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   85568篇
  免费   8067篇
  国内免费   47篇
  93682篇
  2022年   577篇
  2021年   1247篇
  2020年   735篇
  2019年   967篇
  2018年   1159篇
  2017年   1070篇
  2016年   1744篇
  2015年   2837篇
  2014年   3178篇
  2013年   4184篇
  2012年   5207篇
  2011年   5303篇
  2010年   3397篇
  2009年   3096篇
  2008年   4517篇
  2007年   4675篇
  2006年   4511篇
  2005年   4468篇
  2004年   4278篇
  2003年   4140篇
  2002年   3967篇
  2001年   1043篇
  2000年   765篇
  1999年   1064篇
  1998年   1223篇
  1997年   898篇
  1996年   839篇
  1995年   729篇
  1994年   752篇
  1993年   757篇
  1992年   809篇
  1991年   728篇
  1990年   714篇
  1989年   664篇
  1988年   654篇
  1987年   615篇
  1986年   629篇
  1985年   717篇
  1984年   863篇
  1983年   702篇
  1982年   866篇
  1981年   938篇
  1980年   816篇
  1979年   603篇
  1978年   618篇
  1977年   581篇
  1976年   616篇
  1975年   414篇
  1974年   522篇
  1973年   485篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
In vivo EMG biofeedback was found to be an effective pedagogical tool for removing unwanted left-hand tension in nine violin and viola players. Improvement occurred rapidly and persisted throughout a 5-month follow-up period. Further studies will be necessary to assess the effect of biofeedback independent of placebo effects. The brevity of the method and the magnitude of improvement warrant further investigation.  相似文献   
2.
The effects of 5-methoxy-N, N-dimethyltryptamine (5-MeODMT), a serotonin agonist with a preferential action on presynaptic autoreceptors, on prolactin release in male rats was determined. Basal serum prolactin levels were not altered after administration of 1.0, 2.0, 5.0, 10.0 or 20.0 mg/kg of 5-MeODMT.Pretreatment with 5-MeODMT reduced prolactin release by agents that depend on serotonergic neurotransmission for part of their prolactin release stimulation. Prolactin release in response to L-5-hydroxytryptophan (5-HTP) or morphine was significantly reduced by pretreatment of the rats with 5-MeODMT.The results of this experiment indicate that 5-MeODMT act as a presynaptic serotonin autoreceptor stimulant and not as a postsynaptic serotonin agonist on the neuronal systems that control prolactin release.  相似文献   
3.
The ability to metabolically label proteins with 35S-methionine is critical for the analysis of protein synthesis and turnover. Despite the importance of this approach, however, efficient labeling of proteins in vivo is often limited by a low number of available methionine residues, or by deleterious side-effects associated with protein overexpression. To overcome these limitations, we have created a methionine-rich variant of the widely used HA tag, called HAM, for use with ectopically expressed proteins. Here we describe the development of a series of vectors, and corresponding antisera, for the expression and detection of HAM-tagged proteins in mammalian cells. We show that the HAM tag dramatically improves the sensitivity of 35S-methionine labeling, and permits the analysis of Myc oncoprotein turnover even when HAM-tagged Myc is expressed at levels comparable to that of the endogenous protein. Because of the improved sensitivity provided by the HAM tag, the vectors and antisera described here should be useful for the analysis of protein synthesis and destruction at physiological levels of protein expression.  相似文献   
4.
Puerto Rican populations of two species of sea anemones (Bunodosoma cavernata and B. granulifera) which had previously been considered one were assayed electrophoretically for enzymes encoded by 12 loci. The two species shared no common allozymes at 6 of the 12 loci. Genetic distance and identity values based on these allozymes were computed for the Puerto Rican populations and for B. cavernata from Florida and B. granulifera from Panama. The Puerto Rican populations of both species had much higher genetic identities for their geographically distant conspecifics than for each other. These results indicate that the two species are reproductively isolated and should be considered as separate valid species. Average heterozygosities are presented which are the first published for coelenterate species.  相似文献   
5.
6.
7.
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