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   1247698篇
  免费   103513篇
  国内免费   5261篇
耳鼻咽喉   19229篇
儿科学   39092篇
妇产科学   32415篇
基础医学   156108篇
口腔科学   30000篇
临床医学   120883篇
内科学   269318篇
皮肤病学   29005篇
神经病学   106196篇
特种医学   51126篇
外国民族医学   349篇
外科学   211861篇
综合类   21595篇
现状与发展   73篇
一般理论   421篇
预防医学   86107篇
眼科学   28135篇
药学   78811篇
  1篇
中国医学   2112篇
肿瘤学   73635篇
  2021年   13365篇
  2020年   11742篇
  2019年   12884篇
  2018年   21143篇
  2017年   17728篇
  2016年   19620篇
  2015年   21362篇
  2014年   33766篇
  2013年   43376篇
  2012年   46125篇
  2011年   48527篇
  2010年   35013篇
  2009年   36908篇
  2008年   45747篇
  2007年   46521篇
  2006年   48486篇
  2005年   45371篇
  2004年   42728篇
  2003年   39854篇
  2002年   38908篇
  2001年   46518篇
  2000年   46577篇
  1999年   40964篇
  1998年   15716篇
  1997年   14201篇
  1996年   13733篇
  1995年   12827篇
  1994年   11164篇
  1993年   10285篇
  1992年   30273篇
  1991年   29049篇
  1990年   28063篇
  1989年   27035篇
  1988年   25042篇
  1987年   24473篇
  1986年   23603篇
  1985年   22390篇
  1984年   17093篇
  1983年   14634篇
  1982年   9496篇
  1979年   15268篇
  1978年   10937篇
  1977年   9382篇
  1976年   8732篇
  1975年   9489篇
  1974年   11176篇
  1973年   10625篇
  1972年   10091篇
  1971年   9241篇
  1970年   8911篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Comment     
  相似文献   
52.
53.
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   
54.
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   
55.
56.
57.
58.
59.
60.
Dear Sir In the recently published Task force report, under section ‘Fibrinolyticregimens’, the authors recommend not to re-administerstreptokinase for at least 10 years. The reference supportingthis statement is Ref. 51. After evaluating this paper and lookinginto the literature my comments  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