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   438491篇
  免费   13711篇
  国内免费   594篇
耳鼻咽喉   4552篇
儿科学   14731篇
妇产科学   8737篇
基础医学   54096篇
口腔科学   7756篇
临床医学   33053篇
内科学   90197篇
皮肤病学   7744篇
神经病学   40182篇
特种医学   16908篇
外国民族医学   106篇
外科学   61047篇
综合类   3474篇
一般理论   73篇
预防医学   42056篇
眼科学   7738篇
药学   27828篇
中国医学   1444篇
肿瘤学   31074篇
  2023年   1447篇
  2022年   1668篇
  2021年   4835篇
  2020年   2737篇
  2019年   4930篇
  2018年   30473篇
  2017年   22626篇
  2016年   24197篇
  2015年   7022篇
  2014年   7797篇
  2013年   11683篇
  2012年   24830篇
  2011年   38163篇
  2010年   27291篇
  2009年   18378篇
  2008年   34086篇
  2007年   37204篇
  2006年   15773篇
  2005年   17231篇
  2004年   17474篇
  2003年   17237篇
  2002年   14627篇
  2001年   7130篇
  2000年   7426篇
  1999年   6371篇
  1998年   1520篇
  1997年   1250篇
  1996年   1054篇
  1995年   981篇
  1992年   3595篇
  1991年   3244篇
  1990年   3153篇
  1989年   2834篇
  1988年   2622篇
  1987年   2481篇
  1986年   2308篇
  1985年   2103篇
  1984年   1560篇
  1983年   1324篇
  1979年   1339篇
  1978年   963篇
  1977年   896篇
  1975年   909篇
  1974年   1103篇
  1973年   1105篇
  1972年   1039篇
  1971年   1016篇
  1970年   960篇
  1969年   996篇
  1968年   894篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Gallibacterium anatis (previously named Pasteurella haemolytica-like) is considered a normal inhabitant of genital and upper respiratory tracts of healthy chickens, but it is also associated with different pathological conditions. Secreted metalloproteases from field and reference G. anatis cultures were obtained by methanol precipitation and were characterized. Proteins of molecular mass higher than 100 kDa showing proteolytic activity were observed in 10% polyacrylamide gels copolymerized with 1% bovine casein. They were active at alkaline pH, and inhibited by ethylenediamine tetraacetic acid. Their activity was stable at 50 degrees C, but partially inhibited at 60 degrees C, and totally inhibited at higher temperatures. Secreted proteins were able to degrade chicken IgG after 24 h of incubation, and cross-reacted with a polyclonal antibody against purified protease from Actinobacillus pleuropneumoniae. Secreted metalloproteases could play a role in infections caused by G. anatis.  相似文献   
72.
73.
74.

Introduction  

This paper presents the results of a study on the psychometric properties of an authorized Spanish version of the McMaster Family Assessment Device, a self-report measure of family functioning.  相似文献   
75.
76.

Background  

Advances in intensive care medicine have increased survival rates of patients with critical neurological conditions. The focus of prognostication for such patients is therefore shifting from predicting chances of survival to meaningful neurological recovery. This study assessed the variability in long-term outcome predictions among physicians and aimed to identify factors that may account for this variability.  相似文献   
77.
Background Chromium allergy has traditionally been caused by occupational skin contact with cement. In 1983, Danish legislation made the addition of ferrous sulphate compulsory in cement to reduce the water‐soluble chromium content to not more than 2 ppm. An effect from this intervention has previously been demonstrated among Danish construction workers. Objectives To investigate the development of chromium allergy among patients with dermatitis tested between 1985 and 2007 in Denmark. Furthermore, to determine causative exposures in patients with chromium allergy. Patients and methods A retrospective analysis of patch test data was performed (n = 16 228) and charts from patients with chromium allergy were reviewed. Comparisons were made using a χ2 test. Logistic regression analyses were used to test for associations. Results The prevalence of chromium allergy decreased significantly from 3·6% in 1985 to 1% in 1995 (Ptrend < 0·001) but increased to 3·3% in 2007 (Ptrend < 0·001). The frequency of clinically relevant cement exposure decreased significantly among patients with chromium allergy from 12·7% in 1989–1994 to 3·0% (P < 0·01) in 1995–2007, whereas the frequency of relevant leather exposure increased significantly from 24·1% during 1989–1994 to 45·5% during 1995–2007 (P < 0·02). Conclusions Chromium allergy is currently increasing in Denmark due to leather exposure.  相似文献   
78.
Abstract:  Long-term prophylaxis against cytomegalovirus (CMV) started immediately after transplantation in (D+/R−) poses a higher risk of late-onset CMV disease. Delayed CMV prophylaxis could allow a transitory exposure of the immune system to CMV, which would let the immune system mount an adequate CMV-specific cytotoxic response in (D+/R−) patients and confer protection against CMV disease. We included all (D+/R−) solid organ transplant recipients (SOT) performed at our institution (January 3/October 6) who received CMV prophylaxis (mainly with oral valganciclovir) during 100 d. In the first period (until December 4), prophylaxis was initiated immediately after transplantation (conventional prophylaxis: CP). Since January 5, it was initiated after 14 d (delayed prophylaxis: DP). Incidence and severity of CMV disease was compared between both groups. A total of 44 SOT recipients were included (CP: 26 and DP: 18). CMV disease was diagnosed in eight patients (18%), seven of 26 (27%) in the CP group, and one of 18 (5.5%) in the DP group (p = 0.07). CMV colitis was reported in five of 26 patients in the CP group (19%), whereas there were no cases of visceral CMV disease in the DP group (p = 0.048). A 14-d delay in the beginning of long-term prophylaxis against CMV in (D+/R−) is safe and could prevent the onset of late-CMV disease.  相似文献   
79.
80.
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