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   1349683篇
  免费   112807篇
  国内免费   6403篇
耳鼻咽喉   16819篇
儿科学   43217篇
妇产科学   36718篇
基础医学   185152篇
口腔科学   37251篇
临床医学   121702篇
内科学   280564篇
皮肤病学   32090篇
神经病学   111556篇
特种医学   55955篇
外国民族医学   274篇
外科学   211929篇
综合类   31592篇
现状与发展   2篇
一般理论   418篇
预防医学   107370篇
眼科学   28387篇
药学   94352篇
  5篇
中国医学   2282篇
肿瘤学   71258篇
  2018年   13688篇
  2017年   10833篇
  2016年   13038篇
  2015年   14612篇
  2014年   20380篇
  2013年   30272篇
  2012年   37088篇
  2011年   39829篇
  2010年   24912篇
  2009年   24330篇
  2008年   37059篇
  2007年   39525篇
  2006年   40603篇
  2005年   39071篇
  2004年   37306篇
  2003年   36296篇
  2002年   34259篇
  2001年   66143篇
  2000年   67990篇
  1999年   56681篇
  1998年   16794篇
  1997年   15074篇
  1996年   16067篇
  1995年   16273篇
  1994年   15142篇
  1993年   14193篇
  1992年   47147篇
  1991年   45805篇
  1990年   44013篇
  1989年   41857篇
  1988年   38815篇
  1987年   38118篇
  1986年   35909篇
  1985年   34671篇
  1984年   26390篇
  1983年   22129篇
  1982年   13877篇
  1981年   12470篇
  1980年   11741篇
  1979年   23588篇
  1978年   17099篇
  1977年   14402篇
  1976年   13192篇
  1975年   13754篇
  1974年   16107篇
  1973年   15420篇
  1972年   14197篇
  1971年   13049篇
  1970年   11887篇
  1969年   11121篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Neorickettsia helminthoeca (NH), the agent of salmon poisoning disease or canine neorickettiosis (CN), is a bacterial endosymbiont of the nematode Nanophyetus salmincola, and infections are spreading among specific fish‐eating mammalians. This article describes the pathologic and immunohistochemical findings associated with spontaneous NH‐induced infections in dogs from Southern Brazil. The principal pathologic findings were hypertrophy of Peyer patches and lymphadenopathy with lymphocytic proliferation, chronic interstitial pneumonia, and chronic enteritis associated with positive intralesional immunoreactivity to antigens of NH within macrophages and histiocytes. Positive immunoreactivity against canine parvovirus‐2 (CPV‐2) or/and canine distemper virus was not detected in the evaluated intestinal segments or in the samples from the cerebellum and lungs, respectively, from the dogs evaluated. These findings demonstrated that NH was involved in the enteric, pulmonary, and lymphoid lesions herein described, and provide additional information to confirm the occurrence of this bacterial endosymbiont within this geographical location. It is proposed that chronic pneumonia should be considered as a pathologic manifestation of NH‐induced infections. Additionally, our results show that the occurrences of CN seem to be underdiagnosed in Southern Brazil due to the confusion with the incidence of CPV‐2.  相似文献   
4.

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   
5.
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   
6.
7.
8.
9.
10.
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   
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