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   2653122篇
  免费   198362篇
  国内免费   5305篇
耳鼻咽喉   36585篇
儿科学   89024篇
妇产科学   72839篇
基础医学   375995篇
口腔科学   74966篇
临床医学   236920篇
内科学   520975篇
皮肤病学   59434篇
神经病学   206859篇
特种医学   102889篇
外国民族医学   873篇
外科学   405571篇
综合类   60114篇
现状与发展   5篇
一般理论   851篇
预防医学   198996篇
眼科学   62251篇
药学   195685篇
  12篇
中国医学   6289篇
肿瘤学   149656篇
  2019年   20311篇
  2018年   29341篇
  2017年   22208篇
  2016年   24451篇
  2015年   27794篇
  2014年   38709篇
  2013年   57498篇
  2012年   79317篇
  2011年   83756篇
  2010年   49930篇
  2009年   46899篇
  2008年   78669篇
  2007年   83758篇
  2006年   84444篇
  2005年   81221篇
  2004年   78921篇
  2003年   75625篇
  2002年   73354篇
  2001年   134183篇
  2000年   137891篇
  1999年   115665篇
  1998年   31035篇
  1997年   27507篇
  1996年   27806篇
  1995年   26614篇
  1994年   24720篇
  1993年   22857篇
  1992年   89485篇
  1991年   86961篇
  1990年   84084篇
  1989年   80618篇
  1988年   73865篇
  1987年   72446篇
  1986年   67874篇
  1985年   64611篇
  1984年   48040篇
  1983年   40660篇
  1982年   23153篇
  1981年   20845篇
  1979年   42577篇
  1978年   29458篇
  1977年   25088篇
  1976年   23344篇
  1975年   25048篇
  1974年   29917篇
  1973年   28562篇
  1972年   26556篇
  1971年   24252篇
  1970年   22718篇
  1969年   20977篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
11.
12.
13.
14.
15.
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   
16.
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   
17.
18.
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   
19.
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