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   1102075篇
  免费   73276篇
  国内免费   1453篇
耳鼻咽喉   15340篇
儿科学   36115篇
妇产科学   29192篇
基础医学   156730篇
口腔科学   30268篇
临床医学   96943篇
内科学   209317篇
皮肤病学   24988篇
神经病学   82960篇
特种医学   43544篇
外国民族医学   201篇
外科学   167005篇
综合类   22658篇
现状与发展   1篇
一般理论   280篇
预防医学   76117篇
眼科学   25884篇
药学   88646篇
  7篇
中国医学   2981篇
肿瘤学   67627篇
  2021年   8592篇
  2019年   8477篇
  2018年   12203篇
  2017年   9535篇
  2016年   10919篇
  2015年   12098篇
  2014年   16409篇
  2013年   23663篇
  2012年   32526篇
  2011年   34269篇
  2010年   20018篇
  2009年   18789篇
  2008年   31317篇
  2007年   33411篇
  2006年   34083篇
  2005年   32052篇
  2004年   30779篇
  2003年   29439篇
  2002年   28291篇
  2001年   60510篇
  2000年   61987篇
  1999年   51363篇
  1998年   12639篇
  1997年   11121篇
  1996年   11150篇
  1995年   10457篇
  1994年   9458篇
  1993年   8957篇
  1992年   38072篇
  1991年   36499篇
  1990年   36005篇
  1989年   34507篇
  1988年   31069篇
  1987年   30177篇
  1986年   28413篇
  1985年   26642篇
  1984年   19347篇
  1983年   16252篇
  1982年   8917篇
  1979年   17181篇
  1978年   11507篇
  1977年   10345篇
  1976年   8922篇
  1975年   10181篇
  1974年   11769篇
  1973年   11393篇
  1972年   10887篇
  1971年   10197篇
  1970年   9334篇
  1969年   9016篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
22.
Levels of the soluble form of the triggering receptor expressed on myeloid cells (sTREM)-1 are elevated in severe sepsis. However, it is not known whether sTREM-1 measurements can distinguish milder bacterial infections from noninfectious inflammation. The present authors studied whether serum sTREM-1 levels differ in community-acquired pneumonia, exacerbations of chronic obstructive pulmonary disease (COPD), asthma and controls, and whether sTREM-1 may be used as a surrogate marker for the need for antibiotics. Serum sTREM-1 levels in 150 patients with pneumonia, COPD and asthma exacerbations and 62 healthy controls were measured. Serum sTREM-1 levels were significantly elevated in pneumonia (median 295.2 ng x mL(-1)), COPD (280.3 ng x mL(-1)) and asthma exacerbations (184.0 ng x mL(-1)) compared with controls (83.1 ng x mL(-1)). Levels were higher in pneumonia and Anthonisen type 1 COPD exacerbations than in type 2 and 3 COPD and asthma exacerbations. The area under the receiver operating characteristics curve for sTREM-1 as a surrogate marker for the need for antibiotics was 0.77. Serum levels of the soluble form of the triggering receptor expressed on myeloid cells-1 were elevated predominantly in pneumonia and Anthonisen type 1 COPD exacerbations versus type 2 and 3 chronic obstructive pulmonary disease exacerbations, asthma and controls. Serum levels of the soluble form of the triggering receptor expressed on myeloid cells-1 has moderate but insufficient accuracy as a surrogate marker for the need for antibiotics in lower respiratory tract infections.  相似文献   
23.
24.
25.
26.
27.
28.
29.
OBJECTIVE: To establish reference intervals for the fetal right, left and total lung volumes and heart volume between 12 and 32 weeks of gestation. METHODS: Fetal lung and heart volumes were measured using three-dimensional (3D) ultrasound in 650 normal singleton pregnancies at 12-32 weeks. The VOCAL (Virtual Organ Computer-aided AnaLysis) technique was used to obtain a sequence of six sections of each lung and the heart around a fixed axis, each after a 30 degrees rotation from the previous one. The rotation axis for the lungs extended from the apex to the upper limit of the diaphragm dome, and the rotation axis for the heart extended from its apex to its connection to the great vessels. The contour of each of these organs was drawn manually in the six different rotation planes to obtain the 3D volume measurement. In 60 cases the fetal lungs and heart volumes were measured by the same sonographer twice and also by a second sonographer once in order to compare the measurements and calculate intra- and interobserver agreement. RESULTS: The total lung volume and heart volume increased with gestation, from respective mean values of 1.6 and 0.6 mL at 12 weeks to 10.9 and 4.3 mL at 20 weeks and 49.3 and 26.6 mL at 32 weeks. The right to left lung volume ratio did not change significantly with gestation (median, 0.7), whereas the heart to total lung volume ratio increased with gestation from about 0.3 at 12 weeks to 0.5 at 32 weeks. In the Bland-Altman plot, the difference between paired measurements by two sonographers was, in 95% of the cases, less than 0.05, 0.5 and 1.9 mL for each lung at 12-13, 19-22 and 29-32 weeks, respectively, and the corresponding values for the heart volumes were 0.04, 0.4 and 2.3 mL. CONCLUSIONS: In normal fetuses the lung and heart volumes increase between 12 and 32 weeks of gestation. The extent to which in pathological pregnancies possible deviations in these measurements from normal prove to be useful in the prediction of outcome remains to be determined.  相似文献   
30.
We report the case of a 38-year-old woman who presented with chronic lower abdominal pain. Her past medical history included a splenectomy due to abdominal trauma. Ultrasound examination revealed four pelvic tumors which, upon laparotomy, were found to be the result of splenosis. Approximately 100 cases of splenosis have been reported but only a minority of them have been published in the gynecological literature. Our case indicates that those involved in pelvic scanning (even of asymptomatic women) and/or treating those complaining of lower abdominal pain or presenting with pelvic tumors should be aware of splenosis as a possible diagnosis.  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