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   1646821篇
  免费   104397篇
  国内免费   4266篇
耳鼻咽喉   22897篇
儿科学   49470篇
妇产科学   44982篇
基础医学   224232篇
口腔科学   44324篇
临床医学   138161篇
内科学   318943篇
皮肤病学   34635篇
神经病学   132648篇
特种医学   68700篇
外国民族医学   436篇
外科学   254433篇
综合类   35395篇
现状与发展   11篇
一般理论   529篇
预防医学   119508篇
眼科学   38016篇
药学   120823篇
  6篇
中国医学   5117篇
肿瘤学   102218篇
  2021年   12317篇
  2018年   36315篇
  2017年   28687篇
  2016年   32557篇
  2015年   18330篇
  2014年   24261篇
  2013年   34272篇
  2012年   51845篇
  2011年   66280篇
  2010年   45210篇
  2009年   36724篇
  2008年   60380篇
  2007年   65433篇
  2006年   45865篇
  2005年   45701篇
  2004年   45024篇
  2003年   43992篇
  2002年   40982篇
  2001年   66345篇
  2000年   67985篇
  1999年   57495篇
  1998年   15902篇
  1997年   14468篇
  1996年   13767篇
  1995年   13003篇
  1994年   12149篇
  1992年   43848篇
  1991年   42399篇
  1990年   41643篇
  1989年   40543篇
  1988年   37861篇
  1987年   37221篇
  1986年   35684篇
  1985年   33802篇
  1984年   25358篇
  1983年   21521篇
  1982年   12994篇
  1979年   24326篇
  1978年   17378篇
  1977年   15135篇
  1976年   13674篇
  1975年   15508篇
  1974年   18379篇
  1973年   17818篇
  1972年   17043篇
  1971年   15896篇
  1970年   15113篇
  1969年   14508篇
  1968年   13612篇
  1967年   12126篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Generally, a computed tomography scan is conducted for the diagnosis of stroke in the emergency department, because these scans are easier and faster in the detection of stroke. If there are no signs of hemorrhage on computed tomography scan, an ischemic stroke is diagnosed and treated accordingly. A magnetic resonance imaging scan may be taken in order to verify ischemic stroke. This process may lead to improper treatment and is time consuming. To address this situation, case studies are presented in which magnetic resonance imaging diffusion-weighted imaging and gradient recalled echo were performed to detect hemorrhagic and ischemic stroke and particularly, subarachnoid hemorrhage, which is undetectable with a computed tomography scan.  相似文献   
52.
53.
There is increasing evidence that the assessment of eosinophilic airway inflammation using induced sputum and measurement of airway hyperresponsiveness provides additional, clinically important information concerning asthma control. The aim of this study was to directly compare the effects of different treatments on these markers in patients with asthma and persistent symptoms, despite the use of low-dose inhaled corticosteroids. A double-blind four-way crossover study was performed, which compared a 1-month treatment with budesonide 400 mug b.i.d., additional formoterol, additional montelukast and placebo in 49 patients with uncontrolled asthma despite budesonide 100 mug b.i.d., with each treatment separated by a 4-week washout period. The change in sputum eosinophil count with formoterol (2.4 to 3.8% change, 0.6-fold reduction, 95% confidence interval (CI) 0.5-0.9) differed significantly from placebo (2.8 to 2.5% change, 1.1-fold reduction, 95% CI 0.7-1.6) and high-dose budesonide (2.7 to 1.6% change, 1.6-fold reduction, 95% CI 1.2-2.2). The effects of montelukast did not differ from placebo. The changes in methacholine airway responsiveness were small and did not differ between treatments. High-dose budesonide had the broadest range of beneficial effects on other outcomes, including symptom scores, morning peak expiratory flow and forced expiratory volume in one second. In conclusion, treatment given in addition to low-dose inhaled corticosteroids results in modest benefits. Formoterol and high-dose budesonide have contrasting effects on eosinophilic airway inflammation.  相似文献   
54.
55.
Severe adverse effects during the use of ovulation inhibitors occur mostly in women who have an elevated risk for the development of certain diseases owing to hereditary or acquired factors. By means of a careful personal or family history analysis as well as specific laboratory examinations, an existing predisposition may frequently be diagnosed and the individual risk associated with the use of oral contraceptive inhibitors may be estimated. The present contribution describes the potential effects of treatment with ovulation inhibitors on women with thrombophilia, cardiovascular disease, diabetes mellitus, dyslipidemia, overweight or underweight, tumors, psychiatric and neurological diseases and autoimmune disease. The hormonal methods and non-hormonal alternatives available for contraception are elucidated according to existing lesions and risk factors and the advantages and disadvantages are discussed.  相似文献   
56.
There are no data available combining transbronchial needle aspiration (TBNA) of mediastinal lymph nodes and positron emission tomography (PET) in the staging of nonsmall cell lung cancer (NSCLC). The aim of the current study was to determine if these two methods can enhance the negative predictive value of the individual modality alone, for a specific lymph node station, and if this integrated approach can reduce the number of mediastinoscopies. A total of 113 patients with enlarged mediastinal lymph nodes (> or = 1 cm), who underwent both TBNA and PET scanning, were included. In 51 patients, histopathology, confirmed by surgical lymph node dissection, was compared with PET results and TBNA. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy to detect malignant lymphadenopathy was 68 (13/19), 89 (119/134), 46 (13/28), 95 (119/125) and 86% (132/152) for PET, respectively; 54% (6/11), 100 (53/53), 100 (6/6), 91 (53/58) and 92% (59/64), respectively for TBNA; and 100 (11/11), 94 (50/53), 79 (11/14), 100 (50/50) and 95 (61/64) for combined TBNA and PET, respectively. Combination of transbronchial needle aspiration and positron emission tomography has the potential to allow adequate mediastinal staging of nonsmall cell lung cancer with enlarged lymph nodes in most patients without the need for mediastinoscopy.  相似文献   
57.
58.
59.
60.
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