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   1911525篇
  免费   135909篇
  国内免费   4084篇
耳鼻咽喉   25138篇
儿科学   63449篇
妇产科学   53062篇
基础医学   273318篇
口腔科学   54593篇
临床医学   169274篇
内科学   373456篇
皮肤病学   43570篇
神经病学   146658篇
特种医学   72337篇
外国民族医学   281篇
外科学   290800篇
综合类   44858篇
现状与发展   5篇
一般理论   666篇
预防医学   139606篇
眼科学   45680篇
药学   138898篇
  7篇
中国医学   4995篇
肿瘤学   110867篇
  2021年   14341篇
  2019年   15042篇
  2018年   22365篇
  2017年   16984篇
  2016年   18707篇
  2015年   21339篇
  2014年   29411篇
  2013年   43120篇
  2012年   59000篇
  2011年   62063篇
  2010年   37221篇
  2009年   34682篇
  2008年   57651篇
  2007年   61560篇
  2006年   61938篇
  2005年   58938篇
  2004年   56975篇
  2003年   54122篇
  2002年   51963篇
  2001年   100332篇
  2000年   102492篇
  1999年   84529篇
  1998年   21933篇
  1997年   19303篇
  1996年   19243篇
  1995年   18533篇
  1994年   16975篇
  1993年   15658篇
  1992年   63220篇
  1991年   61222篇
  1990年   58874篇
  1989年   56565篇
  1988年   51392篇
  1987年   50043篇
  1986年   47239篇
  1985年   44808篇
  1984年   32905篇
  1983年   27995篇
  1982年   15785篇
  1979年   29005篇
  1978年   20090篇
  1977年   17115篇
  1976年   15857篇
  1975年   16894篇
  1974年   20341篇
  1973年   19687篇
  1972年   18256篇
  1971年   16868篇
  1970年   15779篇
  1969年   14636篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
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   
32.
33.
The precise molecular cause of insulin resistance has not yet been elucidated. Resistance to the normal action of insulin contributes to the pathogenesis of a number of common human disorders, including type 1 (insulin-dependent) and type 2 (non-insulin-dependent) diabetes mellitus, hypertension, and the Metabolic Syndrome X, thus constituting a major public health problem. A disease program aimed at combating this disorder should focus on the identification of targets for therapeutic intervention which may overcome insulin resistance and hence the associated metabolic consequences characteristic of the Metabolic Syndrome. Although the primary defect in the pathogenesis of type 2 diabetes is unknown, genetic and environmental factors are likely to contribute to the manifestation of this progressive metabolic disorder, which is usually not clinically apparent until mid-life. Defects at the level of glucose uptake/phosphorylation characterize insulin resistance in skeletal muscle of type 2 diabetic patients. Identification of putative components of the insulin receptor-signaling pathway may offer insights into mechanisms involved in insulin resistance. Enhanced flux of free fatty acids due to impaired lipid metabolism may contribute to impaired insulin secretion and peripheral insulin resistance. Genes regulating lipolysis are prime candidates for susceptibility towards the metabolic syndrome. Here we describe pathways constituting complex interactions that control glucose homeostasis. We will be considering (1) regulation of glucose uptake by the insulin receptor signaling pathway, and (2) control of adipogenesis and insulin sensitivity by the sterol response element binding protein (SREBP) pathway.  相似文献   
34.
35.
36.
37.
Infections due to Penicillium species other than P.marneffei are rare. We identified a boy with X-linked chronic granulomatous disease (X-CGD) with a pulmonary nodule and adjacent rib osteomyelitis caused by Penicillium piceum. The only sign of infection was an elevated sedimentation rate. P. piceum was isolated by fine needle aspirate and from excised infected tissues. Surgical removal and one year of voriconazole treatment were very well tolerated and led to complete recovery. Microbiological, microscopic and molecular studies support the fungal diagnosis. P. piceum should be considered as a relevant pathogen in immunocompromised patients.  相似文献   
38.
39.
40.
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