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   3555篇
  免费   241篇
  国内免费   147篇
  3943篇
  2024年   20篇
  2023年   131篇
  2022年   73篇
  2021年   106篇
  2020年   229篇
  2019年   223篇
  2018年   157篇
  2017年   211篇
  2016年   193篇
  2015年   162篇
  2014年   180篇
  2013年   760篇
  2012年   59篇
  2011年   82篇
  2010年   74篇
  2009年   111篇
  2008年   79篇
  2007年   103篇
  2006年   91篇
  2005年   104篇
  2004年   70篇
  2003年   69篇
  2002年   78篇
  2001年   72篇
  2000年   60篇
  1999年   58篇
  1998年   49篇
  1997年   44篇
  1996年   31篇
  1995年   35篇
  1994年   31篇
  1993年   18篇
  1992年   14篇
  1991年   21篇
  1990年   17篇
  1989年   10篇
  1988年   7篇
  1987年   10篇
  1986年   14篇
  1985年   15篇
  1984年   13篇
  1983年   3篇
  1982年   7篇
  1981年   11篇
  1980年   11篇
  1979年   19篇
  1978年   2篇
  1977年   4篇
  1976年   1篇
  1975年   1篇
排序方式: 共有3943条查询结果,搜索用时 0 毫秒
151.
Poverty is a community stressor that disproportionally affects ethnic minority families. One aspect of programmatic research on poverty focuses on the psychological sense of economic hardship. In a study of 319 African American, European American, and Mexican American urban families, parents completed objective measures of economic status and scales of perceived economic hardship that were adapted from previous research. Measurement models identified a coherent construct of psychological sense of economic hardship that was essentially equivalent for mothers and fathers, English- and Spanish-speaking Mexican Americans, and the 3 ethnic groups. In support of the validity of this construct, relations between objective indicators of economic status and perceived economic hardship showed equivalence across these same groups.  相似文献   
152.
The effects of manipulations of response requirement, intertrial interval (ITI), and psychoactive drugs (ethanol, phencyclidine, and d-amphetamine) on lever choice under concurrent fixed-ratio schedules were investigated in rats. Responding on the "certain' lever produced three 45-mg pellets, whereas responding on the "risky" lever produced either 15 pellets (p = .33) or no pellets (p .67). Rats earned all food during the session, which ended after 12 forced trials and 93 choice trials or 90 min, whichever occurred first. When the response requirement was increased from 1 to 16 and the ITI was 20 s, percentage of risky choice was inversely related to fixed-ratio value. When only a single response was required but the ITI was manipulated between 20 and 120 s (with maximum session duration held constant), percentage of risky choice was directly related to length of the ITI. The effects of the drugs were investigated first at an ITI of 20 s, when risky choice was low for most rats, and then at an ITI of 80 s, when risky choice was higher for most rats. Ethanol usually decreased risky choice. Phencyclidine did not usually affect risky choice when the ITI was 20 s but decreased it in half the rats when the ITI was 80 s. For d-amphetamine, the effects appeared to he related to baseline probability of risky choice; that is, low probabilities were increased and high probabilities were decreased. Although increase in risky choice as a function of the ITI is at variance with previous ITI data, it is consistent with foraging data showing that risk aversion decreases as food availability decreases. The pharmacological manipulations showed that drug effects on risky choice may be influenced by the baseline probability of risky choice, just as drug effects can be a function of baseline response rate.  相似文献   
153.
A Neuropsychological Approach to Intelligence   总被引:1,自引:0,他引:1  
This paper proposes that current psychometric intelligence tests are limited in evaluating cognitive activity. From a neuropsychological perspective, they fail to measure some fundamental cognitive abilities such as executive functions, memory, and visuospatial abilities. The analysis of the Wechsler Intelligence Scale presented shows that the original rationale for selecting the specific subtests included in the WAIS was unclear. The concept of a g factor in cognition is also analyzed, with the conclusion that the g factor continues to be controversial. The value of intelligence tests in predicting school performance is also criticized. It is proposed that the psychometric concept of general intelligence should be deleted from cognitive and neurological sciences. Finally, it is proposed that, in the future, neuropsychological instruments sensitive to more specific cognitive abilities replace current psychometric intelligence tests.  相似文献   
154.
Differential rates of participation in three categories of risk behaviors (i.e., sexual activity, substance use, violence) were explored, comparing gang members to nonmembers, within a sample of 1,143 inner-city African American adolescent females. The relationship between gang membership and risk behavior also was examined, by exploring the association between a variety of microsystemic influences (e.g., gang, family, school) and participation in risk behaviors. MANOVA analyses indicated that gang members, relative to nonmembers, reported higher rates of participation in each of the three categories of risk behaviors. Stepwise linear regression analyses indicated that gang membership was the variable with the most consistent predictive ability, across all categories of risk, as it entered early in all equations and remained in all three final models after controlling for other statistically significant contextual variables. Findings suggest that intervention efforts aimed at reducing adolescent females' participation in sexual activity, substance use, and violence should consider the influence of gang membership on the participation in these behaviors.  相似文献   
155.
This two-phase panel study examines the development of the congruence between vocational interests and perceived skill requirements. Participants were 492 Dutch men and women between 18 and 26 years old, with a paid job in both phases. Three hypotheses inspired by the theory of work adjustment (Dawis and Lofquist 1984) and congruence theory (Holland 1992) were tested, using a composite index of fit proposed by Cronbach and Gleser (1953). The first hypothesis proposing that participants experiencing incongruence between their vocational interests and their perceived skill requirements are dissatisfied with their job was supported. The hypothesis that incongruence has a positive relationship with job change and a negative relationship with tenure was not confirmed. The expectation that the congruence between vocational interests and perceived skill requirements increases over time was confirmed. Furthermore, exploring determinants of change in vocational interests and perceived skill requirements, it was found that change in these domains was predicted by different variables, educational level being the only common factor. It is concluded that this study supports the longitudinal propositions of prevailing work-related person-environment fit theories.  相似文献   
156.
The purpose of this study was to develop a reliable and valid measure of affective disorder in elderly demented patients. The field lacks instruments which are sensitive to detecting depressive signs in severely as well as mildly and moderately demented subjects. Two samples of subjects were chosen for study. The first sample consisted of subjects from six institutions, which were chosen for study from a probability sample of 25 long-term care institutions in New York City. This sample was part of the Cross-National Institutional Study conducted in New York and London (Gurland et al., 1979; Mann et al., 1984). Thirty patients were selected at random within each institution. The second sample consisted of 52 inpatients at Willard Psychiatric Center, a traditional state psychiatric hospital in upstate New York. All subjects had a chart diagnosis of dementia and were 60 years old or older. The mean age of the sample was 82 years and 56% of the subjects were female. The Feeling-Tone Questionnaire, which was developed for these analyses, consists of 16 dichotomous items and 16 5-point Likert ratings of affect. The reliability of this scale using Cronbach's alpha is .91 for the long-term care institutional sample and .90 for the psychiatric hospital sample. Interrater reliability for two raters on ten cases is .99. Test–retest reliability on ten cases with a 1-day to 2-day interval between trials is .81. A short mood scale was developed from the observational data as a validity measure for the Feeling-Tone Questionnaire. Evidence for the validity of the Feeling-Tone Questionnaire is provided.  相似文献   
157.
Conduct Disorder in Girls: A Review of the Literature   总被引:8,自引:0,他引:8  
The study of Conduct Disorder (CD) has primarily been limited to boys. The lack of research resulted from a premise that CD in girls was rare. However, CD in girls is a relatively common psychiatric diagnosis, and appears to be associated with several serious outcomes, such as Antisocial Personality Disorder and early pregnancy. Understanding gender differences in the course and severity of CD may lead to important information about etiology. Empirical studies on precursors, developmental course, risk factors and treatment for CD in girls are reviewed, while highlighting similarities and differences between girls and boys. Generally, CD symptoms in girls are stable. Precursors to CD in girls probably include Oppositional Defiant Disorder and temperamental factors, but also may include certain negative cognitions. What distinguishes CD in girls is the high risk they have to develop comorbid conditions, especially internalizing disorders. Risk factors for CD in girls partly overlap with those known for boys, but some factors appear to be highly salient for girls. Finally, there may be some significant effects of gender on treatment efficacy. Implications of these findings for future etiologic research are discussed.  相似文献   
158.
Alzheimer's disease remains the most common form of dementia. Dementia symptoms vary depending on individual personality, life experience, and social and cultural influences. As dementia progresses, involvement of multi-disciplinary health care professionals is needed to manage the disease. Alzheimer research is progressing rapidly. While 5% of all Alzheimer's disease may be genetically determined, the majority is not. Susceptibility genes can reveal the risk of contracting Alzheimer's disease. Early life risk factors such as education, nutrition, and vascular disease may increase the likelihood of dementia in later life. In the United States, two acetylcholinesterase inhibitors have been approved as cognitive enhancers. Possible prevention and symptomatic treatment interventions have focused on estrogen replacement therapy, antioxidants, and anti-inflammatory medications. Research advances have improved the clinical management of dementia. Ethical implications to the patient, family, and society are multiple and remain challenging.  相似文献   
159.
The play and language development of 171 toddlers was examined at 14 and 18 months by observing their activities on the Symbolic Play Test and by assessing their language skills using the MacArthur Communicative Development Inventories (MCDI) and the Reynell Developmental Language Scales. Additionally, data from the Bayley Scales of Infant Development and the MCDI were obtained at 24 months, in order to investigate how play and language measures taken at 14 and 18 months predict children's development at the age of 2 years. The results showed that the vocabulary production and symbolic play of the 14-month-old toddlers made a unique contribution to their language and cognitive skills at the age of 2 years, while at 18 months only language variables made a similar contribution. Other-directed pretense discriminated between the children's subsequent language and cognitive skills best, whereas nonsymbolic play had no independent predictive contribution. Significant gender differences were found in the use of nonsymbolic and symbolic play acts already at 14 months. Gender did not, however, contribute to the prediction of the children's subsequent skills, whereas maternal education significantly added to the prediction of the 2-year-olds' maximum sentence length and that of their cognitive development.  相似文献   
160.
We examined the extent to which variations in session duration affected the outcomes of functional analyses. Forty-six individuals, all diagnosed with mental retardation and referred for assessment and treatment of self-injurious or aggressive behavior, participated in functional analyses, consisting of repeated exposure to multiple test conditions during 15-min sessions. For each set of assessment data, new data sets based on session durations of 10 and 5 min were prepared by deleting data from the last 5 and 10 min, respectively, of each session. Each graph (N = 138) was then reviewed individually by graduate students who had previous experience conducting and interpreting functional analyses, but who were blind to both participant identity and session duration. Interpretations of behavioral function based on the 10- and 5-min data sets were then compared with those based on the 15-min data sets. All of the 10-min data sets yielded interpretations identical to those based on 15-min data sets. Interpretations based on the 5-min and 15-min data sets yielded three discrepancies, all of which were the result of increased response rates toward the latter parts of sessions. These results suggest that the efficiency of assessment might be improved with little or no loss in clarity by simply reducing the duration of assessment sessions.  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