全文获取类型
收费全文 | 4521篇 |
免费 | 367篇 |
国内免费 | 2篇 |
出版年
2021年 | 53篇 |
2020年 | 26篇 |
2019年 | 35篇 |
2018年 | 42篇 |
2017年 | 53篇 |
2016年 | 76篇 |
2015年 | 137篇 |
2014年 | 169篇 |
2013年 | 209篇 |
2012年 | 255篇 |
2011年 | 223篇 |
2010年 | 175篇 |
2009年 | 162篇 |
2008年 | 232篇 |
2007年 | 256篇 |
2006年 | 237篇 |
2005年 | 233篇 |
2004年 | 251篇 |
2003年 | 238篇 |
2002年 | 254篇 |
2001年 | 81篇 |
2000年 | 52篇 |
1999年 | 63篇 |
1998年 | 85篇 |
1997年 | 65篇 |
1996年 | 55篇 |
1995年 | 72篇 |
1994年 | 57篇 |
1993年 | 54篇 |
1992年 | 54篇 |
1991年 | 52篇 |
1990年 | 45篇 |
1989年 | 55篇 |
1988年 | 46篇 |
1987年 | 45篇 |
1986年 | 27篇 |
1985年 | 52篇 |
1984年 | 52篇 |
1983年 | 31篇 |
1982年 | 42篇 |
1981年 | 38篇 |
1979年 | 24篇 |
1978年 | 25篇 |
1977年 | 29篇 |
1976年 | 37篇 |
1975年 | 34篇 |
1974年 | 29篇 |
1973年 | 32篇 |
1971年 | 32篇 |
1968年 | 24篇 |
排序方式: 共有4890条查询结果,搜索用时 15 毫秒
31.
32.
Norbert Theiß und Dieter Franz 《Journal of Ornithology》1986,127(4):511-513
Summary Close to the village Trieb in Upper Franconia (50° 09 N/11° 10 E) two cases of second breeding in the Bluethroat could be proved. The birds were colour-banded. Second broods are presumably rather common in the population along the upper River Main. 相似文献
33.
34.
Dieter Stefan Peters 《Acta biotheoretica》1985,34(2-4):157-164
A reconstruction of the anagenetic transformations from fins to tetrapod limbs is represented considering the self-evident mechanical constraints which must have limited the construction and thus the function and the transformation. 相似文献
35.
The Ca2+-binding properties of calmodulin purified from zucchini (Cucurbita pepo L.) has been determined. A value of 3.3 mol Ca2+ per mol of zucchini calmodulin was measured at pH 7.5 by equilibrium chromatography. The far-and near-UV circular-dichroic spectra of the Ca2+-and Mg2+-saturated as well as from the metal-free forms of zucchini calmodulin reveal that upon Ca2+-binding the -helix content increases. A comparison with the spectra of vertebrate calmodulin indicates that both calmodulin have a similar secondary structure, similar Ca2+-induced conformational changes and the same number of Ca2+-binding sites.Abbreviations CAPP
10-(3-aminopropyl)-2-chloro-phenothiazine
- EGTA
ethylene glycol-bis(-aminoethyl ether)-N,N,N,N-tetraacetic acid
- EDTA
ethylenediaminetetraacetic acid
Dedicated to Prof. Dr. Karl Decker on the occasion of his 60th birthday 相似文献
36.
Assembly of the terminal C5b-C9 complement components into the cytolytic C5b-9 complex is accompanied by exposure of characteristic neoantigens on the macromolecule. We report the production and characterization of mouse monoclonal antibodies to C9-dependent neoantigens of human C5b-9. Binding-inhibition assays with EDTA-human plasma and micro-ELISA assays with purified C9 showed that the antibodies did not react with native complement components and thus confirmed the specificity of the antibodies for the neoantigens. The monoclonal antibodies did, however, cross-react with cytolyticaIly inactive, fluid-phase C5b-9 complexes, Thus, expression of the neoantigenic determinants was not dependent on the formation of high molecular weight C9 polymers with the complex, since these are absent in fluid-phase C5b-9. Radioiodinated antibodies could be utilized in immunoradiometric assays for the detection and quantitation of C5b-9 on cell membranes. Cross-reactivities of the antibodies with C9-dependent neoantigens of several other animal species were examined and antibody clones cross-reacting with rabbit (clones 3BI, 3Dg, and 2F3), sheep (clones 3Dg and 2F3) and guinea-pig (clone 3D8) neoantigens were identified . Three of four tested clones (3D8, 2F3, IA12) precipitated C5b-9 complexes in double-diffusion assays, probably due to their interaction with multiple and repeating C9-epitopes on the terminal complexes. The monoclonal antibodies will be of value for definitive identification and quantitation of C5b-9 on cell membranes and in tissues, and for establishing immunoassays for detection and quantitation of terminal fluid-phase C5b-9 complexes in plasma. 相似文献
37.
38.
Dictyosiphon foeniculaceus from Sweden and Newfoundland was studied in laboratory culture. Zoids from unilocular sporangia developed into dioecious microscopic filamentous gametophytes which produced uniseriate plurilocular gametangia in low temperatures (0 to 8 °C). Zygotes and unfused isogametes gave rise to filamentous protonemata on which parenchymatous macroscopic sporophytes were formed. Isolates from Sweden and Newfoundland were interfertile. Although formed in culture, genetically unisexual sporophytes were not detected in nature. Female gametes ofD. foeniculaceus produced a sexual pheromone. It was identified as finavarrene, which is also known as the sperm attractant inAscophyllum nodosum. 相似文献
39.
Dieter C. Wasshausen 《Brittonia》1984,36(1):1-7
40.
Electrorotation—the spin of cells in rotating high frequency electric fields—has been used to investigate properties of human peripheral blood lymphocytes. The rotation spectra of lymphocytes deviate from those of single shell spheres. The deviations are caused by the electrical properties of the nucleus in the cell interior.Electrorotation allows the distinction between successfully stimulated lymphocytes and unstimulated cells after application of concanavalin A. Notwithstanding the fact that only a proportion of the cells will be mitogenically stimulated we detected an enhanced cell membrane conductivity for the whole cell population immediately after the addition of mitogen. 相似文献