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   247375篇
  免费   6708篇
  国内免费   264篇
耳鼻咽喉   2175篇
儿科学   8595篇
妇产科学   4298篇
基础医学   26018篇
口腔科学   2825篇
临床医学   19706篇
内科学   45651篇
皮肤病学   1456篇
神经病学   23540篇
特种医学   11740篇
外科学   40258篇
综合类   3706篇
现状与发展   1篇
一般理论   60篇
预防医学   24276篇
眼科学   4292篇
药学   14293篇
中国医学   723篇
肿瘤学   20734篇
  2023年   297篇
  2022年   528篇
  2021年   1462篇
  2020年   884篇
  2019年   1398篇
  2018年   23306篇
  2017年   18319篇
  2016年   20653篇
  2015年   2545篇
  2014年   3085篇
  2013年   4091篇
  2012年   11960篇
  2011年   26130篇
  2010年   21536篇
  2009年   14116篇
  2008年   23930篇
  2007年   26372篇
  2006年   5434篇
  2005年   7091篇
  2004年   7860篇
  2003年   8654篇
  2002年   6636篇
  2001年   926篇
  2000年   887篇
  1999年   866篇
  1998年   1110篇
  1997年   969篇
  1996年   771篇
  1995年   744篇
  1994年   692篇
  1993年   614篇
  1992年   497篇
  1991年   490篇
  1990年   488篇
  1989年   458篇
  1988年   428篇
  1987年   389篇
  1986年   365篇
  1985年   391篇
  1984年   470篇
  1983年   446篇
  1982年   619篇
  1981年   570篇
  1980年   567篇
  1979年   313篇
  1978年   319篇
  1977年   331篇
  1976年   257篇
  1974年   260篇
  1973年   258篇
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
71.
The optimal allocation of cadaveric kidneys for transplantation with reference to human leukocyte antigen (HLA) match and sharing these organs to a distant center remains controversial. The current analysis was performed using the United Network for Organ Sharing (UNOS) database for cadaveric kidney transplants (Tx) between 1988 and 1997. The graft survivals of zero-mismatch (matched) kidneys with the mate (mismatched) kidneys were compared. There were 2385 donors and 4770 Tx. Significant differences in recipient demographics between matched and mismatched Tx were: fewer African-American race (AA) in the matched group (9.0% vs. 21.9%), higher number of previous Tx (25.5% vs. 14.8%) and elevated mean cold ischemia time (24.0 vs. 22.2 h). Post-Tx dialysis requirements were similar (22.8% vs. 24.1%, p = 0.62) and matched kidneys had to travel more distance (920 vs. 232 miles). Using a Cox model, the matched group had a decreased relative hazard of graft failure of 23.0% (p = 0.0002) or 35% (p < 0.0001) with and without censoring for death. There was significantly better graft survival in the matched recipients in all pairs except AA (matched) and non-AA (mismatched). For older donors (> or = 50 years, n = 1508), the matched grafts survival was marginally significant (p =0.05). Matched kidneys have improved survival compared with the mismatched kidneys despite the longer distance traveled. The benefit of mismatched transplants was predominantly seen in non-AA.  相似文献   
72.
73.
74.
75.
76.
This study investigated analogical reasoning abilities of alcoholics who had been abstinent from alcohol for at least 1 year. Their performance was compared to that of nonalcoholic controls matched as a group for education, age, and gender. Solution times and error rates were modeled using a regression model. Results showed a nonsignificant trend for alcoholics to be faster, but more error prone, than controls. The same componential model applied to both groups, and fit them equally well. Although differences have been found in analogical reasoning ability between controls and alcoholics immediately following detoxification, we find no evidence of differences after extended periods of sobriety.  相似文献   
77.
The simultaneous determination of cerebrospinal fluid (CSF) and plasma adenosine deaminase (ADA) activity was evaluated as a diagnostic aid in tuberculous meningitis (TBM). CSF and plasma ADA activity were determined in four groups of patients: (i) a 'no meningitis' group of 174 children investigated for possible meningitis, but found to be uninfected; (ii) an aseptic meningitis group of 40 children; (iii) a bacterial meningitis group of 31 children; and (iv) a TBM group of 27 patients (24 children and 3 adults). CSF ADA alone was determined in a further 23 children with aseptic meningitis, 19 with bacterial meningitis and 13 children and 7 adults with TBM. Both the CSF/plasma ADA ratio and the absolute CSF ADA activity were raised in TBM (mean values 0,24 and 12,61 U/I respectively) and bacterial meningitis (mean values 0,59 and 15,43 U/I respectively), but not in the aseptic meningitis group (mean values 0,06 and 2,00 U/I) or the 'no meningitis' group (mean values 0,04 and 1,51 U/I). Both values will distinguish TBM from aseptic meningitis, but do not appear to hold any marked advantages over conventional CSF criteria in the diagnosis of TBM.  相似文献   
78.
79.
80.
THE BASIC SCIENCE OF PSYCHOLOGY HAS IDENTIFIED specific ingrained responses that are fundamental elements of human nature, underpin common influence strategies and may apply in medical settings. People feel a sense of obligation to repay a perceived debt. A request becomes more attractive when preceded by a marginally worse request. The drive to act consistently will persist even if demands escalate. Peer pressure is intense when people face uncertainty. The image of the requester influences the attractiveness of a request. Authorities have power beyond their expertise. Opportunities appear more valuable when they appear less available. These 7 responses were discovered decades ago in psychology research and seem intuitively understood in the business world, but they are rarely discussed in medical texts. An awareness of these principles can provide a framework for physicians to help patients change their behaviour and to understand how others in society sometime alter patients' choices.  相似文献   
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