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   3437868篇
  免费   256752篇
  国内免费   9249篇
耳鼻咽喉   46527篇
儿科学   113512篇
妇产科学   95869篇
基础医学   483594篇
口腔科学   94994篇
临床医学   315528篇
内科学   675965篇
皮肤病学   81717篇
神经病学   283579篇
特种医学   131236篇
外国民族医学   1111篇
外科学   513963篇
综合类   74096篇
现状与发展   7篇
一般理论   1340篇
预防医学   268087篇
眼科学   78102篇
药学   249109篇
  8篇
中国医学   7262篇
肿瘤学   188263篇
  2019年   27569篇
  2018年   38674篇
  2017年   29704篇
  2016年   34173篇
  2015年   38470篇
  2014年   53629篇
  2013年   80398篇
  2012年   107357篇
  2011年   113879篇
  2010年   68316篇
  2009年   65194篇
  2008年   105993篇
  2007年   112447篇
  2006年   114298篇
  2005年   110042篇
  2004年   105480篇
  2003年   101706篇
  2002年   98283篇
  2001年   165571篇
  2000年   169557篇
  1999年   142640篇
  1998年   41390篇
  1997年   36818篇
  1996年   36824篇
  1995年   35608篇
  1994年   32493篇
  1993年   30428篇
  1992年   110068篇
  1991年   105663篇
  1990年   102384篇
  1989年   98621篇
  1988年   90482篇
  1987年   88623篇
  1986年   83004篇
  1985年   79439篇
  1984年   59580篇
  1983年   50506篇
  1982年   30225篇
  1981年   26932篇
  1979年   52650篇
  1978年   37281篇
  1977年   31428篇
  1976年   29277篇
  1975年   30856篇
  1974年   36741篇
  1973年   35123篇
  1972年   33002篇
  1971年   30528篇
  1970年   28366篇
  1969年   27005篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
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   
72.
73.
74.
75.
76.
77.

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   
78.
79.
80.
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   
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