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   2193923篇
  免费   159478篇
  国内免费   4530篇
耳鼻咽喉   30591篇
儿科学   73545篇
妇产科学   62716篇
基础医学   319311篇
口腔科学   62878篇
临床医学   189565篇
内科学   429611篇
皮肤病学   48871篇
神经病学   172838篇
特种医学   83754篇
外国民族医学   652篇
外科学   329150篇
综合类   47130篇
现状与发展   1篇
一般理论   673篇
预防医学   172162篇
眼科学   51400篇
药学   163920篇
  4篇
中国医学   4546篇
肿瘤学   114613篇
  2018年   24373篇
  2017年   18041篇
  2016年   20141篇
  2015年   22861篇
  2014年   30782篇
  2013年   47131篇
  2012年   65072篇
  2011年   69595篇
  2010年   40679篇
  2009年   37429篇
  2008年   65201篇
  2007年   69990篇
  2006年   70858篇
  2005年   68425篇
  2004年   66062篇
  2003年   63774篇
  2002年   62113篇
  2001年   96798篇
  2000年   99378篇
  1999年   83812篇
  1998年   23678篇
  1997年   21119篇
  1996年   21274篇
  1995年   20260篇
  1994年   19056篇
  1993年   17663篇
  1992年   67125篇
  1991年   65884篇
  1990年   65081篇
  1989年   62846篇
  1988年   58056篇
  1987年   57425篇
  1986年   54367篇
  1985年   52141篇
  1984年   39103篇
  1983年   33561篇
  1982年   20076篇
  1981年   17914篇
  1979年   36923篇
  1978年   26288篇
  1977年   22582篇
  1976年   21427篇
  1975年   23081篇
  1974年   27544篇
  1973年   26666篇
  1972年   24973篇
  1971年   23376篇
  1970年   21673篇
  1969年   20694篇
  1968年   19393篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
Vaskulitiden     
  相似文献   
74.
75.
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   
76.
77.
Preimplantation genetic diagnosis (PGD) was originally developed to diagnose embryo-related genetic abnormalities for couples who present a high risk of a specific inherited disorder. Because this technology involves embryo selection, the medical, bioethical, and legal implications of the technique have been debated, particularly when it is used to select features that are not related to serious diseases. Although several initiatives have attempted to achieve regulatory harmonization, the diversity of healthcare services available and the presence of cultural differences have hampered attempts to achieve this goal. Thus, in different countries, the provision of PGD and regulatory frameworks reflect the perceptions of scientific groups, legislators, and society regarding this technology. In Brazil, several texts have been analyzed by the National Congress to regulate the use of assisted reproduction technologies. Legislative debates, however, are not conclusive, and limited information has been published on how PGD is specifically regulated. The country requires the development of new regulatory standards to ensure adequate access to this technology and to guarantee its safe practice. This study examined official documents published on PGD regulation in Brazil and demonstrated how little direct oversight of PGD currently exists. It provides relevant information to encourage reflection on a particular regulation model in a Brazilian context, and should serve as part of the basis to enable further reform of the clinical practice of PGD in the country.  相似文献   
78.
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