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   2672369篇
  免费   200749篇
  国内免费   5172篇
耳鼻咽喉   36801篇
儿科学   89344篇
妇产科学   73438篇
基础医学   379212篇
口腔科学   75519篇
临床医学   240640篇
内科学   524732篇
皮肤病学   59590篇
神经病学   208587篇
特种医学   103361篇
外国民族医学   868篇
外科学   407847篇
综合类   60157篇
现状与发展   5篇
一般理论   870篇
预防医学   201782篇
眼科学   62172篇
药学   196855篇
  8篇
中国医学   6112篇
肿瘤学   150390篇
  2019年   20566篇
  2018年   29625篇
  2017年   22364篇
  2016年   24666篇
  2015年   27994篇
  2014年   38974篇
  2013年   58013篇
  2012年   79932篇
  2011年   84447篇
  2010年   50289篇
  2009年   47265篇
  2008年   79326篇
  2007年   84500篇
  2006年   85187篇
  2005年   81988篇
  2004年   79691篇
  2003年   76340篇
  2002年   74159篇
  2001年   134701篇
  2000年   138368篇
  1999年   116129篇
  1998年   31288篇
  1997年   27696篇
  1996年   27929篇
  1995年   26763篇
  1994年   24899篇
  1993年   23010篇
  1992年   89919篇
  1991年   87325篇
  1990年   84430篇
  1989年   80967篇
  1988年   74231篇
  1987年   72789篇
  1986年   68234篇
  1985年   65002篇
  1984年   48348篇
  1983年   40942篇
  1982年   23369篇
  1981年   21008篇
  1979年   42874篇
  1978年   29677篇
  1977年   25269篇
  1976年   23543篇
  1975年   25194篇
  1974年   30133篇
  1973年   28745篇
  1972年   26724篇
  1971年   24425篇
  1970年   22884篇
  1969年   21132篇
排序方式: 共有10000条查询结果,搜索用时 16 毫秒
11.
12.
13.
14.
15.
16.
Comprehensive evidence regarding the treatment of non-anaemic iron deficiency in patients undergoing valvular heart surgery is lacking. This study aimed to investigate the association between non-anaemic iron deficiency and postoperative outcomes in these patients. We retrospectively analysed 321 patients of which 180 (56%) had iron deficiency (defined as serum ferritin < 100 ng.ml-1 or < 300 ng.ml-1 with transferrin saturation < 20%). While the iron-deficient group had lower pre-operative haemoglobin levels than the non-iron deficient group (median (IQR [range]) 134 (127–141 [120–172]) g.l-1, 143 (133–150 [120–179]) g.l-1, p = 0.001), there was no between-group difference in allogeneic red blood cell transfusion. Median (IQR [range]) days alive and out of hospital at postoperative day 90 was 1 day shorter in the iron-deficient group (80 (77–82 [9–85]) days vs. 81 (79–83 [0–85]) days, p = 0.026). In multivariable analysis, only cardiopulmonary bypass duration (p = 0.032) and intra-operative allogeneic red blood cell transfusion (p = 0.011) were significantly associated with reduced days alive and out of hospital at postoperative day 90. Iron deficiency did not exert any adverse influence on secondary outcomes except length of hospital stay. Our findings indicate that non-anaemic iron deficiency alone is not associated with adverse effects in patients undergoing valvular heart surgery when it does not translate into an increased risk of allogeneic transfusion.  相似文献   
17.
Patient navigation is a strategy for overcoming barriers to reduce disparities and to improve access and outcomes. The aim of this umbrella review was to identify, critically appraise, synthesize, and present the best available evidence to inform policy and planning regarding patient navigation across the cancer continuum. Systematic reviews examining navigation in cancer care were identified in the Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, Embase, Cumulative Index of Nursing and Allied Health (CINAHL), Epistemonikos, and Prospective Register of Systematic Reviews (PROSPERO) databases and in the gray literature from January 1, 2012, to April 19, 2022. Data were screened, extracted, and appraised independently by two authors. The JBI Critical Appraisal Checklist for Systematic Review and Research Syntheses was used for quality appraisal. Emerging literature up to May 25, 2022, was also explored to capture primary research published beyond the coverage of included systematic reviews. Of the 2062 unique records identified, 61 systematic reviews were included. Fifty-four reviews were quantitative or mixed-methods reviews, reporting on the effectiveness of cancer patient navigation, including 12 reviews reporting costs or cost-effectiveness outcomes. Seven qualitative reviews explored navigation needs, barriers, and experiences. In addition, 53 primary studies published since 2021 were included. Patient navigation is effective in improving participation in cancer screening and reducing the time from screening to diagnosis and from diagnosis to treatment initiation. Emerging evidence suggests that patient navigation improves quality of life and patient satisfaction with care in the survivorship phase and reduces hospital readmission in the active treatment and survivorship care phases. Palliative care data were extremely limited. Economic evaluations from the United States suggest the potential cost-effectiveness of navigation in screening programs.  相似文献   
18.
19.
In this paper we present a coupled Finite Element Method – Boundary Element Method (FEM-BEM) approach for the solution of the free-boundary axi-symmetric plasma equilibrium problem. The proposed method, obtained from an improvement of the Hagenow-Lackner coupling method, allows to efficiently model the equilibrium problem in unbounded domains by discretizing only the plasma region; the external conductors can be modelled either as 2D or 3D models, according to the problem of interest. The paper explores different iterative methods for the solution of the nonlinear Grad-Shafranov equation, such as Picard, Newton-Raphson and Newton-Krylov, in order to provide a robust and reliable tool, able to handle large-scale problems (e.g. high resolution equilibria). This method has been implemented in the FRIDA code (FRee-boundary Integro-Differential Axisimmetric – https://github. om/matteobonotto/ FRIDA), together with a suitable Adaptive Integration Technique (AIT) for the computation of the source term. FRIDA has been successfully tested and validated against experimental data from RFX-mod device, and numerical equilibria of an ITER-like device.  相似文献   
20.
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