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   52338篇
  免费   1978篇
  国内免费   17篇
  2019年   614篇
  2018年   840篇
  2017年   905篇
  2016年   905篇
  2015年   615篇
  2014年   798篇
  2013年   3855篇
  2012年   1494篇
  2011年   1610篇
  2010年   965篇
  2009年   953篇
  2008年   1394篇
  2007年   1357篇
  2006年   1266篇
  2005年   1136篇
  2004年   1116篇
  2003年   1020篇
  2002年   1094篇
  2001年   1625篇
  2000年   1556篇
  1999年   1165篇
  1998年   610篇
  1997年   500篇
  1996年   483篇
  1992年   943篇
  1991年   893篇
  1990年   918篇
  1989年   897篇
  1988年   863篇
  1987年   842篇
  1986年   873篇
  1985年   940篇
  1984年   749篇
  1983年   687篇
  1982年   569篇
  1981年   522篇
  1979年   868篇
  1978年   623篇
  1977年   538篇
  1976年   549篇
  1975年   736篇
  1974年   815篇
  1973年   815篇
  1972年   699篇
  1971年   631篇
  1970年   609篇
  1969年   688篇
  1968年   803篇
  1967年   708篇
  1966年   712篇
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
211.
Two theoretical approaches to smoking cessation were compared. Participants were randomly assigned either to (a) a traditional treatment program that used contingency contracting and that emphasized the necessity for absolute abstinence (AA) or to (b) a relapse-prevention (RP) treatment that focused on gradual acquisition of nonsmoking skills. It was hypothesized that participants in the RP treatment would be less successful initially but would have better maintenance skills and thus would relapse less during a 1-year follow-up period. Each program was evaluated in two formats: group-based treatment and self-help materials. Results indicated comparable 1-year abstinence rates for all treatments, although more participants dropped out of the self-help formats. Participants in the RP intervention were more likely to lapse sooner after quitting and were more likely to quit again during the 1-year maintenance period. Exploratory analyses of successful participants suggested that women were more successful in the RP program and that men had greater success with the AA approach.  相似文献   
212.
The discrimination of human odour by the dog   总被引:3,自引:0,他引:3  
P G Hepper 《Perception》1988,17(4):549-554
In reply to a suggestion made by Galton in 1875, the ability of dogs to discriminate between the odour of human twins was investigated. In a matching-to-sample simultaneous discrimination task, dogs were tested on their ability to discriminate odours from twins differing only in genetic relatedness or only in environmental factors, particularly diet, or from twins identical in both genetic relatedness and environmental factors. Dogs could discriminate between the odours from twins who differed only in environmental factors and between the odours of twins who differed only in genetic relatedness. However, they were unable to discriminate between odours produced by infant twins identical in both genetic relatedness and environmental factors. Thus twins may be discriminated by dogs as long as they differ in genetic relatedness or environmental factors. The possible source of discriminable odours is discussed and how the effects of genes and environment are mediated considered.  相似文献   
213.
This study was designed to evaluate the possibility that a pattern of cognitive deficit is associated with delinquent behavior, while avoiding some of the methodological problems of previous research. The Self- Report Early Delinquency instrument and a research battery of neuropsychological tests were administered blindly to an unselected cohort of 678 13- year- olds. Because the diagnosis of attention deficit disorder (ADD) was found at markedly elevated rates in the backgrounds of these delinquents, the possibility was examined that the neuropsychological deficits of delinquents might be limited to delinquents with histories of ADD. Although delinquents with past ADD were more cognitively impaired than non-ADD delinquents, both groups scored significantly below nondelinquents on verbal, visuospatial, and visualmotor integration skills. In addition, ADD delinquents scored poorly on memory abilities. Subjects with ADD who had not developed delinquent behavior were not as cognitively impaired as ADD delinquents, suggesting that it is the specific comorbidity of ADD and delinquency that bears neuropsychological study.This work was supported by USPHS Grant 1 R23 MH-42723-01 from the Antisocial and Violent Behavior Branch of the National Institute of Mental Health. The Dunedin Multidisciplinary Health and Development Research Unit is supported by the Medical Research Council of New Zealand. Appreciation is expressed for the methodological advice of Prof. Sarnoff A. Mednick, and for the data collection efforts of Mrs. Pat Brasch, Mrs. Kathleen Campbell, Mr. Rich Poulton, and the psychometrists who administered the WISC-R.  相似文献   
214.
The relationship between anxiety and depression was examined in a sample of 106 children and adolescents referred to an outpatient anxiety disorder clinic for children. Twenty-eight percent of patients with DSM-III diagnoses of anxiety disorders displayed a concurrent major depression. Children with anxiety disorders plus major depression were found (1) to be older, (2) to demonstrate more severe anxiety symptomatology, and (3) to be diagnosed with different rates of certain anxiety-disorder subtypes, when compared to anxious patients without major depression. Nondepressed anxious children and adolescents did not differ from a psychopathological control group in severity of either anxiety or depression symptoms.  相似文献   
215.
Force variability in isometric responses   总被引:2,自引:0,他引:2  
In the present study we examined the contribution of different impulse parameters to peak force variability in an isometric task. Five experiments are reported that each held constant a different impulse parameter while allowing the other impulse parameters to vary. The results indicate that change in force level is the parameter that has the greatest effect on peak force variability, although time to peak force and preload also systematically influence response variability. A formula that accommodates the relation between impulse parameters and force variability is proposed. The data suggest that even in isometric tasks, it is the force-time properties of the impulse, rather than discrete parameters such as peak force, that determine the outcome variability.  相似文献   
216.
217.
218.
Differences between a clinical sample of younger (ages 5 to 11) and older (ages 12 to 19) children meeting DSM-III criteria for overanxious disorder (OAD) were examined. Younger and older children were compared in terms of (1) the rates of OAD diagnoses occurring in the two age groups, (2) sociodemographic characteristics, (3) symptom expression, (4) association with other forms of maladjustment, and (5) self-reported anxiety and depression. The prevalence of OAD diagnoses and sociodemographic characteristics did not differ. Although younger and older OAD children showed similar rates of most specific DSM-III OAD symptoms, older children presented with a higher total number of overanxious symptoms than younger children. Older children more frequently exhibited a concurrent major depression or simple phobia, whereas younger OAD children more commonly had coexisting separation anxiety or attention deficit disorders. Older OAD children reported significantly higher levels of anxiety and depression on self-report measures. Findings indicated that the expression of OAD varies by developmental level.  相似文献   
219.
Serotonergic and opiate interactions in the modulation of drug- and environmental-induced analgesia were assessed in 6-day-old Sprague-Dawley-derived rat pups using tail-flick testing procedures. In these experiments the serotonergic antagonist metergoline was observed to attenuate both the analgesia induced by the opiate agonist morphine and the analgesia induced by isolation from siblings and the dam, an environmental manipulation which has previously been shown to be associated with increases in opiate activity. In contrast, the opiate antagonist naloxone was observed to be ineffective in blocking not only analgesia induced by the serotonergic agonist quipazine, but also analgesia induced by long-term deprivation from the dam and food, a manipulation that has been previously reported to induce increases in serotonergic utilization. These results suggest that in the neonate, as in the adult, the serotonergic modulation of nociception appears to occur "downstream" from the opiate systems serving to regulate nociception following both drug- and environmental-induced alterations in pain sensitivity. Analgesia induced by long-term deprivation from food and the dam appears to be strongly related to increases in serotonergic activity and relatively unaffected by opiate antagonism, whereas analgesia induced by isolation from siblings and the dam may be related to increases in opiate activity, but modulated by serotonergic systems serving to regulate pain responsivity. Thus alterations in the environment, mediated at least in part by alterations in opiate and serotonergic activity, appear to play an important role in influencing the sensitivity of the neonate to pain stimuli.  相似文献   
220.
The development of the understanding of affective meaning in music was investigated. Subjects aged 4, 5, 6, and 19 assigned verbal labels to musical segments previously determined by adults to be representative of one of four affects (happy, sad, angry, afraid). Analysis of correct interpretations and errors revealed a pattern of interactions among age, sex, and affect indicating that the ability to verbalize an understanding of affective meaning in music consistent with that of adult subjects is present during the preschool years. Age-related similarities in performance, as well as differences favoring both younger and older subjects, were observed and were discussed in relation to recent research in, and theories of, affective development and communication.The authors thank H. Julia Hannay, Edward Kemery, Shiela MacDonald, and Robert McGrath for their assistance in this research. The conceptual inspiration of Joseph Intrieri is gratefully acknowledged. We also thank Leslie Brody, Robin Hornik, and several anonymous reviewers for their comments on an earlier draft of the paper. Portions of this research were presented at the Southeastern Conference on Human Development, Baltimore, April 1982.  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