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   139944篇
  免费   7343篇
  国内免费   1618篇
耳鼻咽喉   2247篇
儿科学   3450篇
妇产科学   5968篇
基础医学   21226篇
口腔科学   4399篇
临床医学   10014篇
内科学   25161篇
皮肤病学   3098篇
神经病学   9911篇
特种医学   4312篇
外国民族医学   3篇
外科学   18774篇
综合类   5286篇
一般理论   35篇
预防医学   10219篇
眼科学   3805篇
药学   12706篇
中国医学   848篇
肿瘤学   7443篇
  2021年   1388篇
  2019年   1294篇
  2018年   1983篇
  2017年   1429篇
  2016年   1481篇
  2015年   1763篇
  2014年   2367篇
  2013年   3103篇
  2012年   4383篇
  2011年   4764篇
  2010年   2770篇
  2009年   2305篇
  2008年   3964篇
  2007年   4392篇
  2006年   4456篇
  2005年   3979篇
  2004年   3869篇
  2003年   3647篇
  2002年   3367篇
  2001年   7331篇
  2000年   7513篇
  1999年   6177篇
  1998年   1974篇
  1997年   1410篇
  1996年   970篇
  1992年   4044篇
  1991年   4069篇
  1990年   3835篇
  1989年   3894篇
  1988年   3821篇
  1987年   3651篇
  1986年   3470篇
  1985年   3324篇
  1984年   2331篇
  1983年   1998篇
  1982年   1082篇
  1979年   2343篇
  1978年   1451篇
  1977年   1184篇
  1976年   1115篇
  1975年   1464篇
  1974年   1783篇
  1973年   1817篇
  1972年   1713篇
  1971年   1573篇
  1970年   1455篇
  1969年   1453篇
  1968年   1329篇
  1967年   1122篇
  1966年   1064篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.

Background  

There are few effective strategies reported for the primary prevention of low back pain (LBP). Core stabilization exercises targeting the deep abdominal and trunk musculature and psychosocial education programs addressing patient beliefs and coping styles represent the current best evidence for secondary prevention of low back pain. However, these programs have not been widely tested to determine if they are effective at preventing the primary onset and/or severity of LBP. The purpose of this cluster randomized clinical trial is to determine if a combined core stabilization exercise and education program is effective in preventing the onset and/or severity of LBP. The effect of the combined program will be compared to three other standard programs.  相似文献   
102.
Pleural effusion is a common complication of various diseases. Conventional methods are not always capable of establishing the cause of pleural effusion, so alternative tests are needed. The aim of this study was to explore means of discriminating between different pleural effusion groups, malignant, parapneumonic and tuberculous, based on the combined function of seven biological markers. Adenosine deaminase (ADA), interferon-gamma, C-reactive protein (CRP), carcinoembryonic antigen, interleukin-6, tumour necrosis factor-alpha and vascular endothelial growth factor concentration levels were measured in pleural fluid from 45 patients with malignant, 15 with parapneumonic and 12 with tuberculous pleural effusion. Receiver operating characteristic curve analysis, multinomial logit modelling and canonical variate analysis were applied to discriminate the pleural effusion groups. The three groups could be discriminated successfully using the measured markers. The most important parameters for discrimination were ADA and CRP concentration levels. An individual with an ADA concentration level of >45 U.L(-1) and a CRP concentration of <4 mg.dL(-1) was more likely to belong to the tuberculous pleural effusion group, whereas one with an ADA concentration level of <40 U.L(-1) and a CRP concentration of >6 mg.dL(-1) was more likely to belong to the parapneumonic pleural effusion group, and one with a CRP concentration of <4 mg.dL(-1) to the malignant pleural effusion group. The combination of adenosine deaminase and C-reactive protein levels might be sufficient for discriminating between the three different groups of exudative pleural effusion: malignant, tuberculous and parapneumonic.  相似文献   
103.
104.
The effect of ferritins from horse (FH) and bovine (FB) spleen and murine liver (FM) on the survival rate of CFW mice lethally infected with Escherichia coli (strain 8440-78 K 80/B) was evaluated. Ferritins given intravenously 24 h before intravenous inoculation of bacteria, protected mice most effectively from death due to infection. The effect was dose dependent. At 500 micrograms of ferritin per mouse, the maximum survival rates were 86% (FH), 81% (FM) and 79% (FB), while only 5% of the control mice survived up to the 30th day. The survival rates of animals injected with bovine serum albumin (BSA) and heat-inactivated FB were 8 and 25%, respectively. Intraperitoneal injection of FB was as effective as intravenous in enhancing the resistance of mice against bacteria. These data provide evidence for the beneficial role of tissue ferritins in nonspecific antibacterial resistance.  相似文献   
105.
106.
107.
108.
109.
110.
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