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   2604092篇
  免费   185000篇
  国内免费   7605篇
耳鼻咽喉   35219篇
儿科学   85680篇
妇产科学   72565篇
基础医学   365370篇
口腔科学   69737篇
临床医学   235498篇
内科学   519076篇
皮肤病学   62639篇
神经病学   215218篇
特种医学   100166篇
外国民族医学   736篇
外科学   387422篇
综合类   50441篇
现状与发展   5篇
一般理论   971篇
预防医学   197349篇
眼科学   57222篇
药学   190283篇
  8篇
中国医学   5364篇
肿瘤学   145728篇
  2021年   20321篇
  2019年   20891篇
  2018年   29808篇
  2017年   22959篇
  2016年   26606篇
  2015年   29814篇
  2014年   41000篇
  2013年   61273篇
  2012年   81306篇
  2011年   85820篇
  2010年   51681篇
  2009年   49463篇
  2008年   79871篇
  2007年   85021篇
  2006年   86812篇
  2005年   82963篇
  2004年   80005篇
  2003年   77314篇
  2002年   74377篇
  2001年   128639篇
  2000年   131563篇
  1999年   110650篇
  1998年   31319篇
  1997年   27948篇
  1996年   28237篇
  1995年   27401篇
  1994年   25084篇
  1993年   23439篇
  1992年   85175篇
  1991年   81578篇
  1990年   78805篇
  1989年   76069篇
  1988年   69479篇
  1987年   68012篇
  1986年   63555篇
  1985年   60528篇
  1984年   44958篇
  1983年   37956篇
  1982年   22481篇
  1981年   20010篇
  1979年   38979篇
  1978年   27462篇
  1977年   23275篇
  1976年   21508篇
  1975年   22827篇
  1974年   26795篇
  1973年   25377篇
  1972年   23758篇
  1971年   21962篇
  1970年   20188篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
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   
42.

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   
43.
44.
45.
46.
47.
48.
49.
Sinus venosus atrial septal defect (SV‐ASD) usually coexists with partial anomalous pulmonary vein connection (PAPVC). It is a difficult diagnosis in transthoracic echocardiography (TTE) due to eccentric position of defects. We present a rare case of atypical anatomical variation in PAPVC, which was never described before. Two right pulmonary veins drained into superior vena cava, which overrode SV‐ASD and interatrial septum, a third pulmonary vein into the right atrium. Complete diagnosis could not be set after TTE, nor transesophageal echocardiography, whereas angio‐CT was finally conclusive. This diagnostic approach allowed the surgical planning.  相似文献   
50.
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