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   2610965篇
  免费   191439篇
  国内免费   7587篇
耳鼻咽喉   34590篇
儿科学   85977篇
妇产科学   72212篇
基础医学   368190篇
口腔科学   70591篇
临床医学   237249篇
内科学   519996篇
皮肤病学   63010篇
神经病学   216594篇
特种医学   100885篇
外国民族医学   736篇
外科学   390204篇
综合类   50475篇
现状与发展   5篇
一般理论   988篇
预防医学   198324篇
眼科学   57059篇
药学   190341篇
  8篇
中国医学   5392篇
肿瘤学   147165篇
  2021年   20535篇
  2019年   21299篇
  2018年   30197篇
  2017年   23405篇
  2016年   27078篇
  2015年   30247篇
  2014年   41374篇
  2013年   62132篇
  2012年   82259篇
  2011年   86743篇
  2010年   52137篇
  2009年   50059篇
  2008年   81021篇
  2007年   85768篇
  2006年   87399篇
  2005年   83436篇
  2004年   80330篇
  2003年   77581篇
  2002年   74873篇
  2001年   129072篇
  2000年   132054篇
  1999年   111066篇
  1998年   31644篇
  1997年   28221篇
  1996年   28461篇
  1995年   27667篇
  1994年   25311篇
  1993年   23665篇
  1992年   85405篇
  1991年   81824篇
  1990年   79017篇
  1989年   76301篇
  1988年   69678篇
  1987年   68184篇
  1986年   63739篇
  1985年   60757篇
  1984年   45168篇
  1983年   38113篇
  1982年   22560篇
  1981年   20087篇
  1979年   39041篇
  1978年   27495篇
  1977年   23286篇
  1976年   21508篇
  1975年   22857篇
  1974年   26814篇
  1973年   25413篇
  1972年   23795篇
  1971年   21989篇
  1970年   20212篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
To determine percent of patients without malignancy and ≤ 40 years of age with high cumulative radiation doses through recurrent CT exams and assess imaging appropriateness. From the cohort of patients who received cumulative effective dose (CED) of ≥ 100 mSv over a 5-year period, a sub-set was identified with non-malignant disease. The top 50 clinical indications leading to multiple CTs were determined. Clinical decision support (CDS) system scores were analyzed using a widely adopted standard of 1–3 (red) as “not usually appropriate,” 4–6 (yellow) “may or may not be appropriate,” and 7–9 (green) “usually appropriate.” Clinicians reviewed patient records to assess compliance with appropriate use criteria (AUC). 9.6% of patients in our series were with non-malignant conditions and 1.4% with age ≤ 40 years. CDS scores (rounded) were 2% red, 38% yellow, 27% green, and 33% unscored CTs. Clinical society guidelines for CT exams, wherever available, were followed in 87.5 to 100% of cases. AUCs were not available for several clinical indications as also referral guidelines for serial CT imaging. More than half of CT exams were unrelated to follow-up of a primary chronic disease. We are faced with a situation wherein patients in age ≤ 40 years require or are thought to require many CT exams over the course of a few years but the radiation risk creates concern. There is a fair number of conditions for which AUC are not available. Suggested solutions include development of CT scanners with lesser radiation dose and further development of appropriateness criteria.  相似文献   
62.
63.
64.
65.
66.
67.

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   
68.
69.
70.

Introduction

Several studies demonstrated that simulator-acquired skill transfer to the operating room is incomplete. Our objective was to identify trainee characteristics that predict the transfer of simulator-acquired skill to the operating room.

Methods

Trainees completed baseline assessments including intracorporeal suturing (IS) performance, attentional selectivity, self-reported use of mental skills, and self-reported prior clinical and simulated laparoscopic experience and confidence. Residents then followed proficiency-based laparoscopic skills training, and their skill transfer was assessed on a live-anesthetized porcine model. Predictive characteristics for transfer test performance were assessed using multiple linear regression.

Results

Thirty-eight residents completed the study. Automaticity, attentional selectivity, resident perceived ability with laparoscopy and simulators, and post-training IS performance were predictive of IS performance during the transfer test.

Conclusions

Promoting automaticity, self-efficacy, and attention selectivity may help improve the transfer of simulator-acquired skill. Mental skills training and training to automaticity may therefore be valuable interventions to achieve this goal.  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