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   3354415篇
  免费   253830篇
  国内免费   5945篇
耳鼻咽喉   49625篇
儿科学   106870篇
妇产科学   92775篇
基础医学   478226篇
口腔科学   97071篇
临床医学   300338篇
内科学   648058篇
皮肤病学   70043篇
神经病学   278105篇
特种医学   134105篇
外国民族医学   1184篇
外科学   508935篇
综合类   75006篇
现状与发展   2篇
一般理论   1242篇
预防医学   262080篇
眼科学   79273篇
药学   251871篇
  61篇
中国医学   6312篇
肿瘤学   173008篇
  2018年   34390篇
  2017年   26538篇
  2016年   29874篇
  2015年   33569篇
  2014年   46981篇
  2013年   71976篇
  2012年   97671篇
  2011年   103274篇
  2010年   60712篇
  2009年   57268篇
  2008年   98491篇
  2007年   105657篇
  2006年   106616篇
  2005年   104434篇
  2004年   100558篇
  2003年   97381篇
  2002年   96051篇
  2001年   150034篇
  2000年   155107篇
  1999年   131146篇
  1998年   38413篇
  1997年   34526篇
  1996年   34256篇
  1995年   32883篇
  1994年   30937篇
  1993年   28769篇
  1992年   104827篇
  1991年   101977篇
  1990年   99240篇
  1989年   95914篇
  1988年   89037篇
  1987年   87595篇
  1986年   83242篇
  1985年   79821篇
  1984年   60391篇
  1983年   51670篇
  1982年   31442篇
  1981年   27968篇
  1979年   57082篇
  1978年   40362篇
  1977年   34226篇
  1976年   32353篇
  1975年   34680篇
  1974年   42089篇
  1973年   40110篇
  1972年   37914篇
  1971年   35097篇
  1970年   32962篇
  1969年   30943篇
  1968年   28693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