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   26081篇
  免费   2257篇
  国内免费   2012篇
  2024年   104篇
  2023年   647篇
  2022年   753篇
  2021年   1084篇
  2020年   1191篇
  2019年   1347篇
  2018年   1108篇
  2017年   1003篇
  2016年   1025篇
  2015年   1297篇
  2014年   1554篇
  2013年   2296篇
  2012年   1108篇
  2011年   1288篇
  2010年   918篇
  2009年   1402篇
  2008年   1467篇
  2007年   1424篇
  2006年   1291篇
  2005年   1033篇
  2004年   972篇
  2003年   826篇
  2002年   667篇
  2001年   550篇
  2000年   470篇
  1999年   429篇
  1998年   414篇
  1997年   410篇
  1996年   315篇
  1995年   258篇
  1994年   227篇
  1993年   218篇
  1992年   193篇
  1991年   160篇
  1990年   148篇
  1989年   116篇
  1988年   110篇
  1987年   89篇
  1986年   74篇
  1985年   82篇
  1984年   54篇
  1983年   37篇
  1982年   58篇
  1981年   45篇
  1980年   31篇
  1979年   20篇
  1978年   12篇
  1977年   7篇
  1976年   5篇
  1975年   4篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
ABSTRACT   The phrase persistent vulnerability reflects the enduring relationship of the rural population in Ceará with a highly variable climate. Persistence underscores the historical and unyielding nature of this vulnerability. Yet contrary to once-catastrophic rates of mortality etched in a public consciousness, no one dies from severe droughts and few people flee them as in the past. Government relief and social transfers have become the institutionalized form of adaptation, giving way to the counterintuitive reality that drought stabilizes the food and income supply for poor people. We analyze how maladaptive risk reduction, which is embedded in clientilistic social relations, undermines resilience, and we examine pathways toward a more sustainable adaptive relationship.  相似文献   
2.
  1. Download : Download high-res image (133KB)
  2. Download : Download full-size image
Highlights
  • •Flow cytometry analysis is used to isolate ASC speck(+) NPC cells.
  • •Proteome analysis of ASC speck(+) NPC cells reveals enriched mitochondrial OxPhos proteins.
  • •OxPhos proteins mediate NLRP3 inflammasome activation through mtROS.
  • •OxPhos proteins, NDUFB8 and ATP5B are correlated with NPC local recurrence.
  相似文献   
3.
Heat stress reduces maize yield and several lines of evidence suggest that the heat lability of maize endosperm ADP-glucose pyrophosphorylase (AGPase) contributes to this yield loss. AGPase catalyzes a rate-limiting step in starch synthesis. Herein, we present a novel maize endosperm AGPase small subunit variant, termed BT2-TI that harbors a single amino acid change of residue 462 from threonine to isoleucine. The mutant was isolated by random mutagenesis and heterologous expression in a bacterial system. BT2-TI exhibits enhanced heat stability compared to wildtype maize endosperm AGPase.The TI mutation was placed into another heat-stable small subunit variant, MP. MP is composed of sequences from the maize endosperm and the potato tuber small subunit. The MP-TI small subunit variant exhibited greater heat stability than did MP. Characterization of heat stability as well as kinetic and allosteric properties suggests that MP-TI may lead to increased starch yield when expressed in monocot endosperms.  相似文献   
4.
To study bacterial behavior under varying hydration conditions similar to surface soil, we have developed a system called the Pressurized Porous Surface Model (PPSM). Thin liquid films created by imposing a matric potential of − 0.4 MPa impact gene expression and colony development in Pseudomonas putida.  相似文献   
5.
Summary A temperature shift-up accompanied by a reduction in RNA polymerase activity in Escherichia coli causes an increased rate of initiation leading to a 1.7- to 2.2-fold increase in chromosome copy number. A temperature shift-up without a reduction in polymerase activity induces only a transient non-scheduled initiation of chromosome replication caused by heat shock with no detectable effect on chromosome copy number.  相似文献   
6.
7.
Cells employ pro-survival and pro-adaptive pathways to cope with different forms of environmental stress. When stress is excessive, and the damage caused by it is unsustainable, cells engage pro-death pathways, which are in place to protect the host from the deleterious effects of harmed cells. Two important pathways that determine the balance between survival and death of stressed cells are the integrated stress response (ISR) and the mammalian target of rapamycin (mTOR), both of which converge at the level of mRNA translation. The two pathways have established avenues of communication to control their activity and determine the fate of stressed cells in a context-dependent manner. The functional interplay between the ISR and mTOR may have significant ramifications in the development and treatment of human diseases such as diabetes, neurodegeneration and cancer.  相似文献   
8.
9.
10.
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