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   2404388篇
  免费   196912篇
  国内免费   4288篇
耳鼻咽喉   34609篇
儿科学   73842篇
妇产科学   63721篇
基础医学   338409篇
口腔科学   67908篇
临床医学   220885篇
内科学   473403篇
皮肤病学   48259篇
神经病学   203584篇
特种医学   96528篇
外国民族医学   887篇
外科学   362917篇
综合类   56501篇
现状与发展   1篇
一般理论   1015篇
预防医学   195180篇
眼科学   55780篇
药学   179296篇
  4篇
中国医学   4403篇
肿瘤学   128456篇
  2018年   25045篇
  2017年   19408篇
  2016年   21235篇
  2015年   23990篇
  2014年   34510篇
  2013年   52452篇
  2012年   70989篇
  2011年   74710篇
  2010年   43801篇
  2009年   42048篇
  2008年   70872篇
  2007年   75207篇
  2006年   76072篇
  2005年   74110篇
  2004年   71245篇
  2003年   68720篇
  2002年   67882篇
  2001年   112634篇
  2000年   116701篇
  1999年   98549篇
  1998年   28175篇
  1997年   25775篇
  1996年   25639篇
  1995年   24767篇
  1994年   23320篇
  1993年   21717篇
  1992年   79493篇
  1991年   76490篇
  1990年   73650篇
  1989年   70920篇
  1988年   65916篇
  1987年   64864篇
  1986年   61399篇
  1985年   58472篇
  1984年   44302篇
  1983年   37720篇
  1982年   22954篇
  1981年   20411篇
  1979年   41332篇
  1978年   29014篇
  1977年   24381篇
  1976年   22853篇
  1975年   23985篇
  1974年   29650篇
  1973年   28049篇
  1972年   26240篇
  1971年   24158篇
  1970年   22759篇
  1969年   21093篇
  1968年   19138篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
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   
72.
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   
73.
74.
灾难的时代错误:灾害医学的过去、现在和将来(一)   总被引:1,自引:0,他引:1  
灾难,特别是地震、火山、洪水以及与战争有关的事件如饥饿和流行性传染病,是人类有记录的经历的一部分。从意大利庞贝的火山爆发,到约翰斯顿的洪水、第二次世界大战和黑色瘟疫,到西班牙流感,都发生了灾难,这不会被传说和历史书籍长期忘却。不过,在20世纪中叶以前,那些灾难的发生相对较少,且相距时间较长。从20世纪中叶以来,灾难的本质发生了变化。从恐怖分子使用“新技术”,到与气候有关的导致亿万美元经济损失的事件,表明这个世界正在发生变化。仅仅在最近的50~60年间,造成多种多样的伤亡事件,其危险性和频率的增加引人注目,并且注定要在接…  相似文献   
75.
The aim of the present study was to explore differences in the clinical expression, clinical diagnoses and management of airway diseases in a primary-care setting. Patients aged >or=35 yrs who had ever smoked were enrolled when they presented for any reason to one of eight rural primary-care practices. Respiratory symptom questionnaires and spirometry were administered. In total, 1,034 patients had acceptable and reproducible spirometry, of whom 550 (53%) were males and 484 (47%) were females. Males smoked more than females (41.2 versus 29.2 pack-yrs) respectively, and were more likely to have a pre-bronchodilator forced expiratory volume in one second/forced vital capacity <0.70 at 22.4 versus 11.8%, respectively. However, more females than males reported breathlessness (51.0 versus 42.8%, respectively), a prior diagnosis compatible with airflow obstruction and taking respiratory medications (23.4 versus 14.9%, respectively). In conclusion, the current results suggest that females are more likely than males to report breathlessness and be prescribed respiratory medications independent of differences in the severity of airflow obstruction.  相似文献   
76.
77.
78.
79.
High levels of tumor necrosis factor-alpha (TNF-alpha), a pro-inflammatory cytokine, are present in the wound fluid of chronic nonhealing wounds. This leads to increased inflammation, cytokine expression, and ultimately results in impaired wound healing and tissue destruction. Etanercept is a recombinant fusion protein that consists of the soluble TNF receptor (p75) linked to the Fc portion of human IgG1. It is an effective inhibitor of TNF-alpha and has been shown to provide rapid and sustained improvement in rheumatoid arthritis by acting as a soluble receptor binding TNF-alpha and preventing its proinflammatory activities. Therefore, the aim of this study was to determine whether Etanercept could inhibit TNF-alpha activity in chronic wound fluid. Wound fluid was collected from the venous leg ulcers of 16 different patients. The effect of Etanercept on TNF-alpha activity was evaluated using both a TNF-alpha bioassay and an enzyme-linked immunoassay. Etanercept was found to reduce the cytotoxic effect of chronic wound fluid on L929 fibroblasts by approximately 30% and neutralized TNF-alpha binding in the enzyme-linked immunoassay by up to 80%. Direct application of Etanercept to chronic wounds may therefore reduce the inflammatory activity of TNF-alpha, which could reduce the chronicity of venous leg ulcers and thus aid in the healing of these wounds.  相似文献   
80.
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