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   62206篇
  免费   2526篇
  国内免费   20篇
  2020年   631篇
  2019年   788篇
  2018年   1096篇
  2017年   1131篇
  2016年   1187篇
  2015年   872篇
  2014年   1015篇
  2013年   4681篇
  2012年   1903篇
  2011年   2030篇
  2010年   1272篇
  2009年   1256篇
  2008年   1804篇
  2007年   1823篇
  2006年   1627篇
  2005年   1440篇
  2004年   1330篇
  2003年   1242篇
  2002年   1349篇
  2001年   2017篇
  2000年   1994篇
  1999年   1501篇
  1998年   709篇
  1997年   624篇
  1996年   624篇
  1993年   562篇
  1992年   1260篇
  1991年   1159篇
  1990年   1154篇
  1989年   1057篇
  1988年   1023篇
  1987年   998篇
  1986年   1063篇
  1985年   1077篇
  1984年   897篇
  1983年   821篇
  1982年   579篇
  1981年   575篇
  1979年   953篇
  1978年   682篇
  1975年   786篇
  1974年   842篇
  1973年   927篇
  1972年   793篇
  1971年   740篇
  1970年   667篇
  1969年   681篇
  1968年   874篇
  1967年   788篇
  1966年   666篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
972.
A classifier based on the linear regression model was developed to automatically detect sharp transients in EEG, matching the definition of spikes and sharp waves accepted by IFSECN. Practical applications proved the accuracy of the method which succeeded in detecting 84% of sharp transients previously found by an experienced electronencephalographer. Computerized search for sharp transients in EEG records will be particularly useful in long term EEG records obtained from epileptic patients.  相似文献   
973.
The results of an evaluation of the perfusion scintigraphy findings of 350 hospitalised neurological patients and 55 more strictly selected neurosurgical patients with cerebrovascular complaints, revealed an accuraty of 83%, a sensitivity of 89%, and a specificity of 83%. The selection of the patients had no influence on the results as a whole. Compared with contrast-medium angiography, incorrect diagnosis must be expected in 17% of the cases. This includes erroneous negative findings in 10% of the cases. Grounds for misinterpretations are suggested, and the biological and methodological limitations of the method are set forth.  相似文献   
974.
The paper is concerned with an attempt to generalize and categorize current hypotheses on the biochemical basis of ECT. The hypotheses are critically evaluated with respect to the relevance of their experimental fundamentals. Thus, certain hypotheses are valid only in a qualified sense. Particular interest is focussed on those conceptions which try to correlate ECT-induced changes in synaptic receptor sensitivities (up-/down-regulation) with super- resp. subsensitivity hypotheses of psychoses. In this connection, noradrenergic and opioid systems on the one hand, and the axis hypothalamus-hypophysis on the other hand seem to play a dominant role.  相似文献   
975.
The paper investigates 54 myelograms and their influence on diagnostic thinking efficacy, on patient management efficacy, and on ultimate outcome efficacy, using statistical methods. Conventional myelography contributes to diagnostic thinking efficacy having a LLR- value of approximately 0.9. With an accuracy value of 0.95 it can be regarded as a reliable method of diagnosis. It alters diagnostic thinking efficacy in no less than 83% (94%) of the cases and patients management efficacy in 89%. Thus, by definition, myelography may be said to affect the state of health of the myelographed patients in 94.4%.  相似文献   
976.
The use of computer based diagnostic decision and artificial intelligence are discussed in relation to the problems of validity and reliability of psychiatric diagnoses. The authors suggest a definition of a computer aided classificator as an existent decision system for an automatically analysis of findings.  相似文献   
977.
This article attempts to apply a theory of aggression as motivation to overcome obstacles to the understanding of phobic states and their formation. The role of aggression in the genesis of phobic conditions is discussed, and the traditional analytic view of aggression as instinctual drive is contrasted with a motivational approach. The motivational view offers the advantage of a clearer understanding of the stimulus contexts, representational connections, and both real and imaginary object connections that are lacking in the more traditional understanding of aggression as a biological drive.  相似文献   
978.
Four of our own cases that presented a clinical picture of dementia are discussed. A study of the relative literature has failed to reveal any "swing" in the pattern of the clinical condition: Just as it did ninety years age, paralytic dementia accounts today for well over 60% of all cases, those clinical pictures erroneously regarded as "typical" "classic", accounting for a mere 10%-15% of cases. The need for routine lues serology is pointed out.  相似文献   
979.
An investigation into the diagnostic value of psychometric methods for the diagnosis of depressive states involved five psychometric questionnaires, one concentration test procedure, and one problem-solving approach to register cognitive processes. The data obtained for 80 depressive patients of varied aetiology were compared with those of sample of 80 neurotics without depressive aberration. Even univariate comparisons revealed statistically significant differences between the two samples. Multivariate methods (factor analysis, discriminative analysis) yielded more differentiated information. The "Scale for depression depth measurements" was found to be of particular diagnostic relevance; it was standardized for the time being.  相似文献   
980.
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