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   40461篇
  免费   877篇
  国内免费   5篇
  41343篇
  2020年   377篇
  2019年   433篇
  2018年   583篇
  2017年   597篇
  2016年   667篇
  2015年   501篇
  2014年   580篇
  2013年   2671篇
  2012年   1117篇
  2011年   1079篇
  2010年   692篇
  2009年   647篇
  2008年   970篇
  2007年   962篇
  2006年   836篇
  2005年   806篇
  2004年   756篇
  2003年   706篇
  2002年   711篇
  2001年   1285篇
  2000年   1239篇
  1999年   908篇
  1998年   412篇
  1992年   873篇
  1991年   818篇
  1990年   830篇
  1989年   725篇
  1988年   717篇
  1987年   688篇
  1986年   724篇
  1985年   803篇
  1984年   602篇
  1983年   562篇
  1982年   380篇
  1981年   371篇
  1980年   356篇
  1979年   692篇
  1978年   439篇
  1977年   427篇
  1976年   426篇
  1975年   592篇
  1974年   679篇
  1973年   715篇
  1972年   623篇
  1971年   586篇
  1970年   579篇
  1969年   563篇
  1968年   756篇
  1967年   665篇
  1966年   598篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
We measured subjective-tone identification thresholds evoked by acoustically filtered complex tones and compared them to Mandarin-Chinese tone-phoneme identification thresholds previously measured under the same filtering conditions. Tone phonemes were identified at intensities below subjective-tone identification thresholds, suggesting subjective tone is not necessary for tone-phoneme identification. Lower subjective-tone thresholds evoked by resolved harmonics rather than unresolved harmonics were consistent with pattern recognition theories of pitch perception.The authors thank Donald Gans and Richard Klich for all their help.  相似文献   
102.
Reports that the dihydropyridine Ca2+ channel antagonists may facilitate memory led to the present study of the behavioral effects of nifedipine. Ninety-two 4-day-old male chicks received 0, 100 nM, 100 microM, or 10 mM nifedipine. Drugs were administered in volumes of 2 microliters into the fourth cerebral ventricle 5 min before training on a visual discrimination task. Nifedipine did not produce any detectable changes in behavior during acquisition trials. Retention, however, was impaired 24 h after training in the 100 nM and 100 microM nifedipine-treated chicks, which made significantly more errors than controls. Nifedipine did not affect the amount of time required to complete the task. No effects on body weight gain were detected, suggesting that the memory impairment was not due to a change in feeding behavior. These data are discussed in terms of the role of calcium-dependent processes in memory.  相似文献   
103.
A multivariate hierarchical model of specific cognitive abilities was fitted to data from 7-year-old adopted and nonadopted sibling pairs in the Colorado Adoption Project in order to assess differential genetic influence on specific mental abilities. Model fitting results and Schmid-Leiman (Schmid & Leiman, 1957) transformations reveal significant heritable variation for verbal, spatial, and memory factors independent of general cognitive ability for the eight ability tests examined. In contrast, environmental influences are primarily measure-specific. The results suggest genetic effects in middle childhood that differentially influence mental ability scores.  相似文献   
104.
Patterns of coping with cancer.   总被引:12,自引:0,他引:12  
We identified five patterns of coping in a sample of 603 cancer patients: "seeking or using social support," "focusing on the positive," "distancing," "cognitive escape-avoidance," and "behavioral escape-avoidance." Relationships of these coping patterns to sociodemographic characteristics, medical factors, stress appraisals, psychotherapeutic experience, and emotional distress were tested using correlational and regression techniques. Type of cancer, time since diagnosis, and whether a person was currently in treatment had few or no relationships to coping. The specific cancer-related problem (e.g., pain, fear of future) was also not associated with how individuals coped. Perceptions of its stressfulness, however, were related to significantly more coping through social support and more of both forms of escape-avoidance. Coping through social support, focusing on the positive, and distancing was associated with less emotional distress, whereas using cognitive and behavioral escape-avoidance was associated with more emotional distress. Implications of the results for understanding coping processes and intervention with cancer patients are discussed.  相似文献   
105.
Anterior cerebral asymmetry and the nature of emotion.   总被引:14,自引:0,他引:14  
This article presents an overview of the author's recent electrophysiological studies of anterior cerebral asymmetries related to emotion and affective style. A theoretical account is provided of the role of the two hemispheres in emotional processing. This account assigns a major role in approach- and withdrawal-related behavior to the left and right frontal and anterior temporal regions of two hemispheres, respectively. Individual differences in approach- and withdrawal-related emotional reactivity and temperament are associated with stable differences in baseline measures of activation asymmetry in these anterior regions. Phasic state changes in emotion result in shifts in anterior activation asymmetry which are superimposed upon these stable baseline differences. Future directions for research in this area are discussed.  相似文献   
106.
107.
Summary The effects of noncontingency between subjects' responses and outcomes were examined with respect to treatment-and-posttest similarity and skill in the task. The experimental design consisted of three groups. The first group had to solve chess problems with objective solutions and received veridical feedback; each member of the second group faced problems with no objective solutions, and received the same feedback as the member of the first group he was yoked with, but without any control on it; the control group received a waiting task. It was found at the end of the experiment that the group with unsolvable problems was more depressed than the two other groups. The mid-strength players were the most sensitive to the manipulation, and the weakest players showed little effect of learned helplessness. It was also found that the effects were proportional to the degree of similarity between the treatment and the posttest. The results limit the domain of applicability of the learned-helplessness model.  相似文献   
108.
Postinstitutional arrests and state hospitalizations of 191 patients placed on conditional release (CONREP group) were compared to those of 44 patients released from the same California state hospital with no aftercare due to expiration of commitment terms (MAXOUT group). The two groups were not randomly determined but were comparable in demographic characteristics and rates of preprogram arrest. The CONREP group had a significantly lower community-period arrest rate than did the MAXOUT group (p <.001). Survival rate analyses, using time until arrest and time until revocation as dependent variables, suggested that revocations during the first 240 days of community re-entry reduced the potential arrest rate within the CONREP group. Results were discussed in terms of the “criminalization hypothesis” as well as the crime-preventive possibilities of the conditional release mechanism.  相似文献   
109.
An expanded view of health is advocated for assessment and treatment of individual clients in helping them achieve and maintain their maximum potential for high-level wellness. In addition, moderating variables, such as culture, age, and gender differences, have an impact on every dimension of health and wellness. In this article a multidimensional systems model for wellness is described, and gender differences along those dimensions are reviewed. Application of the model and implications for counseling are discussed. Finally, two illustrative case examples, one man and one woman, are described.  相似文献   
110.
Gerontologists have long been concerned with the impact of individual-difference factors on memory. This study used a large sample (N = 2,495) of adult volunteers aged 18 to 90 years to determine if a set of individual-difference variables--vocabulary, education, depression, gender, marital status, and employment status--mediates the effects of aging on a wide range of laboratory-analogue tests of everyday memory. The data indicated that age was consistently the most significant predictor of memory performance, followed by vocabulary and gender. Vocabulary totally mediated age effects on a prose memory measure, and partial mediation of aging effects--primarily by vocabulary and gender--was observed on 5 other memory tests. These data suggest that when health samples of volunteers serve as research subjects, these individual differences can affect some memory test scores, but age remains the best overall predictor of memory performance.  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