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   1161214篇
  免费   77034篇
  国内免费   2081篇
耳鼻咽喉   16022篇
儿科学   37262篇
妇产科学   30776篇
基础医学   164934篇
口腔科学   31532篇
临床医学   101897篇
内科学   222490篇
皮肤病学   26202篇
神经病学   89451篇
特种医学   46336篇
外国民族医学   223篇
外科学   175360篇
综合类   23238篇
现状与发展   1篇
一般理论   308篇
预防医学   79553篇
眼科学   25927篇
药学   93135篇
  10篇
中国医学   3297篇
肿瘤学   72375篇
  2021年   9145篇
  2019年   9213篇
  2018年   13104篇
  2017年   10284篇
  2016年   11556篇
  2015年   12975篇
  2014年   17519篇
  2013年   25483篇
  2012年   34917篇
  2011年   36830篇
  2010年   21936篇
  2009年   20396篇
  2008年   33952篇
  2007年   36278篇
  2006年   36701篇
  2005年   34853篇
  2004年   33897篇
  2003年   32629篇
  2002年   31634篇
  2001年   63320篇
  2000年   64739篇
  1999年   53580篇
  1998年   13478篇
  1997年   11798篇
  1996年   11742篇
  1995年   11038篇
  1994年   9959篇
  1993年   9462篇
  1992年   39377篇
  1991年   37868篇
  1990年   37108篇
  1989年   35593篇
  1988年   32088篇
  1987年   31084篇
  1986年   29301篇
  1985年   27408篇
  1984年   19891篇
  1983年   16759篇
  1982年   9236篇
  1979年   17561篇
  1978年   11790篇
  1977年   10572篇
  1976年   9157篇
  1975年   10467篇
  1974年   12105篇
  1973年   11703篇
  1972年   11152篇
  1971年   10459篇
  1970年   9585篇
  1969年   9281篇
排序方式: 共有10000条查询结果,搜索用时 31 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