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   3212731篇
  免费   262859篇
  国内免费   9327篇
耳鼻咽喉   45381篇
儿科学   101103篇
妇产科学   86597篇
基础医学   447276篇
口腔科学   92109篇
临床医学   294817篇
内科学   635564篇
皮肤病学   69771篇
神经病学   270122篇
特种医学   129258篇
外国民族医学   1111篇
外科学   490591篇
综合类   77138篇
现状与发展   3篇
一般理论   1305篇
预防医学   263058篇
眼科学   73989篇
药学   234311篇
  9篇
中国医学   5777篇
肿瘤学   165627篇
  2018年   33031篇
  2016年   29348篇
  2015年   33066篇
  2014年   47035篇
  2013年   71405篇
  2012年   92651篇
  2011年   98709篇
  2010年   59547篇
  2009年   57345篇
  2008年   93123篇
  2007年   99246篇
  2006年   100358篇
  2005年   97756篇
  2004年   93802篇
  2003年   90844篇
  2002年   88443篇
  2001年   147601篇
  2000年   152575篇
  1999年   128490篇
  1998年   38740篇
  1997年   34931篇
  1996年   35239篇
  1995年   34719篇
  1994年   32527篇
  1993年   30460篇
  1992年   105034篇
  1991年   101802篇
  1990年   98221篇
  1989年   94096篇
  1988年   87575篇
  1987年   86352篇
  1986年   81736篇
  1985年   78545篇
  1984年   59874篇
  1983年   51023篇
  1982年   31567篇
  1981年   28382篇
  1980年   26698篇
  1979年   55746篇
  1978年   39885篇
  1977年   33610篇
  1976年   31385篇
  1975年   32932篇
  1974年   40146篇
  1973年   38247篇
  1972年   35761篇
  1971年   33136篇
  1970年   30956篇
  1969年   28840篇
  1968年   26519篇
排序方式: 共有10000条查询结果,搜索用时 406 毫秒
111.
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   
112.
113.
114.
115.
116.
117.
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   
118.
119.
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   
120.
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