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   3130449篇
  免费   227306篇
  国内免费   8382篇
耳鼻咽喉   42983篇
儿科学   99819篇
妇产科学   85648篇
基础医学   440982篇
口腔科学   88169篇
临床医学   284515篇
内科学   615255篇
皮肤病学   73616篇
神经病学   255708篇
特种医学   120883篇
外国民族医学   800篇
外科学   475415篇
综合类   62983篇
现状与发展   5篇
一般理论   1146篇
预防医学   235246篇
眼科学   70957篇
药学   231477篇
  10篇
中国医学   6544篇
肿瘤学   173976篇
  2019年   24017篇
  2018年   34196篇
  2017年   26336篇
  2016年   30462篇
  2015年   34311篇
  2014年   47130篇
  2013年   70490篇
  2012年   93675篇
  2011年   99002篇
  2010年   59587篇
  2009年   57223篇
  2008年   93213篇
  2007年   98818篇
  2006年   100722篇
  2005年   96635篇
  2004年   93126篇
  2003年   89700篇
  2002年   86951篇
  2001年   155604篇
  2000年   159595篇
  1999年   134652篇
  1998年   37541篇
  1997年   33156篇
  1996年   33398篇
  1995年   32272篇
  1994年   29623篇
  1993年   27729篇
  1992年   104459篇
  1991年   100356篇
  1990年   97347篇
  1989年   94038篇
  1988年   86123篇
  1987年   84416篇
  1986年   79117篇
  1985年   75554篇
  1984年   55902篇
  1983年   47348篇
  1982年   27355篇
  1981年   24335篇
  1979年   49465篇
  1978年   34445篇
  1977年   29463篇
  1976年   26946篇
  1975年   28853篇
  1974年   34291篇
  1973年   32479篇
  1972年   30490篇
  1971年   28404篇
  1970年   26460篇
  1969年   25327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.

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