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   71345篇
  免费   2122篇
  国内免费   30篇
  2020年   604篇
  2019年   762篇
  2018年   4254篇
  2017年   3590篇
  2016年   3174篇
  2015年   935篇
  2014年   994篇
  2013年   4664篇
  2012年   2193篇
  2011年   4039篇
  2010年   3414篇
  2009年   2443篇
  2008年   3216篇
  2007年   3596篇
  2006年   1458篇
  2005年   1512篇
  2004年   1427篇
  2003年   1262篇
  2002年   1254篇
  2001年   1785篇
  2000年   1700篇
  1999年   1278篇
  1998年   690篇
  1997年   589篇
  1996年   535篇
  1995年   522篇
  1994年   504篇
  1993年   527篇
  1992年   1020篇
  1991年   957篇
  1990年   949篇
  1989年   852篇
  1988年   815篇
  1987年   804篇
  1986年   809篇
  1985年   860篇
  1984年   674篇
  1983年   581篇
  1982年   472篇
  1979年   656篇
  1978年   489篇
  1976年   448篇
  1975年   589篇
  1974年   622篇
  1973年   594篇
  1972年   539篇
  1971年   474篇
  1968年   539篇
  1967年   541篇
  1966年   475篇
排序方式: 共有10000条查询结果,搜索用时 343 毫秒
871.
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   
872.
873.
874.
875.
876.
877.
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   
878.
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   
879.
6 adult subjects (3 men, 3 women) produced highly similar spontaneous speech utterances in quiet and with 90-dB SPL white noise. The frequency of occurrence of perceptual judgments of primary stressing in an utterance was not affected by the masking noise. This finding supplements our previous report that variability for stress production of fundamental frequency (fo) during spontaneous speech was preserved under short-term auditory disruption. Also, it adds further support to the contention that fo is under open-loop regulation.  相似文献   
880.
Children's perception of parental exercise: influence of sex and age   总被引:1,自引:0,他引:1  
The purpose of the study was to document children's perception of parental exercise, relating these perceptions to (1) the self-reported parents' habits of exercise, and (2) the children's own activity patterns. The subjects were 198 students of both sexes, aged 12 to 14 yr. and enrolled in school Grades 7 to 9. A standard questionnaire assessed their perceptions of parental and personal physical activity. Both parents of each subject also reported their respective levels of habitual physical activity. Congruence between the children's perceptions and the self-reported exercise habits of the opposite-sex parent differed for boys and girls, increasing for boys and decreasing for girls between Grades 7 and 9. No significant associations were observed between the children's perception of parental exercise patterns and their own like habits. This suggests that during adolescence parental influences are minimized by other factors, personal or environmental.  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