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   3428841篇
  免费   256254篇
  国内免费   9200篇
耳鼻咽喉   46446篇
儿科学   113316篇
妇产科学   95753篇
基础医学   481936篇
口腔科学   94780篇
临床医学   314954篇
内科学   674072篇
皮肤病学   81392篇
神经病学   282638篇
特种医学   130974篇
外国民族医学   1111篇
外科学   512567篇
综合类   74095篇
现状与发展   7篇
一般理论   1336篇
预防医学   267797篇
眼科学   77841篇
药学   248406篇
  8篇
中国医学   7249篇
肿瘤学   187617篇
  2019年   27460篇
  2018年   38518篇
  2017年   29573篇
  2016年   33983篇
  2015年   38260篇
  2014年   53306篇
  2013年   80037篇
  2012年   106810篇
  2011年   113304篇
  2010年   67895篇
  2009年   64789篇
  2008年   105324篇
  2007年   111741篇
  2006年   113594篇
  2005年   109299篇
  2004年   104839篇
  2003年   101074篇
  2002年   97661篇
  2001年   165443篇
  2000年   169508篇
  1999年   142533篇
  1998年   41229篇
  1997年   36700篇
  1996年   36737篇
  1995年   35522篇
  1994年   32432篇
  1993年   30352篇
  1992年   110053篇
  1991年   105648篇
  1990年   102374篇
  1989年   98618篇
  1988年   90484篇
  1987年   88636篇
  1986年   83040篇
  1985年   79461篇
  1984年   59578篇
  1983年   50518篇
  1982年   30211篇
  1981年   26929篇
  1979年   52680篇
  1978年   37295篇
  1977年   31416篇
  1976年   29266篇
  1975年   30849篇
  1974年   36737篇
  1973年   35120篇
  1972年   32996篇
  1971年   30524篇
  1970年   28371篇
  1969年   27006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