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   2891084篇
  免费   237727篇
  国内免费   5491篇
耳鼻咽喉   42750篇
儿科学   88546篇
妇产科学   78429篇
基础医学   409524篇
口腔科学   84189篇
临床医学   262098篇
内科学   560945篇
皮肤病学   59022篇
神经病学   243034篇
特种医学   116090篇
外国民族医学   1042篇
外科学   440552篇
综合类   72621篇
现状与发展   3篇
一般理论   1175篇
预防医学   233621篇
眼科学   69431篇
药学   216247篇
  4篇
中国医学   5375篇
肿瘤学   149604篇
  2018年   28639篇
  2016年   24556篇
  2015年   27903篇
  2014年   40260篇
  2013年   61490篇
  2012年   82781篇
  2011年   87272篇
  2010年   51382篇
  2009年   49115篇
  2008年   82836篇
  2007年   88730篇
  2006年   89354篇
  2005年   87212篇
  2004年   84421篇
  2003年   81537篇
  2002年   80234篇
  2001年   130074篇
  2000年   134583篇
  1999年   113974篇
  1998年   33502篇
  1997年   30591篇
  1996年   30178篇
  1995年   29176篇
  1994年   27472篇
  1993年   25592篇
  1992年   93069篇
  1991年   89842篇
  1990年   86954篇
  1989年   83768篇
  1988年   78087篇
  1987年   77084篇
  1986年   72925篇
  1985年   70006篇
  1984年   53490篇
  1983年   45765篇
  1982年   28268篇
  1981年   25281篇
  1980年   23790篇
  1979年   51321篇
  1978年   36369篇
  1977年   30627篇
  1976年   28625篇
  1975年   30360篇
  1974年   37578篇
  1973年   35936篇
  1972年   33679篇
  1971年   31115篇
  1970年   29428篇
  1969年   27674篇
  1968年   25178篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
82.
83.
84.
Caring for patients with end-stage kidney disease (ESKD) in the United States is challenging, due in part to the complex epidemiology of the disease's progression as well as the ways in which care is delivered. As CKD progresses toward ESKD, the number of comorbidities increases and care involves multiple healthcare providers from multiple subspecialties. This occurs in the context of a fragmented US healthcare delivery system that is traditionally siloed by provider specialty, organization, as well as systems of payment and administration. This article describes the role of care fragmentation in the delivery of optimal ESKD care and identifies research gaps in the evidence across the continuum of care. We then consider the impact of care fragmentation on ESKD care from the patient and health system perspectives and explore opportunities for system-level interventions aimed at improving care for patients with ESKD.  相似文献   
85.
86.
87.
88.
89.
Red cell exchange (RCE) is a common procedure in adults with sickle cell disease (SCD). Implantable dual lumen Vortex (DLV) ports can be used for RCE in patients with poor peripheral venous access. We performed a retrospective cohort study of RCE procedures performed in adults with SCD. The main objective of the study was to compare the inlet speed, duration of procedures and rate of complications performed through DLV ports to those performed through temporary central venous and peripheral catheters. Twenty‐nine adults with SCD underwent a total of 318 RCE procedures. Twenty adults had DLV ports placed and 218 procedures were performed using DLV ports. Mean length of follow‐up after DLV port placement was 397 ± 263 days. Six DLV ports were removed due to infection and 1 for malfunction after a mean of 171 ± 120 days. Compared to temporary central venous and peripheral catheters, DLV port procedures had a greater rate of procedural complications, a longer duration, and a lower inlet speed (all P < 0.01). When accounting for the maximum allowable inlet speed to avoid citrate toxicity, 40% of DLV port procedures were greater than 10% below maximum speed, compared to 7 and 14% of procedures performed through temporary central venous and peripheral catheters (P < 0.0001). In conclusion, DLV ports can be used for RCE in adults with SCD, albeit with more procedural complications and longer duration. The smaller internal diameter and longer catheter of DLV ports compared to temporary central venous catheters likely accounts for the differences noted. J. Clin. Apheresis 30:353–358, 2015. © 2015 Wiley Periodicals, Inc.  相似文献   
90.
The catechol-O-methyltransferase (COMT) enzyme is a major determinant of prefrontal dopamine levels. The Val158Met polymorphism affects COMT enzymatic activity and has been associated with variation in executive function and affective processing. This study investigated the effect of COMT genotype on the flexible modulation of the balance between processing self-generated and processing stimulus-oriented information, in the presence or absence of affective distractors. Analyses included 124 healthy adult participants, who were also assessed on standard working memory (WM) tasks. Relative to Val carriers, Met homozygotes made fewer errors when selecting and manipulating self-generated thoughts. This effect was partly accounted for by an association between COMT genotype and visuospatial WM performance. We also observed a complex interaction between the influence of affective distractors, COMT genotype and sex on task accuracy: male, but not female, participants showed a sensitivity to the affective distractors that was dependent on COMT genotype. This was not accounted for by WM performance. This study provides novel evidence of the role of dopaminergic genetic variation on the ability to select and manipulate self-generated thoughts. The results also suggest sexually dimorphic effects of COMT genotype on the influence of affective distractors on executive function.  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