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   2525118篇
  免费   201137篇
  国内免费   4625篇
耳鼻咽喉   36497篇
儿科学   78836篇
妇产科学   67709篇
基础医学   354667篇
口腔科学   72677篇
临床医学   227794篇
内科学   494439篇
皮肤病学   51869篇
神经病学   209564篇
特种医学   104328篇
外国民族医学   961篇
外科学   383450篇
综合类   57213篇
现状与发展   1篇
一般理论   980篇
预防医学   204577篇
眼科学   58830篇
药学   188101篇
  6篇
中国医学   4555篇
肿瘤学   133826篇
  2018年   27471篇
  2017年   22308篇
  2016年   23416篇
  2015年   27470篇
  2014年   37265篇
  2013年   53878篇
  2012年   77248篇
  2011年   76714篇
  2010年   44569篇
  2009年   44109篇
  2008年   70765篇
  2007年   75645篇
  2006年   76683篇
  2005年   81521篇
  2004年   80228篇
  2003年   74002篇
  2002年   69058篇
  2001年   115062篇
  2000年   117683篇
  1999年   101802篇
  1998年   28240篇
  1997年   25710篇
  1996年   25682篇
  1995年   24835篇
  1994年   23356篇
  1993年   21726篇
  1992年   83720篇
  1991年   81139篇
  1990年   78598篇
  1989年   75619篇
  1988年   70281篇
  1987年   69025篇
  1986年   65547篇
  1985年   62131篇
  1984年   46801篇
  1983年   39731篇
  1982年   23595篇
  1981年   20892篇
  1979年   44119篇
  1978年   30747篇
  1977年   25717篇
  1976年   24060篇
  1975年   25952篇
  1974年   32101篇
  1973年   30200篇
  1972年   28466篇
  1971年   26389篇
  1970年   24882篇
  1969年   23121篇
  1968年   20976篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
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   
73.
74.
75.
76.
77.
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   
78.
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   
79.
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