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   57654篇
  免费   4994篇
  国内免费   175篇
耳鼻咽喉   483篇
儿科学   1796篇
妇产科学   1271篇
基础医学   7708篇
口腔科学   1198篇
临床医学   5966篇
内科学   11804篇
皮肤病学   888篇
神经病学   5392篇
特种医学   1863篇
外国民族医学   4篇
外科学   7996篇
综合类   943篇
一般理论   54篇
预防医学   5561篇
眼科学   1103篇
药学   4335篇
  1篇
中国医学   146篇
肿瘤学   4311篇
  2023年   308篇
  2022年   463篇
  2021年   928篇
  2020年   647篇
  2019年   950篇
  2018年   1157篇
  2017年   834篇
  2016年   918篇
  2015年   1115篇
  2014年   1574篇
  2013年   2215篇
  2012年   3288篇
  2011年   3609篇
  2010年   2010篇
  2009年   1860篇
  2008年   3085篇
  2007年   3441篇
  2006年   3375篇
  2005年   3446篇
  2004年   3149篇
  2003年   2999篇
  2002年   2831篇
  2001年   1140篇
  2000年   1071篇
  1999年   1110篇
  1998年   743篇
  1997年   591篇
  1996年   613篇
  1995年   529篇
  1994年   466篇
  1993年   471篇
  1992年   804篇
  1991年   712篇
  1990年   673篇
  1989年   597篇
  1988年   590篇
  1987年   579篇
  1986年   534篇
  1985年   557篇
  1984年   550篇
  1983年   448篇
  1982年   435篇
  1981年   426篇
  1980年   408篇
  1979年   395篇
  1978年   343篇
  1977年   300篇
  1976年   273篇
  1974年   287篇
  1973年   263篇
排序方式: 共有10000条查询结果,搜索用时 12 毫秒
21.
22.
23.
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   
24.
25.
The substitution of leucine for valine at amino acid position 34 of the factor XIII gene is commonly referred to as FXIII Val34Leu polymorphism. The homozygous leucine/leucine genotype has been reported to confer protection against venous thromboembolism, but previous studies have not evaluated a population limited to those with idiopathic venous thromboembolism. The primary objective of the study was to determine whether the FXIII Val34Leu polymorphism is independently associated with the occurrence of idiopathic venous thromboembolism. We prospectively enrolled consecutive patients with at least one objectively confirmed idiopathic venous thromboembolism. Friends of cases were recruited as controls and matched to cases by sex, ethnicity, and age. All participants were tested for the FXIII Val34Leu polymorphism in addition to several well-known thrombophilias. Data from 309 cases and 306 controls were analyzed. The FXIII leucine/leucine genotype was present in 4.9% of cases and 6.5% of controls. An adjusted odds ratio of 0.59 (95% confidence interval, 0.25-1.38) was found for the recessive model and 0.69 (95% confidence interval, 0.46-1.02) for the dominant model. Our results do not support an independent association of the FXIII Val34Leu polymorphism with idiopathic venous thromboembolism in our Caucasian Canadian study population.  相似文献   
26.
27.
28.
29.
The findings of a study of the frequency and type of psychotropic drugs that nonpsychiatric residents prescribed for nonpsychiatric patients in a teaching hospital in 1982 were compared with the findings of a similar study in the same hospital nine years earlier. The overall percentage of patients receiving psychotropic drugs remained almost the same, at less than 10 percent. However, in 1982 residents prescribed antidepressants almost four times as often as in 1973, and the use of antianxiety agents decreased. Deficiencies in chart documentation of psychotropic prescribing and the tendency to use conservative dosages remained unchanged from the earlier study.  相似文献   
30.
Such research evidence as exists on effective drug strategies in prevention and education draws attention to the importance of involving parents along with other community agencies and school governors. Much depends nevertheless on the way in which 'involvement' is interpreted and the assumptions that are made about parents' knowledge of drugs and drug education as well as their attitudes to drug issues. As the age of initial experimentation and contact with drugs continues to fall, the importance of enskilling parents to support drug education programmes for 5 year olds and upwards continues to rise. This paper reports the first wide ranging survey of parents' knowledge of drugs and drug issues across an entire English county embracing younger as well as older children. The need for more coordinated, informed and systematic guidance to parents is established.  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