全文获取类型
收费全文 | 12871篇 |
免费 | 865篇 |
国内免费 | 6篇 |
出版年
2023年 | 128篇 |
2022年 | 272篇 |
2021年 | 462篇 |
2020年 | 367篇 |
2019年 | 445篇 |
2018年 | 545篇 |
2017年 | 461篇 |
2016年 | 633篇 |
2015年 | 781篇 |
2014年 | 839篇 |
2013年 | 904篇 |
2012年 | 1027篇 |
2011年 | 971篇 |
2010年 | 624篇 |
2009年 | 526篇 |
2008年 | 637篇 |
2007年 | 586篇 |
2006年 | 544篇 |
2005年 | 474篇 |
2004年 | 411篇 |
2003年 | 328篇 |
2002年 | 279篇 |
2001年 | 160篇 |
2000年 | 160篇 |
1999年 | 114篇 |
1998年 | 76篇 |
1997年 | 43篇 |
1996年 | 50篇 |
1995年 | 67篇 |
1994年 | 56篇 |
1993年 | 23篇 |
1992年 | 67篇 |
1991年 | 73篇 |
1990年 | 39篇 |
1989年 | 53篇 |
1988年 | 44篇 |
1987年 | 50篇 |
1986年 | 41篇 |
1985年 | 35篇 |
1984年 | 28篇 |
1983年 | 27篇 |
1982年 | 22篇 |
1981年 | 19篇 |
1979年 | 24篇 |
1978年 | 19篇 |
1976年 | 18篇 |
1975年 | 23篇 |
1973年 | 19篇 |
1972年 | 16篇 |
1970年 | 18篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
High density of transmembrane glycoproteins on the flagellar surface of boar sperm cells 总被引:3,自引:2,他引:1
下载免费PDF全文
![点击此处可从《The Journal of cell biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Membrane halves of boar sperm flagella were produced by freeze-fracture and labeled in situ with concanavalin A and wheat germ agglutinin; the lectins were visualized with protein-gold complexes. Concanavalin A and wheat germ agglutinin binding sites partition with both protoplasmic and exoplasmic halves of the membrane. A high density of lectin marking was found on protoplasmic membrane halves; we conclude that the label corresponds to transmembrane glycoproteins that, on freeze-fracture, are dragged across the outer (exoplasmic) half of the phospholipid bilayer. Our demonstration of numerous transmembrane proteins in sperm flagella offers the structural setting for previous models on flagellar surface motility that postulate accessibility of motile membrane components to the submembranous cytoskeleton. 相似文献
62.
In cotton plants ( Gossypium hirsutum L. cv. B.J.A.) the temperature of the roots affected both root and shoot growth, as did the temperature of the shoot. Drought resistance increased when the temperature imposed on roots (27°C) was lower than that imposed on shoots (17°C); the result was a decrease in both transpiration and flow of root sap. Stomatal characteristics as measured by density, index and resistance, depended only on shoot temperature. Differences in drought resistance, depended only on shoot temperature. Differences in drought resistance seem to be a result of changes in transpiration flow modulated by the amount of absorbed water. 相似文献
63.
Oxygen consumption rates (QO2) of laboratory reared stage one zoeae of Pandalus borealis (Krøyer) at 1.5, 3, 4.5, 6, and 9°C were 1.5, 2.2, 2.6, 3.6 and 4.1μ O2 · mg?1 · h?1, respectively. These values of QO2 correspond to 0.26, 0.38, 0.44, 0.60, and 0.70 μl O2 · individual?1 · h?1. At 10.5 °C oxygen consumption rates decreased suggesting thermally induced respiratory stress.The equation log10QO2 = 0.55 log10T°C + 0.086 describes the relationship between QO2 (μl O2 · mg?1 · h?1) and sea-water temperature between 1.5 and 9°C. Corresponding values of QO2 for an individual (μl O2 · h?1) exhibited the relationship log10QO2 = 0.55 log10T°C ?0.686.The minimum daily metabolic caloric requirements for an individual zoea ranged from 0.04 at 3 °C to 0.07 calories per day at 8 °C. The number of calories ingested daily ranged from 0.4 to 0.5 at 3 to 8 °C. 相似文献
64.
65.
66.
67.
68.
A rapid posttranslational myristylation of a 68-kD protein in D. discoideum 总被引:2,自引:1,他引:1
下载免费PDF全文
![点击此处可从《The Journal of cell biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Cells incubated with [3H]myristate were shown to rapidly and specifically acylate a 68-kD protein, p68, in a developmentally-regulated manner. The fatty acid incorporated into p68 was identified as myristate, and is linked to the protein via an amide bond, apparently to an NH2-terminal glycine. The acylation of p68 in D. discoideum displays some unusual properties. Unexpectedly, myristylation of p68 is a posttranslational event and occurs in the presence of inhibitors of protein synthesis. Another unusual finding was that although p68 is a stable protein, the acyl moiety is removed with a half time of approximately 15 min. 相似文献
69.
A A da Gama 《Journal of theoretical biology》1990,142(2):251-260
A model for the through-bond electronic interaction between electron donor and acceptor in proteins is developed. We use a one-electron Hamiltonian, write the Dyson's equation in site representation and solve it by using a Green's function formalism with some renormalization ideas. An expression for Tab which describes the exponential decay with distance bond per bond is obtained. Covalent, non-covalent and convergent pathways are considered and no periodic approximation is needed. 相似文献
70.
Nunes V. Casals T. Gallano P. Giménez F. J. Kere J. Williamson R. Estivill X. 《Human genetics》1989,83(3):305-306
Summary We report a rare allele detected using pMP6d-9, a probe very closely linked to cystic fibrosis (CF), on digestion with MspI. This allele has been found in normal and CF chromosomes, and therefore cannot be related to the mutation causing the disease. 相似文献