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   5598篇
  免费   748篇
  国内免费   1篇
  6347篇
  2022年   51篇
  2021年   75篇
  2020年   48篇
  2019年   64篇
  2018年   79篇
  2017年   97篇
  2016年   97篇
  2015年   157篇
  2014年   173篇
  2013年   224篇
  2012年   268篇
  2011年   284篇
  2010年   176篇
  2009年   166篇
  2008年   204篇
  2007年   207篇
  2006年   189篇
  2005年   190篇
  2004年   173篇
  2003年   166篇
  2002年   165篇
  2001年   186篇
  2000年   157篇
  1999年   144篇
  1998年   84篇
  1997年   67篇
  1996年   49篇
  1995年   54篇
  1994年   67篇
  1993年   66篇
  1992年   108篇
  1991年   97篇
  1990年   111篇
  1989年   110篇
  1988年   98篇
  1987年   105篇
  1986年   87篇
  1985年   116篇
  1984年   99篇
  1983年   100篇
  1982年   67篇
  1981年   59篇
  1980年   63篇
  1979年   82篇
  1978年   54篇
  1977年   66篇
  1976年   64篇
  1975年   48篇
  1974年   52篇
  1973年   61篇
排序方式: 共有6347条查询结果,搜索用时 7 毫秒
951.
The purpose of the present study was to evaluate olfactory event-related potentials (OERPs) elicited by amyl acetate from subjects performing a visuomotor tracking task compared with the no-task conditions of eyes open and eyes closed. Task condition did not produce any reliable effects for any amplitude measure. Task type weakly influenced only P2 latency. Elder adults evinced smaller P2 and N1/P2 amplitudes and longer N1 and P2 latencies than young adults. The results suggest that tracking task performance is not necessary to obtain robust OERPs from normal subjects of a wide age range.  相似文献   
952.
953.
954.
Contractile activity of neonatal cardiac myocytes stimulated hypertrophic growth as compared with nonbeating cells that were depolarized with 50 mM KCl. Growth of contracting myocytes was associated with an increased rRNA content as measured by the total RNA/DNA ratio. The fractional rates of rRNA synthesis (K8) and rRNA degradation were determined in contracting and nonbeating myocytes to assess their relative contributions in increasing rRNA content during growth. The values for K8 were calculated from the specific radioactivity of 3'-[3H]UMP in 18 and 28 S rRNA after purification by hybridization to cloned rDNA. The cellular [3H]UTP pool served as the precursor for rRNA synthesis in myocytes that were labeled with 50 microM [3H]uridine. K8 values for 18 and 28 S rRNA in contracting myocytes were accelerated by 59 and 53%, respectively, after 3 days as compared with nonbeating myocytes. Calculations of the rate of cellular rRNA synthesis, which took into account the increased content of myocyte rRNA, revealed that synthesis of both 18 and 28 S rRNA was accelerated 2-fold after 2 days of contraction. The derived values for degradation of 18 and 28 S rRNA were increased marginally in contracting myocytes, but cellular rRNA degradation rates averaged 57% higher. The difference between cellular rates of rRNA synthesis and degradation in contracting myocytes accounted for the 30% increase in rRNA content. These data demonstrated that increased rRNA content in contracting myocytes resulted from acceleration of the fractional rate of rRNA synthesis.  相似文献   
955.
956.
In the design of potent and selective sphingosine-1-phosphate receptor agonists, we were able to identify two series of molecules based on phenylamide and phenylimidazole analogs of FTY-720. Several designed molecules in these scaffolds have demonstrated selectivity for S1P receptor subtype 1 versus 3 and excellent in vivo activity in mouse. Two molecules PPI-4621 (4b) and PPI-4691 (10a), demonstrated dose responsive lymphopenia, when administered orally.  相似文献   
957.
958.

Background  

Candidate single nucleotide polymorphisms (SNPs) from genome-wide association studies (GWASs) were often selected for validation based on their functional annotation, which was inadequate and biased. We propose to use the more than 200,000 microarray studies in the Gene Expression Omnibus to systematically prioritize candidate SNPs from GWASs.  相似文献   
959.
960.
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