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   2174234篇
  免费   171778篇
  国内免费   5177篇
耳鼻咽喉   28906篇
儿科学   73403篇
妇产科学   62054篇
基础医学   312760篇
口腔科学   60005篇
临床医学   197035篇
内科学   427152篇
皮肤病学   50420篇
神经病学   177198篇
特种医学   83023篇
外国民族医学   752篇
外科学   324509篇
综合类   51711篇
现状与发展   3篇
一般理论   820篇
预防医学   172304篇
眼科学   49874篇
药学   155035篇
  4篇
中国医学   4862篇
肿瘤学   119359篇
  2019年   17085篇
  2018年   24277篇
  2017年   18661篇
  2016年   21166篇
  2015年   23720篇
  2014年   33236篇
  2013年   50127篇
  2012年   67155篇
  2011年   71379篇
  2010年   42230篇
  2009年   40149篇
  2008年   66305篇
  2007年   70212篇
  2006年   71140篇
  2005年   68690篇
  2004年   66180篇
  2003年   63278篇
  2002年   61104篇
  2001年   105598篇
  2000年   108225篇
  1999年   90160篇
  1998年   25498篇
  1997年   23019篇
  1996年   23054篇
  1995年   22042篇
  1994年   20213篇
  1993年   18921篇
  1992年   69434篇
  1991年   66942篇
  1990年   64911篇
  1989年   62165篇
  1988年   56753篇
  1987年   56277篇
  1986年   52562篇
  1985年   50364篇
  1984年   38159篇
  1983年   32199篇
  1982年   19560篇
  1981年   17461篇
  1979年   34397篇
  1978年   24479篇
  1977年   20489篇
  1976年   19332篇
  1975年   20067篇
  1974年   24327篇
  1973年   23434篇
  1972年   21734篇
  1971年   19992篇
  1970年   18887篇
  1969年   17489篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
41.
42.
43.

Objective

To examine whether a healthy weight intervention embedded in the Parents as Teachers (PAT) home visiting program, which was previously found to improve mothers’ body mass index (BMI) and obesity-related behaviors, changed the BMI of preschool children or maternal feeding practices.

Methods

This stratified randomized trial included preschool-aged children at risk for overweight whose mothers were overweight or had obesity (n?=?179). The Healthy Eating and Active Living Taught at Home (HEALTH) intervention was based on the Diabetes Prevention Program. Differences were examined using repeated-measures mixed-ANOVA models.

Results

Compared with PAT usual care, the HEALTH intervention had no effect on children's BMI or maternal feeding practices. However, combined analyses showed that children's BMI percentile decreased (P??=?.007), BMI z-scores were maintained (P??=?.19), and 3 of 8 feeding practices improved over time (P < .05).

Conclusions and Implications

Additional research is needed to assess the effectiveness of PAT to prevent preschool-age obesity using rigorous designs (eg, group-randomized trials) and to identify its active components. HEALTH is ready to be scaled up to prevent maternal weight gain through embedding within the national PAT program.  相似文献   
44.
45.

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   
46.
47.
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   
48.
49.
50.
We report two British cases of liver abscess, due to Klebsiella pneumoniae and associated with synchronous infection elsewhere, which required liver resection for definitive treatment. They illustrate the geographic spread of aggressive K pneumoniae liver infection and demonstrate the importance of early aggressive treatment.  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