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   75070篇
  免费   2274篇
  国内免费   32篇
  2020年   647篇
  2019年   803篇
  2018年   4255篇
  2017年   3603篇
  2016年   3197篇
  2015年   977篇
  2014年   1076篇
  2013年   5076篇
  2012年   2261篇
  2011年   4114篇
  2010年   3425篇
  2009年   2515篇
  2008年   3269篇
  2007年   3658篇
  2006年   1557篇
  2005年   1596篇
  2004年   1535篇
  2003年   1375篇
  2002年   1382篇
  2001年   1848篇
  2000年   1748篇
  1999年   1337篇
  1998年   759篇
  1997年   682篇
  1996年   588篇
  1995年   581篇
  1994年   563篇
  1993年   601篇
  1992年   1088篇
  1991年   1011篇
  1990年   1002篇
  1989年   912篇
  1988年   872篇
  1987年   872篇
  1986年   859篇
  1985年   905篇
  1984年   739篇
  1983年   643篇
  1982年   549篇
  1980年   509篇
  1979年   721篇
  1978年   580篇
  1976年   523篇
  1975年   679篇
  1974年   695篇
  1973年   646篇
  1972年   588篇
  1971年   523篇
  1968年   570篇
  1967年   567篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
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   
952.
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   
953.
954.
955.
956.
957.
958.
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   
959.
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   
960.
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   
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