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   2621376篇
  免费   191457篇
  国内免费   7613篇
耳鼻咽喉   34846篇
儿科学   86425篇
妇产科学   72553篇
基础医学   369444篇
口腔科学   71341篇
临床医学   238193篇
内科学   521370篇
皮肤病学   63469篇
神经病学   217548篇
特种医学   101624篇
外国民族医学   736篇
外科学   391647篇
综合类   50581篇
现状与发展   5篇
一般理论   992篇
预防医学   198669篇
眼科学   57527篇
药学   190843篇
  8篇
中国医学   5406篇
肿瘤学   147219篇
  2021年   20338篇
  2019年   21069篇
  2018年   30214篇
  2017年   23384篇
  2016年   27198篇
  2015年   30290篇
  2014年   41381篇
  2013年   62165篇
  2012年   82419篇
  2011年   87029篇
  2010年   52299篇
  2009年   49946篇
  2008年   81476篇
  2007年   86463篇
  2006年   87962篇
  2005年   84064篇
  2004年   81078篇
  2003年   78455篇
  2002年   75624篇
  2001年   129559篇
  2000年   132828篇
  1999年   111365篇
  1998年   31600篇
  1997年   28203篇
  1996年   28442篇
  1995年   27566篇
  1994年   25256篇
  1993年   23635篇
  1992年   85336篇
  1991年   81708篇
  1990年   78930篇
  1989年   76240篇
  1988年   69605篇
  1987年   68156篇
  1986年   63683篇
  1985年   60705篇
  1984年   45177篇
  1983年   38126篇
  1982年   22638篇
  1981年   20141篇
  1979年   39119篇
  1978年   27565篇
  1977年   23405篇
  1976年   21646篇
  1975年   22937篇
  1974年   26907篇
  1973年   25513篇
  1972年   23823篇
  1971年   22032篇
  1970年   20256篇
排序方式: 共有10000条查询结果,搜索用时 359 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.

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   
67.
68.
69.

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   
70.
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