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   39963篇
  免费   4140篇
  国内免费   11篇
  2023年   175篇
  2022年   348篇
  2021年   670篇
  2020年   486篇
  2019年   566篇
  2018年   701篇
  2017年   631篇
  2016年   1043篇
  2015年   1727篇
  2014年   1881篇
  2013年   2329篇
  2012年   2865篇
  2011年   2783篇
  2010年   1849篇
  2009年   1609篇
  2008年   2246篇
  2007年   2234篇
  2006年   2125篇
  2005年   1894篇
  2004年   1887篇
  2003年   1680篇
  2002年   1650篇
  2001年   654篇
  2000年   611篇
  1999年   623篇
  1998年   432篇
  1997年   352篇
  1996年   339篇
  1995年   350篇
  1994年   309篇
  1993年   305篇
  1992年   414篇
  1991年   355篇
  1990年   349篇
  1989年   363篇
  1988年   364篇
  1987年   334篇
  1986年   268篇
  1985年   298篇
  1984年   303篇
  1983年   269篇
  1982年   257篇
  1981年   231篇
  1980年   209篇
  1979年   215篇
  1978年   181篇
  1977年   183篇
  1976年   182篇
  1975年   198篇
  1973年   164篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
  1. Download : Download high-res image (63KB)
  2. Download : Download full-size image
Highlights
  • •MS-based clinical assay that accurately determines phospho Rab10 occupancy.
  • •Stable isotope labeled phosphopeptide injected as a standard with endogenous tryptic phospho Rab peptide for accurate ratio determination.
  • •Determination of pRab levels in neutrophils of Parkinson disease patients.
  • •Relevance of pRab levels as marker of PD.
  相似文献   
73.
74.
The low-molecular-mass form of two distinct catechol O-methyltransferase activities (S-adenosyl-L-methionine: catechol O-methyltransferase, COMT, EC 2.1.1.6) has been purified to homogeneity from rat liver using 40-70% ammonium sulfate precipitation, gel filtration on Sephadex G-100, adsorption on hydroxyapatite C and ion-exchange chromatography on DEAE-Sepharose CL-6B. The relative molecular mass Mr, determined by sodium dodecyl sulfate/polyacrylamide gel electrophoresis is 22 400 +/- 500. Irradiation of the enzyme in the presence of 8-azido-[methyl-3H]AdoMet results in the specific labeling of the catalytic site of the enzyme. Photolabeling was successful with crude COMT preparations and with the isolated enzyme. Immunocytochemical studies present new information about the localization of the low-molecular-mass form in the liver parenchyma. Subcellularly COMT immunoreactivity could be attributed exclusively to the compartment with glycogen granules. Nucleus, mitochondria and endoplasmic reticulum showed no immunostaining.  相似文献   
75.
Data from eight published studies were combined to show that the influence of traffic density on Pb contents in roadside soils increases with proximity to the road.  相似文献   
76.
77.
78.
Analysis of the flight behaviour of siskins (Carduelis spinus) was made possible by tethering them with a harness to a flight balance in a wind tunnel. It could be shown that the breast feathers work as an air-current sense organ influencing the siskins' flight pattern and the aerodynamic parameters.  相似文献   
79.
80.
The aim of this study was to examine the concurrent validity of the Kinexon local positioning system (LPS) in comparison with the Vicon motion capture system used as the reference. Five recreationally active men performed ten repetitions of linear sprints, medio-lateral side-to-side and handball-specific movements both in the centre and on the side of an indoor field. Validity was assessed for peak speed, peak acceleration and peak deceleration using standardised biases, Pearson coefficient of correlation (r), and standardised typical error of the estimate. With the exception of peak decelerations during specific movements in the centre and peak acceleration and deceleration during linear sprints on the side of the field, the standardised typical error of the estimate (TEE) values were all small to moderate (0.06–0.48), standardised bias ranged between 0.01 and 2.85 and Pearson coefficient values were all > 0.90 for all variables in all conditions. Peak acceleration and deceleration during linear sprints on the side of the field showed the largest TEEs and the greatest differences between the two systems. The ultra-wideband based (UWB) local positioning system had acceptable validity compared with Vicon to assess players’ movements in handball with the exception of high accelerations and decelerations during linear sprints on the side of the field.  相似文献   
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