全文获取类型
收费全文 | 70173篇 |
免费 | 2672篇 |
国内免费 | 38篇 |
出版年
2020年 | 745篇 |
2019年 | 894篇 |
2018年 | 1318篇 |
2017年 | 1348篇 |
2016年 | 1405篇 |
2015年 | 927篇 |
2014年 | 1158篇 |
2013年 | 5858篇 |
2012年 | 2148篇 |
2011年 | 2330篇 |
2010年 | 1379篇 |
2009年 | 1377篇 |
2008年 | 2070篇 |
2007年 | 2049篇 |
2006年 | 1813篇 |
2005年 | 1643篇 |
2004年 | 1602篇 |
2003年 | 1477篇 |
2002年 | 1548篇 |
2001年 | 2270篇 |
2000年 | 2188篇 |
1999年 | 1664篇 |
1998年 | 873篇 |
1997年 | 744篇 |
1996年 | 677篇 |
1994年 | 652篇 |
1993年 | 676篇 |
1992年 | 1348篇 |
1991年 | 1263篇 |
1990年 | 1283篇 |
1989年 | 1176篇 |
1988年 | 1125篇 |
1987年 | 1130篇 |
1986年 | 1117篇 |
1985年 | 1196篇 |
1984年 | 930篇 |
1983年 | 826篇 |
1982年 | 668篇 |
1979年 | 973篇 |
1978年 | 730篇 |
1975年 | 888篇 |
1974年 | 927篇 |
1973年 | 898篇 |
1972年 | 810篇 |
1971年 | 716篇 |
1970年 | 649篇 |
1969年 | 702篇 |
1968年 | 834篇 |
1967年 | 810篇 |
1966年 | 744篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
251.
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
252.
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
253.
There is some controversy concerning whether or not the visual abilities of the newborn are mediated entirely through subcortical pathways or whether the visual cortex is functioning at birth. A critical test of cortical functioning is discrimination of orientation: orientation-selective neurons are found in the visual cortex but not in subcortical parts of the visual system. An experiment is described in which newborn infants were habituated to a square-wave grating oriented 45 degrees from vertical. After habituation, significant preferences for the novel, mirror-image, grating were found, a result which argues for some degree of visual cortical functioning at birth. 相似文献
254.
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
255.
Selma A. Lewis Jim Johnson Patricia Cohen Marc Garcia Carmen Noemi Velez 《Journal of abnormal child psychology》1988,16(4):459-471
Twenty-six suicide attempters, 9 to 18 years of age, were compared with 725 nonattempters on measures of school achievement, educational goals, socioeconomic status, and depression. As has been found in studies using clinical samples, suicide attempters in our communitybased sample had significantly lower school achievement than nonattempters. The relationship between attempted suicide and low school achievement seemed to be explained by the effects of depression. Lower-SES youth tended to be more likely to attempt suicide than higher-SES youths. However, SES appeared to have little effect on the relationship between attempted suicide and school achievement. Results also suggest that children of mothers with low educational goals for them may be more at risk for attempted suicide than youths whose mothers have higher educational goals for their children.This research was supported by the National Institute of Mental Health, Grant No. MH36971. 相似文献
256.
257.
Cyd C. Strauss Cynthia G. Last Michel Hersen Alan E. Kazdin 《Journal of abnormal child psychology》1988,16(1):57-68
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
258.
Force variability in isometric responses 总被引:2,自引:0,他引:2
K M Newell L G Carlton 《Journal of experimental psychology. Human perception and performance》1988,14(1):37-44
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
259.
260.