全文获取类型
收费全文 | 5795篇 |
免费 | 602篇 |
国内免费 | 2篇 |
专业分类
6399篇 |
出版年
2023年 | 32篇 |
2022年 | 58篇 |
2021年 | 135篇 |
2020年 | 97篇 |
2019年 | 113篇 |
2018年 | 136篇 |
2017年 | 127篇 |
2016年 | 186篇 |
2015年 | 283篇 |
2014年 | 285篇 |
2013年 | 338篇 |
2012年 | 415篇 |
2011年 | 437篇 |
2010年 | 262篇 |
2009年 | 202篇 |
2008年 | 323篇 |
2007年 | 331篇 |
2006年 | 299篇 |
2005年 | 275篇 |
2004年 | 255篇 |
2003年 | 233篇 |
2002年 | 220篇 |
2001年 | 120篇 |
2000年 | 108篇 |
1999年 | 104篇 |
1998年 | 74篇 |
1997年 | 52篇 |
1996年 | 56篇 |
1995年 | 51篇 |
1994年 | 28篇 |
1993年 | 33篇 |
1992年 | 59篇 |
1991年 | 48篇 |
1990年 | 65篇 |
1989年 | 54篇 |
1988年 | 44篇 |
1987年 | 33篇 |
1986年 | 41篇 |
1985年 | 28篇 |
1984年 | 31篇 |
1983年 | 27篇 |
1982年 | 27篇 |
1981年 | 27篇 |
1980年 | 16篇 |
1979年 | 15篇 |
1978年 | 15篇 |
1977年 | 13篇 |
1974年 | 14篇 |
1973年 | 16篇 |
1971年 | 14篇 |
排序方式: 共有6399条查询结果,搜索用时 15 毫秒
1.
In the present note the author presents history of the discovery and of the status of the excavation of the site La Isabela,
the first settlement planned by Columbus in the New World during his second trip to America in the summer of 1493. 相似文献
2.
J Ignacio Andrés Jesús Alcázar José M Alonso Adolfo Díaz Javier Fernández Pilar Gil Laura Iturrino Encarna Matesanz Theo F Meert Anton Megens Victor K Sipido 《Bioorganic & medicinal chemistry letters》2002,12(2):249-253
Following the programme started at Janssen Research Foundation searching for 5-HT(2A/2C) antagonists, we now report on the synthesis of a series of substituted 2-(Dimethylaminomethyl)-2,3,3a,8-tetrahydrodibenzo[c,f]isoxazolo[2,3-a]azepine derivatives. The 5-HT(2A), 5-HT(2C) and H(1) receptor affinities as well as the mCPP antagonistic activity of the compounds synthesised is described. 相似文献
3.
4.
A Osuna L M Ruiz-Perez M C Lopez S Castanys F Gamarro D G Craciunescu C Alonso 《The Journal of parasitology》1987,73(2):272-277
The present report deals with the alterations produced by cis-diamminedichloroplatinum (II) (DDP), and 2 of its analogs: cis-Pt(II)(tranylcypromine)2Cl2 and cis-Pt(II)(benzothiazole)2Cl2 in cultured epimastigote forms of Trypanosoma cruzi. Studies have been performed at the ultrastructural level and the inhibitory effect of these complexes on macromolecule synthesis, evaluated by 3H-thymidine, 3H-uridine, and 3H-leucine incorporation, has been investigated. DDP at concentrations of 50 and 100 micrograms/ml does not inhibit significantly the incorporation of radioactive precursors, but a clear decrease was observed with the 2 analogs. Eight hours of treatment at a concentration of 10 micrograms/ml rendered in all 3 cases an increase in autophagic vacuoles and lipids as well as an abnormal condensation of the nucleus chromatin. 相似文献
5.
Summary Phenotypic analyses of genetic combinations involving the gene extramacrochaetae (emc) reveal its participation in the differentiation of both sensory elements and wing veins. The study of near-amorphic alleles of emc in mitotitc recombination clones indicates that it also affects cell proliferation. These clones show abnormal sizes, shapes and spatial distribution. They differentiate extra sensory elements as well as extra veins. A gain of function mutation in the gene causes opposite phenotypes in both differentiation systems. The effects of the mutant on proliferation and patterning are consistent with the emc gene being involved in the transfer of information between neighbouring cells, which leads to the spatial expression of the achaetescute gene complex and genes involved in vein formation. 相似文献
6.
Transport of ethanol in baker’s yeast 总被引:1,自引:0,他引:1
Ethanol is transported into various strains of baker's yeast by simple diffusion (no effect of inhibitors and a linear concentration dependence of the initial rate of uptake and final distribution in cells). It distributes itself in 96.6 +/- 16.2% of intracellular water. 相似文献
7.
8.
W B Dandliker R Alonso V A de Saussure F Kierszenbaum S A Levison H C Schapiro 《Biochemistry》1967,6(5):1460-1467
9.
Oscar Felsenfeld 《Microbiological reviews》1965,29(1):46-74
10.