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   1589984篇
  免费   129090篇
  国内免费   3935篇
耳鼻咽喉   20791篇
儿科学   51569篇
妇产科学   44644篇
基础医学   224575篇
口腔科学   41718篇
临床医学   145114篇
内科学   321770篇
皮肤病学   36216篇
神经病学   134721篇
特种医学   60281篇
外国民族医学   473篇
外科学   236454篇
综合类   35670篇
现状与发展   6篇
一般理论   693篇
预防医学   125321篇
眼科学   36143篇
药学   111045篇
  1篇
中国医学   3593篇
肿瘤学   92211篇
  2021年   13647篇
  2019年   14475篇
  2018年   19916篇
  2017年   15074篇
  2016年   17066篇
  2015年   19316篇
  2014年   27380篇
  2013年   41077篇
  2012年   56285篇
  2011年   59501篇
  2010年   34762篇
  2009年   33179篇
  2008年   55235篇
  2007年   58590篇
  2006年   58754篇
  2005年   57344篇
  2004年   54730篇
  2003年   52188篇
  2002年   50249篇
  2001年   75148篇
  2000年   76349篇
  1999年   63829篇
  1998年   19357篇
  1997年   17439篇
  1996年   17359篇
  1995年   16438篇
  1994年   14904篇
  1993年   14046篇
  1992年   47566篇
  1991年   45038篇
  1990年   42922篇
  1989年   40973篇
  1988年   37578篇
  1987年   36637篇
  1986年   34253篇
  1985年   32673篇
  1984年   25402篇
  1983年   21496篇
  1982年   13887篇
  1981年   12314篇
  1979年   21769篇
  1978年   15676篇
  1977年   13043篇
  1976年   12226篇
  1975年   12335篇
  1974年   14805篇
  1973年   14240篇
  1972年   13238篇
  1971年   11966篇
  1970年   11352篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
There is a sharp difference in how one views TCR structure–function–behaviour dependent on whether its recognition of major histocompatibility complex‐encoded restriction elements (R) is germline selected or somatically generated. The generally accepted or Standard model is built on the assumption that recognition of R is by the V regions of the αβ TCR, which is not driven by allele specificity, whereas the competing model posits that recognition of R is allele‐specific. The establishing of allele‐specific recognition of R by the TCR would rule out the Standard model and clear the road to a consideration of a competing construct, the Tritope model. Here, the case for allele‐specific recognition (germline selected) is detailed making it obvious that the Standard model is untenable.  相似文献   
32.
33.
34.
35.
36.
37.

Objectives

Expedient extubation after cardiac surgery has been associated with improved outcomes, leading to postoperative extubation frequently during overnight hours. However, recent evidence in a mixed medical-surgical intensive care unit population demonstrated worse outcomes with overnight extubation. This study investigated the impact of overnight extubation in a statewide, multicenter Society of Thoracic Surgeons database.

Methods

Records from 39,812 patients undergoing coronary artery bypass grafting or valve operations (2008-2016) and extubated within 24 hours were stratified according to extubation time between 06:00 and 18:00 (day) or between 18:00 and 6:00 (overnight). Outcomes including reintubation, mortality, and composite morbidity-mortality were evaluated using hierarchical regression models adjusted for Society of Thoracic Surgeons predictive risk scores. To further analyze extubation during the night, a subanalysis stratified patients into 3 groups: 06:00 to 18:00, 18:00 to 24:00, and 24:00 to 06:00.

Results

A total of 20,758 patients were extubated overnight (52.1%) and were slightly older (median age 66 vs 65 years, P < .001) with a longer duration of ventilation (4 vs 7 hours, P < .001). Day and overnight extubation were associated with equivalent operative mortality (1.7% vs 1.7%, P = .880), reintubation (3.7% vs 3.4%, P = .141), and composite morbidity-mortality (8.2% vs 8.0%, P = .314). After risk adjustment, overnight extubation was not associated with any difference in reintubation, mortality, or composite morbidity-mortality. On subanalysis, those extubated between 24:00 and 06:00 exhibited increased composite morbidity-mortality (odds ratio, 1.18; P = .001) but no difference in reintubation or mortality.

Conclusions

Extubation overnight was not associated with increased mortality or reintubation. These results suggest that in the appropriate clinical setting, it is safe to routinely extubate cardiac surgery patients overnight.  相似文献   
38.
Metabolism describes the series of chemical reactions that are concerned with the provision of energy to biological systems. They may be divided into reactions involved in energy yield (catabolism: demand exceeds supply), and energy storage (anabolism: supply exceeds demand). Regulation of these pathways is critical for homeostasis, and derangements in metabolism are seen in a wide variety of pathological processes. Understanding metabolism is key to the treatment of many diseases, notably diabetes, as well as underpinning clinical nutritional support.  相似文献   
39.
40.
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