全文获取类型
收费全文 | 13715篇 |
免费 | 1449篇 |
国内免费 | 2篇 |
出版年
2021年 | 174篇 |
2020年 | 110篇 |
2019年 | 124篇 |
2018年 | 140篇 |
2017年 | 144篇 |
2016年 | 229篇 |
2015年 | 362篇 |
2014年 | 470篇 |
2013年 | 605篇 |
2012年 | 646篇 |
2011年 | 645篇 |
2010年 | 433篇 |
2009年 | 334篇 |
2008年 | 511篇 |
2007年 | 576篇 |
2006年 | 506篇 |
2005年 | 519篇 |
2004年 | 489篇 |
2003年 | 436篇 |
2002年 | 474篇 |
2001年 | 411篇 |
2000年 | 404篇 |
1999年 | 343篇 |
1998年 | 177篇 |
1997年 | 154篇 |
1996年 | 151篇 |
1995年 | 130篇 |
1994年 | 149篇 |
1993年 | 131篇 |
1992年 | 247篇 |
1991年 | 242篇 |
1990年 | 244篇 |
1989年 | 221篇 |
1988年 | 226篇 |
1987年 | 244篇 |
1986年 | 185篇 |
1985年 | 208篇 |
1984年 | 187篇 |
1983年 | 180篇 |
1982年 | 146篇 |
1981年 | 135篇 |
1980年 | 126篇 |
1979年 | 179篇 |
1978年 | 170篇 |
1977年 | 129篇 |
1976年 | 132篇 |
1975年 | 138篇 |
1974年 | 146篇 |
1973年 | 124篇 |
1972年 | 149篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
991.
992.
Verjovski-Almeida S Leite LC Dias-Neto E Menck CF Wilson RA 《Trends in parasitology》2004,20(7):304-308
993.
994.
995.
Bogani D Warr N Elms P Davies J Tymowska-Lalanne Z Goldsworthy M Cox RD Keays DA Flint J Wilson V Nolan P Arkell R 《Genesis (New York, N.Y. : 2000)》2004,40(2):109-117
Dominantly acting mutations that produce visible phenotypes are frequently recovered, either during routine maintenance of colonies or from mutagenesis experiments. We have studied 12 dominant mouse mutations that cause a tail dysmorphology, a coat spotting phenotype, or a combination of these. The majority of these mutations act in a semidominant manner with the homozygous state associated with embryonic lethality and a visible phenotype at or before midgestation. The homozygous phenotypes include axis truncation and neural crest cell defects, as may be expected from the heterozygous phenotypes. The majority of mutations, however, also produced other phenotypes that include neural tube closure defects and aberrant heart looping. In one coat spotting mutant the homozygous condition is lethal before neural crest cell production commences. The mutated genes often function in processes additional to those alluded to by the heterozygous phenotype. 相似文献
996.
Early steps in the development of the forebrain 总被引:2,自引:0,他引:2
The tremendous complexity of the adult forebrain makes it a challenging task to elucidate how this structure forms during embryonic development. Nevertheless, we are beginning to understand how a simple epithelial sheet of ectoderm gives rise to the labyrinthine network of cells that constitutes the functional forebrain. Here, we discuss early events in forebrain development--those that lead to the establishment of the anterior neural plate and the regional subdivision of this territory into the different domains of the prospective forebrain. 相似文献
997.
998.
Wilson M 《Current biology : CB》2004,14(16):R666-R667
Do graded potential synapses work the same way as action potential synapses? Recent work emphasizes the differences and suggests that graded potential synapses are not all the same either. 相似文献
999.
1000.
Theoretical interest in the distributions of species abundances observed in ecological communities has focused recently on the results of models that assume all species are identical in their interactions with one another, and rely upon immigration and speciation to promote coexistence. Here we examine a one-trophic level system with generalized species interactions, including species-specific intraspecific and interspecific interaction strengths, and density-independent immigration from a regional species pool. Comparisons between results from numerical integrations and an approximate analytic calculation for random communities demonstrate good agreement, and both approaches yield abundance distributions of nearly arbitrary shape, including bimodality for intermediate immigration rates. 相似文献