首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   104367篇
  免费   20535篇
  国内免费   5755篇
  130657篇
  2024年   179篇
  2023年   1135篇
  2022年   2653篇
  2021年   4699篇
  2020年   4774篇
  2019年   6890篇
  2018年   6890篇
  2017年   6295篇
  2016年   7303篇
  2015年   8899篇
  2014年   9381篇
  2013年   10299篇
  2012年   9201篇
  2011年   7980篇
  2010年   6892篇
  2009年   5259篇
  2008年   4610篇
  2007年   3798篇
  2006年   3302篇
  2005年   2813篇
  2004年   2341篇
  2003年   1991篇
  2002年   1734篇
  2001年   1532篇
  2000年   1455篇
  1999年   1288篇
  1998年   699篇
  1997年   678篇
  1996年   683篇
  1995年   637篇
  1994年   572篇
  1993年   394篇
  1992年   588篇
  1991年   448篇
  1990年   412篇
  1989年   288篇
  1988年   251篇
  1987年   239篇
  1986年   168篇
  1985年   195篇
  1984年   113篇
  1983年   118篇
  1982年   73篇
  1981年   59篇
  1980年   38篇
  1979年   61篇
  1977年   30篇
  1974年   38篇
  1973年   34篇
  1972年   30篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
Five polymorphic microsatellite loci were characterized for Penaeus (Litopenaeus) vannamei. Loci were isolated using a partial Sau3A1 genomic library by the sequencing of randomly selected clones and by a biotinylated (CT)10 and (GT)10 probes screening procedure. The last strategy resulted in the most useful data. About 40% of the clones showed a previously reported satellite/microsatellite (PVS1), reducing the chance of finding new microsatellite regions. Whereas two of the microsatellite loci with more than 10 alleles will be useful for mating analysis in a breeding program, the others might prove useful for population genetic studies.  相似文献   
93.
94.
95.
96.
Ovarian cancer G protein-coupled receptor 1 (OGR1) is a proton-sensing molecule that can detect decreases in extracellular pH that occur during inflammation. Although OGR1 has been shown to have pro-inflammatory functions in various diseases, its role in autoimmunity has not been examined. We therefore sought to determine whether OGR1 has a role in the development of T cell autoimmunity by contrasting the development of experimental autoimmune encephalomyelitis between wild type and OGR1-knockout mice. OGR1-knockout mice showed a drastically attenuated clinical course of disease that was associated with a profound reduction in the expansion of myelin oligodendrocyte glycoprotein 35-55-reactive T helper 1 (Th1) and Th17 cells in the periphery and a reduced accumulation of Th1 and Th17 effectors in the central nervous system. We determined that these impaired T cell responses in OGR1-knockout mice associated with a reduced frequency and number of dendritic cells in draining lymph nodes during EAE and a higher production of nitric oxide by macrophages. Our studies suggest that OGR1 plays a key role in regulating T cell responses during autoimmunity.  相似文献   
97.
The fecundity reduction with aging is referred as the reproductive aging which comes earlier than that of chronological aging. Since humans have postponed their childbearing age, to prolong the reproductive age becomes urgent agenda for reproductive biologists. In the current study, we examined the potential associations of α‐ketoglutarate (α‐KG) and reproductive aging in mammals including mice, swine, and humans. There is a clear tendency of reduced α‐KG level with aging in the follicle fluids of human. To explore the mechanisms, mice were selected as the convenient animal model. It is observed that a long term of α‐KG administration preserves the ovarian function, the quality and quantity of oocytes as well as the telomere maintaining system in mice. α‐KG suppresses ATP synthase and alterations of the energy metabolism trigger the nutritional sensors to down‐regulate mTOR pathway. These events not only benefit the general aging process but also maintain ovarian function and delay the reproductive decline. Considering the safety of the α‐KG as a naturally occurring molecule in energy metabolism, its utility in reproduction of large mammals including humans deserves further investigation.  相似文献   
98.
99.
100.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号