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   2537536篇
  免费   201813篇
  国内免费   4641篇
耳鼻咽喉   36651篇
儿科学   79170篇
妇产科学   67941篇
基础医学   356373篇
口腔科学   73141篇
临床医学   228740篇
内科学   497760篇
皮肤病学   52180篇
神经病学   210668篇
特种医学   104534篇
外国民族医学   961篇
外科学   384893篇
综合类   57227篇
现状与发展   1篇
一般理论   990篇
预防医学   206101篇
眼科学   58936篇
药学   188745篇
  6篇
中国医学   4585篇
肿瘤学   134387篇
  2018年   28121篇
  2017年   22668篇
  2016年   23735篇
  2015年   27831篇
  2014年   37649篇
  2013年   54483篇
  2012年   78354篇
  2011年   77934篇
  2010年   45107篇
  2009年   44466篇
  2008年   71784篇
  2007年   76688篇
  2006年   77668篇
  2005年   82461篇
  2004年   81041篇
  2003年   74777篇
  2002年   69761篇
  2001年   115166篇
  2000年   117861篇
  1999年   101882篇
  1998年   28294篇
  1997年   25734篇
  1996年   25703篇
  1995年   24865篇
  1994年   23377篇
  1993年   21745篇
  1992年   83747篇
  1991年   81178篇
  1990年   78625篇
  1989年   75643篇
  1988年   70296篇
  1987年   69050篇
  1986年   65554篇
  1985年   62134篇
  1984年   46815篇
  1983年   39752篇
  1982年   23605篇
  1981年   20895篇
  1979年   44126篇
  1978年   30739篇
  1977年   25719篇
  1976年   24058篇
  1975年   25963篇
  1974年   32117篇
  1973年   30207篇
  1972年   28466篇
  1971年   26391篇
  1970年   24895篇
  1969年   23132篇
  1968年   20980篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
71.
72.
73.
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   
74.
75.
76.
77.
78.
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   
79.
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   
80.
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