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   2704209篇
  免费   192667篇
  国内免费   8010篇
耳鼻咽喉   35365篇
儿科学   88271篇
妇产科学   73756篇
基础医学   379113篇
口腔科学   72434篇
临床医学   246121篇
内科学   539477篇
皮肤病学   64548篇
神经病学   225076篇
特种医学   104401篇
外国民族医学   742篇
外科学   403883篇
综合类   51921篇
现状与发展   7篇
一般理论   1095篇
预防医学   204962篇
眼科学   59334篇
药学   196268篇
  10篇
中国医学   5526篇
肿瘤学   152576篇
  2021年   22036篇
  2019年   22683篇
  2018年   31845篇
  2017年   24621篇
  2016年   28469篇
  2015年   32089篇
  2014年   44214篇
  2013年   65596篇
  2012年   87986篇
  2011年   92806篇
  2010年   55887篇
  2009年   53706篇
  2008年   86744篇
  2007年   92134篇
  2006年   93506篇
  2005年   89878篇
  2004年   86398篇
  2003年   83366篇
  2002年   80207篇
  2001年   129537篇
  2000年   132165篇
  1999年   111702篇
  1998年   32889篇
  1997年   29211篇
  1996年   29323篇
  1995年   28373篇
  1994年   25939篇
  1993年   24278篇
  1992年   85758篇
  1991年   82149篇
  1990年   79258篇
  1989年   76517篇
  1988年   69910篇
  1987年   68433篇
  1986年   63944篇
  1985年   60931篇
  1984年   45438篇
  1983年   38412篇
  1982年   23052篇
  1981年   20551篇
  1979年   39261篇
  1978年   27737篇
  1977年   23582篇
  1976年   21786篇
  1975年   23068篇
  1974年   26998篇
  1973年   25569篇
  1972年   23897篇
  1971年   22081篇
  1970年   20299篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
BACKGROUND: The incidence of malignant melanoma of the skin has risen in every part of the world where reliable cancer registration data are found. OBJECTIVE: Our study aims to describe the changing incidence of and survival from invasive cutaneous malignant melanoma in Malta, by analysing the data from the 211 cases that were registered at the Malta National Cancer Registry between 1993 and 2002. RESULTS: The age standardized incidence rates for invasive cutaneous malignant melanoma rose from 3.7 per 100,000 population per year for males and 5.1 for females in the first 5-year period, to 8.0 per 100,000 population per year for males and 5.9 for females in the second 5-year period. In both sexes, numbers of thin (< or = 1.0 mm) invasive melanomas increased significantly between 1993 and 2002; males also registered a significant increase in intermediate-thickness (1.01-4.0 mm) melanomas. The increase in numbers of thin and intermediate-thickness melanomas between the two 5-year periods was greatest in patients aged 60 years and over. The overall absolute 5-year survival rate for the first period was 74% and for the second period 92%. CONCLUSION: Numbers of reported cases of invasive cutaneous malignant melanoma in Malta have more than doubled during the 10-year study period. This is mostly due to a marked rise in the diagnosis of thin melanomas in both sexes, occurring mainly in patients aged 60 years and over. As thin melanomas are of low metastasizing potential, this has resulted in an increase in survival between the two 5-year study periods.  相似文献   
92.
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   
93.
Southgate  M. Therese 《JAMA》2006,296(13):1564
  相似文献   
94.
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   
95.
96.
97.
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   
98.
99.
100.
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