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   1410891篇
  免费   115883篇
  国内免费   3337篇
耳鼻咽喉   18384篇
儿科学   46600篇
妇产科学   41058篇
基础医学   201080篇
口腔科学   37807篇
临床医学   126244篇
内科学   284810篇
皮肤病学   33403篇
神经病学   117115篇
特种医学   53985篇
外国民族医学   464篇
外科学   211156篇
综合类   32761篇
现状与发展   3篇
一般理论   487篇
预防医学   110053篇
眼科学   31515篇
药学   98591篇
  1篇
中国医学   3349篇
肿瘤学   81245篇
  2021年   10957篇
  2019年   11758篇
  2018年   16674篇
  2017年   12743篇
  2016年   14356篇
  2015年   16105篇
  2014年   22670篇
  2013年   33496篇
  2012年   45568篇
  2011年   48105篇
  2010年   28229篇
  2009年   27141篇
  2008年   44418篇
  2007年   46930篇
  2006年   47504篇
  2005年   45966篇
  2004年   43795篇
  2003年   41769篇
  2002年   40254篇
  2001年   73036篇
  2000年   74552篇
  1999年   61590篇
  1998年   17003篇
  1997年   15441篇
  1996年   15593篇
  1995年   14804篇
  1994年   13402篇
  1993年   12596篇
  1992年   45862篇
  1991年   43506篇
  1990年   41508篇
  1989年   39573篇
  1988年   36195篇
  1987年   35359篇
  1986年   32872篇
  1985年   31289篇
  1984年   23829篇
  1983年   20037篇
  1982年   12213篇
  1981年   10783篇
  1979年   20716篇
  1978年   14586篇
  1977年   12087篇
  1976年   11368篇
  1975年   11623篇
  1974年   13990篇
  1973年   13540篇
  1972年   12642篇
  1971年   11477篇
  1970年   10915篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
21.
22.
ABSTRACT

This project examined 55 picture books featuring transgender, gender expansive or genderqueer protagonists or narrators published between 2008 and 2018. The purpose of the study was to determine how this genre of children’s literature supports and challenges four gender assumptions: the gender binary, gender essentialism, sex/gender congruency and gender stability. Additionally, this critical analysis explored misgendering within this genre and themes of social rejection and acceptance. Protagonists and narrators were permitted a degree of gender nonconformity, however, the majority of picture books missed opportunities for a more complete exploration of gender possibilities.  相似文献   
23.
24.
25.
26.
There is a sharp difference in how one views TCR structure–function–behaviour dependent on whether its recognition of major histocompatibility complex‐encoded restriction elements (R) is germline selected or somatically generated. The generally accepted or Standard model is built on the assumption that recognition of R is by the V regions of the αβ TCR, which is not driven by allele specificity, whereas the competing model posits that recognition of R is allele‐specific. The establishing of allele‐specific recognition of R by the TCR would rule out the Standard model and clear the road to a consideration of a competing construct, the Tritope model. Here, the case for allele‐specific recognition (germline selected) is detailed making it obvious that the Standard model is untenable.  相似文献   
27.
28.
BACKGROUND The adenoma detection rate(ADR) is inversely associated with the incidence of interval colorectal cancer and serves as a benchmark quality criterion during screening colonoscopy. However, adenoma miss rates reach up to 26% and studies have shown that a second inspection of the right colon in retroflected view(RFV) can increase ADR.AIM To assess whether inspection of the whole colon in RFV compared to standard forward view(SFV) can increase ADR.METHODS Patients presenting for screening or surveillance colonoscopy were invited to participate in this randomized controlled trial and randomized into two arms. In RFV arm colonoscopy was initially performed with SFV, followed by a second inspection of the whole colon in RFV. In the SFV arm first withdrawal was performed with SFV, followed by a second inspection of the whole colon again with SFV. Number, size and morphology of polyps found during first and second inspection in each colonic segment were recorded and all polyps were removed and sent for histopathology in separate containers.RESULTS Two hundred and five patients were randomly assigned to the RFV(n = 101) and SFV(n = 104) arm. In the RFV arm, both polyp detection rate(PDR) and ADR were increased under second inspection in RFV(PDR 1~(st) SFV: 39.8%, PDR 2~(nd)RFV: 46.6%; ADR 1~(st) SFV: 35.2%, ADR 2~(nd) RFV: 42%). Likewise, in the SFV arm,PDR and ADR were increased under second inspection(PDR 1~(st) SFV: 37.5%, PDR 2~(nd) SFV: 46.6%; ADR 1~(st) SFV: 34.1%, ADR 2~(nd)SFV: 44.3%) with no significant differences in ADR and PDR between the SFV and RFV arm. Mean number of adenomas per patient(APP) was increased in the RFV and SFV(APP RFV arm: 1~(st) SFV: 1.71; 2~(nd) RFV: 2.38; APP SFV arm: 1~(st) SFV: 1.83, 2~(nd)SFV:2.2). The majority of adenomas additionally found during second inspection in RFV or in SFV were located in the transverse and left-sided colon and were 5 mm in size.CONCLUSION Second inspection of the whole colon leads to increased adenoma detection with no differences between SFV and RFV. Hence, increased detection is most likely a feature of the second inspection itself but not of the inspection mode.  相似文献   
29.
30.
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