skull was blasted out by lime miners in the early 1930s and was broken into several pieces before being dumped on the hillside. Two of the surrounding parts of the cranial vault have been recovered, but the face has not yet bee... | 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 | SK 1590 From an adult skull: two palatal fragments (a) and (b), with an incomplete right I2, C, P3 (9.25×13.3 mm), P4 (10.2×14.5 mm) and M1 (13.2×14.9 mm), all worn; crushed and distorted mandible (c) with parts of premolar and molar teeth. Associated were the head of a femur (d) and parts of an innominate bone in poor... | 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 | SK 1591 Isolated left M1 (13.0×14.4 mm), fairly worn with part of the root system.
SK 1524 Isolated left M3; most of the mesial portion of an unerupted and incompletely developed crown.
SK 1514 Mandibular fragment in very poor condition with roots of two molars and crown of one.
SK 1595 Fragment of a maxilla with sligh... | 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 | cave entrance shortly before their inclusion in the deposit. The diabase tools both have weathered cortices, but it is known that diabase weathers while it is enclosed in a damp breccia deposit. The one quartzite chopper had been waterworn after manufacture, but before fossilization. It was originally assumed that all ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | On the basis of this study, it seems that the foreign stones at Swartkrans were almost certainly derived from an old gravel associated with the stream course. Artificial transportation need not be invoked because, if the gravel lay within the catchment area of the cave entrance, it would have been washed into the under... | 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 | likely to have been used by a wide variety of animals, as well as primitive man. The sample of 14,000 fossil bone fragments currently being analysed comes from a thickness of deposit which probably took several thousand years to accumulate. At Swartkrans we are not dealing with an impressive concentration of bones, but... | 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 | Second to porcupines, primitive men rated high in importance as collectors of bone fragments in caves during the South African Stone Age. A detailed comparative study of human bony food remains from various Southern African caves has led me to conclude that these accumulations are characterized by the extreme fragmenta... | 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 | (lion); canids: Canis mesomelas (jackal), Vulpes sp. (fox); viverrids: Cynictis penicillata (mongoose). 中文
Both the Crocuta and the Hyaena are regarded as early representatives of the extant spotted and brown hyaenas, while Lycyaena and Leecyaena represent extinct genera, the former showing characteristics which have b... | 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 | likely that they would have contributed bones to the Swartkrans accumulation and that some of these may have been modified by the loss competent bone-crushing hyaenas, such as Lycyaena and Leecyaena before fossilization. (It is unlikely that the bones found today as fossils were ever thoroughly worked over by spotted o... | 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 a woodland habitat, leopards have little difficulty in finding suitable trees for storage of their prey, but the situation in open country is rather different. Swartkrans is situated today on the open highveld, an area of undulating grassland, almost devoid of trees except along the watercourses. Study of the compos... | 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 | concentration of microfaunal remains in the deposit, to give a remarkably complete picture of the animals hunted by the owls in the vicinity of the cave. In the same way, the larger faunal remains at Swartkrans are very likely to contain evidence of the range of animals hunted by leopards in this particular area. 中文
St... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | The greater part of the Swartkrans bone accumulation shows characteristics consistent with those of leopard food remains, and suggests a situation where the leopards had been regularly harried by hyaenas. There are, however, several features of the bone collection which require special explanation. These involve the 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 | parts such as ribs, vertebral processes and scapulae. These observations were confirmed in the feeding experiments and, when the cheetahs had fed on a springbuck for instance, almost the whole skeleton remained. When a baboon of equivalent weight was eaten, however, a very different result was obtained. The cheetahs we... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | One of the australopithecine skull pieces form Swartkrans appears to bear direct evidence of leopard activity. The specimen, SK 54, consists of much of the calvaria of a subadult hominid thought to have been a Paranthropus. It was found at the site in 1949 and subsequently prepared by Dr. Robinson in Wisconsin, using 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 | In a recent survey of the evidence for intrahuman killing in the Pleistocene, Roper13 mentions this particular specimen and quotes Ardrey’s argument14 that the holes indicate that the australopithecine was struck twice on the back of the head with a pointed object. I believe that it is more likely that the two holes we... | 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 will be seen that the figure of 33 mm, representing the distance between the holes in the fossil skull, falls well within the leopard rang and coincides with the mean figure for lower canine spacings in the female skulls measured. It must be remembered, however, that the fossil leopards seem to have been a fraction ... | 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 renewed work at Swartkrans would not have been possible without the support of the Wenner-Gren Foundation for Anthropological Research; in particular I wish to thank Mrs. L. Osmundsen for her interest in the project. I also thank the trustees of the Transvaal Museum and the South African CSIR for their support; 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 | 布雷恩在这篇关于该遗址的报告中不仅谈到了一个不可思议的发现——一件曾被豹子的犬齿刺穿的南方古猿头骨,还论证了这里的石器与在东非奥杜威峡谷发现的类似。布雷恩的最新诠释是:在斯瓦特克朗斯遗址中至少有一部分并非原始人类的居住之所,而是豹的巢穴,里面有豹留下的食余垃圾。 英文
斯瓦特克朗斯是南非的5个南方古猿洞穴遗址之一,在此出土了60多件大型原始人科——傍人粗壮种个体的标本,这里是唯一一处发现人属化石与南方古猿化石相伴生的洞穴遗址。 英文
本文描述的新发现澄清了许多关于斯瓦特克朗斯的重要争议。在这里发现了一系列新的原始人类化石(包括两块脊椎骨,鲁滨逊博士[1]将对此进行详细记述),因而使我们有可能将无可置疑的石器文化与人科联系起来。玛丽·... | 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 | 在下暴雨时,土壤、岩石和其他碎片从这种杆状通道漏下去,于是在大洞穴里杆状通道的排放点之下就形成了一个岩屑锥。排放点本身就是以沉积物中岩石和粗粒的丰度来确定的,较细的碎片倾向于被带到洞穴中更深的地方。很可能通过约50英尺以上的山腰凹陷处的一条垂直杆状通道可以排泄到这个区域(图1)。 英文
图1.穿过斯瓦特克朗斯山腰的南–北向剖面图。这里重建出来的上半部分已经在下部的含化石沉积物开始堆积时逐渐被剥蚀而不复存在了。
英文
斯瓦特克朗斯洞穴系统形成于两个断层面的交汇处,这从航空照片上可以很清楚地看到。它们的交角约为87度,在该处的地表之上可能曾经有过一个巨大的岩棚,杆状通道就是从这里开始向下降至地面以下的大洞穴的。如果对洞穴形式的这种... | 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 | SK 1586 几乎完整的成人下颌骨,在化石化过程中破碎严重,含右I1、I2、M1(断裂)、M2(15.0 mm×14.9 mm)和M3(16.7 mm×15.0 mm);还有左I1、M1和M2(15.0 mm×13.8 mm)。这是在斯瓦特克朗斯发现的最粗壮的下颌骨之一。发现于1965年9月1日。
SK 1648 一件成人下颌骨的前部,变形严重,含磨损的右M1和M2(15.7 mm×14.5 mm)、左M1(不完整)以及其他牙齿的牙根。发现于1966年11月4日。
单独的牙齿
SK 1593 右P3(9.8 mm×12.2 mm),磨损严重,牙根系统几乎完整。发现于1966年3月24日。
SK 3974 右M1(14.9 mm×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 | 沿着河谷的两岸很少见到河相砾石,而约翰斯顿小姐从距离洞穴1.5英里以内的3处不同地点收集到了152块外来石块以便与斯瓦特克朗斯样本进行比较。比较结果显示:斯瓦特克朗斯的外来石块非常类似于在洞穴附近的那些与河道有关联的砾石。被水冲蚀的石英岩鹅卵石在斯瓦特克朗斯样本中确实比在砾石中略多一些,但是二者在脉石英岩块中的百分比丰度却没有明显的差异。两个样本中石块的重量也几乎完全相等。砾石样本中石块的形状也与在斯瓦特克朗斯收集到的石块的形状没有太大的差别。 英文
基于此项研究,看来几乎可以肯定斯瓦特克朗斯的外来石块就是来自于与河道有关的古砾石。这个过程并不需要人工运输,因为:如果砾石位于洞口的集水区之内,那么它们早就会和地面的其他碎屑一起被冲到... | 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
化石斑鬣狗和棕鬣狗被认为是现生斑鬣狗和棕鬣狗的早期代表者,而狼鬣狗和李氏鬣狗则代表已灭绝的属。狼鬣狗的特征被认为是“反映了对更多偏向食肉、更少偏向食腐的习性的一种次生适应性——这种变化可能是由与更强大的食腐动物进行竞争而产生的选择压力引起的”[11]。李氏鬣狗的特征是前面的颊齿与一种进步鬣狗的很像,所以李氏鬣狗可能是来自克罗姆德拉伊的贝拉斯鬣狗的祖先。 英文
三种不同的剑齿虎标本均破损严重。尤尔指出:由于食肉动物可以用裂齿进行有效的撕裂,所以它们习惯于将肉切成薄片,并且前臼齿退化以至于它们“只能应付极其小的骨头”[11]。认为剑齿虎会将其猎物的骨架几乎完整地保留下来很有意义,因为各类鬣狗将各取所需,这样剑齿虎也就无需具有粉碎更... | 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 | 除非捕杀行为是发生在靠近人类住所之处,否则豹根本不会将它们的猎物拖到其他动物难以接近的地方。它们一般会在捕杀动物的地方就地进食,对猎物骨架的破坏也很小,因为一次捕猎只吃掉猎物的一小部分肉,几天之后便进行一次新的捕杀。因此很难定义“有代表性”的豹子食余垃圾的特征。这些食余垃圾的性质将取决于食物的可利用率以及斑鬣狗等主要食腐动物给豹造成的压力。 英文
斯瓦特克朗斯的大部分化石堆积所表现出来的特征与豹的食余垃圾相符,并且由此可以说明豹经常遭遇被鬣狗掠夺的处境。然而,这些骨骼堆积还有其他一些特征需要另行解释。例如为什么保存下来的骨骼部位不成比例。在牛科动物骨架的例子中,我们已经证明其中某些部位将比另一些部位更不容易被破坏,因而可以预测出哪些... | 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 | 那么这两个孔究竟是哪个物种造成的以及当损伤发生时南方古猿的头部处于什么位置,这些仍然是疑问。 英文
斯瓦特克朗斯化石包括的食肉动物化石从狮子到黄獴大小不等。这些化石所代表的动物类型大多与现生物种有很密切的关系,所以尽管化石化材料非常破碎,但是我们可以用现代头骨来说明典型的犬齿间距。利用德兰士瓦博物馆的收藏品,我们对7件现存物种头骨的上下犬齿齿尖之间的距离进行了测量(表2)。 英文
表2.7件食肉动物头骨上的上、下犬齿齿尖之间的距离
英文
图5中画出了所得的结果,某些已灭绝物种的估计范围也在图中标出。根据不太完整的材料推断:已知的斯瓦特克朗斯剑齿虎的犬齿间距介于狮子和斑鬣狗之间。李氏鬣狗的正型标本头骨(SK 314)在大小上与斑鬣... | 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 | Technology. He won a Nobel Prize for this work in 1975. 中文
DNA seems to have a critical role in the multiplication and transforming ability of RNA tumour viruses1. Infection and transformation by these viruses can be prevented by inhibitors of DNA synthesis added during the first 8–12 h after exposure of cells to the v... | 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 preparation of purified R-MLV was incubated in conditions of DNA polymerase assay. The preparation incorporated radioactivity from 3H-TTP into an acid-insoluble product (Table 1). The reaction required Mg2+, although Mn2+ could partially substitute and each of the four deoxyribonucleoside triphosphates was necessary ... | 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 | previously described12. The radioactivity of an unincubated sample was subtracted from each value (less than 7 percent of the incorporation in the complete reaction mixture). 中文
Fig. 1. Incorporation of radioactivity from 3H-TTP by the R-MLV DNA polymerase in the presence and absence of ribonuclease. A 1.5-fold standa... | 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 | loss of acid-insoluble product. The product is therefore protected from the enzyme, probably by the envelope of the virion, although merely diluting the reaction mixture into 10 mM MgCl2 enables the product to be digested by deoxyribonuclease (Table 2). 中文
Table 2. Characterization of the Polymerase Product
For experi... | 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. 2. Localization of DNA polymerase activity in R-MLV by isopycnic centrifugation. A preparation of R–MLV containing 150 μg of protein in 50 μl. was layered over a linear 5.2 ml. gradient of 15–50 percent sucrose in PBS–EDTA. After centrifugation for 2 h at 60,000 r.p.m. in the Spinco “SW65” rotor, 0.27 ml. fraction... | 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 | for the reaction. Hybridization experiments are in progress to determine if the DNA is complementary in base sequence to the viral RNA. 中文
Table 3. Effect of Ribonuclease on the DNA Polymerase Activity of Rauscher Mouse Leukaemia Virus
In experiment 1, for the preincubation, 15 μg of viral protein in 5 μl. of solution... | 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 | When 3H-TTP was the precursor, standard reaction conditions were used (see Table 1). When 3H-GTP was the precursor, the reaction mixture contained, in 0.1 ml., 5 μmoles Tris-HCl (pH as indicated), 0.6 μmoles magnesium acetate, 0.3 μmoles mercaptoethanol, 9 μmoles NaCl, 0.08 μmole each of ATP, CTP, UTP; and 0.001 μmole ... | 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 | was assayed in standard reaction mixture by incubation for 2 h. An unincubated control sample had radioactivity corresponding to 0.14 pmole which was subtracted from the experimental values. 中文
These experiments indicate that the virions of Rauscher mouse leukaemia virus and Rous sarcoma virus contain a DNA polymerase.... | 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 | Kates, J. R., and McAuslan, B. R., Proc. US Nat. Acad. Sci., 58, 134 (1967).
Munyon, W., Paoletti, E., and Grace, J. T. J., Proc. US Nat. Acad. Sci., 58, 2280 (1967).
Shatkin, A. J., and Sipe, J. D., Proc. US Nat. Acad. Sci., 61, 1462 (1968).
Borsa, J., and Graham, A. F., Biochem. Biophys. Res. Commun., 33, 895 (1968).... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 英文
表1.劳舍尔小鼠白血病病毒的DNA聚合酶的性质
R–MLV制剂由美国国家癌症研究所病毒资源组提供。通过差速离心法将病毒从受感染的瑞士小鼠血浆中纯化出来。每ml制剂的滴度为104.88脾肿大剂量(终点值的50%)。使用前,将制剂在105,000 g下离心30分钟,并将沉淀物悬浮于0.137 M NaCl、0.003 M KCl、0.01 M磷酸盐缓冲液(pH值7.4)、0.6 mM EDTA(PBS–EDTA)(译者注:PBS为磷酸缓冲液,EDTA为乙二胺四乙酸)中,使最终体积为初始体积的1/20。浓缩的病毒悬浮液含有3.1 mg/ml蛋白。在0.1 ml反应混合物中含有5 μmol Tris–HCl(pH值8.3,37°C)... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 英文
图2.用等密度梯度离心法对R–MLV中DNA聚合酶活性的定位。将50 μl含150 μg蛋白质的R–MLV样品铺在5.2 ml用PBS–EDTA配制的15%~50%的蔗糖线性梯度上面。使用斯平科公司“SW65”型转头在60,000转/分钟的条件下离心2小时,然后按每份0.27 ml收集梯度组分,并从每个梯度组分中取出0.1 ml在标准反应混合物中孵育60分钟。随后收集酸不溶性物质并对其进行放射性计数。通过测定每个组分的折射率来确定其密度。箭头指示出了在密度为1.16处光散射物质的一个尖锐的可见条带。
英文
模板是RNA
致癌RNA病毒粒子中含有RNA,但是没有DNA[15,16]。因此,病毒粒子DNA聚合酶的模板很可能是... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 英文
表5.劳斯肉瘤病毒DNA聚合酶的性质
反应系统
反应120分钟后掺入到样品中的3H–TMP的pmol数
完全的反应系统
2.06
无醋酸镁
0.12
无dATP
0.19
由彼得–沃格特博士提供的劳斯肉瘤病毒布拉格株(C亚株)制剂[16]的滴度为每ml 5×107个病灶形成单位。用差速离心法从组织培养液中纯化病毒。使用前先对样品进行离心,然后将沉淀物溶解为上述R–MLV实验中初始体积的1/10。对于每次检测,取15 μl浓缩的劳斯肉瘤病毒样品,在标准反应混合物中孵育2小时后进行测定。未孵育的对照样品的放射性相当于0.14 pmol,这个值要从各组实验数据中减去。 英文
这些实验表明:在劳舍尔小鼠白血病病毒和劳斯肉瘤病... | 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 | hypothesis—replication of RNA tumour viruses takes place through a DNA intermediate, not through an RNA intermediate as does the replication of other RNA viruses7. 中文
Formation of the provirus is normal in stationary chicken cells exposed to Rous sarcoma virus (RSV), even in the presence of 0.5 μg/ml. cycloheximide (ou... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | To observe full activity of the enzyme, it was necessary to treat the virions with a non-ionic detergent (Tables 1 and 4). If the treatment was at 40°C the presence of dithiothreitol (DTT) was necessary to recover activity. In most preparations of virions, however, there was some activity: 5–20 percent of the disrupted... | 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 | Virus treated with “Nonidet” and dithiothreitol at 0°C was incubated in the standard polymerase assay with the substitutions listed. 中文
Fig. 2. MgCl2 requirement. Virus treated with “Nonidet” and dithiothreitol at 0°C was incubated in the standard polymerase assay with different concentrations of MgCl2.
中文
When 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 | Disrupted virions were incubated with ribonuclease A (Worthington) which was heated at 80°C for 10 min, or with lysozyme at the indicated concentration in the specified conditions, and a standard polymerase assay was performed. 中文
To determine whether the enzyme is present in supernatants of normal cells or in RNA leuk... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | To determine if the polymerase might also make RNA, disrupted virions were incubated with the four ribonucleotide triphosphates, including 3H-UTP (Schwarz, 3.2 Ci/mmole). With either MgCl2 or MnCl2 in the incubation mixture, no incorporation was detected. In a parallel incubation with deoxyribonucleotide triphosphates,... | 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 | Baluda, M. B., and Nayak, D. P., in Biology of Large RNA Viruses (edit. by Barry, R., and Mahy, B.) (Academic Press, London, 1970).
Temin, H. M., Nat. Cancer Inst. Monog., 17, 557 (1964).
Kates, J. R., and McAuslan, B. R., Proc. US Nat. Acad. Sci., 57, 314 (1967).
Munyon, W., Paoletti, E., and Grace, J. T., Proc. US Na... | 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
聚合酶检测所用试剂的总体积为0.125 ml,其中含有:脱氧腺苷三磷酸(dATP)、脱氧胞苷三磷酸(dCTP)和脱氧鸟苷三磷酸(dGTP)各0.125 μmol(卡尔生物化学公司)(溶于pH 值为8.0的0.02 M Tris–HCl缓冲液中,其中还含有0.33 M EDTA和1.7 mM 2–巯基乙醇);1.25 μmol MgCl2和2.5 μmol KCl;2.5 μg磷酸烯醇丙酮酸盐(卡尔生物化学公司);10 μg丙酮酸激酶(卡尔生物化学公司);2.5 μCi 3H–胸苷三磷酸(3H–TTP)(许瓦兹制药有限公司)(12 Ci/mmol);0.025 ml酶(通过破碎活性为108个病灶形成单位的施密特–鲁宾病毒得到,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 | 英文
为了确定这种酶到底是存在于正常细胞的上清液中还是存在于RNA白血病病毒中,我们又进行了表4中的实验。即使在使用“诺乃洗涤剂”处理后,正常细胞的上清液也不具有活性。而禽类成髓细胞瘤病毒(AMV)的病毒粒子具有活性且在用“诺乃洗涤剂”处理后,其活性会提高10倍。 英文
表4.聚合酶的来源
用前文所述的方法(表2中的实验)制备施密特–鲁宾病毒(SRV)。由差速离心法得到禽类成髓细胞瘤病毒(AMV)的病毒粒子和未感染细胞的离心沉淀物。所有破碎的样品都在0°C下用“诺乃洗涤剂”和DTT处理,并用标准的聚合酶检测实验进行分析。每个管中所用的样品分别来自45 ml SRV培养液、20 ml AMV培养液和20 ml未感染细胞培养液。 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 | THERE is considerable current interest in the possible existence of a new form of water reported by Deryagin1, not only because of the universal presence of water, but also because it would almost certainly require a new type of chemical bond. The oldest and simplest schematic representation of the electronic distribut... | 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 | shift, relative to the normal liquid, observed recently by NMR6,7. Closed systems (rings) are generally favoured over open systems, both in two and three dimensions. In anomalous water, rings in three dimensions are favoured because they lower the energy of the relatively small, delocalized, covalent-like σ bonding and... | 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 | bonding and the oxygen-oxygen repulsion component, symmetrically placed hydrogens are decidedly less stable than the conventional asymmetric hydrogen bond and achievement of a stability approaching that of the asymmetric bond must be obtained through the properties of O–. There are two sources of this added stabilizati... | 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 | oxygen in (H3O)+ is too small and that in (OH)– too large, which makes this resonance form improbable. The other model8 assumes symmetric hydrogen bonds and xs and os distributed around oxygens much as in Fig. 1; but it does not emphasize the negative charge on oxygen. The oxygens are placed on a pseudo-wurtzite struct... | 400套付费套装书 |
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