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   1488923篇
  免费   129477篇
  国内免费   6420篇
耳鼻咽喉   21525篇
儿科学   48935篇
妇产科学   38953篇
基础医学   203576篇
口腔科学   37647篇
临床医学   156324篇
内科学   303258篇
皮肤病学   33684篇
神经病学   126734篇
特种医学   54419篇
外国民族医学   366篇
外科学   222637篇
综合类   29625篇
现状与发展   73篇
一般理论   506篇
预防医学   122833篇
眼科学   32363篇
药学   101094篇
  6篇
中国医学   3218篇
肿瘤学   87044篇
  2021年   14028篇
  2020年   12404篇
  2019年   13979篇
  2018年   23327篇
  2017年   19143篇
  2016年   21014篇
  2015年   22940篇
  2014年   35276篇
  2013年   46843篇
  2012年   50322篇
  2011年   53121篇
  2010年   37120篇
  2009年   38323篇
  2008年   48932篇
  2007年   49745篇
  2006年   52088篇
  2005年   47937篇
  2004年   45207篇
  2003年   42108篇
  2002年   40962篇
  2001年   64600篇
  2000年   65613篇
  1999年   55502篇
  1998年   18072篇
  1997年   16475篇
  1996年   16239篇
  1995年   15431篇
  1994年   13501篇
  1993年   12417篇
  1992年   43010篇
  1991年   42274篇
  1990年   40582篇
  1989年   38609篇
  1988年   35662篇
  1987年   34657篇
  1986年   33123篇
  1985年   31455篇
  1984年   23725篇
  1983年   20194篇
  1982年   12349篇
  1979年   21222篇
  1978年   15214篇
  1977年   12509篇
  1976年   12173篇
  1975年   12408篇
  1974年   15093篇
  1973年   14760篇
  1972年   13698篇
  1971年   12677篇
  1970年   11763篇
排序方式: 共有10000条查询结果,搜索用时 12 毫秒
21.
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   
22.
23.
24.
25.
26.
27.
28.
29.
AIM: To evaluate whether the introduction of a strict protocol approach based on the systemic evaluation of critically ill pregnant women with complications of abortion affected outcome. SETTING: Indigent South Africans managed in the regional and tertiary hospitals of the Pretoria Academic Complex. METHOD: Since 1997 a standard definition of severe acute maternal morbidity (SAMM) has been used in the Pretoria Academic Complex. All cases of SAMM and maternal deaths were entered on the Maternal Morbidity and Mortality Audit System programme. A comparison of outcome of severely ill women who had complications of abortion was made between 1997-1998 (original protocol) and 2002-2004 (strict protocol). OUTCOME MEASURES: The mortality index and prevalence of organ system failure or dysfunction. RESULTS: In 1997-1998 there were 43 women with SAMM who survived and a further 10 maternal deaths due to complications of abortion, compared with 107 women with SAMM and 7 maternal deaths during 2002-2004. The mortality index declined from 18.9% in 1997-1998 to 6.1% in 2002-2004 (p = 0.02, odds ratio 0.28, 95% confidence limits 0.10 - 0.79). Significantly more women had hypovolaemic shock in 2002-2004 compared with 1997-1998 (54.4% v. 35.8%, p = 0.04), but fewer women had immune system failure including septic shock (18.4% v. 47.2%, p = 0.0002) and metabolic dysfunction (0 v. 5.7%, p = 0.03) and there was a trend to less renal failure (10.5% v. 22.6%, p = 0.06) and cardiac failure (4.4% v. 13.2%, p = 0.08). CONCLUSION: The strict protocol approach based on systemic evaluation in managing critically ill pregnant women with complications of abortion, coupled with an intensive, regular feedback mechanism, has been associated with a reduction in the mortality index.  相似文献   
30.
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