全文获取类型
收费全文 | 12212篇 |
免费 | 809篇 |
国内免费 | 23篇 |
专业分类
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 |
出版年
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.
Frances Rudnick Levin Judith M. Hess David A. Gorelick Nancy A. Kreiter Paul J. Fudala 《The American journal on addictions / American Academy of Psychiatrists in Alcoholism and Addictions》1993,2(2):109-115
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