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   3226260篇
  免费   248469篇
  国内免费   5626篇
耳鼻咽喉   47231篇
儿科学   102491篇
妇产科学   89428篇
基础医学   459331篇
口腔科学   92875篇
临床医学   289314篇
内科学   626204篇
皮肤病学   66667篇
神经病学   265234篇
特种医学   128155篇
外国民族医学   1170篇
外科学   489788篇
综合类   74136篇
现状与发展   2篇
一般理论   1195篇
预防医学   255015篇
眼科学   75915篇
药学   242872篇
  5篇
中国医学   6005篇
肿瘤学   167322篇
  2018年   31990篇
  2016年   27204篇
  2015年   30914篇
  2014年   44080篇
  2013年   67447篇
  2012年   91321篇
  2011年   96791篇
  2010年   56962篇
  2009年   54332篇
  2008年   92254篇
  2007年   98971篇
  2006年   100116篇
  2005年   97747篇
  2004年   94249篇
  2003年   90930篇
  2002年   89976篇
  2001年   146224篇
  2000年   151103篇
  1999年   128026篇
  1998年   37275篇
  1997年   33582篇
  1996年   33518篇
  1995年   32282篇
  1994年   30364篇
  1993年   28242篇
  1992年   103587篇
  1991年   100792篇
  1990年   98087篇
  1989年   94786篇
  1988年   88083篇
  1987年   86654篇
  1986年   82333篇
  1985年   78836篇
  1984年   59598篇
  1983年   51044篇
  1982年   30952篇
  1981年   27527篇
  1980年   25802篇
  1979年   56259篇
  1978年   39771篇
  1977年   33684篇
  1976年   31852篇
  1975年   34046篇
  1974年   41421篇
  1973年   39471篇
  1972年   37305篇
  1971年   34547篇
  1970年   32440篇
  1969年   30446篇
  1968年   28186篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Chronic obstructive pulmonary disease (COPD) is characterised by a local pulmonary inflammatory response to respiratory pollutants and by systemic inflammation. Tumour necrosis factor (TNF)-alpha has been implicated in systemic effects of COPD and operates by binding the p55 (R1) and p75 (R2) TNF-alpha receptors. To investigate the contribution of each TNF-alpha receptor in the pathogenesis of COPD, the present study examined the effects of chronic air or cigarette smoke (CS) exposure in TNF-alpha R1 knockout (KO) mice, TNF-alpha R2 KO mice and wild type (WT) mice. CS was found to significantly increase the protein levels of soluble TNF-alpha R1 (by four-fold) and TNF-alpha R2 (by 10-fold) in the bronchoalveolar lavage of WT mice. After 3 months, CS induced a prominent pulmonary inflammatory cell influx in WT and TNF-alpha R1 KO mice. In TNF-alpha R2 KO mice, CS-induced pulmonary inflammation was clearly attenuated. After 6 months, no emphysema was observed in CS-exposed TNF-alpha R2 KO mice in contrast to WT and TNF-alpha R1 KO mice. CS-exposed WT and TNF-alpha R1 KO mice failed to gain weight, whereas the body mass of TNF-alpha R2 KO mice was not affected. These current findings suggest that both tumour necrosis factor-alpha receptors contribute to the pathogenesis of chronic obstructive pulmonary disease, but tumour necrosis factor-alpha receptor-2 is the most active receptor in the development of inflammation, emphysema and systemic weight loss in this murine model of chronic obstructive pulmonary disease.  相似文献   
32.
33.
34.
Low molecular weight heparins are widely used in the prophylaxis and treatment of thrombotic disorders. The effect of low molecular weight heparins on coagulation was examined ultrastructurally in an animal model. A test and a control group was formed, each consisting of five rabbits. Nadroparine (225 Institute of Chaoy Unit/kg twice daily) was applied to the test group for 10 days. The control group received 1 ml saline solution subcutaneously. Blood and vascular tissue samples collected at the end of the 10th day were evaluated under a JEM 100 B electron microscope. Platelet degranulation and agglutination was observed in the control group. Fibrin materials were detected in the cytoplasms and surroundings of degranulated platelets. Erythrocyte accumulation was remarkable on the vascular endothelium with intact coagulation periods. In the test group, outer membranes of platelets, hyalomere, and granular structures in the granulomeres were detected to be nearly intact. There were rare erythrocytes in the large vascular lumens. The aggregation phase had occurred but no agglutination was detected. Nadroparine seems to preserve consistency of lipoprotein membranes of platelets and granular structures containing enzymes, which contribute to the coagulation mechanisms.  相似文献   
35.
Summary: A female patient with isovaleric acidaemia had a successful outcome from pregnancy.  相似文献   
36.
37.
38.
39.
40.
Vitiligo and psoriasis are both common skin disorders. However, psoriasis strictly confined to pre-existing vitiligo areas is rare and suggests a causal relationship. We report here on two patients with a strict anatomical colocalization of vitiligo and psoriasis. The histopathological examinations showed typical changes for both diseases together with a dense infiltrate of CD4+ and CD8+ T cells. By immunohistochemistry, intracytoplasmatic granzyme B and tumour necrosis factor alpha (TNF-alpha) were detected within the T-cell population, suggesting the functional activity of these cells and the creation of a local T helper 1 (Th1)-cytokine milieu. Additionally, in one patient we could identify anti-melanocytic T cells by tetramer staining and enzyme-linked immunospot (ELISPOT) analysis. These skin-infiltrating lymphocytes might trigger, by the local production of Th-1 cytokines such as TNF-alpha and interferon-gamma (IFN-gamma), the eruption of psoriatic plaques in patients with a genetic predisposition for psoriasis.  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