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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 | larger than the signal being studied. 中文
Recent developments in instrumentation have been successfully aimed at reducing the non-seismic noise in instruments by more effectively sealing and isolating them, and at broadening their response to cover a wide spectrum. There is also promise in the siting of instruments down... | 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 surface wave magnitude Ms can equally well be related to the yield, and is a more useful measure, for it seems to obey a relation (for hard rock) of the form
Ms=1.3 log10Y + 1.5
over a range from at least 1 kton to 1 mton. 中文
Discrimination
In the early development of the subject, the concentration on the detection... | 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 | More recent work on the spectra of P waves has shown that even explosions of very small magnitude are significantly richer in high frequencies (2 to 3 Hz) than are earthquakes. This accords with generally accepted ideas of the nature of earthquake and explosion sources. Regional variations present problems, however; 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 | Fig. 2. An Ms : mb diagram for Eurasia based on WWSSN recordings by Marshall and Basham. ○, Earthquakes; ●, presumed explosions.
中文
Earthquakes and explosions generate other seismic phases—shear or S waves and horizontally polarized surface waves called Love waves. In addition P waves have a long period component. Al... | 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 thresholds of detection are such that an earthquake is likely to be seen both by its P and Rayleigh waves or by neither. This means that there are few earthquakes which are assigned an mb but cannot be placed on the diagram because Ms is not measurable. On the other hand, there may be explosions which have, for ins... | 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 clearly indicates a difference in excitation between 20 s Rayleigh waves and 1 s P waves for the two types of event. A natural question is how this difference arises, and the question is not purely academic, because in attempting to lower the threshold (that is to bring in points with lower Ms and mb) it is valu... | 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 more direct and at present more successful approach to the problem of the smaller magnitude events which are as yet beyond the global network’s accessibility is to do pilot work in a region where there is the opportunity to get close in to events. Accordingly much research has been concentrated on observations of exp... | 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 | Several instrumental developments and deployments are under way at the moment. A small number of high quality, long period seismometers are now set up (in Spain, Israel, Thailand, Australia, Alaska and New Jersey). Others, suitable for deep boreholes where noise may be substantially reduced, are in production. Two larg... | 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 | At this stage, economics may control the threshold more than seismology. For instance, Professor J. N. Brune of the University of California, San Diego, recently estimated that a thorough programme to upgrade seismic capabilities to such a high level would cost at least $200 million. 中文
How might a major programme reas... | 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 | development of arrays centred on good stations. The establishment of new stations in favourable locations would also make sense. 中文
Beyond this stage it is not easy to speculate. Once one has started reinstrumenting the globe there is no limit to the ingenuity that could be employed. Political and economic realities, 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 | Another natural hazard is that of explosion-like earthquakes. If the time interval for which Fig. 2 had been compiled were expanded, earthquakes of quite high magnitude (an mb of 5.0 for instance) but which produce barely discernible surface waves would eventually be found. These earthquakes, which come from very limit... | 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 there are prospects of reducing the yield threshold to a figure of a few kton in hard rock, it must be borne in mind that a violator is unlikely to fire his explosions in granite. As a threshold of 2 kton in hard rock would be very difficult to achieve, this might be turned into a statement that all tests unde... | 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 explosion on the basis of its lack of Rayleigh waves? Obviously this question depends on whether all earthquakes with an mb of 4.5 have detectable Rayleigh waves (we eliminate the masked event problem). The answer is that on present experience they do, with the exception of a limited number of events mentioned earli... | 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 | I shall conclude with a description of recent activity beyond the laboratory. In 1968 the Stockholm International Peace Research Institute (SIPRI) convened a conference of seismologists from ten countries, east and west, at which technical progress since 1958 was reviewed. Subsequent SIPRI Progress Reports, the latest ... | 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 was kindly supplied by P. W. Basham and P. D. Marshall, and represents work done by them3 at the Department of Energy, Mines and Resources, Ottawa, Canada. 中文
(241, 19-24; 1973)
David Davies
Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, Massachusetts 02173
References:
Neild, R., and Rui... | 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
1958年,禁止核试验首次成为国际问题,在日内瓦举行的关于技术问题的会议明确指出,地震学需要取得实质性的进展,使得仪器观测毫不含糊地指出具有几千吨(kton)当量水平的爆炸的发生。确实,那次会议和随后的商谈中可用数据甚少(当时只有两次或者三次规模很小的地下试验),因此,首要目标是建立包括大约170个台站的国际台网,该台网能够检测到一定阈值之上的地震信号,但是不必确定其来源。人们期望,绝大多数地震事件可以通过其位置、深度、辐射模式和信号形状明确地体现出天然地震的特征,但还剩余少数事件有待于进一步研究。在早期的国际磋商过程中,详细讨论了如何对一小部分可疑事件发生的地点进行检查——检查的数量和性质是争议较大的问题。同时,苏联对于检查... | 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 | 结果是,通过观察其放大率可调控的胶片记录,6 s微震常常占据主导,而1 s和20 s信号则因此无法达到最佳放大。对磁带记录进行数据处理的可能则消除了这一障碍。 英文
建于美国的第一批台阵的孔径为4 km。它在很多方面体现了日内瓦会议对于国际台网阵列的设想。在此孔径范围内布设了多达16台的地震仪,来自所有地震仪的信号不经过相位调整就叠加起来。远震信号到达时信号明显变化——信号以至少10 km·s–1直至24 km·s–1水平速度沿地表传播,在典型的场地对应的入射角小于20°。因此,直接叠加不会严重减弱小孔径台阵观测到的1 s信号。通过这些小型台阵发现,特别是当仪器间距大于0.5 km时噪声在这一频率段是相干的,因此信噪比的增益将介于1... | 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 | 例如,震中距离60°处周期1 s内的地面位移为10 nm意味着震级为4.7的事件。 英文
面波震级是通过测量周期为T(通常约为20 s)的瑞利波的地面位移A,并应用下面的公式而得到的:
英文
Ms震级4.0的事件,在30°距离和20 s周期处将有300 nm的地面位移。 英文
对于地震来说,Ms与mb之间有经验性的、离散较大的关系,其最佳拟合式为:
Ms=1.59mb–3.9
后面我将进一步讨论这一关系。 英文
将Ms和mb与爆炸当量联系起来是可能的。硬质岩石中的2 kton爆炸产生mb为4.0的地震事件,20 kton爆炸则产生mb为5.0的地震事件。爆炸当量提高一个数量级对应于震级加一的关系因为几个理由而无法成立。我曾经提到... | 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
每个点还代表了确定的面波震级,而且按照习惯,在接受一个数值之前需要至少有四个地震台站检测到面波(这是对地震辐射图案加以认可的一种十分粗略的方法)。Ms为4.0的事件肯定能因其瑞利波而被检测到,但是Ms为3.0的事件就不大可能被检测到了。这在一定程度上是由于噪声的缘故,不过接收器的位置也很重要,因为它们需要尽可能靠近事件发生地。 英文
检测阈值是指一次地震有可能同时被P波和瑞利波检测到,或者都未检测到。这意味着,几乎不会有这样的地震,即测得了mb但由于没有测得Ms而无法在Ms : mb图上加以绘制。另一方面,有可能存在这样的爆炸,比如说,mb4.5和(通过外推法)Ms2.5的爆炸。如果需要两个参数同时确定才能识别一次事件的话,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 | 看来有理由期待,基于这些仪器,阈值至少能减少一半,即硬质岩石中10 kton当量水平。这相当于说,在监测苏联时,几乎所有Ms大于等于2.8的事件都会在四个或更多个彼此远离的地震台显示出可检测到的面波。这是一个很适度的目标;只凭两个大型台阵加上泰国和以色列的新建地震台站就可以实现这一目标。 英文
不过,相当低的阈值也是可能达到的。对美国西部研究的外推指出,期待识别能力达到Ms为2.0(硬质岩石中2〜3 kton)是合理的。如何才能达到这一目标呢?如果监测台网可以充分扩展,那么被监测的国家就必须想尽办法将其试验场移动到尽可能远的位置。对于苏联来说,有可能在距离监测台网中最近的地震仪30°的位置进行试验,而在这一距离,Ms 2.0的爆炸所... | 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 | 冲积层的沉积厚度限制了爆炸深度,但另一方面,爆炸必须在足够深度引发才能避免形成沉降坑。在冲积层实验之后往往形成弹坑,也就存在明显的被检测到的危险。因此违约者将不得不考虑在冲积层引爆的风险,并且可以充分肯定,安全试验的当量水平是远小于20 kton。 英文
“反面证据”
对于Ms : mb识别技术感到隐约的不安是合理的。这项技术总是把大量科学技术置于一份图表之中,而且还可能被错误地应用。例如,尽管图2中所示的地震事件具有相当的代表性,其中只能包含有限的爆炸事件;其中大多数来自于一个试验场所,因此不是真正的独立样本。再说,试验场所是可以随意移动的,因此识别结果也只能代表过去而不是将来。只有当我们看到识别科学很好地建立起来时,才能减少疑虑... | 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
(王耀杨 翻译;吴庆举 审稿)
DNA Replication Sites within Nuclei of Mammalian Cells
J. A. Huberman et al.
Editor’s Notes
Nearly 20 years after the structure of DNA was published, molecular biologists were still struggling to understand how DNA, the genetic material, is replicated in living cells of higher organisms (eukaryotes)... | 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 | associated with the membrane apparently moved into the nuclear interior after a 1 h chase13. 中文
On the other hand, most electron microscope autoradiographic experiments suggest that replication can take place throughout the nucleus. For instance, Comings and Kakefuda14 generally found grains located throughout the nucl... | 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 | synthesized during a pulse as short as 2 min. Huberman and Riggs19 have shown that the rate of DNA replication in Chinese hamster cells can be as much as 2.5 μm min–1, although most replication seems to occur at rates between 0.5 and 1.2 μm min–1. Thus as much as 5 μm of DNA could be synthesized during a 2 min pulse. I... | 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. Autoradiography of unsynchronized CHO cells exposed to 3H-TdR for 0.5 min. A and B, grains distributed over entire nucleus. C and D, grains distributed around nuclear membrane. E, clustered grain distribution. F, mixed grain distribution. CHO cells were grown on Petri plates in Joklik-modified MEM (Grand 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 | membrane either just above or just below the section plane. While this might explain some central grains, it certainly cannot explain most of them. Because the cells are sectioned with random orientations, we can get some idea of the frequency of invaginations which might bring nuclear membrane within 1.25 μm of the se... | 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 | To express quantitatively the proportion of cells showing peripheral labelling, we have modified the method of Williams and Ockey16. We defined central grains as those further than 1.25 μm from the nearest nuclear membrane, and peripheral grains to be those closer than 1.25 μm to the nuclear membrane. The “central acti... | 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 | Only 13% of the cells in Fig. 3 have central activities of less than 0.25, showing that DNA synthesis can go on at sites away from the nuclear membrane. The nuclear membrane is therefore not essential for DNA replication in Chinese hamster cells. But the fact that many cells do show a predominantly peripheral pattern r... | 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 | slides were coated with autoradiographic stripping film (“Kodak AR-10”) and exposed for 7 days. After development, the slides were stained with Giemsa stain, then mounted under “Permount”. At least 312 cells were scanned to determine the percent of cells labelled at each time point.
† The total number of grains over ea... | 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 | To test these possibilities, we first pulse-labelled synchronized cells for 0.5 min during the first half of the S phase (6 h after release from mitosis), and then chased with non-radioactive thymidine to late S phase (12 h after release from mitosis). Although the cells were examined in late S phase, they showed no hi... | 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 | Thus DNA has a stable location in the nucleus. Because some of the unsynchronized cells must have divided during the chase, our results suggest that DNA bound closely to the membrane in one generation is also bound to the membrane in the succeeding generation. 中文
Because we cannot detect any difference in labelling pat... | 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 | unexpected pattern may be related to the finding12 that polyoma virus infection causes mouse satellite DNA, which is normally late replicating23-25, to replicate before bulk DNA. 中文
Because Comings and Kakefuda’s14 results must be discounted owing to cell damage, it seems that DNA synthesis can occur throughout the nuc... | 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 | inside the cell to some material that causes their separation from bulk DNA during lysate fractionation. 中文
As experiments with mammalian8-11,13 and bacterial2,3,5 cells used similar techniques and gave the same results, it is possible that the growing point in bacteria may also not be attached to the membrane. 中文
We 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 | Comings, D. E., and Kakefuda, T., J. Mol. Biol., 33, 225 (1968).
Blondel, B., Exp. Cell Res., 53, 348 (1968).
Williams, C. A., and Ockey, C. H., Exp. Cell Res., 63, 365 (1970).
Erlandson, R. A., and de Harven, E., J. Cell Sci., 8, 353 (1971).
Kay, R. R., Haines, M. E., and Johnston, I. R., FEBS Lett., 16, 233 (1971).
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 | 英文
下面三个小组的研究得到的结果略有不同:布隆德尔[15]用脉冲处理KB细胞(一种口腔癌细胞)2分钟,威廉姆斯和奥克伊[16]用脉冲处理中国仓鼠细胞10分钟或者更长时间,以及厄兰森和德阿尔旺[17]用脉冲处理HeLa细胞15分钟。与科明斯和挂札[14]的结论相一致的是,上述三个研究组都认为在S期的大部分时期,颗粒存在于整个细胞核中。但是与科明斯和挂札的结论不同的是,他们发现与S期初期相比这些颗粒在S期末期出现周边模式的频率更高。凯[18]等人的细胞分级分离实验同样阐明了DNA与核膜的结合主要是发生在复制的后期,而不是复制的初期。 英文
高分辨放射自显影法
不考虑更接近细胞核核膜的复制时期到底出现在S期的哪个阶段,大部分电子显微放射... | 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
我们使用HeLa细胞进行了部分的预实验,在这些实验中,HeLa细胞具有形状更加规则的细胞核,并且在核周围都出现了中间颗粒(图2)。甚至在单细胞0.5 μm厚的连续切片上都有中间颗粒的存在。从S期早期的普遍标记模式到S期后期的周边标记模式的变化说明普遍标记并不是由切割造成的假象。最后,细胞核内部的膜结构并不能解释中间颗粒的问题。其他电子显微镜观察者从未观察到这种膜,除了内陷的周边核膜,我们在切片中也没有观察到这种膜的存在。 英文
图2. HeLa细胞置于3H-TdR1.5分钟后的放射自显影图。用添加5%马血清的改良乔克利克基础培养基(购自格兰德岛生物公司)悬浮培养细胞。加入3H-TdR(20Ci·mmol–1,购自新英格兰核公... | 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图,有丝分裂后10小时统计了13个标记的细胞核,有丝分裂后12小时统计了16个标记的细胞核。
英文
DNA稳定的位置
如果DNA是在核膜处(或者在细胞核内其他的位置)合成的,那么DNA应该首先转移至核膜进行复制,然后再远离核膜。因而长脉冲或者脉冲追踪形成的颗粒模型应该与短脉冲处理所形成的颗粒模型不同。另一方面,如果DNA复制可以在细胞核的任意区域进行,那么DNA没有必要转移,而且脉冲追踪标记后的颗粒模型应该与简单脉冲标记的颗粒模型一致。 英文
为了验证这些可能性,我们首先脉冲标记处于S期的前半期(有丝分裂完成后的6小时)的同步化细胞0.5分钟,然后用非放射性的胸腺核苷追踪至S期的后期(有丝分裂完成后的12小时)。尽管对这些细胞... | 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
细胞分级分离实验的重新解释
尽管许多关于DNA在细胞核内合成位点的细胞分级分离实验[8-11,13]已经被诠释为倾向于支持复制位点与细胞核核膜相连的观点,但是这并不是唯一可能的解释。同样合理的一种可能性是,细胞裂解后,由于生长点的某种特殊结构属性(如大多是单链),可能导致其与体内其他大部分的DNA相比能够结合更多的蛋白、膜或者其他物质。当然,也可能生长点确实与细胞内的一些物质相连,造成生长点与体内主体DNA在细胞裂解分离过程中分离。 英文
因为在哺乳动物细胞[8-11,13]和细菌细胞[2,3,5]上开展的实验研究使用了相似的实验技术,并得到相同的结果,所以在细菌体内生长点很有可能也不与膜相连。 英文
特别感谢伊莱恩和罗伯特·... | 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 | One model has been described in detail by Corby et al.3. The mode of computation essentially consists of integration forward in time from an initial state for a considerable number of model days using physical parameters appropriate to a given season and obtaining the mean seasonal state by averaging the later computed... | 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. Temperature differences, in °C near the model surface, between the computation with an ice-free arctic and the computation with ice at the mean climatological position. Hatched areas indicate regions of cooling in the ice-free experiment.
中文
Other results from these experiments show a distinct southward displa... | 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 | Smagorinsky, J., Manabe, S., and Holloway, J.L., Monthly Weather Review, 93, 727 (1965).
Kasahara, A., and Washington, W. M., Monthly Weather Review, 95, 389 (1967).
Corby, G. A., Gilchrist, A., and Newson, R. L., Quart. J. Roy. Met. Soc., 98, 809 (1972).
Warshaw, M., and Rapp, R. R., R-908-ARPA (1972).
大气环流模式对北极冰盖消融的... | 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;王鹏云 审稿)
Deep-sea Sediment Source Areas: Implications of Variable Rates of Movement between California and the Pacific Plate
J. R. Hein
Editor’s Note
The San Andreas Fault is the most conspicuous source of earthquakes in the US state of California. The fault is the boundary between the tectonic plate to 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 | The Delgada submarine fan lies off northern California, south of the Mendocino Fracture Zone, and is at least Oligocene in age4. The fan lies in a unique position on the eastern edge of the Pacific plate directly adjacent to the varied lithology of source areas on the American plate to the east. If the fan has passed 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 | The Delgada fan is assumed to be one basin of deposition and to have been built by turbidity current and hemipelagic deposition from continental source areas. A simple model of evolution of the fan can be constructed so that the changes in mineralogy and style of deformation of mineral grains are consistent with the ch... | 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 rate of motion of 5.5 to 7.0 cm yr–1 for the past 4 m.y. yielded by this method agrees with the rate calculated from marine magnetic anomalies3 and adds validity to the choice of space-time boundaries. Reasonable variations in the placement of the palaeogeographic boundaries and possible errors in time boundaries 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 | 本文中,加利福尼亚大学圣克鲁斯分校的詹姆斯·海因利用美国自然科学基金委员会资助下的深海钻探航次所搜集到的数据展示了一种独创性的方法,用于解释在过去的2,500万年中两个板块是如何相对运动的。据估算,两个板块间的相对位移为5.5~7.0厘米/年。 英文
新近研究表明,圣安德烈亚斯断层的运动在加速[1],然而之前的研究却并没有指出太平洋板块和美洲板块之间的运动速率是随时间而变化的。圣安德烈亚斯断层以及相关断裂体系的错移约束了某给定时段内的一个平均运动速率值,并且与广阔板块边界上区域内的运动有关。因此,它并不能表示两个板块之间的总相对运动量或速率变化[2]。磁异常可以用来测量两个板块之间的相对运动以及速率变化。但是,加利福尼亚湾湾口地区的... | 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
在这里,我要特别感谢阿特沃特、布克里、科、加里森、格里格斯、萨姆纳以及赖特(深海钻探计划第五航次)给予的帮助。 英文
(齐红艳 李任伟 翻译;李三忠 审稿)
In vitro Fertilization of Rat Eggs
H. Miyamoto and M. C. Chang
Editor’s Note
Chinese American scientist Min Chueh Chang is probably best known for his work developing the oral contraceptive, but here he builds on a wealth of animal in vi... | 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 | to 58 h later; the rats were killed 14 to 16 h after injection of HCG. Oviducts were placed under light paraffin oil, equilibrated with 5% CO2 in air in the presence of a small volume of saline, in a watch glass kept at 37°C and the eggs in cumulus clot were released by dissecting the ampular portion of the oviducts. 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 | clot and then centrifuged. Serum was sterilized by filtration through a millipore filter and stored under paraffin oil at 2 to 5°C for no longer than five days. The uterine fluid was collected from oestrous rats by means of a syringe needle. Insemination was performed by adding 0.4 ml. of the sperm suspension to the eg... | 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 | eggs when epididymal sperm, which had been pre-incubated for 2 to 7 h in the medium containing rat serum and uterine fluid, were used, they remained motile for longer than uterine-incubated sperm. This, and the higher proportion of eggs penetrated by sperm recovered from the uterus 10 to 11 h after mating demonstrated ... | 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 | Received June 19; revised August 8, 1972.
References:
Austin, C. R., Aust. J. Sci. Res., Series B, Biol. Sci., 4, 581 (1951).
Chang, M. C., Nature, 168, 697 (1951).
Thibault, C., Dauzier, L., and Wintenberger, S., C. R. Soc. Biol., 148, 789 (1954).
Chang, M. C., Nature, 184, 466 (1959).
Brackett, B. G., and Williams,... | 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 | 从发情前期过渡到发情期的夜晚,排卵通常发生在2:00左右[21],因此发情前期的大鼠分别于次日6:00~7:00和9:30~10:30被处死时,卵细胞被视为处于排卵后大约4~5 h和7.5~8.5 h。通过在发情期早上腹腔注射30国际单位的孕马血清(PMS)并在52~58 h后注射30国际单位的人绒毛膜促性腺激素(HCG),实现成熟大鼠超排卵;注射HCG14~16 h后处死大鼠。在表面皿上盛放少量盐水并用轻质石蜡油覆盖,在含5%CO2的空气中于37°C进行平衡,再将输卵管置于轻质石蜡油下,然后通过切开输卵管壶腹部释放卵丘细胞块内的卵子。准备好授精用的精子。以图1中的方式用准备好的精子对卵子授精。 英文
培养8~12 h后,移出卵细胞... | 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88个未受精的卵细胞中也发现了额外精子(1~11个),这提示由于卵细胞在体外变质,导致卵黄阻断精子的穿透。大鼠卵细胞体内受精时多精受精的发生率约为1.2%[22]。而相比之下,仓鼠[6]和小鼠[15]卵细胞体外多精受精发生率要高。尽管最近布雷古拉报道了大鼠卵细胞体外受精[20],但其使用的方法、发表的照片以及体内未受精的大鼠卵细胞高频率的卵裂[23],使得他的论断没有说服力。 英文
本研究得到了美国公共卫生署和福特基金会的资助。我们感谢罗丝·巴特克女士的帮助。 英文
(吴彦 翻译;曹文广 审稿)
Earth-Moon Mass Ratio from Mariner 9 Radio Tracking Data
S. K. Wong... | 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 mass ratio was determined from range and doppler data obtained over a period of 15 weeks (June 5 to September 15, 1971). The data coverage is shown in Table 1. We also show the statistics from the best determination. The data reduction was performed using the JPL Double Precision Orbit Determination Program1, which... | 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 | al., paper presented at AAS/AISS Astrodynamics Conference, August 1970). Third, another possible cause of range error is the Z component of station location. This component is parallel to the Earth’s spin axis. The computed range value is sensitive to incorrect Z values when the probe declination becomes large in absol... | 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 | Case 1, Doppler only (doppler weight=0.015 Hz) with standard estimated parameter set. Case 2, Range only (range weight=100 m) with standard estimated parameter set. Case 3, Doppler and range (doppler weight=0.015 Hz, range weight=100 m) with standard estimated parameter set. Case 4, Doppler and range (doppler weight=0.... | 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 | computed from the last five interplanetary spacecraft launched (Pioneers 8 and 9 and Mariners 6, 7 and 9) showed a spread of only 0.0004. The values for Pioneers 8 and 9 and Mariners 6, 7 and 9 are 81.3004, 81.3008, 81.3004, 81.3005 and 81.3007, respectively. This provides a good indication of the accuracy of μ–1. 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 | ‡ 1 Hz=65 mm/s;1 RU(测距单位)≈1 m; 1 ns≈0.15 m。
英文
深空探测网有三类测距系统:Mu、Tau和Mark1A。Mu和Tau系统可以测量行星距离,而Mark1A系统的单程有效范围仅限于大约107km。使用这些测距数据的权重需要考虑以下因素:第一,假设不存在外部误差,Mu、Tau系统精确度为大约20 m,这包括系统噪声、转发器和地面设备的定标误差。Mark 1A测距系统精确度为大约30 m。第二,由于射电信号穿过了地球的电离层和行星际空间的等离子体,所以其光程也会发生变化。群光程增加,而相光程减小,这影响了由射电信号得到的测距和多普勒测量结果。地球电离层中的带电粒子会造成多达15 m的测距误差;行... | 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
(冯翀 翻译;沈志侠 审稿)
Do Honey Bees Have a Language?
P. H. Wells and A. M. Wenner
Editor’s Note
In 1946, German ethologist Karl von Frisch proposed that honey bees communicate by means of an elaborate dance, a method used to guide foragers to food. Bee biologists Patrick H. Wells and Adrian M. Wenner greeted the theory wi... | 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 | Investigators who believe that honey bees have a language have since challenged our conclusion3-5, and two other recent articles6-7, while not including a discussion of our results, cannot be reconciled with our interpretations. Our purpose here is to examine the principal objections to our interpretations and present ... | 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 foragers are experienced at a food site, they are again recruited to it by odour cues rather than by language8,9 and, when odour cues are rigorously excluded, recruitment of new foragers fails2,10. For example, on control days of our experiments reported in 1969 when no scented sucrose was made available (days 4, ... | 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 | Esch and Bastian6 reported interesting new data but did not relate their findings to the literature on forager recruitment. In each of their experiments, a group of bees was trained to feed at a scent-marked site near the hive, and ten of the foragers were marked and confined temporarily in a cage. The feeder was next ... | 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 spite of these negative results, Esch and Bastian consider that their data support the language hypothesis. Because four bees found the feeder on their first flights, it is inferred that, “since they could not have searched the entire experimental area in such a short time ...”, successful re-recruits must have had ... | 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 article by Gould, Henerey and MacLeod7 contains many data not available earlier, but some of their data do not fall in line with what one might expect from the dance language hypothesis. As in the study by Esch and Bastian, their experiments were “... designed to examine the behaviour of individual recruits as each... | 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 greater number of marked bees arrived at the station regularly visited by the foragers which recruited them than to the one 240 m from it, and some successful bees found the food source quickly (two in less than a minute), so Gould et al. concluded that quantitative information was communicated by the dance. The auth... | 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 the mean flight time of bees which flew out but failed to find the feeder was twice that of the successful recruits. Mautz noted that one bee found a goal at 400 m after following only five waggle cycles of the dance. 中文
As with Gould et al., and with Esch and Bastian, Mautz assumed that his feeder locations were n... | 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 his second experiment, Lindauer put out three stations in a geometry similar to that used in our experiments2 and trained bees to stations 1 and 3 but not to 2. Then, with scented sucrose at all three stations (a variation from our design), he collected recruits. Although the stations were deliberately asymmetrical ... | 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 | Thus all the authors we have discussed4-7 explicitly or implicitly assumed that the feeding stations they established in the field were in no way distinctive to bees and that the environment can be made symmetrical with respect to odours and other factors. They also assumed that, in order to find the food, a recruit mu... | 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 summer of 1970 we did experiments using a single frame observation hive and two feeding stations located 150 m from it in approximately opposite directions (west and east of the hive, but slightly north of it). The hive and stations were located at the University of California, Santa Barbara. Both stations were ... | 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 hive had glass sides and was equipped with a clear plastic atrial chamber inside a diffusely lighted observation room. Hive conditions (well populated, and with little natural forage) ensured that our marked foragers danced in the atrial chamber, rather than on the comb. These dances were on a horizontal surface, 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 | These oriented dances were not distributed evenly throughout the experimental period, but occurred sporadically. For example, 40% of them occurred on one day, August 30, 1970. Occurrence of a block of oriented dances on a given day did not appear to influence recruitment. A comparison of data for August 30, 1970 (which... | 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 experimental design is not rigorous enough to define the asymmetry in environmental cues used by recruits while searching for and locating a particular feeder in the field, but quantitative directional information does not appear to be a part of that system. 中文
While doing this set of experiments, we also gathered ... | 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 | More generally, we feel that honey bee foraging ecology is regulated by a complex system of hive, environmental and behavioural variables. With sufficient knowledge, it should be possible to manipulate the system and predict the consequences for the foraging ecology of a honey bee colony. We then might say that we unde... | 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 | evidence. 中文
The ingenious step and fan experiments of von Frisch have been repeated many times, and our own published data clearly show that when his procedures are closely followed, without insertion of additional controls, distributions of successful recruits may be expected to resemble those obtained by him14,15. 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 | It is exactly here that we have difficulty with the language hypothesis of honey bee orientation. Each time we have inserted previously omitted controls or altered the experimental design to create new test implications, the distribution of successful recruits to feeders located in the field is no longer that predicted... | 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 | discussing the relevant data in terms of philosophy of science which we consider to be more powerful19,20. 中文
An inherent weakness of Lindauer’s teleological argument can be illustrated by giving one interesting example from another field of biology. Methyl eugenol is extremely attractive to male oriental fruit flies. ... | 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 situation involves disoriented dances performed by foragers on a horizontal surface. In an experiment using a tilted hive, von Frisch got approximately equal recruitment in four directions while regular foragers were fed in only one direction. Later that day, with the hive put upright again, he got preferentia... | 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 believe that experimentation does not “prove” or “disprove” hypotheses, but rather affects their credibility. If the credibility of a hypothesis at any given time is determined by the total body of relevant information available, then the language hypothesis of forager recruitment was very credible in 1946 when von ... | 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 | Gould, J. L., Henerey, M., and MacLeod, M. C., Science, 169, 544 (1970).
Johnson, D. L., and Wenner, A. M., Anim. Behav., 14, 261 (1966).
Johnson, D. L., Anim. Behav., 15, 487 (1967).
Wells, P. H., and Wenner, A. M., Physiol. Zool., 44, 191 (1971).
Wenner, A. M., J. Apic. Res., 2, 25 (1963).
Von Frisch, K., Tansprache ... | 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 | 我们在干燥的野外建一个蜂巢,并且在距它200米的地方设立了排成一行的三个实验站点。那些实验站点间距约150米,而且通常微风不会吹向蜂巢或从蜂巢吹来。相反,风从1号站点吹向3号站点,而2号站点在中间。 英文
在3个小时的实验中,我们在1号站点和3号站点用有香味的蔗糖各喂食10只标记后的普通觅食蜂。捕获新招引的蜜蜂并杀死。第二天,我们在1号站点和3号站点提供无香味的蔗糖,同时在2号站点提供有香味的蔗糖,其中2号站点还没有蜂巢里的蜜蜂来过。在这种情况下,按照语言假说预测将在1号站点和3号站点捕获新招引的觅食蜂,因为这两个站点均被来自蜂巢的觅食蜂光顾过。然而,如果蜜蜂觅食是靠嗅觉来定位食物源,它们应该去该蜂巢的蜜蜂从来没有光顾过的2号站点。... | 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 | 如果从蜂箱中飞出的被招引蜜蜂是简单地以均等的机会飞向了各方向,如同车轮上的辐条,则2%的蜜蜂会飞向与食物站位置偏离7°的范围内,这个结果与埃施和巴斯蒂安的观察相一致。 英文
从更普遍的意义上来说,埃施和巴斯蒂安获取的数据并不能支持冯·弗里施的论断[12]:“......尾部摇摆的舞蹈能够给出目标的距离和方向。......这种对于方位的描述能够使得新来的蜜蜂迅速而准确地找到被指示的花朵,即使这些花儿在数公里外......在整个动物王国里,蜜蜂的这一系列技能是独一无二的。”他们也不能排除下面这种可能性,即重新招引的觅食蜂可能利用风向和气味来寻找它们曾经受到训练的气味。 英文
古尔德、黑纳雷和麦克劳德的论文[7]有很多早期无法获得的数据,... | 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 | 为了与这一推论相符合,林道尔将招引到的蜜蜂到达的不均等归因于语言交流。因此,就如同以上几位作者一样,(对于蜜蜂而言)未经验证的环境气味均匀性假设对林道尔推理论证至关重要。 英文
在第二个实验中,林道尔设置了3个在几何位置上与我们的实验[2]中所设置的相似的站点,并且训练蜜蜂到1号站点和3号站点而非2号站点。然后在3个站点都涂上有香味的蔗糖(与我们实验设计的不同之处),他收集了招引来的蜜蜂。尽管这些站点被故意设置得不对称(在2号站点没有觅食蜂),但被捕获的招引蜂中有将近1/4到达了2号站点。而蜜蜂语言假说预测招引到的蜜蜂应该只到达1号站点和3号站点。 英文
为了用语言假说解释这些数据,林道尔提出特别的辅助性假设——潜在的招引蜂将它们的... | 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 | 它们所跳的舞蹈是在同一个水平面上的,其中没有任何可识别的方向信息,舞蹈中直线(摇摆)的那部分很显然是随机导向的,而且在每一个舞蹈节拍内的导向都是高度变化着的。 英文
总之,在实验观察的11天中(33小时)总共有1,793次舞蹈是由标记过的蜜蜂跳的,136次舞蹈是没标记过的以自然食物源为食的觅食蜂跳的,因此在我们研究期间蜂巢中93%的舞蹈是由我们标记过的觅食蜂所舞出的。 英文
尽管我们在消除蜂巢中的导向性舞蹈方面取得了巨大的成功,但是我们偶然发现一只被标记了的觅食蜂进入蜂巢并且在垂直于巢脾的平面跳舞,这种现象将会使支持语言假说的人产生极大的兴趣,所以我们将在继续其他方面研究之前展示有关导向性舞蹈的研究数据。 英文
在33个小时的实验中... | 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 | 他得出的结论是,招引蜂离开蜂巢后,它们的成功招引和分布取决于影响气味分布的各野外变量之间的相互作用[18]。因而,各种来源的证据表明气味在调节蜜蜂觅食生态的变量系统中起着很重要的作用。 英文
嗅觉理论和语言假说在觅食蜂招引的预测价值上的比较是一种用于确定气味在系统中重要性程度的尝试[2]。令我们惊奇的是:我们的研究结果和解释引起了相关生物学家高度两极化的争论。在这方面我们必须强调这种争论的出现并不是源于针对同一证据主体不同方面的可接受性的观点差异。 英文
冯·弗里施的这种独创性的步骤和有趣的实验已经被重复了许多次,我们自己发表的数据也清楚地表明:在没有加入额外对照实验的情况下,严格按照冯·弗里希的步骤操作,成功招引到的蜜蜂的分布与他... | 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
第二种情况是觅食蜂在水平面上表演的非导向性舞蹈。在一个采用倾斜蜂巢的实验中,冯·弗里施仅从一个固定方向喂食常规采食的觅食蜂,但他在四个方向招引到的蜜蜂数量大致相等。当天晚些时候,重新将蜂巢放正,他发现被觅食蜂造访过的食物源方向更具招引的优势[12]。我们更倾向于另外一个实验设计,实验中蜜蜂可以造访两个或更多的站点,同时它们相互之间可以作为对照,我们据此设置了实验。我们发现,我们关于非导向性舞蹈有效性的实验数据(见表3)与冯·弗里施的数据不符。在我们11天的观察中,新的招引蜂会优先抵达跳舞的觅食蜂造访过的站点,即使该舞蹈中没有导向性的元素。 英文
第三种情况是蜜蜂绕过障碍找到位于另一边的食物站。冯·弗里施在一个实验中,训练被标记... | 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 | them. 中文
Although the technology exists for exchanging radio messages with extraterrestrial civilizations, a successful search for such civilizations among the many stars that might support them could take more than a thousand years, even if most habitable planets are occupied by communicative civilizations. 中文
THAT 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 | K1 have habitable planets; PHP is zero for stars outside this range. Dole’s estimates involve many assumptions, and improved values of PHP will undoubtedly become available in time, but his values are adequate for present purposes. They show, first, that several tens of stars must be searched, even if f is of order uni... | 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 | Von Hoerner6 has analysed this problem in general terms, pointing out that it is necessary to develop an optimal search strategy for both transmitter and receiver, and then to assume that the target civilization will perform the same analysis and arrive at the same conclusion. I present here a strategy for which the pr... | 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 transmitter strategy thus defined, it is possible to determine the optimal receiver strategy and evaluate the rate of success. From the point of view of the receiver, let us redefine Pc to be the probability that a given star has a civilization that sends a contact signal to the receiving star every T years at... | 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 optimal receiver strategy is now clear. The success rate is maximized if each listening period ∆τ is devoted to the star for which (PHP/T) exp (–τ/T) is greatest. As the search progresses, the number of stars included in the search increases steadily, for each star within range the value of τ increases, and the ins... | 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 | provided the receiving civilization knows the value of m. 中文
The conclusion, therefore, is disappointing. If every habitable planet has a communicative civilization there might be 50 such civilizations within 100 light year of us18. We possess the technology to exchange messages with this multitude of other worlds, if ... | 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 | Webb, J. A., in Interstellar Communication (edit. by Cameron, A. G. W.), 188 (W. A. Benjamin, New York, 1963).
Hubbert, M. K., in Resources and Man (Committee on Resources and Man of the National Academy of Sciences-National Research Council), 157 (W. H. Freeman, San Francisco, 1969).
Extraterrestrial Civilizations (ed... | 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 | 为了通过一定程度的努力向尽可能多的恒星发送信号,发射机时间必须被不同目标恒星共享。那么,给一个特定恒星发送信号的频率应该是多少呢? 英文
冯·赫尔纳[6]大体上分析了这个问题,他指出,有必要针对发射机和接收机建立一个优化的搜寻策略,他假设目标文明也会进行同样的分析并得到相同的结论。这里我提出一个策略,以此可以估计成功的概率,至少可以表示为f的一个函数。 英文
一个最佳的搜寻策略是应该使用我们和目标文明共享的所有信息。这包括候选恒星的光谱型以及相关的PHP值;也包括选取最佳的工作频段使得不可避免的背景噪声在此频段最小[1–5],还要考虑离候选恒星的距离。 英文
最后这个计算结果将给出我们多久向指定恒星发射一次信息的唯一指标。对于一颗距... | 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 | 这些情况可能会限制我们搜寻超级文明[16]。 英文
本研究部分得到了美国国家航空航天局基金的支持。 英文
(周旻辰 翻译;沈志侠 审稿)
On the Origin of Deuterium
F. Hoyle and W. A. Fowler
Editor’s Note
Deuterium is hydrogen that contains a neutron in its nucleus. It is relatively abundant in the universe, most having been created in the first few minutes after the Big Bang. Here Fre... | 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 | Jefferts, Penzias and Wilson4 report line emission from a cloud within the Orion Nebula at 144,828 MHz and attribute it to the J=2 to J=1 transition in DCN. In a separate investigation of the J=1 to J=0 transition at 72,414 MHz, the hyperfine components expected for DCN have also been found5, setting the identification... | 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 | where ρb is the baryon mass density and T9 is the radiation temperature measured in units of 109 K, we found D/H comparable with the terrestrial ratio of 1.5×10–4 when h≃6×10–6. Setting T9=2.7×10–9 K for the present temperature leads to ρb≃10–31 g ml.–1 for the present baryon density, which is in good agreement with es... | 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 | Investigations going back to the middle nineteen fifties have repeatedly shown that D is best produced astrophysically under non-thermodynamic conditions. We imagine α particles projected at high speed into an ionized gas composed mainly of hydrogen. If the gas temperature has some moderate value, say 105 K for definit... | 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 | required. For greatest efficiency we must look therefore to processes involving speeds ~ c/3. 中文
Such speeds have indeed been found for shock waves generated by stellar explosions11. The shock wave starts in the region of the explosion at a speed not much different from the speed of sound, which is always much less tha... | 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 energy in question, whether radiant or in the form of relativistic particles, would escape from the source at speed c if it were not for the material of the surrounding envelope. But as the envelope becomes more tenuous the radiation is able to push material ahead of it at speeds which approach more and more to 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 | Material flowing through the front experiences a change of velocity vi– vs=6vi/7, which for vi=c/3 is 2c/7. If we now think of the material in terms of individual particles, instead of from the point of view of continuum mechanics, the particles experience a change in velocity of 2c/7 as they pass from being upstream t... | 400套付费套装书 |
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