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   12212篇
  免费   809篇
  国内免费   23篇
耳鼻咽喉   159篇
儿科学   344篇
妇产科学   236篇
基础医学   1588篇
口腔科学   140篇
临床医学   2127篇
内科学   2394篇
皮肤病学   152篇
神经病学   987篇
特种医学   336篇
外国民族医学   9篇
外科学   1213篇
综合类   120篇
一般理论   10篇
预防医学   1160篇
眼科学   342篇
药学   644篇
  1篇
中国医学   6篇
肿瘤学   1076篇
  2023年   55篇
  2022年   93篇
  2021年   185篇
  2020年   130篇
  2019年   157篇
  2018年   226篇
  2017年   177篇
  2016年   183篇
  2015年   221篇
  2014年   339篇
  2013年   472篇
  2012年   718篇
  2011年   832篇
  2010年   456篇
  2009年   384篇
  2008年   720篇
  2007年   820篇
  2006年   715篇
  2005年   781篇
  2004年   712篇
  2003年   665篇
  2002年   667篇
  2001年   230篇
  2000年   224篇
  1999年   222篇
  1998年   125篇
  1997年   102篇
  1996年   103篇
  1995年   100篇
  1994年   96篇
  1993年   49篇
  1992年   155篇
  1991年   146篇
  1990年   131篇
  1989年   112篇
  1988年   120篇
  1987年   104篇
  1986年   98篇
  1985年   78篇
  1984年   85篇
  1983年   82篇
  1982年   70篇
  1981年   61篇
  1980年   58篇
  1979年   73篇
  1978年   43篇
  1977年   40篇
  1976年   49篇
  1975年   38篇
  1974年   38篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
N-Hydroxythalidomide (1d), a potential metabolite of thalidomide (1a), was synthesized from N-phthalyglutaminic acid anhydride (1b) and O-tetrahydropyraline hydroxylamine, followed by deprotection. The teratogenicity of 1d was studied using the Hen's-Egg-Test model which had been found applicable for 1a. 1d was more teratogenic to chicken embryos compared to 1a. The percentage of teratogenic malformations in the 1d groups was 28-46%, whereas the percentage in the 1a groups was 20-23%. The oxygen protected precursor N-hydroxythalidomide (1c) was less teratogenic (11-15%).  相似文献   
2.
3.
The authors systematically evaluated the frequency patterns of cocaine use in 85 cocaine-dependent outpatients and found four patterns of use: continuous (27%), intermittent patterned (35%), intermittent nonpatterned (25%), and occasional (13%). Few subjects reported consistent cycling between binges and crashes. There were no significant differences in patterns of use associated with gender, race, educational level, route of administration, or recency of heroin use. Continuous users and occasional users were older than intermittent users. Because different contingencies may control patterned vs. nonpatterned cocaine use, pattern of use may have implications for treatment, even in individuals reporting similar amounts of cocaine use.  相似文献   
4.
5.
B J Hess 《Vision research》1990,30(4):597-602
The design and fabrication of a dual-search coil for measuring three-dimensional eye movements in experimental animals is described. The coil configuration is rigid and allows reliable precalibration in the magnetic field. It is implanted beneath the conjunctiva on the eye ball using the conventional implantation technique.  相似文献   
6.
7.
8.
9.
10.
CONTEXT: The limited information available on the oral health status of rural children in the United States makes it difficult to devise policy strategies to address perceived problems. PURPOSE: To document the oral health status and dental care utilization of US children by place of residence, METHODS: Data from National Health Interview Surveys for 1995, 1997, and 1998, and from the third National Health and Nutrition Examination Survey (1988-1994) were analyzed. FINDINGS: Children residing in rural areas were more likely to be uninsured for dental care than were children from urban areas (41.1% versus 34.7%). A greater percentage of rural than urban children reported unmet dental needs (7.5% versus 5.6%); there was no difference in self-reported poor dental status. Urban children were more likely than rural children to have visited the dentist in the past year (73.6% versus 69.9%) and were also more likely to be regular users of dental care (61.7% versus 51.4%). Differences in percentage of rural and urban children with caries lesions and caries experience were not significant. CONCLUSIONS: Children residing in rural areas have less access to and utilization of dental care compared to children residing in urban areas. Moreover, poor rural children display less utilization of dental services than poor urban children. Differences in the sum of decayed and filled primary teeth and the sum of decayed, missing, and filled permanent teeth were not significant.  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