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   80097篇
  免费   3366篇
  国内免费   41篇
  83504篇
  2020年   937篇
  2019年   1119篇
  2018年   1587篇
  2017年   1578篇
  2016年   1687篇
  2015年   1196篇
  2014年   1441篇
  2013年   6761篇
  2012年   2695篇
  2011年   2703篇
  2010年   1623篇
  2009年   1683篇
  2008年   2302篇
  2007年   2304篇
  2006年   2078篇
  2005年   1759篇
  2004年   1788篇
  2003年   1685篇
  2002年   1644篇
  2001年   2614篇
  2000年   2517篇
  1999年   1872篇
  1998年   869篇
  1997年   782篇
  1996年   829篇
  1995年   796篇
  1994年   752篇
  1993年   747篇
  1992年   1556篇
  1991年   1434篇
  1990年   1422篇
  1989年   1339篇
  1988年   1345篇
  1987年   1230篇
  1986年   1225篇
  1985年   1315篇
  1984年   1075篇
  1983年   961篇
  1982年   738篇
  1979年   1124篇
  1978年   820篇
  1975年   894篇
  1974年   1044篇
  1973年   1086篇
  1972年   946篇
  1971年   857篇
  1969年   759篇
  1968年   955篇
  1967年   847篇
  1966年   812篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
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   
982.
A program using behavioral practice, assertiveness training, and social and contrived reinforcers was developed to establish and maintain automobile safety belt use by young children. Sixteen children (ages 4.8 to 7 years) who never used their safety belts during a 5-day preexperimental observation period were randomly assigned to two groups of eight each. A multiple baseline design across groups was used to evaluate the effectiveness of the training program. During the 8-day baseline period for Group 1, no children used their safety belts when unobtrusively observed while being driven from school. During the 26-day intervention period, the children were buckled up on 96% of the observations. Follow-up probes conducted 2–3 months after program discontinuance found safety belt use to range from 86% to 100%. For Group 2, the 14-day baseline safety belt use averaged 6% and increased to a mean of 81% during the 20-day training and maintenance program. Follow-up probes 2–3 months later found safety belt use to occur during 75% to 96% of the observations. Parent questionnaires indicated the generalizability and social validity of the program.  相似文献   
983.
We examined the effects of a peer initiation intervention with high- and low-status nonhandicapped students on the behavior of untrained peers toward handicapped students. In the context of a counterbalanced withdrawal design, high- and low-status nonhandicapped students were taught to direct social initiations to eight severely handicapped students during recess activities. The interactions of the high-status students resulted in higher levels of initiations by untrained peers toward the handicapped students than did the interactions of the low-status students. Social response levels were also differentially affected by the status of the peer initiator.  相似文献   
984.
Correspondences between verbal responding (saying) and nonverbal responding (doing) may be organized in terms of the classes of verbal/nonverbal relations into which particular instances of verbal/nonverbal response sequences can enter. Contingency spaces, which display relations among events in terms of the probability of one event given or not given another, have been useful in analyses of nonverbal behavior. We derive a taxonomy of verbal/nonverbal behavior relations from a contingency space that takes into account two conditional probabilities: the probability of a nonverbal response given a verbal response and that probability given the absence of the verbal response. For example, positive correspondence may be said to exist as a response class when the probability of doing is high given saying but is otherwise low. Criteria for other generalized classes, including negative correspondence, follow from this analysis.  相似文献   
985.
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   
986.
M J Werebe 《Adolescence》1987,22(85):129-142
In order to determine how adolescents perceive their relationships, a set of eight drawings representing one, two or three characters, whose sex and relationships where not clearly defined, were shown to 403 Parisian adolescents (227 girls and 176 boys) aged 15 to 19. The majority of data converge for all subjects, regardless of the sex, curriculum or socioeconomic factors. The subjects consistently identify more mixed-sex dyads and triads than same-sex in all pictures. This predominance does not imply that the adolescents perceived all relationships as having a romantic connotation. Some data seem consistent with the traditional sex role stereotypes. The subjects' responses do not seem to reflect the reality of their own peer relationships.  相似文献   
987.
988.
989.
990.
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