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   53401篇
  免费   2152篇
  国内免费   31篇
  2020年   619篇
  2019年   786篇
  2018年   1136篇
  2017年   1103篇
  2016年   1155篇
  2015年   773篇
  2014年   959篇
  2013年   4672篇
  2012年   1703篇
  2011年   1874篇
  2010年   1082篇
  2009年   1097篇
  2008年   1679篇
  2007年   1665篇
  2006年   1460篇
  2005年   1320篇
  2004年   1302篇
  2003年   1166篇
  2002年   1204篇
  2001年   1771篇
  2000年   1667篇
  1999年   1285篇
  1998年   681篇
  1997年   578篇
  1996年   529篇
  1995年   530篇
  1994年   505篇
  1993年   525篇
  1992年   1017篇
  1991年   962篇
  1990年   947篇
  1989年   859篇
  1988年   826篇
  1987年   811篇
  1986年   813篇
  1985年   863篇
  1984年   678篇
  1983年   584篇
  1982年   478篇
  1979年   666篇
  1978年   493篇
  1976年   456篇
  1975年   597篇
  1974年   629篇
  1973年   610篇
  1972年   548篇
  1971年   483篇
  1968年   546篇
  1967年   545篇
  1966年   480篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
871.
Twenty six clinically healthy smokers were studied with transient pattern visual-evoked potentials. In comparison with a sample of "normal" subjects we found a difference of some parameters (P less than 0.05): the P2-latency and the interocular difference of latency on average were 6-7 ms respectively 2 ms larger. Thirteen subjects have had a prolonged P2-latency (P less than 0.05) and/or a difference in interocular latencies larger than 5 ms. These findings may suggest on subclinical disturbances of visual system and indicators of an special sensitivity of that person. The findings are possibly related to tobacco-alcohol amblyopia.  相似文献   
872.
The dipeptidyl-peptidase activity of 650 liquores cerebrospinalis was obtained by means of the substrate Gly-Pro-NHNp (Gly-Pro-4-nitroanilid) at pHs of 5.5 and 7.4. In comparison with a reference collective, the suitability of the method as a supplementary liquor parameter in neurological psychiatric diagnosis was examined. The introduction of the measurement at pH 7.4 can be particularly recommended for the distinguishing of bacterial and nonbacterial meningitis.  相似文献   
873.
874.
875.
On the occasion ofPsychometrika's fiftieth anniversary, the past twenty-five years' developments in mental test theory are reviewed, with special emphasis on the topics receiving attention in the pages of this journal. (Analogous reviews forPsychometrika's first quarter century were given by Gulliksen and Guilford in 1961.) Much of the recent progress in test theory (and in other branches of psychometrics as well) has been made by treating the problems in this field as being essentially ones of statistical inference. It is concluded that (a) research in test theory is in a healthy state and (b)Psychometrika is an important source of information about that research.  相似文献   
876.
877.
878.
879.
Taste sensitivity for sodium chloride in solution and sensitivity and preference for sodium chloride in bread were measured in 14 male patients undergoing hemodialysis. There was an increase in sensitivity to salt taste following dialysis only when assessed using the bread samples. Patients on a lower sodium diet were more sensitive to salt taste in bread. Although the taste changes were not related to the decreases in serum sodium or to copper, greater increases in sensitivity were related to greater increases in serum zinc during dialysis.  相似文献   
880.
For 40 males who smoked 20 cigarettes a day titratable acidity of the urine was significantly correlated with nicotine/cotinine excretion at several sample intervals, as was urinary pH, but not urinary acidity and daily cigarette consumption or serum COHB.  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