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   2364772篇
  免费   176230篇
  国内免费   3390篇
耳鼻咽喉   32217篇
儿科学   76332篇
妇产科学   62988篇
基础医学   350570篇
口腔科学   63884篇
临床医学   213366篇
内科学   461276篇
皮肤病学   51965篇
神经病学   186997篇
特种医学   88554篇
外国民族医学   489篇
外科学   356754篇
综合类   47712篇
现状与发展   13篇
一般理论   869篇
预防医学   184149篇
眼科学   54624篇
药学   176428篇
  11篇
中国医学   4607篇
肿瘤学   130587篇
  2021年   19651篇
  2019年   20065篇
  2018年   27711篇
  2017年   20824篇
  2016年   23205篇
  2015年   26136篇
  2014年   36847篇
  2013年   54906篇
  2012年   76120篇
  2011年   80867篇
  2010年   47878篇
  2009年   45245篇
  2008年   75756篇
  2007年   80642篇
  2006年   81348篇
  2005年   78786篇
  2004年   75343篇
  2003年   72596篇
  2002年   70243篇
  2001年   108867篇
  2000年   111549篇
  1999年   93649篇
  1998年   27160篇
  1997年   23804篇
  1996年   24160篇
  1995年   22825篇
  1994年   21018篇
  1993年   19799篇
  1992年   72076篇
  1991年   70123篇
  1990年   68456篇
  1989年   65713篇
  1988年   60350篇
  1987年   59182篇
  1986年   55271篇
  1985年   53056篇
  1984年   39381篇
  1983年   33454篇
  1982年   19919篇
  1979年   35898篇
  1978年   25693篇
  1977年   21264篇
  1976年   20359篇
  1975年   21848篇
  1974年   26174篇
  1973年   24830篇
  1972年   23220篇
  1971年   22062篇
  1970年   20261篇
  1969年   19327篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
82.
83.
84.
85.
86.
87.
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   
88.
The present study aimed at measuring seropositivities for infection by Ascaris suum and Toxocara canis using the excretory/secretory (E/S) antigens from Ascaris suum (AES) and Toxocara canis (TES) within an indigenous population. In addition, quantification of cytokine expressions in peripheral blood cells was determined. A total of 50 Warao indigenous were included; of which 43 were adults and seven children. In adults, 44.1% were seropositive for both parasites; whereas children had only seropositivity to one or the other helminth. For ascariosis, the percentage of AES seropositivity in adults and children was high; 23.3% and 57.1%, respectively. While that for toxocariosis, the percentage of TES seropositivity in adults and children was low; 9.3% and 14.3%, respectively. The percentage of seronegativity was comparable for AES and TES antigens in adults (27.9%) and children (28.6%). When positive sera were analyzed by Western blotting technique using AES antigens; three bands of 97.2, 193.6 and 200.2 kDas were mostly recognized. When the TES antigens were used, nine major bands were mostly identified; 47.4, 52.2, 84.9, 98.2, 119.1, 131.3, 175.6, 184.4 and 193.6 kDas. Stool examinations showed that Blastocystis hominis, Hymenolepis nana and Entamoeba coli were the most commonly observed intestinal parasites. Quantification of cytokines IFN-γ, IL-2, IL-6, TGF-β, TNF-α, IL-10 and IL-4 expressions showed that there was only a significant increased expression of IL-4 in indigenous with TES seropositivity (p < 0.002). Ascaris and Toxocara seropositivity was prevalent among Warao indigenous.  相似文献   
89.
90.
A 42‐year‐old man presented with a viral prodrome and tested positive for influenza A. He rapidly deteriorated developing cardiogenic shock, rhabdomyolysis, and acute kidney injury. Patient improved 1 week later with supportive measures including vasopressors, inotropes, and an intraaortic balloon pump. We report this case as it highlights the discordance between echocardiographic ventricular wall thickening as a result of myocardial edema, and electrocardiographic findings at presentation, with a reversal in findings at time of resolution. Additionally, there was some suggestion of a regional pattern to the reduced longitudinal strain.  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