path stringclasses 189
values | ext stringclasses 1
value | size_bytes int64 569k 327M | mtime stringdate 2025-09-26 17:48:05 2025-09-26 19:10:03 | text stringlengths 40 2k | source stringclasses 1
value |
|---|---|---|---|---|---|
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | All lunar samples were vacuum pyrolysed at 681°C. After pumping out the gases from the mass spectrometer, the samples were subsequently pyrolysed at 1,084°C and analysed as before. The contribution of carbon to the gases is shown in Table 1. The core samples and the fines showed CO2 in almost equal quantities from 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 | The lunar samples were pyrolysed in a stream of He at 700°C for 7.5 min in a modified Hamilton pyrolysis unit3-5. The He stream (3–5 ml./min) from the fused quartz pyrolysis tube was connected to a Perkin–Elmer model 226 gas chromatograph. It also served as the carrier gas for this unit. In turn the gas chromatograph w... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | pyrolysis technique. In a control experiment benzene was pyrolysed in He at 600°C and yielded traces of, predominantly, biphenyl with lesser amounts of naphthalene. Pre-Cambrian rock samples which had given He pyrolysis products similar to those found in the lunar samples were subjected to vacuum pyrolysis at 500°C 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 | contains C2F4, C2H2F2; 4, C4F4H2; 5, C3F6; 6, C4H6; and on trace C: 1, CO absent; 3, CH4, CO, CO2; 4, CO2, Ne, possibly COS; 5, CO2, C3H6. Compounds 7 and 9–11 can be artefacts.
中文
Trace amounts of fluorocarbon compounds were also observed in some of the pyrolysed samples, but these were probably “Teflon” contaminati... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | amino-acids is approximately 1/20 of that in sample 12001, 34 and the distribution again suggests hand contamination. In sample 12033, 8 the amino-acid content appeared to be zero. Urea, however, was present even in this sample. It seems, therefore, that these samples did not contain the amino-acids found in Apollo 11 ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Fig. 4. A and B, Transmitted light photomicrographs of “twisted” glass dumbbell and glass sphere with opening, respectively; C and D, scanning electron micrographs of beads after pyrolysis at 1,084°C; E, freshly broken surface of interior rock chip (note absence of vesicles); F, partially broken glass bead showing cavi... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Sample locations (a)—(g) are taken from ref. 10. 中文
Lunar samples 12023, 8, 12042, 13, the core sample from a depth of 39 cm, and a freshly broken surface of the rock chip, were examined by a scanning electron microscope. The core sample and sample 12023, 8 were also examined after pyrolysis at 1,084°C. The fines were ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | dumbbell shown in Fig. 4I is covered with what appear to be impact craters with lips, which might have been caused by impacts from hypervelocity particles of about 0.1–0.2 μm in size. Lower velocity and larger impacting particles, ~1.0 μm in diameter, show impact prints but remained attached to this dumbbell without pe... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Wasserburg, G. J., and Papanastassiou, D. A., Geol. Soc. Amer. Abstract, 2, 715 (1970).
Nagy, B., Drew, C. M., Hamilton, P. B., Modzeleski, V. E., Murphy, Sr. M. E., Scott, W. M., Urey, H. C., and Young, M., Science, 167, 770 (1970).
Nagy, B., Scott, W. M., Modzeleski, V. E., Nagy, L. A., Drew, C. M., McEwan, W. S., Th... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 英文
真空热解
将月球样品置于为适应质谱的气体进样系统而设计的石英管内并在真空中热解。调节系统以保证生成的所有气体在到达所需的热解温度时都能被导入到质谱仪的离子源中。在热解前,用质谱仪的真空系统对盛放样品的石英管进行20 min的除气处理。接着在这个石英管的周围安插一个可移动的加热炉。在质谱分析过程中热解温度保持恒定。 英文
阿波罗12号采集的微粒土、土芯物质和岩屑样品中的总碳量来自于CH4、CO和CO2,以p.p.m.(译者注:百万分之一)表示。在进行质谱检测前,我们根据对不同量上述气体的计算作出相应的校准曲线。为了避免在判断月球样品中的CO含量时出现不确定性,我们在m/e=28处进行了高分辨测定,以便区分出CO、N2和C2H4的... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | A,月球表面微粒土(样品12042,13);C,月球沟槽中的微粒土(样品12023,8);E,月球物质回收实验所的渥太华石英砂对照样品。谱峰代号如下,对所有迹线:1,H2、CH4、CO;2,C2H4、C2H6;3,CO2、C3H6;4,C4H8;5,C4H6;6,C5H8(7号峰前面的小峰,仅出现在迹线A中);7,C5H6;8,苯;9,噻吩;10,甲苯;11,取代基为二碳的烷基苯;12,邻二甲苯;13,苯乙烯;14,茚;15,萘;16和17,甲基萘;18,联苯。迹线E特有的峰:1a,CH4、C3H8;2a,CO2、C2H4。此外,对于迹线A:1,还含有Ne;2,C2F4。对于迹线C:2,CO2。正如纳吉和普雷蒂等人所指出的那样,化合... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 英文
图4.A和B分别是用透射光显微镜拍摄的“扭曲”玻璃哑铃和有孔玻璃球的照片;C和D为在1,084°C热解后对熔珠拍摄的扫描电子显微镜照片;E,岩石内部的岩屑新切开的断面(请注意没有气泡);F,部分破裂的玻璃熔珠在表面附近出现空穴;G,有破口的薄壁玻璃熔珠的一部分(请注意箭头所指的片状物,很可能产生自与一个熔融微粒的碰撞);H,玻璃熔珠的一部分,看上去好像有若干个气孔;I,玻璃哑铃的一端,上面有由超速撞击导致的小孔。请注意图中箭头所指的是一个只留下印痕但未穿透表面的大且速度慢的微粒。
英文
从形态学角度来看,可能除了很多玻璃熔珠表面会有附着于其上的细小颗粒状物质以外,土芯样品和表面微粒土样品并没有什么不同。来自于土芯样品的玻... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 英文
(王耀杨 翻译;周江 审稿)
Nonbiotic Origin of Optical Activity
L. Mörtberg
Editor’s Note
All the molecules in living things are asymmetrical in the sense that they contain at least one atom that is attached to other parts of the molecule in such a way that they cannot be superimposed on the another by rotation, although the r... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | All these hypotheses except the last rest on the assumption of local and/or occasional excess of one of the antipodal forms of an asymmetric agent. In the absence of any explanation as to how such excesses could arise over sufficiently wide areas and periods of time, they therefore reduce to hypotheses about chance occ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Light passing no-perpendicularly through a boundary from one region to another (Fig. 2) with a different refractive index will be refracted. A magnetic field non-perpendicular to the direction that the light would take in the second region will cause a refractive separation of right and left circularly polarized light,... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | situation will clearly be the reverse. 中文
Fig. 1. A planet orbiting a “sun” as described in point (1) in the text. The planet is represented by the solid circle to the left and the “sun” is to the right. The light rays are symbolized by straight arrows. The dashed circle represents the “boundary” between atmosphere an... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | immediately surrounding the “north” pole, where the field-lines are almost parallel to the planetary axis, constitutes an exception to this, however. In this area a component of the field will be parallel to the rays all the time. It is difficult to say precisely which effect should predominate on the northern hemisphe... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | In any given position in the orbit, the system in non-superimposable on its mirror image and is asymmetric. “Half a year” later the mirror image turns up, however. There is thus symmetry when the whole “year” is considered. 中文
(3) Let the orbit be elliptical (Fig. 4). When the “sun” is large in comparison with the plan... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | integration above. (A pronounced example is Mars.) 中文
As discussed in point (2), for a large α, one form chiral light predominates in the equatorial region when one hemisphere has “summer” and vice versa. Given these “seasonal” excesses of the respective circularly polarized light forms, the light form that is in exces... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | With roughly the same reasoning as above, one could visualize similar effects that could cause net asymmetry on an entire planet. Take, for example, a rotating “sun” that possesses a magnetic field coinciding with its axis and has its equator tilted relative to the orbit of a planet. If the planet has an elliptical orb... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Received November 30, 1970; revised March 19, 1971.
References:
Kuhn, W., and Braun, E., Naturwissenschaften, 17, 227 (1929).
Ulbricht, T. L. V., Quart. Rev., 13, 48 (1959).
Harada, K., Naturwissenschaften, 57, 114 (1970).
Waring, C. E., and Custer, R. L., in Techniques of Organic Chemistry (edit. by Weissberger, 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
图1.正文第(1)点中所描述的围绕“太阳”运转的一颗行星。左侧的实线圆代表行星,而“太阳”则位于右侧。光线用直箭头表示。虚线圆代表大气与太空之间的“边界”。弯箭头代表从“南”到“北”的磁力线。
英文
图2.两条反向圆偏振光线在磁场中的分离随折射率梯度而增加。光线用实箭头表示,nr是右旋圆偏振光线的折射率,nl是反向偏振光线的折射率。虚线箭头代表磁力线。n1、n2和n3表示在没有外场存在的情况下光线在三个不同的物质层中向下依次增加的折射率。
英文
在光线以接近于直角进入大气的区域中,几乎没有折射发生。对称性推理表明:若将行星视为整体来看,应该不会出现一种圆偏振光形式的净过剩,因而也就不会有以光化学方式产生的不对称物质... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 英文
在轨道中的每一点上,行星系统都是不对称的,而且当α≠0时对全“年”来说也是如此。这一点可以从前面几种情况中推导出来。这些效应的数量级是很难估计出来的,而对于现在的地球来说,它们的数值无疑是很小的。对气体而言,它们的费尔德常数很小(不过在波长较短处一般会大一些,此时光有更显著的光化学效应),这时大气的稀薄以及由此引发的折射率梯度的浅薄、磁场的微弱、赤道与椭圆之间的角度很小,以及所有因素中最为重要的一个——现有轨道的离心率不够大等都只能导致很小的效应。但在数十亿年以前,所有这些方面的情况都可能会大为不同。此外,目前还没有一种通用的方法能够从理论上说明某个由圆偏振光导致的光化学反应能产生出多大程度的化学不对称性[5]。 英文
利用与... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | SYMBIOTIC fixation of atmospheric nitrogen by leguminous plants is perhaps the most quantitatively important agency by which this element is incorporated into the biosphere, and is the principal process for maintaining nitrogen fertility in agriculture. The interaction of plants of the family Leguminoseae and specific ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | When the primary root was approximately 4 cm long, it was excised aseptically, and a 5 mm explant was removed 2.5 cm behind the growing tip. This explant of root origin was placed on the surface of 50 ml. of agar-solidified MS medium supplemented with 15% whole coconut milk (CM, Grand Island Biological Co.) and 2 mg/l.... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | ml. Erlenmeyer flasks and incubated at 30 ̊±1°C with constant shaking. Subcultures of the bacterial cultures were carried out at 7 day intervals to maintain vigorous stocks. At regular intervals aliquots of the R. japonicum cultures were examined microscopically and checked for nodulating activity by application to see... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | fitted with phase contrast optics. 中文
At the same time similar cell samples were overlaid with 5% glutaraldehyde in Millonig’s phosphate buffer (pH 7.2–7.4) and fixed for 60 min at room temperature. The fixed samples were rinsed for 20 min, post fixed for 60 min at room temperature with 1% OsO4, washed with phosphate 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 | Following the initial penetration of the plant cells by Rhizobia (3–7 days after bacterial inoculation of the cell culture flask), the cell cultures were transferred to fresh media, both liquid and agar-solidified, for development of stage 2. The following media were utilized: (1) MS, (2) MS plus 10–15% whole CM and (3... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | soybeans, the use of a different strain of R. japonicum (ATCC 10324) resulted in a lower over-all nitrogenase activity although electron microscopy showed bacterial penetration of the cultured cells. Cotyledonary tissue has shown no propensity to establish a symbiotic association in the conditions of this study. 中文
Ta... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | microorganismal contaminants present. The media used for maintenance of the plant cell cultures were also found to be devoid of microorganisms and N2-fixing activity; the bacterial inoculum contained only Rhizobia and exhibited no N2-fixing activity. Thus it is clear that free-living N2-fixing bacteria are not responsi... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | It has further been found that following initial bacterial penetration of the cultured cells, depletion of exogenous supplies of plant growth factors (cytokinins and auxins) in the environment leads to increased cellular penetration by the microorganisms and greater nitrogenase induction. This suggests that the symbios... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | The acetylene to ethylene reducing activities (and nitrogenase activity by analogy) achieved so far in the in vitro symbiotic system are of the order of 1% of those found in soybean nodules. Microscopic examinations of the symbiotic cell masses in culture showed that only 1–10% of the total cell population was infected... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Hardy, R. W. F., Holsten, R. D., Jackson, E. K., and Burns, R. C., Plant Physiol., 43, 1185 (1968).
Millonig, G., J. Appl. Phys., 32, 1637 (1961).
Gamborg, O. L., and LaRue, T. A. G., Nature, 200, 604 (1968).
Stewart, E. P., and Freebairn, H. T., Plant Physiol., 42, Suppl., S-30 (1967).
Goodchild, D. J., and Bergersen,... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 为了保持住一个积极分裂的细胞群体,以20~30天为间隔对这个液态体系进行传代培养。采用类似方法处理大豆子叶组织,以建立同一来源的细胞培养体系。 英文
细菌的生长
将大豆根瘤菌菌株61A76(由威斯康星州密尔沃基市根瘤菌剂公司的乔·伯顿博士提供)和ATCC 10324放置于包含以下成分的液态培养基中进行培育(单位为克/升):K2HPO4,1.0;KH2PO4,1.0;FeCl3·6H2O,0.005;MgSO4·7H2O,0.36;CaSO4·2H2O,0.17;KNO3,0.70;酵母提取物,1.0和甘露醇,3.0。调节此培养基的pH值到6.4,然后在121°C下高压蒸汽灭菌15分钟。将细菌接种物加入到含有40毫升上述液态培养基的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 | 将被细菌填满的植物细胞转移到不含任何外源生长添加剂的MS培养基中后,细菌的入侵范围最广(图3a)。当添加全脂CM(图3b)和CM与2,4–D的混合物(图3c)时,被根瘤菌占据的细胞数量明显减少。对上述每一种试验条件下的培养进行固氮酶活性检测的结果(表1和表2)显示,酶活性与细菌入侵程度直接相关(表1)。在这些分析测试中,没有根瘤菌介入的组织几乎不具有将乙炔还原为乙烯的活性(表1)[11,12]。表2显示:尽管两个阿克姆大豆根细胞培养物对根瘤菌菌株61A76的反应有很大的差别,但乙炔–乙烯还原法的测定结果表明,在这些液态系统中形成了一种确定的能够固氮的共生关系。尝试用肯特大豆根细胞在液态培养体系中建立有效共生关系的成功率较低。即使是阿... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 英文
到目前为止,从体外共生体系中获得的使乙炔转变成乙烯的还原活性(以及由此推出的固氮酶活性)是在大豆根瘤中发现的1%左右。用显微镜对培养物中共生细胞群体的观察结果显示:在整个细胞种群中,只有1%~10%的细胞被细胞内的微生物感染。但在根瘤中看似有超过90%的细胞含有细菌,因此每个细胞的活性有可能与完整根瘤中的细胞活性相当,这也与细菌感染只发生在愈伤组织表面下的细胞相一致(图3),可以设想此处的生理条件更近似于完整根部的皮层。在组织培养中,初期感染是通过改变愈伤组织的外周细胞而发生的,并不像在完整根部中那样,是通过根毛细胞发生的。这表明体内共生或许也可以被设想为是在适当条件下通过侵入表皮细胞发生的,而不是通过侵入根毛发生的。 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 | As the volume of ocean water is hardly likely to have decline during Phanerozoic time, and might indeed have been augmented by a small percentage, Egyed argued that the facts could only be explained by a gradual increase in the Earth’s volume, so that ocean water drained more or less progressively from the continents i... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | In the first place, many ancient shields have persisted for millions of years as positive areas and sediment sources. Maintenance of relief following removal of sediment would naturally result from isostatic adjustment, but obviously this could not persist indefinitely because the shields would achieve isostatic stabil... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | flysch-type marine sedimentation and vulcanicity are transformed into stable shield areas or cratons, on which only continental or shallow marine sediments were laid down, the latter often only at the margins. The conversion of the Caledonian geosyncline of the North Atlantic region into the “Old Red Sandstone Continen... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | If we take 300 m as a figure of the right order of magnitude for the amount of secular lowering of sea level since the early Palaeozoic, this would be accounted for by an average thickening of the continental crust of perhaps twice this amount. Such a figure implies an increase of only about 1 mm in 103 yr, with no mor... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | The two most notable departures from a more or less gradual lowering of relative sea level in the Phanerozoic are the pronounced regression of the late Permian and early Triassic, and the equally striking transgression of the late Cretaceous. This is brought out more clearly in the less accurate Strakhov curve of Fig. ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Kuenen, Ph. H., Marine Geol. (Wiley, New York, 1950).
Hallam, A., Earth Sci. Rev., 5, 45 (1969).
Hallam, A., Amer. J. Sci., 261, 397 (1963).
Van Andel, T., and Heath, G. R., Mar. Geophys. Res., 1, 5 (1970).
Valentine, J. W., and Moores, E. M., Nature, 228, 657 (1970).
Smith, A. G., and Hallam, A., Nature, 225, 139 (197... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 该理念认为:以复理石型海洋沉积作用和火山活动为特征的构造活动带均转变成了稳定的地盾或克拉通,只有陆源沉积物或浅海沉积物可以沉积在地盾或克拉通之上,而浅海沉积物通常仅存于其边缘。泥盆纪时期,北大西洋地区的加里东地槽转化成“老红砂岩陆地”就是一个很好的实例,因为它从前一直是一个正地形,直到进入中生代以后才因北美和欧洲大陆的分离而遭到破坏。 英文
根据对过去大约6亿年间海平面相对位置变化的粗略判断,可以大致估算出陆壳加厚的量及加厚速率。埃杰德[1]利用斯特拉霍夫的数据推断出,寒武纪时海平面比现在高出约500米;利用泰尔米埃夫妇的数据得出,在中奥陶纪时海平面比现在高出约275米。屈嫩[10]根据全球等高线图得出了以下结论:在当前条件下,海平... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | The Australian F. MacFarlane Burnet was one of the pioneers of the modern understanding of the immune response of animals (including people) to infectious pathogens. For his pioneering work he was awarded a Nobel Prize for medicine in 1960. In this article, he raises questions about the similarities between immune reac... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | and hagfish11-13 as representative modern cyclostomes, the most primitive extant vertebrates. It is probably a fair summary of the results to say that homograft rejection is well shown; there are other T-type (cell-mediated) responses and restricted and weak antibody responses. The immunoglobulins have typical vertebra... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | as if it were just an inert attachment surface. Clearly, therefore, there is recognition of foreignness within the species and recognition must always be the basic phenomenon of immunity. 中文
Sexual reproduction of Botryllus is dominated by mechanisms to avoid self-fertilization since the organisms are hermaphrodite, li... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | surrounding an A ovum from an AB individual are presumably diploid and AB, and prevent the entry of either an A or a B spermatozoon. Any other type of spermatozoon, such as C or D, encounters no obstruction. 中文
Other Colonial Forms
Both phenomena seem “designed” to ensure the greatest degree of heterozygosity in all vi... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | As far as the evolution of adaptive immunity is concerned, it can be assumed that the phenomena Oka described for colonial ascidians, and probably also those of Theodor in the Anthozoa, facilitate the achievement and maintenance of heterozygosis. In the better studied system of Oka, the aspect of immediate interest to ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | one out of many alternative candidates. An antibody reacts visibly with only one of a thousand antigens. In the Botryllus examples we must postulate that there is a positive recognition of the presence of a common allele in the somatic cell genome, a positive recognition of conspecificity by the mutually damaging react... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | of another DNA sequence which will code for a complementary three-dimensional structure that will react specifically with the product of A. It seems more promising to consider the situation where the + and – complementary receptors are controlled by distinct genes. There is much to be said for an ad hoc assumption 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 | Fig. 1. A diagram to suggest the type of +/– relationship between recognition units that is postulated for Botryllus. A positive receptor is shown as a projection, the corresponding complementary negative receptor by a depression of the same shape. Where there is a reciprocal relationship (R) allowing receptor union (h... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | of specific stimulation, would have to be able to take on the blast form and proliferate. 中文
It is probably unwise to attempt to imagine the various steps by which such changes could be made. One can foresee a period of great research activity in these fields of tissue fusion and rejection in invertebrates and protocho... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | countless streams running into the lakes which were suitable for larval development. Lamprey proliferation reduced the economically significant fish species to such a level that the lakes’ fishing industry was destroyed. The subsequent ecological history of the Great Lakes is of great interest but not relevant to my th... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | At this stage it is necessary to attempt a formal comparison at the genetic level of what is observed in the colonial ascidians and what holds for homograft reactions in mammals. If in both the simplifying assumption is made that histocompatibility is determined by alleles of a single gene, we can consider the results ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | between AB and AC and, following recognition of C, provoke a destructive local reaction. The parasitic embryonic form and the adjacent host cells will be killed, thrown off and the region repaired. The result will be wholly equivalent to the repair of a traumatic wound or of a patch of localized bacterial or other type... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | The requirement for segregation of the communities of colonial forms has sufficient similarity to suggest that the basic recognition mechanism was adapted to this new “immunological” requirement. But in the tunicates the recognition factors conduced to stable relationships between cells. As long as our potential parasi... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | histocompatibility patterns of the species should be represented in the complementary patterns (–) of the immunocytes, there would be a drive to establish the necessary information in the germ line. Perhaps it is not altogether naive to suggest that when the genetic mechanism which generates diversity of immune pattern... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | The capacity to recognize the difference between self and not-self appears early in animal evolution and is well marked in at least two colonial marine forms: Eunicella, an anthozoan (Coelenterata), and Botryllus, a colonial ascidian (Tunicata). In the ascidian, Oka’s work has allowed analysis of the genetics of recogn... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | As Oka has pointed out, there are important similarities in the self-sterility of Botryllus colonies and self-incompatibility in flowering plants. Under the guidance of Professor J. S. Turner and Miss Mary Ellis, I have consulted enough of the recent literature on self-incompatibility in plants to feel that it might be... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | can fertilize strain A. 中文
To take a classical example. Crane and Lawrence21 tabulated fifty-two varieties of cherry to show that they fell into twenty-four compatibility groups, the three largest containing nine, eight and four varieties respectively. All the incompatibilities shown in the table are symmetrical. This ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | and BD offspring can be obtained. When these are mated, the types of offspring are:
中文
These are essentially the same rules as obtain in Botryllus. The symmetry of the reaction is not always complete and it is well known that irradiation of pollen will often allow fertilization of the normally self-incompatible strai... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | simple saline extracts of ragweed pollen were located in the inner (intine) part of the cell wall of the pollen grain. Studies by immuno-electrophoresis showed that their pollen extracts contained as least seven antigens, some of which were likely to be enzymes known to be present in the intine. They noted, however, th... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Probably only two basic hypotheses are possible. Both agree that one allele codes for proteins in two different sites. Both have been formulated by Lewis, the second being the one he currently favours. In the first, the allele codes for two distinct proteins, one for the pollen tube, one for the style. The proteins SP ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | results in cessation of growth. In view of the symmetry of the relationship, we assume that both + and – patterns are present on both sides and that the cells of style, being diploid, will carry + and – patterns of each gene A + B. 中文
Because there are many plants which are self-fertilizing and more which show minor de... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Reverting once more to Jerne’s16 concept that the organism “knows” what are the structures of the histocompatibility antigens which the species can produce, we can hardly avoid pondering—heretically, no doubt—whether there is any genetic way by which a nucleotide sequence coding for an amino-acid group A–B–C–D can auto... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Jerne, N. K., in Immune Surveillance (edit. by Smith, R. T., and Landy, M.), 343 (Academic Press, New York and London, 1970).
Howell, J. H., in Phylogeny of Immunity (edit. by Smith, R. T., Miescher, P. A., and Good, R. A.), 263 (University of Florida, Gainesville, 1966).
Ritchie, A., Palaeontology, 11, 21 (1968).
Burn... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 群落始于由一个受精卵发育而来的幼体,但是一旦这个幼体定居下来,就会出芽产生新的个体,最终形成群落。因此,每个群落本质上是一个由相同遗传单元组成的克隆体。正如我们所料,如果群落I一分为二,并且两个部分都能独立生长,然后使它们相互接触,那么这两个子群落就会融合在一起,重组为一个单一的群落。然而,如果将一个属于同一物种但不相关的群落II与群落I放在一起互相接触,就会发生主动排斥,并且两个群落间会形成一道由坏死物质组成的屏障。最后,如果用另一种大致相同类型的混合海鞘——拟菊海鞘,与菊海鞘I或II放在一起互相接触,将什么都不发生。一种会覆盖在另一种上生长,就好像下面只是一种非生物的附着表面。因此,很明显,菊海鞘能够识别同一物种内的外来物质,而... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 识别问题的关键是生物组织或细胞A与两个或更多大致类似的实体X1、X2、X3等发生接触或发生其他可定义的关系。如果在一个例子中(比如与X1)发生了可论证和可重复的反应,但与X2和X3等则未见此类现象,那么就可以说A能够主动识别X1。有时,例如就菊海鞘来说,赖以识别一种特征有别于“所有其他”特征的个体反应表现为抑制坏死或其他一些不可避免的反应。此问题的关键是,识别只有在能从很多可供选择的候选项中识别出一个时才是有意义的。一个抗体显然只会与上千抗原中的一个发生反应。在菊海鞘的例子中,我们必须假定存在三种主动识别:一是通过体细胞基因组中的一个共同等位基因的主动识别,二是通过发生相互破坏反应的同物种间的主动识别,三是通过精子的主动识别——精子... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 要实现这一点,需要三个前提条件:第一,相互识别的系统必须十分精细,并且分化出了一些专门用于识别和用于局部破坏反应的细胞;第二,这些细胞的识别功能必须逐渐特化,直到能够产生多种多样的免疫模式,每一免疫模式限制在单克隆内;第三,在某些特定的刺激条件下,这样的“免疫细胞”必须能以爆发形式大量增殖。 英文
试图想象出实现这些变化所需的多步过程很可能是不明智的。可以预见未来十年将是大量研究活动集中在无脊椎动物和原索动物的组织融合与排斥领域的时期。毫无疑问,很多有趣现象将会被一批一批地揭示出来。一些研究可能会进一步沿适应性免疫方向进行,而不是沿群体海鞘方向发展。当务之急是进行更加广泛的比较研究,从对结果的正确分析中应该能够得到一段清晰的进化史。... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 这种结果完全等同于外伤修复以及局部细菌斑块或表面上其他类型的寄生性侵入的修复。除了由特化的抗C细胞引起的部分之外,这种反应的每一方面都在任何无脊椎动物的能力范围之内。所有后生动物为了生存都必须能够处理由细菌引起的初期感染和修复细小伤口。这可能是一种很复杂的行为,但并不需要具备适应性免疫系统。为了达到图2显示的结果,我们仅需要在两个系列的组织间加上一道免疫屏障,它的功能通常被认为与有胎盘类哺乳动物胚胎滋养层的功能相同。 英文
图2.表明胎生子代(AC)与母体组织(AB)的可能关系的示意图(见正文)。
英文
到目前为止,我一直在考虑以下这种危险,那就是胎生动物在错误位置产生的胚胎可能会变成一种破坏性的寄生物。当我们把可能性拓展至原... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 但还是能够直观地感觉到通过拓展对无脊椎动物和原索动物的研究,特别是在基因水平上的研究,有可能在以下两方面受到特别的启示:一是关于免疫模式多样性的产生进程的本质,二是关于组织相容性基因在决定免疫模式多样性的本质中的显著重要性,正如贝纳塞拉夫、杰尼、麦克德维特和其他人所强调的那样。 英文
开花植物中的“自我识别”
像奥卡已经指出的那样,菊海鞘群落的自交不育性和开花植物的自交不亲和性之间存在着重要的相似性。在特纳教授和玛丽·埃利斯小姐的指导下,我已经查阅了足够多的关于植物自交不亲和性的最新文献。我的感觉是:对于一名免疫学家来说,用动物中自我识别进化的前述讨论来评论植物中的自交不亲和性可能会有助于自己的研究。 英文
自交不亲和性在开花植物中... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 他在矮牵牛花的花柱组织中也有类似的发现;而林斯肯斯用放射性同位素标记法显示,花粉蛋白和花柱蛋白的复合体是在不相容的授粉过程中形成的。诺克斯等人[25]利用免疫荧光技术证实:用豚草花粉的简单生理盐水提取物使兔子免疫后,大多数能激活兔子体内抗体的抗原位于花粉颗粒的细胞壁内部(内壁)。免疫电泳的研究结果表明:在花粉提取物中至少含有7种抗原,其中的一些很可能是已知存在于内壁中的酶。然而他们特别提到,一些与细胞壁关联的抗原物质有可能参与了不亲和反应。也许还应补充一点,更有趣的研究方向是:在一些合适的物种中,寻找S等位基因编码的不亲和蛋白与使人类被试者产生花粉过敏反应的蛋白之间的可能关系。 英文
从本文的研究角度考虑,花粉管不能有效生长这一过程... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 英文
再一次重提杰尼[16]的概念,即生物体“知道”本物种所能产生的组织相容性抗原的结构,我们不得不考虑——毫无疑问,这与常规思路背道而驰——是否存在一种遗传学方式,通过它,编码一个氨基酸组A–B–C–D的核苷酸序列能自动产生另一氨基酸序列,(比如说是)P–Q–R–S,使P–Q–R–S能“识别”A–B–C–D。给人的一种直观感觉是,可能在最后的分析中要根据某种相互识别需求来确定对生物体内20种氨基酸的“选择”以及遗传密码的形式。 英文
(吕静 翻译;刘京国 审稿)
Detection of Radio Emission from Cygnus X–1
L. L. E. Braes and G. K. Miley
Editor’s ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | The flux density of the radio source is 0.021±0.004 f.u. and its position, determined by a least-squares fit to the antenna pattern, is in 1950 coordinates: α=19 h 56 min 28.9 s±0.2 s, δ=35° 03′ 56′′ ± 3′′. This can be compared with the X-ray position determined by the Uhuru satellite which is α=19 h 56 min 25 s ± 15 s... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Braes, L. L. E., and Miley, G. K., Astron. Astrophys. (in the press).
探测到天鹅座X-1的射电辐射
布拉埃斯,米利
编者按
天鹅座X–1是1964年一枚载有X射线探测器的火箭升空后所发现的第一批X射线源之一。但是在当时,X射线探测器的空间分辨率很差。卢克·布拉埃斯和乔治·米利在本文中报道了来自该天区的随时间变化的射电辐射,并证明其来源于天鹅座X–1的射电对应体。这使得人们可以确定天鹅座X–1的轨道。现在我们知道,天鹅座X–1是一个大约9倍太阳质量的黑洞,它与一颗蓝超巨星互相绕转。两者之间的距离只有日地距离的20%左右,蓝超巨星的星风被吸积并在黑洞周围形成吸积盘。... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | the neutral atmosphere along, producing the right direction of atmospheric rotation, also with roughly the right magnitude. Scientists continue to explore the true cause of super-rotation today. 中文
SEVERAL mechanisms have been proposed to explain the super-rotation of the Earth’s upper atmosphere discovered by King-Hel... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Second, super-rotation (or prevailing west winds) may be set up by non-linear coupling between the diurnally varying pressure and density fields originating from the solar heat input5-7. Here, prevailing west winds blow only within the lower latitudes (|φ| < 30°) while at middle and high latitudes the prevailing wind 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 | The plasma of the F layer drifts within the combined electric and geomagnetic fields like
where B is the geomagnetic induction. In the case of an ideal co-axial geomagnetic dipole field, equations (2) and (3) result in a prevailing eastward drift of the ions of
where B0 is the geomagnetic induction at the equator. At... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 大气学家汉斯·福兰德在本文中指出,高层大气和电离层等离子体之间的异常相互作用可能就是特快自转现象出现的原因。如他所述,地球磁层在电离层诱发了一个电场,从而产生了离子向东漂移的趋势。在赤道面上,这个漂移速度约为60 m/s。他认为:在这样的高度上,离子与中性气体的碰撞将会在中性大气中产生拉力,由此产生的大气自转的方向和速度的数量级都很合适。现在,科学家们仍在不断探索大气特快自转的真正原因。 英文
人们提出了若干种机制来解释金–海莱[1]发现的地球高层大气的特快自转现象。这些机制可分为两大类。第一大类认为,高层大气内部对太阳辐射的吸收是特快自转的原动力;而第二大类则认为,主要驱动力来自于高层大气以外。第一大类又被细分成三个小类,每个小类... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 英文
(齐红艳 翻译;于涌 审稿)
Estimation of Nuclear Explosion Energies from Microbarograph Records
J. W. Posey and A. D. Pierce
Editor’s Note
Physicists in the 1970s sought accurate means for estimating the yield of nuclear explosions, especially in tests then being conducted by the United States and the Soviet Union. Here Joe Po... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | where E is energy release, pFPT is the first peak to trough pressure amplitude (see Fig. 1), re is radius of the Earth, r is the great circle distance from burst point to observation point, Hs is a lower atmosphere scale height, c is a representative sound speed, and T1,2 is the time interval between first and second p... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | MT−1 where Y is the explosion yield in MT. The abscissa gives the period T1,2 in s. Note that the plot is full logarithmic. The solid line represents the theoretical relation, equation (1) with c and Hs taken as 310 m s–1 and 8 km, respectively. 中文
The scatter about the theoretical curve could be due to various causes;... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 如果要用以前的理论[7,9]来解释这些波形,就需要较为确切地知道连接爆炸源和微压计之间路径上方的平均气温和风廓线。这样的风廓线是不可能精确得到的,并且在每一个点上的值都是有所不同的,而且因为风廓线中看似微小的变化就能使波形发生相当大的改变,所以即使只是想要根据这些微压计记录值估计出核爆炸产生能量输出的数量级恐怕也并非易事。然而,我们最近将在别处发表的一篇文章中对此项工作进行进一步的报道——我们成功地推导出了特定波形特征和能量输出之间存在的近似理论关系,这种方法对大气结构变化不是很敏感。其关系式如下:
式中:E代表释放出的能量,pFPT是从第一个波峰到波谷的压力变化幅度(见图1),re表示地球半径,r表示从爆炸点到观测点的大圆距离,... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | pheromone, which the researchers extracted from the midguts of virgin females. This is the first documented report of a sex pheromone-like substance found in plants. 中文
DURING an investigation of several essential oil preparations for juvenile hormone activity1, we discovered that a volatile component(s) in several con... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Bioassays were performed according to Bodenstein3. Thus, the compound in hexane solution, was absorbed on a piece of Whatman No. 1 filter paper (1 cm2) and held within the 2 1. rearing jar with forceps. The sensitivity of male cockroaches to the natural sex pheromone and to the pheromone mimics is greatly magnified by ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | of several species, notably Aralia spinosa L. and several Compositae produced strong responses from the male cockroaches without solvent extraction. The active material seemed to be present mostly in the fruits and in the stems just beneath the outer cuticle, and varied with the season or stage of growth of the plants.... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | withstood refluxing in 5% methanolic potassium hydroxide but was destroyed by treatment with 10% methanolic base. Pheromonal activity was destroyed by brief treatment with sodium borohydride in methanol and then quantitatively regenerated by oxidation with chromic acid in acetone. Treatment of the crude extract in hexa... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Bowers, W. S., Fales, H. M., Thompson, M. J., and Uebel, E. C., Science, 154, 1020 (1966).
Roth, L. M., and Willis, E. R., Amer. Midland Naturalist, 47, 61 (1952).
Bodenstein, W. G., Ann. Entomol. Soc. Amer., 63, 336 (1970).
Riddiford, L. M., Science, 158, 139 (1967).
美洲蜚蠊的性外激素类似物
鲍尔斯,博登施泰因
编者按
因为作者发现完全可以从植物中提取出一些能使雄性... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 最后的分离纯化采用的是以硝酸银包覆的硅胶为载体的柱层析法。在比较了气–液色谱、红外光谱、核磁共振谱和质谱的分析结果之后,我们发现从几种植物中分离得到的活性烃类组分均属于同一类物质。由质谱分析得出母离子的分子量是204,这与实验式C15H24相吻合。其裂解后的质量分布也完全支持这一分子式。大约0.1 μg该物质就能使10组经过隔离的雄性蜚蠊中的8组产生性兴奋。对其结构的研究已经开始进行。 英文
表2.含有能使雄性美洲大蠊产生类似性冲动反应的烃类物质的开花植物[3]
英文
性外激素的特异性常常见诸报道,而现在却发现有好几种结构都能使大蠊产生性兴奋,这使人感到十分尴尬。虽然我们最终也许能在这些植物源物质与蜚蠊天然性外激素之间建立起某种... | 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 | THE physiological and pharmacological effects of L-glutamate have received much attention since its implication in the aetiology of the “Chinese restaurant syndrome”1-3. Although an excess of L-glutamic acid (GA) as the monosodium salt (MSG) was known to cause retinopathy in experimental animals4-7, brain lesions have ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | weight). Pyridoxine HC1 (5.0 mg per 100 g body weight) was administered intraperitoneally to some animals 30 min before MSG treatment. For EEG recording, animals were prepared under pentobarbital and chlorprothixene anaesthesia with chronically implanted stainless steel electrodes and then allowed to recover for 1 week... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | To ascertain whether the effects of MSG could be attributed to the administration of excess sodium per se and/or to the tonicity of the solution injected, two groups (eight and four rats respectively) were injected with either NaCl or sodium DL-lactate (2.5 mmol/ml., 2 mmol/100 g body weight). None of the animals devel... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | The resulting change in the relative concentrations of GA and GABA may determine the seizure activity. Other possibilities such as a disturbance in the electrolyte balance do exist and a detailed neurochemical study of L-glutamate-induced convulsions is necessary. 中文
We thank George Strutt, Robert Brackbill and John Ko... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Wiechert, P., and Göllnitz, G., J. Neurochem., 15, 1265 (1968).
Wiechert, P., and Göllnitz, G., J. Neurochem., 17, 137 (1970).
Elliot, K. A. C., and van Gelder, N. M., J. Neurochem., 3, 28 (1958).
Kamrin, R. P., and Kamrin, A. A., J. Neurochem., 6, 219 (1961).
Roberts, E., Rothstein, M., and Baxter, C. F., Proc. Soc. E... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | 英文
为了确定MSG的作用是否可以归因于给予过量的钠和/或注射液的张力,我们给两组动物(分别为8只大鼠和4只大鼠)分别注射了NaCl或者DL–乳酸钠(2.5 mmol/ml, 2 mmol/100 g体重)。没有一只动物发生注射MSG后出现的症状特征。 英文
MSG处理的动物中有11只动物记录了脑电图,有5只动物在2 h的记录时间内出现了强直阵挛性抽搐。这种形式的痉挛发作具有高幅尖波的典型特征。 英文
这样,MSG的剂量比奥尔尼[8]在成年小鼠中以及阿达莫和拉特纳[12]在幼年大鼠中所用的剂量更小就能够导致成年大鼠的强直阵挛性发作。将维生素B6用于已经是维生素B6过量(30 mg/kg饲料)的动物,能显著增加痉挛性颤抖的发生率。应当... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | The cranium was embedded in a mass of calcareous matrix measuring approximately 20×12×8 cm. All the bones were covered by matrix with the exception of a small portion of the right supra-orbital region and the posterior part of the palate. Indeed, so few identifiable parts were visible that it is remarkable it was recog... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | is likely that they broke off first and were transported downhill by erosion, possibly as far as the present river course. 中文
The matrix in which the cranium was embedded is indistinguishable from the limestone concretions that frequently occur within the tuffaceous clay that overlies the basalt at DK and elsewhere (th... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | Bed I. It includes choppers of various forms, generally made on water-worn lava cobbles, polyhedrons, discoids, sub-spheroids, heavy and light duty scrapers and burins. Although the tools are of the usual Oldowan types, a proportion of the choppers, polyhedrons and discoids are smaller than those from higher levels of ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0307. 《自然》百年科学经典(英汉对照版)(第五卷)(1966-1972).epub | .epub | 16,876,645 | 2025-09-26T19:07:54.356078 | The vault fragments were first separated and then completely cleaned of matrix under a binocular microscope. The facial fragments were more difficult to separate because they were interlocked and rammed against each other, but once they were free of matrix there were perfect joins between the nasals and the rest 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 | The cranium is still warped slightly and it is doubtful whether it can be completely straightened out, particularly as the sides of the vault are missing. The right petrous and tympanic plate are still in their crushed position and it would be a major operation to attempt to restore these bones to their proper relation... | 400套付费套装书 |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.