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   2367373篇
  免费   198164篇
  国内免费   4204篇
耳鼻咽喉   34262篇
儿科学   72740篇
妇产科学   62930篇
基础医学   334404篇
口腔科学   67516篇
临床医学   214939篇
内科学   466806篇
皮肤病学   47927篇
神经病学   200708篇
特种医学   95950篇
外国民族医学   886篇
外科学   360160篇
综合类   56176篇
现状与发展   1篇
一般理论   978篇
预防医学   189906篇
眼科学   55401篇
药学   177548篇
  4篇
中国医学   4366篇
肿瘤学   126133篇
  2018年   24228篇
  2016年   20590篇
  2015年   23305篇
  2014年   33568篇
  2013年   50870篇
  2012年   68824篇
  2011年   72363篇
  2010年   42508篇
  2009年   40907篇
  2008年   68827篇
  2007年   73156篇
  2006年   74054篇
  2005年   72081篇
  2004年   69393篇
  2003年   67052篇
  2002年   66328篇
  2001年   112488篇
  2000年   116548篇
  1999年   98373篇
  1998年   27874篇
  1997年   25531篇
  1996年   25460篇
  1995年   24611篇
  1994年   23167篇
  1993年   21569篇
  1992年   79410篇
  1991年   76410篇
  1990年   73553篇
  1989年   70814篇
  1988年   65796篇
  1987年   64769篇
  1986年   61301篇
  1985年   58381篇
  1984年   44161篇
  1983年   37549篇
  1982年   22801篇
  1981年   20230篇
  1980年   18937篇
  1979年   41229篇
  1978年   28921篇
  1977年   24253篇
  1976年   22762篇
  1975年   23910篇
  1974年   29595篇
  1973年   28025篇
  1972年   26223篇
  1971年   24147篇
  1970年   22727篇
  1969年   21064篇
  1968年   19115篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
83.
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   
84.
85.
86.
87.
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   
88.
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   
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