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   2683176篇
  免费   191103篇
  国内免费   7831篇
耳鼻咽喉   35378篇
儿科学   87562篇
妇产科学   73717篇
基础医学   377823篇
口腔科学   72751篇
临床医学   243979篇
内科学   534368篇
皮肤病学   63918篇
神经病学   222839篇
特种医学   103402篇
外国民族医学   744篇
外科学   398036篇
综合类   50924篇
现状与发展   6篇
一般理论   1052篇
预防医学   206440篇
眼科学   58433篇
药学   194141篇
  9篇
中国医学   5512篇
肿瘤学   151076篇
  2021年   21836篇
  2019年   22266篇
  2018年   31241篇
  2017年   24283篇
  2016年   28144篇
  2015年   31557篇
  2014年   43361篇
  2013年   64417篇
  2012年   86198篇
  2011年   90660篇
  2010年   54606篇
  2009年   52489篇
  2008年   84261篇
  2007年   89327篇
  2006年   90727篇
  2005年   86731篇
  2004年   83136篇
  2003年   80213篇
  2002年   77053篇
  2001年   130527篇
  2000年   133405篇
  1999年   112519篇
  1998年   32368篇
  1997年   28852篇
  1996年   29111篇
  1995年   28141篇
  1994年   25749篇
  1993年   24074篇
  1992年   86668篇
  1991年   82955篇
  1990年   80050篇
  1989年   77323篇
  1988年   70653篇
  1987年   69049篇
  1986年   64599篇
  1985年   61565篇
  1984年   45728篇
  1983年   38656篇
  1982年   22884篇
  1981年   20367篇
  1979年   39602篇
  1978年   27899篇
  1977年   23657篇
  1976年   21813篇
  1975年   23135篇
  1974年   27148篇
  1973年   25717篇
  1972年   24044篇
  1971年   22248篇
  1970年   20422篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
OBJECTIVE: To evaluate the prenatal distribution, associated conditions and outcome of the different types of right aortic arch (RAA) detected in fetal life. METHODS: This was a retrospective review of all cases of RAA detected prenatally between 1998 and 2005 in two tertiary referral centers. RESULTS: In the study period 71 cases of RAA were detected; 26 (37%) had RAA with aberrant left subclavian artery, 23 (32%) had RAA with mirror-image branching, 20 (28%) had RAA of unknown type and two (3%) had double aortic arch. While 20/26 cases with RAA and aberrant left subclavian artery were isolated findings, all 23 cases with RAA and mirror-image branching were associated with cardiac defects, namely tetralogy of Fallot (43%) or pulmonary atresia with ventricular septal defect (22%). Of the 20 cases with RAA, 19 of unknown type were associated with heterotaxy syndromes and had additional cardiac malformations and ambiguities of the situs. The two cases with DAA were isolated findings. Seven cases in our series (10%) had a microdeletion 22q11 and these were significantly associated with extracardiac malformations. The outcome in our series depended solely on the associated cardiac and extracardiac malformations, with the exception of one infant with isolated DAA, in whom a surgical correction was warranted. CONCLUSIONS: RAA detected in fetal life is associated frequently with other cardiac/non-cardiac malformations, heterotaxy syndromes and microdeletions 22q11. The associated conditions vary depending on the branching type of the brachiocephalic vessels and the presence of extracardiac malformations.  相似文献   
92.
Southgate  M. Therese 《JAMA》2006,296(13):1564
  相似文献   
93.
Volume and profile of alcohol consumption among students and classmates as predictors of aggression and victimization: a multilevel analysis among Swiss adolescents

Objective:  

To test the effects of the volume of alcohol consumption and drinking patterns on alcohol-related aggression and victimization, both at the individual and class levels.  相似文献   
94.
95.
96.
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   
97.
98.
99.
100.
Clinicopathological and electron microscopical findings of eight cases of enzootic nasal adenocarcinoma of sheep, diagnosed solely in one big flock in Slovenia between years 2001 and 2003 are described. All affected sheep were female, their mean age was 4.5 ± 1.5 years and they either belonged to the Istrian pramenka breed (five sheep) or were crossbreeds (three sheep). Tumours that arose from the ethmoid area of the nasal cavity were unilateral in six cases (75%) and bilateral in two cases (25%). All tumours were classified as adenocarcinomas by histopathological examination and they displayed either a combination of tubular and papillary growth or less often solely tubular proliferation. No metastases were detected in regional lymph nodes, brain or other organs. Electron microscopical studies performed on the reprocessed paraffin‐embedded tissues revealed the presence of the virus‐like particles with an average diameter between 70 and 90 nm.  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