全文获取类型
收费全文 | 59862篇 |
免费 | 2313篇 |
国内免费 | 23篇 |
出版年
2019年 | 610篇 |
2018年 | 869篇 |
2017年 | 893篇 |
2016年 | 967篇 |
2015年 | 716篇 |
2014年 | 852篇 |
2013年 | 4212篇 |
2012年 | 1603篇 |
2011年 | 1635篇 |
2010年 | 1062篇 |
2009年 | 988篇 |
2008年 | 1504篇 |
2007年 | 1449篇 |
2006年 | 1303篇 |
2005年 | 1186篇 |
2004年 | 1141篇 |
2003年 | 1093篇 |
2002年 | 1124篇 |
2001年 | 1775篇 |
2000年 | 1734篇 |
1999年 | 1301篇 |
1998年 | 629篇 |
1997年 | 588篇 |
1996年 | 577篇 |
1992年 | 1234篇 |
1991年 | 1173篇 |
1990年 | 1169篇 |
1989年 | 1048篇 |
1988年 | 1048篇 |
1987年 | 1015篇 |
1986年 | 1066篇 |
1985年 | 1135篇 |
1984年 | 897篇 |
1983年 | 804篇 |
1982年 | 572篇 |
1981年 | 585篇 |
1979年 | 1008篇 |
1978年 | 709篇 |
1977年 | 657篇 |
1976年 | 662篇 |
1975年 | 864篇 |
1974年 | 1035篇 |
1973年 | 1096篇 |
1972年 | 890篇 |
1971年 | 877篇 |
1970年 | 825篇 |
1969年 | 846篇 |
1968年 | 1103篇 |
1967年 | 979篇 |
1966年 | 932篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
871.
The acquired immune deficiency syndrome (AIDS) has rapidly become the most serious medical consequence of injecting illicit drugs. Its potential impact on intravenous (IV) drug use is enormous. Human immunodeficiency virus (HIV, also known as HTLV-III and LAV), the virus that causes AIDS, appears, usually, to lead to lifelong infection. At present there is no effective treatment, and the treatments under development may require lifelong antiviral therapy. Since most of the antibody produced in response to HIV infection does not neutralize the virus, and since there is substantial genetic variation in the virus, it will be difficult to develop a vaccine. Even after vaccines are developed, testing their safety and efficacy will be formidable problems. Until either effective treatment or vaccines are developed, control of the epidemic among IV drug users must be attempted through behavior change/prevention efforts. In this paper we will review the epidemiology of AIDS among IV drug users and characteristics of the IV drug-use subculture relevant to prevention efforts. We will then identify different target groups for these prevention efforts, present available evidence about behavior change in these groups, and then briefly discuss how to prevent transmission of HIV to heterosexual partners who are not themselves IV drug users and to the children of IV drug users. 相似文献
872.
Fourth-, fifth-, and sixth-grade students responded to a questionnaire concerning their experiences with electronic videogames and computers. Teacher ratings of academic achievement, personality characteristics, and behavior patterns were also obtained for each student. These data were used to examine a number of hypotheses concerning potential harmful or beneficial effects of electronic videogames on school-age children, and to provide preliminary evidence concerning the correlates of computer usage by school-age children. Videogame usage showed significant positive correlations with teacher ratings of impulsivity, significant negative correlations with ratings of academic achievement, and little relationship to rated sociability. Videogame use also proved positively related to other social activities and to microcomputer use. 相似文献
873.
Histories of sexual abuse in adolescent male runaways 总被引:3,自引:0,他引:3
In this study, data on sexual victimization in the histories of 89 Canadian male runaways as well as information on physical victimization, family structure, family financial stability, delinquent and criminal activities, and reasons for running away from home were evaluated. The population of male runaways evidenced dramatically higher rates of sexual and physical abuse than did randomly sampled populations. Sexually abused and nonsexually abused male runaways shared characteristics noted in the literature as common to runaways: problem families, high rates of delinquency, depression, tension, low self-image, and history of physical abuse. Sexually abused male runaways differed from nonsexually abused runaways in their reactions to their runaway event, with sexually abused male runaways responding in highly avoidant patterns coupled with extreme withdrawal from all types of interpersonal relationships. These differences are explained as consistent with known sequelae of sexual abuse, and the implications for treatment by runaway shelters and for further research are suggested. 相似文献
874.
875.
876.
877.
Functional parallelism in spoken word-recognition 总被引:24,自引:0,他引:24
W D Marslen-Wilson 《Cognition》1987,25(1-2):71-102
878.
879.
Hand movements: a window into haptic object recognition 总被引:15,自引:0,他引:15
880.