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   4018篇
  免费   269篇
  国内免费   17篇
耳鼻咽喉   13篇
儿科学   58篇
妇产科学   77篇
基础医学   424篇
口腔科学   37篇
临床医学   535篇
内科学   779篇
皮肤病学   42篇
神经病学   271篇
特种医学   15篇
外科学   414篇
综合类   62篇
一般理论   1篇
预防医学   987篇
眼科学   39篇
药学   241篇
  1篇
中国医学   45篇
肿瘤学   263篇
  2024年   7篇
  2023年   66篇
  2022年   161篇
  2021年   208篇
  2020年   175篇
  2019年   212篇
  2018年   203篇
  2017年   198篇
  2016年   141篇
  2015年   164篇
  2014年   247篇
  2013年   498篇
  2012年   181篇
  2011年   185篇
  2010年   165篇
  2009年   190篇
  2008年   215篇
  2007年   187篇
  2006年   142篇
  2005年   125篇
  2004年   113篇
  2003年   87篇
  2002年   95篇
  2001年   74篇
  2000年   31篇
  1999年   30篇
  1998年   27篇
  1997年   29篇
  1996年   21篇
  1995年   12篇
  1994年   17篇
  1993年   9篇
  1992年   5篇
  1991年   9篇
  1990年   4篇
  1989年   8篇
  1988年   2篇
  1987年   4篇
  1986年   4篇
  1985年   8篇
  1984年   6篇
  1983年   8篇
  1982年   10篇
  1981年   5篇
  1980年   6篇
  1979年   4篇
  1977年   1篇
  1976年   1篇
  1975年   2篇
  1973年   1篇
排序方式: 共有4304条查询结果,搜索用时 15 毫秒
91.
92.
A Friend is truly a treasure, in accordance with age and competence’s qualitative changes. The aim of this study was to con?rm the increase in friendship competence and its multifactorial nature in 3- up to 10-year-old children, and to verify gender differences, and parenting in?uences on the concept of friendship. A semi-structured interview was administered in a natural context to 3- to 10-year-old children (N?=?167; Mean?=?7.6 years; SD?=?2.16). According to Selman’s Model, the coding provides ?ve sub-categories: (1) friendship; (2) social perspective taking; (3) emotions understanding; (4) social interaction strategies; and (5) aggressiveness. Three parental style questionnaires were administered to parents. Results point up an increase in social skills according to age. The Friendship Interview turned out to be a reliable tool able to investigate how the concept of friendship is also structured in preschool children.  相似文献   
93.
94.
95.
96.
97.
98.
Total sleep deprivation (TSD) is known to alter cognitive processes. Surprisingly little attention has been paid to its impact on social cognition. Here, we investigated whether TSD alters levels‐1 and ‐2 visual perspective‐taking abilities, i.e. the capacity to infer (a) what can be seen and (b) how it is seen from another person's visual perspective, respectively. Participants completed levels‐1 and ‐2 visual perspective‐taking tasks after a night of sleep and after a night of TSD. In these tasks, participants had to take their own (self trials) or someone else's (other trials) visual perspective in trials where both perspectives were either the same (consistent trials) or different (inconsistent trials). An instruction preceding each trial indicated the perspective to take (i.e. the relevant perspective). Results show that TSD globally deteriorates social performance. In the level‐1 task, TSD affects the selection of relevant over irrelevant perspectives. In the level‐2 task, the effect of TSD cannot be unequivocally explained. This implies that visual perspective taking should be viewed as partially state‐dependent, rather than a wholly static trait‐like characteristic.  相似文献   
99.
African swine fever virus (ASFV) is the causative agent of African swine fever (ASF) which reaches up to 100% case fatality in domestic pigs and wild boar and causes significant economic losses in the swine industry. Lack of knowledge of the function of ASFV genes is a serious impediment to the development of the safe and effective vaccine. Herein, I267L was identified as a relative conserved gene and an early expressed gene. A recombinant virus (SY18ΔI267L) with I267L gene deletion was produced by replacing I267L of the virulent ASFV SY18 with enhanced green fluorescent protein (EGFP) cassette. The replication kinetics of SY18ΔI267L is similar to that of the parental isolate in vitro. Moreover, the doses of 102.0 TCID50 (n = 5) and 105.0 TCID50 (n = 5) SY18ΔI267L caused virulent phenotype, severe clinical signs, viremia, high viral load, and mortality in domestic pigs inoculated intramuscularly as the virulent parental virus strain. Therefore, the deletion of I267L does not affect the replication or the virulence of ASFV. Utilizing the fluorescent-tagged virulence deletant can be easy to gain a visual result in related research such as the inactivation effect of some drugs, disinfectants, extracts, etc. on ASFV.  相似文献   
100.
African Swine Fever (ASF), a hemorrhagic disease with a high mortality rate in suids, is transmitted via direct and indirect contact with infectious animals and contaminated fomites, respectively. ASF reached Europe in 2014, affecting 14 of the 27 EU countries including, recently, the Italian peninsula. The fast and unprecedented spread of ASF in the EU has highlighted gaps in knowledge regarding transmission mechanisms. Fomites, such as contaminated clothing and footwear, farming tools, equipment and vehicles have been widely reported in the spread of ASF. The absence of available vaccines renders biosecurity measures, cleaning and disinfection procedures an essential control tool, to a greater degree than the others, for the prevention of primary and secondary introductions of ASF in pig farms. In this review, available data on the virucidal activity of chemical compounds as disinfectants against the ASF virus (ASFV) are summarized together with laboratory methods adopted to assess the virucidal activity.  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