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   275篇
  免费   36篇
  国内免费   36篇
  2024年   1篇
  2023年   9篇
  2022年   3篇
  2021年   14篇
  2020年   15篇
  2019年   26篇
  2018年   22篇
  2017年   14篇
  2016年   10篇
  2015年   13篇
  2014年   15篇
  2013年   36篇
  2012年   9篇
  2011年   8篇
  2010年   10篇
  2009年   16篇
  2008年   11篇
  2007年   10篇
  2006年   10篇
  2005年   9篇
  2004年   8篇
  2003年   7篇
  2002年   7篇
  2001年   9篇
  2000年   8篇
  1999年   9篇
  1998年   2篇
  1997年   4篇
  1996年   3篇
  1995年   1篇
  1994年   2篇
  1992年   2篇
  1991年   2篇
  1990年   2篇
  1989年   2篇
  1988年   3篇
  1987年   3篇
  1986年   2篇
  1984年   1篇
  1982年   1篇
  1981年   1篇
  1980年   1篇
  1979年   2篇
  1978年   4篇
排序方式: 共有347条查询结果,搜索用时 78 毫秒
11.
Despite being in existence for many decades, normative decision theory has not become a commonly used tool for real-world decisions. This paper considers the reasons for this situation and suggestions for circumventing them. The main suggestion involves a two-stage framework in terms of the information available to the decision maker and his/her expectations under the available acts. This framework is well suited for decisions with incomplete structure, which is typical of real decision situations. Within this framework a specific multiplicative model is also discussed.  相似文献   
12.
Data in social and behavioral sciences are often hierarchically organized though seldom normal, yet normal theory based inference procedures are routinely used for analyzing multilevel models. Based on this observation, simple adjustments to normal theory based results are proposed to minimize the consequences of violating normality assumptions. For characterizing the distribution of parameter estimates, sandwich-type covariance matrices are derived. Standard errors based on these covariance matrices remain consistent under distributional violations. Implications of various covariance estimators are also discussed. For evaluating the quality of a multilevel model, a rescaled statistic is given for both the hierarchical linear model and the hierarchical structural equation model. The rescaled statistic, improving the likelihood ratio statistic by estimating one extra parameter, approaches the same mean as its reference distribution. A simulation study with a 2-level factor model implies that the rescaled statistic is preferable.This research was supported by grants DA01070 and DA00017 from the National Institute on Drug Abuse and a University of North Texas faculty research grant. We would like to thank the Associate Editor and two reviewers for suggestions that helped to improve the paper.  相似文献   
13.
Three experiments were conducted to examine pigeons' postponement of signaled extinction periods (timeouts) from a schedule of food reinforcement when such responding neither decreased overall timeout frequency nor increased the overall frequency of food reinforcement. A discrete-trial procedure was used in which a response during the first 5 s of a trial postponed an otherwise immediate 60-s timeout to a later part of that same trial but had no effect on whether the timeout occurred. During time-in periods, responses on a second key produced food according to a random-interval 20-s schedule. In Experiment 1, the response-timeout interval was 45 s under postponement conditions and 0 s under extinction conditions (responses were ineffective in postponing timeouts). The percentage of trials with a response was consistently high when the timeout-postponement contingency was in effect and decreased to low levels when it was discontinued under extinction conditions. In Experiment 2, the response-timeout interval was also 45 s but postponement responses increased the duration of the timeout, which varied from 60 s to 105 s across conditions. Postponement responding was maintained, generally at high levels, at all timeout durations, despite sometimes large decreases in the overall frequency of food reinforcement. In Experiment 3, timeout duration was held constant at 60 s while the response-timeout interval was varied systematically across conditions from 0 s to 45 s. Postponement responding was maintained under all conditions in which the response-timeout interval exceeded 0 s (the timeout interval in the absence of a response). In some conditions of Experiment 3, which were designed to control for the immediacy of food reinforcement and food-correlated (time-in) stimuli, responding postponed timeout but the timeout was delayed whether a response occurred or not. Responding was maintained for 2 of 3 subjects, suggesting that behavior was negatively reinforced by timeout postponement rather than positively reinforced by the more immediate presentation of food or food-correlated (time-in) stimuli.  相似文献   
14.
FOK判断等级及其准确性的实验研究   总被引:4,自引:1,他引:3  
通过实验集中探讨了FOK判断等级及其准确性的影响因素。实验以中文字串为学习材料,使用组内设计的实验方法研究了被激活信息的量和强度对FOK等级及准确性的影响。实验结果表明:FOK判断的等级是由被激活信息的总量决定的,和被激活信息的正确与否无关;FOK判断的准确性是由被激活信息的强度决定的;且二者之间是有内在联系的。  相似文献   
15.
The statistical characterisation and synthetic reproduction of a polycrystalline material's microstructure is assisted by mathematically representing its morphology by a tessellation model. The generalised balanced power diagram (GBPD) is a tessellation model that was shown in previous studies to accurately reproduce the microstructure morphology of various materials by closely matching micrographs obtained through electron microscopy. These studies employed costly optimisation procedures to determine the best-fit model parameters, limiting the scalability of the model. In this work, it is shown that setting the tessellation cell parameters to values such that the shape moments of the corresponding grains are matched results in a quality of fit that is commensurate with optimisation procedures. This fitting approach decouples the interaction among grains when fitting the tessellation parameters and, most notably, provides analytical, closed-form expressions for all the model parameters. The performance of this parameter fitting approach is demonstrated on multiple micrographs of various materials, and it compares similarly to the performance of optimisation procedures reported in recently published literature. As the fitted parameter values are obtained through trivial computations, this approach enables extensive scalability of the GBPD model such that it can be used to represent extremely large characterisation data sets.  相似文献   
16.
There is a growing body of evidence that suggests that cognitive vulnerabilities to depression or anxiety may lead individuals to generate negative interpersonal life events. However, there has been no study to date that examines the effects of co-occurring vulnerabilities to depression and anxiety. In a sample of 304 participants, we examined the potential interaction of co-occurring negative cognitive style, a vulnerability to depression and looming cognitive style, vulnerability to anxiety. Results indicate that co-occurring cognitive vulnerabilities synergistically predict higher levels of negative interpersonal life events six weeks later, even when controlling for initial levels of stressful life events and symptoms of depression and anxiety. Thus, co-occurring vulnerabilities may have stronger stress generating effects than would be expected from the additive effects of each vulnerability considered separately. This finding highlights the importance of examining cognitive vulnerabilities as interactive effects rather than as individual vulnerabilities.  相似文献   
17.
Background and Objectives: Although there is supporting evidence for the stress generation hypothesis (i.e., the tendency for depression-prone individuals to experience more negative dependent events influenced by their behaviors and characteristics), additional research is required to advance current understanding of the specific types of dependent events relevant to this effect. The present study elaborated on the stress generation hypothesis, in which the content of negative dependent events experienced by individuals is contingent upon, and matches, the nature of their particular vulnerabilities. This extension was tested within the context of Cole's competency-based model of depression. Design: Participants (n = 185) were assessed at two time-points separated by a four-month interval. Methods: Self-perceived competence in academic, social, and appearance domains at the initial time-point were examined in relation to negative life events prospectively occurring over the four-month follow-up period, assessed using the “contextual threat” method. Results: Partial support was obtained for vulnerability-specific stress generation. Stress-generation specificity was found for self-perceived competence in appearance and academic domains, but not for self-perceived social competence. Conclusions: The current findings are consistent with the possibility of a more complex relation between self-perceived social competence and domain-congruent stress generation. Individuals may be more likely to experience negative dependent events in domains matching their specific vulnerabilities.  相似文献   
18.
Automatic generation of questions and evaluating their answers is a highly challenging task in natural language processing and educational technology. This work focuses on generating subjective questions and also an evaluation system is suggested for assessing the answers. For generating the questionnaires, key-phrases are extracted from the course curriculum (syllabus). Next, based on the key-phrases, different types of subjective questions are generated. Finally, the evaluation of student’s responses is achieved using a multi-criteria-decision-making approach. It uses a set of model answers taken from different textbooks and subject experts to evaluate the answers. Multiple measures are used to assess the answers by comparing them with this model set. The results of the profound system reveal that the automated appraisal process can reduce the manual effort of the human.  相似文献   
19.
The multisensory response enhancement (MRE), occurring when the response to a visual target integrated with a spatially congruent sound is stronger than the response to the visual target alone, is believed to be mediated by the superior colliculus (SC) (Stein & Meredith, 1993). Here, we used a focused attention paradigm to show that the spatial congruency effect occurs with red (SC-effective) but not blue (SC-ineffective) visual stimuli, when presented with spatially congruent sounds. To isolate the chromatic component of SC-ineffective targets and to demonstrate the selectivity of the spatial congruency effect we used the random luminance modulation technique (Experiment 1) and the tritanopic technique (Experiment 2). Our results indicate that the spatial congruency effect does not require the distribution of attention over different sensory modalities and provide correlational evidence that the SC mediates the effect.  相似文献   
20.
The term 1.5 generation has broadly been used to refer to individuals who migrate in childhood or adolescence. It has served as a distinction from the first generation, who voluntarily migrated in adulthood, and from the second generation, born in the host society. The experiences and cultural identities of 1.5-generation children have generally been described as located in between two worlds. However, the present qualitative study conducted among 1.5-generation Chinese living in Spain does not support these views. It shows that some children feel unequivocally Chinese, while the experiences of others reflect much more nuance and complexity that resists categorization. A dialogical perspective is proposed as a multilayered and intersectional approach from which to explore these identities.  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