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   3256824篇
  免费   254512篇
  国内免费   6314篇
耳鼻咽喉   48318篇
儿科学   100582篇
妇产科学   89638篇
基础医学   456572篇
口腔科学   96410篇
临床医学   291922篇
内科学   633323篇
皮肤病学   69065篇
神经病学   270487篇
特种医学   129714篇
外国民族医学   1265篇
外科学   496479篇
综合类   78249篇
现状与发展   7篇
一般理论   1310篇
预防医学   253220篇
眼科学   78464篇
药学   244755篇
  7篇
中国医学   6380篇
肿瘤学   171483篇
  2018年   31911篇
  2016年   27549篇
  2015年   31021篇
  2014年   44529篇
  2013年   67968篇
  2012年   90752篇
  2011年   95930篇
  2010年   56542篇
  2009年   54636篇
  2008年   91525篇
  2007年   98073篇
  2006年   98956篇
  2005年   96588篇
  2004年   93021篇
  2003年   90169篇
  2002年   89029篇
  2001年   149842篇
  2000年   154931篇
  1999年   131402篇
  1998年   37488篇
  1997年   34155篇
  1996年   33287篇
  1995年   32157篇
  1994年   30135篇
  1993年   28036篇
  1992年   105072篇
  1991年   101439篇
  1990年   98443篇
  1989年   95280篇
  1988年   88509篇
  1987年   87238篇
  1986年   83098篇
  1985年   79404篇
  1984年   59997篇
  1983年   51125篇
  1982年   31078篇
  1981年   27837篇
  1980年   26082篇
  1979年   56877篇
  1978年   40265篇
  1977年   34424篇
  1976年   31822篇
  1975年   34550篇
  1974年   41983篇
  1973年   40231篇
  1972年   38069篇
  1971年   35445篇
  1970年   33492篇
  1969年   31432篇
  1968年   28917篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
91.
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   
92.
93.
94.
95.
96.
97.
98.
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   
99.
100.
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