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   2794篇
  免费   242篇
  国内免费   34篇
耳鼻咽喉   11篇
儿科学   109篇
妇产科学   49篇
基础医学   309篇
口腔科学   40篇
临床医学   244篇
内科学   612篇
皮肤病学   30篇
神经病学   208篇
特种医学   190篇
外科学   518篇
综合类   55篇
一般理论   14篇
预防医学   281篇
眼科学   29篇
药学   197篇
中国医学   1篇
肿瘤学   173篇
  2021年   34篇
  2020年   24篇
  2019年   29篇
  2018年   23篇
  2017年   27篇
  2016年   31篇
  2015年   46篇
  2014年   50篇
  2013年   72篇
  2012年   108篇
  2011年   118篇
  2010年   88篇
  2009年   85篇
  2008年   90篇
  2007年   121篇
  2006年   107篇
  2005年   98篇
  2004年   100篇
  2003年   96篇
  2002年   95篇
  2001年   86篇
  2000年   91篇
  1999年   85篇
  1998年   57篇
  1997年   54篇
  1996年   46篇
  1995年   47篇
  1994年   24篇
  1993年   38篇
  1992年   64篇
  1991年   56篇
  1990年   65篇
  1989年   80篇
  1988年   55篇
  1987年   66篇
  1986年   51篇
  1985年   56篇
  1984年   43篇
  1983年   42篇
  1982年   37篇
  1981年   32篇
  1980年   30篇
  1979年   41篇
  1978年   44篇
  1977年   34篇
  1976年   27篇
  1975年   40篇
  1971年   27篇
  1970年   24篇
  1969年   21篇
排序方式: 共有3070条查询结果,搜索用时 31 毫秒
1.
2.
A simple circuit design is described which provides LED readout of transmitted and reflected pulsed rf power. The utility of monitoring these variables in physiological NMR studies is discussed.  相似文献   
3.
Colonoscopy and bacteraemia: an experience in 50 patients   总被引:1,自引:0,他引:1  
There is little consensus concerning the incidence of bacteraemia during colonoscopy and the need for antibiotic prophylaxis in susceptible patients. Hepatic abscesses in one patient which may have been related to prior colonoscopic examinations led the authors to carry out a prospective study of 50 patients undergoing colonoscopy. Multiple blood cultures were carried out to maximise the positive yield of transient bacteraemia and to attempt to determine the time when bacteraemia is most likely to occur. Five patients had positive blood cultures. In two patients S epidermidis was isolated, but only from the precolonoscopic blood sample. In three subjects enteric organisms were cultured from blood samples obtained during the procedure. In one of these three the same organism was cultured from the preendoscopic blood sample so that in only two patients (4%) could the bacteraemia be attributed to the colonoscopy. These results would suggest that the risk of bacteraemia during colonoscopy is low.  相似文献   
4.
OBJECTIVES: Angioplasty is often used in the management of lower limb ischaemia and can reduce the need for infrainguinal bypass in some patients. There is an associated failure rate with this technique and bypass surgery is often used in this situation as a secondary limb salvage procedure. We aimed to evaluate the outcome of infrainguinal bypass grafting following failed attempt at angioplasty. METHODS: All cases of infrainguinal bypass at a single centre over a seven year period were identified and notes reviewed. Cases were divided into four groups according to their indication for surgery; acute ischaemia, chronic critical ischaemia, failed angioplasty and an 'other' group including aneurysmal disease and claudicants. The failed angioplasty group was compared with the other three groups. Survival analysis was performed using Kaplan Meier curves and groups compared in terms of long term patency and survival. RESULTS: Primary patency was 61.2% in the failed angioplasty group at 12 months compared with 60.6% in the other groups (P=1.11). There was also no significant difference in primary patency at 60 months (50% vs 40.6%, P=0.26). Survival at 12 months was also comparable between the groups (failed angioplasty group 74.2% compared with 77.3% in the other groups, P=0.662) as was 60 months survival (33.3% and 35.4% respectively, P=0.166). DISCUSSION: In this study, outcome of infrainguinal bypass following failed angioplasty was comparable to outcome of surgery performed for another indication. This paper supports the use of distal bypass surgery for limb salvage in cases where minimal access techniques have failed.  相似文献   
5.
6.
麦冬类中药组织切片计算机三维重建图鉴   总被引:9,自引:0,他引:9  
利用计算机技术实现麦冬类中药组织连续切片三维重建与动态显示,为计算机辅助生药学鉴定和教学提供了新的三维图像技术和研究资料。  相似文献   
7.
用混合粘合剂碳糊电极测定丁螺环酮   总被引:6,自引:1,他引:5  
用混合粘合剂碳糊电极测定丁螺环酮张正奇,曾鸽鸣,刘传桂,黎艳飞(湖南大学化学化工系,长沙410082)碳糊电极无毒,制作方便,表面更新容易,应用电位范围广,在药物分析中已有应用[1~5]。我们在液体石腊中加入添加剂,组成混合粘合剂,可显著改善电极的检...  相似文献   
8.
Prospective study of relative weight, height, and risk of breast cancer   总被引:1,自引:0,他引:1  
We examined relative weight and height in relation to subsequent breast cancer risk among 115,534 women 30 to 55 years of age and free from cancer in 1976. By 1984, six hundred fifty-eight premenopausal and 420 postmenopausal breast cancers were documented during 734,716 person-years. Among premenopausal women, risk of breast cancer decreased significantly with increasing relative weight (relative risk for the highest category was 0.6). A similar inverse association was seen for recalled relative weight at 18 years of age. Postmenopausal breast cancer was not associated with relative weight, either recent or at age 18. Height was not associated with breast cancer risk among premenopausal women and only weakly related among postmenopausal women. These data suggest that obesity among premenopausal and early postmenopausal women does not increase breast cancer risk substantially.  相似文献   
9.
10.
Summary.  Platelet membranes provide procoagulant surfaces for the assembly and expression of the factor X-activating complex and promote the proteolytic activation and assembly of the prothrombinase complex resulting in normal hemostasis. Recent studies from our laboratory and others indicate that platelets possess specific, high-affinity, saturable, receptors for factors XI, XIa, IX, IXa, X, VIII, VIIIa, V, Va and Xa, prothrombin, and thrombin. Studies described in this review support the hypothesis that the factor X-activating complex on the platelet surface consists of three receptors (for the enzyme, factor IXa; the substrate, factor X; and the cofactor, factor VIIIa), the colocalization of which results in a 24 million-fold acceleration of the rate of factor X activation. Whether the procoagulant surface of platelets is defined exclusively by procoagulant phospholipids, or whether specific protein receptors exist for the coagulant factors and proteases, is currently unresolved. The interaction between coagulation proteins and platelets is critical to the maintenance of normal hemostasis and is pathogenetically important in human disease.  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