全文获取类型
收费全文 | 2531篇 |
免费 | 86篇 |
国内免费 | 5篇 |
专业分类
2622篇 |
出版年
2022年 | 11篇 |
2021年 | 11篇 |
2020年 | 34篇 |
2019年 | 32篇 |
2018年 | 69篇 |
2017年 | 58篇 |
2016年 | 54篇 |
2015年 | 42篇 |
2014年 | 68篇 |
2013年 | 334篇 |
2012年 | 108篇 |
2011年 | 114篇 |
2010年 | 63篇 |
2009年 | 71篇 |
2008年 | 95篇 |
2007年 | 101篇 |
2006年 | 112篇 |
2005年 | 105篇 |
2004年 | 81篇 |
2003年 | 84篇 |
2002年 | 79篇 |
2001年 | 49篇 |
2000年 | 42篇 |
1999年 | 53篇 |
1998年 | 56篇 |
1997年 | 36篇 |
1996年 | 32篇 |
1995年 | 36篇 |
1994年 | 37篇 |
1993年 | 38篇 |
1992年 | 32篇 |
1991年 | 38篇 |
1990年 | 23篇 |
1989年 | 28篇 |
1988年 | 14篇 |
1987年 | 20篇 |
1986年 | 20篇 |
1985年 | 23篇 |
1984年 | 25篇 |
1983年 | 27篇 |
1982年 | 28篇 |
1981年 | 24篇 |
1980年 | 15篇 |
1979年 | 20篇 |
1978年 | 25篇 |
1977年 | 18篇 |
1976年 | 13篇 |
1975年 | 18篇 |
1974年 | 19篇 |
1968年 | 11篇 |
排序方式: 共有2622条查询结果,搜索用时 0 毫秒
81.
82.
A modified form of Nathanson and Becker's (1983) Health Belief Model Questionnaire and other measures designed to assess cognitive processing were administered to low-income black adolescent female clients of an inner-city comprehensive health care clinic. The purpose of the study was to explore determinants of sexual activity and contraceptive use. Subjects were classified as not sexually active (n = 50), sexually active/noncontracepting (n = 20), or sexually active/contracepting (n = 72). Not sexually active subjects tended to be younger, more career motivated, to have a father at home, to be more influenced by family values, and to have more conservative attitudes regarding adolescent sexuality than did sexually active subjects. Sexually active/noncontracepting subjects tended to report fewer benefits and more barriers to the use of contraception. Level of cognitive processing did not differ among the three groups, but was at a lower-than-expected level for age. Finally, inconsistent contraceptive use was common to both sexually active groups. 相似文献
83.
Social influence processes affecting adolescent substance use 总被引:14,自引:0,他引:14
Social influence is central to models of adolescent substance use. Nonetheless, researchers fail to delineate the various forms of social influence. A framework that distinguishes between active (explicit drug offers) and passive (social modeling and overestimation of friends' use) social pressure was tested. The effect of these processes on alcohol and cigarette use was examined with 526 seventh graders taking part in an alcohol prevention program. Hierarchical regression analyses demonstrated that pretest measures of alcohol use, offers, modeling, and overestimation each accounted for unique variance in posttest alcohol use. Similar results were obtained for cigarette smoking. The general model was not significantly different for boys and girls, or for prior users and prior nonusers, supporting the generalizability of the framework. Implications for intervention programs are discussed. 相似文献
84.
In a sample of 261 state hospital sexual offenders, Minnesota Multiphasic Personality Inventory (MMPI) profiles did not differ for offenders with adult victims versus offenders with child victims when offender age was controlled. MMPI 2-point analyses for the whole sample revealed five common codes that were independent of victim maturity. The sample was randomly divided in half and subjected to a cluster-analytic procedure which revealed two MMPI clusters. The first cluster was unelevated, with Scale 4 as its high point. The second cluster had multiple elevations, with Scales 8, 4, 2, and 7 as the highest scales. These clusters were replicated in a cluster analysis of the second half of the sample. However, when the sample was recombined, the two clusters were not externally validated basis on demographic and criminological variables. The results suggest that common psychological variables among sexual offenders may have more discriminative value than victim maturity in developing sexual offender taxonomies. 相似文献
85.
This study examined the extent to which the validity scales of the Minnesota Multiphasic Personality Inventory-2 (MMPI-2) could identify subjects who were faking bad or faking good and differentiate between psychiatric patients and normal subjects who were faking bad. Subjects were 106 undergraduate college students and 50 psychiatric patients. Results indicate that the mean profiles and optimal cutoff scores resembled those previously reported for the original MMPI. Accurate identification of persons who were faking bad or faking good was achieved. It was possible to differentiate between the psychiatric patients and normal persons who were faking bad, but different cutoff scores were needed to differentiate between normals taking the test under standard instructions and those instructed to fake bad. Optimal cutoff scores were suggested. 相似文献
86.
Dr. Graham Priest 《Studia Logica》1982,41(2-3):249-268
The paper concerns time, change and contradiction, and is in three parts. The first is an analysis of the problem of the instant of change. It is argued that some changes are such that at the instant of change the system is in both the prior and the posterior state. In particular there are some changes from p being true to p being true where a contradiction is realized. The second part of the paper specifies a formal logic which accommodates this possibility. It is a tense logic based on an underlying paraconsistent prepositional logic, the logic of paradox. (See the author's article of the same name Journal of Philosophical Logic 8 (1979).) Soundness and completeness are established, the latter by the canonical model construction, and extensions of the basic system briefly considered. The final part of the paper discusses Leibniz's principle of continuity: Whatever holds up to the limit holds at the limit. It argues that in the context of physical changes this is a very plausible principle. When it is built into the logic of the previous part, it allows a rigorous proof that change entails contradictions. Finally the relation of this to remarks on dialectics by Hegel and Engels is briefly discussed. 相似文献
87.
88.
Two response measures that described the consistency and accuracy of motor performance were investigated. A pursuit tracking task was used as the vehicle whereby changes in perceptual motor performance could be monitored over several learning trials. The intra-individual variability of a subject's tracking response was compared to the root mean squared error that was accumulated during each block of trials. Whereas both response measures were sensitive to the changes in performance that occured as a result of practice, neither could be considered sufficiently informative as to be used as a sole indicator of skill acquisition. It appears that both consistency and error measures are needed to describe the subjects' performance as they acquire a perceptual motor skill. 相似文献
89.
Two groups of subjects were given pairings of a slide of a triangle (CS1) with an aversive loud noise (US). After first-order conditioning a different figure (CS2+) was paired with CS1, whilst a third figure acted as a non-paired control (CS20). Conditioned second-order skin conductance responses (SCRs) were established to CS2+ for all subjects who had undergone first-order conditioning. Following second-order conditioning, SCRs to CS1 were extinguished and CS2+ was subsequently tested for retention of its SCR evoking properties. For the group of subjects who believed they had an avoidance response available during the second-order conditioning phase, CR2 failed to survive extinction of CR1. However, for the group of subjects who had no perceived control over US presentation, extinction of cr1 did not eliminate CR2. This latter finding is consistent with associative analyses of second-order conditioning in animals and has clinical implications for the treatment of fear-related problems. 相似文献
90.
Eye movements were recorded as subjects read sentences containing temporary structural ambiguities. In accord with the garden-path theory of sentence comprehension, shorter reading times were found for sentences conforming to certain independently motivated parsing strategies (late closure and minimal attachment) than for comparable sentences which violate these strategies. Further, longer fixation durations were associated with the very first fixation in the region of the sentence which disambiguated the sentence, suggesting that the human sentence-parsing mechanism operates in a rather systematic fashion, immediately computing the structural consequences of fixated material for the analysis of preceding material. The pattern of regressive eye movements did not conform to the view that the parsing mechanism automatically returns to the beginning of the sentence to revise an incorrect analysis of linguistic material nor did it support the view that the parsing mechanism systematically backtracks through the sentence until the source of the erroneous analysis is located. Rather, the pattern of regressions indicated that the parsing mechanism typically engages in selective reanalysis, exploiting whatever information it has available about the type of error it has committed to guide its reanalysis attempts. Finally, it is emphasized that an understanding of the parser's revision procedures is essential to an explanation of why certain linguistic structures cannot be successfully parsed by humans. 相似文献