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   1098045篇
  免费   73683篇
  国内免费   1521篇
耳鼻咽喉   15273篇
儿科学   35368篇
妇产科学   29147篇
基础医学   156022篇
口腔科学   30049篇
临床医学   97183篇
内科学   208556篇
皮肤病学   24794篇
神经病学   83262篇
特种医学   43688篇
外国民族医学   201篇
外科学   166605篇
综合类   22264篇
现状与发展   1篇
一般理论   274篇
预防医学   76258篇
眼科学   25562篇
药学   87780篇
  8篇
中国医学   2906篇
肿瘤学   68048篇
  2021年   8186篇
  2019年   8343篇
  2018年   11933篇
  2017年   9368篇
  2016年   10616篇
  2015年   11854篇
  2014年   16105篇
  2013年   23170篇
  2012年   32155篇
  2011年   33947篇
  2010年   19905篇
  2009年   18624篇
  2008年   31316篇
  2007年   33350篇
  2006年   33879篇
  2005年   32183篇
  2004年   30877篇
  2003年   29547篇
  2002年   28445篇
  2001年   60675篇
  2000年   62098篇
  1999年   51473篇
  1998年   12691篇
  1997年   11172篇
  1996年   11156篇
  1995年   10478篇
  1994年   9471篇
  1993年   8980篇
  1992年   38125篇
  1991年   36597篇
  1990年   36013篇
  1989年   34536篇
  1988年   31112篇
  1987年   30208篇
  1986年   28426篇
  1985年   26687篇
  1984年   19340篇
  1983年   16249篇
  1982年   8927篇
  1979年   17141篇
  1978年   11471篇
  1977年   10302篇
  1976年   8896篇
  1975年   10119篇
  1974年   11707篇
  1973年   11325篇
  1972年   10797篇
  1971年   10132篇
  1970年   9270篇
  1969年   8969篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
22.
23.
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   
24.
25.
26.
27.
28.
29.
30.
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   
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