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   1711997篇
  免费   124616篇
  国内免费   3867篇
耳鼻咽喉   21852篇
儿科学   55932篇
妇产科学   46466篇
基础医学   243981篇
口腔科学   49111篇
临床医学   152669篇
内科学   336420篇
皮肤病学   39312篇
神经病学   133017篇
特种医学   65043篇
外国民族医学   242篇
外科学   259336篇
综合类   39019篇
现状与发展   4篇
一般理论   537篇
预防医学   124901篇
眼科学   40508篇
药学   125247篇
  7篇
中国医学   4498篇
肿瘤学   102378篇
  2021年   12977篇
  2019年   13728篇
  2018年   20182篇
  2017年   15428篇
  2016年   16911篇
  2015年   19331篇
  2014年   26665篇
  2013年   38527篇
  2012年   53609篇
  2011年   56441篇
  2010年   33416篇
  2009年   31333篇
  2008年   52560篇
  2007年   55916篇
  2006年   56322篇
  2005年   53595篇
  2004年   51779篇
  2003年   49242篇
  2002年   47450篇
  2001年   91995篇
  2000年   93752篇
  1999年   77193篇
  1998年   20005篇
  1997年   17513篇
  1996年   17605篇
  1995年   16928篇
  1994年   15459篇
  1993年   14240篇
  1992年   57498篇
  1991年   55374篇
  1990年   53060篇
  1989年   50843篇
  1988年   46239篇
  1987年   45022篇
  1986年   42299篇
  1985年   40059篇
  1984年   29440篇
  1983年   24993篇
  1982年   13991篇
  1979年   25582篇
  1978年   17632篇
  1977年   14982篇
  1976年   13932篇
  1975年   14619篇
  1974年   17693篇
  1973年   16987篇
  1972年   15706篇
  1971年   14491篇
  1970年   13462篇
  1969年   12549篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
971.
Although England/Wales, Italy, and the United States share a common policy of deinstitutionalization, their mental health systems differ considerably. Each country's civil commitment standards define patient eligibility criteria along one of two primary dimensions--need for treatment or degree of dangerousness. These differential selection criteria result in mental health systems serving different subgroups of the total population. The criteria in England/Wales target older women; in the United States, younger men; and in Italy, a group balanced in age and sex. Implications for the current debate on civil commitment policies are considered.  相似文献   
972.
973.
974.
975.
Site-directed mutagenesis of the vaccinia virus gene encoding a type I DNA topoisomerase implicates Tyr-274 as the active-site residue that forms a covalent adduct with DNA during cycles of DNA-strand breakage and reunion. Replacement of Tyr-274 by phenylalanine results in loss of the ability of the enzyme to relax negatively supercoiled DNA as well as to form the covalent DNA-protein intermediate. Substitution of phenylalanine for tyrosine at nine other sites in the protein has no apparent effect on enzyme activity. Amino acid sequence alignment reveals Tyr-274 to be homologous to Tyr-727 and Tyr-771, respectively, of the type I topoisomerases from Saccharomyces cerevisiae and Saccharomyces pombe; Tyr-727 and Tyr-771 have been shown to represent the active-site tyrosines of those enzymes. Sequence comparison of the active-site regions defines a motif Ser-Lys-Xaa-Xaa-Tyr common to the viral and cellular type I topoisomerases, including the human enzyme.  相似文献   
976.
S Bilancini  M Lucchi 《Phlébologie》1989,42(1):151-156
The subject of enlarged legs is vast and complex. Up to now there has been no organic classification of the clinical picture involved. The basic problem is that of the criterion on which to base the classification. Literature on this subject has opted for the pathogenic criterion because it seems to facilitate the formulation of a classification which is of use to the doctor. One possibility would be to divide the syndrome into vascular and non-vascular swollen legs. The first group could in turn be separated into macro-circulating and micro-circulatory. The micro-circulatory forms can be primitive or secondary. Amongst the secondary micro-circulatory forms, two other groups can be singled out: secondary forms with local cause and secondary forms caused by organic pathology. However, there are clinical forms which are on the periphery of these different groups and these forms are subject to discussion regarding nosographic localization.  相似文献   
977.
A case of Bonnet syndrome associated with blindness due to bilateral eye disease and a posterior parasagittal meningioma is reported. It is assumed that visual afferent deprivation alone is not enough to produce the syndrome and that, in most instances, a 'cerebral factor' must be operative if hallucinoses are to occur. The distinction between hallucinosis and hallucinations is favored and a common neural circuit for the mediation of hallucinotic imageries in general is suggested. One should not immediately put the blame on obvious eye or visual pathways affections when facing cases of Bonnet syndrome, as they are not likely to explain the complex array of images perceived by any given patient. On the contrary, the possibility of a clinically covert intracranial disease should be always raised and intensively looked for.  相似文献   
978.
Dawn and dusk simulation as a therapeutic intervention   总被引:1,自引:0,他引:1  
  相似文献   
979.
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