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   106404篇
  免费   6797篇
  国内免费   442篇
耳鼻咽喉   1203篇
儿科学   2755篇
妇产科学   1898篇
基础医学   13371篇
口腔科学   1913篇
临床医学   11432篇
内科学   21414篇
皮肤病学   1417篇
神经病学   10529篇
特种医学   4055篇
外国民族医学   3篇
外科学   16979篇
综合类   1243篇
一般理论   140篇
预防医学   8923篇
眼科学   2172篇
药学   6822篇
中国医学   107篇
肿瘤学   7267篇
  2023年   578篇
  2022年   962篇
  2021年   2166篇
  2020年   1381篇
  2019年   2164篇
  2018年   2641篇
  2017年   1880篇
  2016年   2052篇
  2015年   2340篇
  2014年   3543篇
  2013年   4865篇
  2012年   7747篇
  2011年   8192篇
  2010年   4682篇
  2009年   4261篇
  2008年   7287篇
  2007年   7662篇
  2006年   7407篇
  2005年   7078篇
  2004年   6912篇
  2003年   6267篇
  2002年   5917篇
  2001年   1072篇
  2000年   744篇
  1999年   1063篇
  1998年   1288篇
  1997年   987篇
  1996年   804篇
  1995年   744篇
  1994年   658篇
  1993年   646篇
  1992年   602篇
  1991年   584篇
  1990年   471篇
  1989年   442篇
  1988年   423篇
  1987年   422篇
  1986年   377篇
  1985年   406篇
  1984年   400篇
  1983年   339篇
  1982年   397篇
  1981年   351篇
  1980年   287篇
  1979年   175篇
  1978年   202篇
  1977年   181篇
  1976年   152篇
  1974年   134篇
  1973年   142篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
23.
24.
25.
26.
Cerebrospinal fluid (CSF) from 7 patients with infantile spasms (mean age: 6.7 months) was collected before and after treatment with adrenocorticotropic hormone (ACTH). The concentration of neurotransmitter metabolites was analyzed using high-performance liquid chromatography and compared to the metabolite concentration in the CSF from 7 age-matched controls (mean age: 6.1 months). Pretreatment levels of CSF 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid, 3-methoxy-4-hydroxyphenyl glycol (MHPG), and kynurenine were significantly lower in infantile spasm patients compared to controls. Following treatment, marked increases in 5-HIAA and decreases in kynurenine levels were observed in the CSF of the 5 infants whose seizures were eliminated or reduced by ACTH. In the 2 nonresponders 5-HIAA levels decreased. The level of MHPG was reduced slightly in 5 infants, including the 2 nonresponders, and was increased in 2 responders. CSF homovanillic acid levels increased in 4 infantile spasm infants and decreased in 3 following ACTH. These data demonstrate that the presence of seizures in infantile spasms is associated with a significant decrease in serotonergic activity and that elimination of seizures by ACTH is accompanied by increased serotonin turnover. The simultaneous increase of 5-HIAA and decrease of kynurenine, an alternate metabolite of tryptophan, suggests an underlying disturbance of tryptophan metabolism in infantile spasms. The possibility that elimination of seizures by ACTH may be related to decreased production of certain kynurenine metabolites, particularly quinolinic acid, is discussed.  相似文献   
27.
OBJECTIVES: To determine whether the increase in the incidence of injury found for the first summer season in which rugby league (RL) was played in the UK was repeated in subsequent summer seasons. DESIGN: A retrospective and prospective cohort study design. SETTING AND PARTICIPANTS: Injuries were recorded from all players who took part in 141 games over 3 summer seasons (1997 to 1999) for 1 professional team. These were compared against rates from previously collected data for 3 earlier winter and 1 summer season. ASSESSMENT OF RISK FACTORS: For each injury it was recorded in which season it occurred; how many games or training sessions, if any, were subsequently missed; the type, site and severity of injury. MAIN OUTCOME MEASURES: Injuries were reported as rate per 1000 hours, also broken down into severity according to the number of games missed and whether subsequent training sessions were missed. RESULTS: A sustained increase in injury incidence has been found comparing summer RL over RL played in the winter. There was an increase in injury rates for all sites and types, but not all reached significance. CONCLUSIONS: Data collected over 6 seasons indicate a higher risk of sustaining an injury playing summer RL, but the cause may be related to a combination of factors. These may include the ground or weather conditions associated with summer rugby, player characteristics or changes in the game itself and future research needs to investigate these further.  相似文献   
28.
29.
This study examined the temporal concordance between the onset of childhood anxiety disorders and the points of onset and ending of child sexual abuse (CSA). Sexually abused children (N = 158) were assessed with structured diagnostic interviews. Onset ages for lifetime prevalence anxiety disorders were combined and sequenced with the onset and ending of sexual abuse. Hazard rates were calculated. Departures from the overall linear hazard trajectory for onsets were modeled using piecewise growth curve analyses. Increases from the overall trajectory were found around the point of sexual abuse onset for most childhood anxiety disorders. Decreases were found around the ending of sexual abuse. The risk for developing new anxiety disorders after the onset of sexual abuse showed a positive dose-effect relation with abuse severity. The findings add support to the idea that CSA can have a direct link to childhood anxiety disorders, apart from confounded vulnerability factors, postabuse events, or stable family background factors. The findings are contrasted with those from cross-sectional partial correlation studies that have suggested that there is little direct connection between sexual abuse and mental health outcomes.  相似文献   
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