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   2486055篇
  免费   204316篇
  国内免费   4322篇
耳鼻咽喉   36164篇
儿科学   77059篇
妇产科学   65920篇
基础医学   352252篇
口腔科学   71739篇
临床医学   225555篇
内科学   488147篇
皮肤病学   51172篇
神经病学   212527篇
特种医学   100677篇
外国民族医学   896篇
外科学   377045篇
综合类   56746篇
现状与发展   2篇
一般理论   1044篇
预防医学   197803篇
眼科学   58133篇
药学   185443篇
  4篇
中国医学   4545篇
肿瘤学   131820篇
  2018年   26790篇
  2017年   20995篇
  2016年   23369篇
  2015年   25760篇
  2014年   36305篇
  2013年   55689篇
  2012年   74967篇
  2011年   79124篇
  2010年   46323篇
  2009年   43651篇
  2008年   75465篇
  2007年   80104篇
  2006年   80753篇
  2005年   78701篇
  2004年   75609篇
  2003年   73244篇
  2002年   72257篇
  2001年   116150篇
  2000年   121078篇
  1999年   101114篇
  1998年   29098篇
  1997年   26531篇
  1996年   26269篇
  1995年   25310篇
  1994年   23845篇
  1993年   22199篇
  1992年   80247篇
  1991年   77146篇
  1990年   74303篇
  1989年   71591篇
  1988年   66503篇
  1987年   65481篇
  1986年   61926篇
  1985年   59176篇
  1984年   44892篇
  1983年   38209篇
  1982年   23425篇
  1981年   20817篇
  1980年   19400篇
  1979年   41720篇
  1978年   29342篇
  1977年   24699篇
  1976年   23115篇
  1975年   24308篇
  1974年   29960篇
  1973年   28345篇
  1972年   26535篇
  1971年   24475篇
  1970年   23000篇
  1969年   21313篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
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   
82.
83.
84.
85.
86.
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   
87.
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   
88.
89.
90.
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