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   321篇
  免费   24篇
  2023年   4篇
  2022年   8篇
  2021年   7篇
  2020年   12篇
  2019年   17篇
  2018年   24篇
  2017年   12篇
  2016年   15篇
  2015年   11篇
  2014年   21篇
  2013年   38篇
  2012年   28篇
  2011年   23篇
  2010年   14篇
  2009年   8篇
  2008年   15篇
  2007年   13篇
  2006年   10篇
  2005年   11篇
  2004年   11篇
  2003年   7篇
  2002年   7篇
  2001年   4篇
  2000年   1篇
  1999年   1篇
  1997年   1篇
  1996年   2篇
  1995年   1篇
  1994年   3篇
  1993年   1篇
  1992年   1篇
  1991年   2篇
  1990年   3篇
  1989年   1篇
  1987年   1篇
  1985年   1篇
  1984年   1篇
  1983年   2篇
  1981年   1篇
  1979年   1篇
  1977年   1篇
排序方式: 共有345条查询结果,搜索用时 15 毫秒
141.
142.
Despite the benefits of precision agriculture and precision viticulture production systems, its rate of adoption in the Portuguese Douro Demarcated Region remains low. We believe that one way to raise it is to address challenging real-world problems whose solution offers a clear benefit to the viticulturist. For example, one of the most demanding tasks in wine making is harvesting. Even for humans, the environment makes grape detection difficult, especially when the grapes and leaves have a similar color, which is generally the case for white grapes. In this paper, we propose a system for the detection and location, in the natural environment, of bunches of grapes in color images. This system is able to distinguish between white and red grapes, and at the same time, it calculates the location of the bunch stem. The system achieved 97% and 91% correct classifications for red and white grapes, respectively.  相似文献   
143.
Automatic imitation has been often confounded with spatial compatibility effects. Heyes (2011) called attention to this confound, and proposed some criteria which must be satisfied before these effects could be unequivocally taken to be an index of the functioning of the human mirror system. Evidence satisfying such criteria has been reported by Catmur and Heyes (2011), using a relatively unfamiliar finger abduction movement. However, because many previous studies relied on more familiar actions, we aimed at testing whether analogous effects could be obtained with a more practiced key-pressing task. In Experiment 1, we used anatomical controls (i.e., views of right vs. left hands) under conditions affording mirror imitation, and showed that spatial compatibility masked the effects of automatic imitation. Experiment 2 used rotated conditions to control for this spatial-anatomical confound, and it showed unequivocal effects of automatic imitation, which were obtained regardless of its relation to the spatial stimulus-response mapping. These results cast some doubts on the interpretation of previous reports relying exclusively on scenes presented from a mirror perspective, and suggest the convenience of using both rotated scenes and anatomical controls in order to assess automatic imitation.  相似文献   
144.
The overall goals of this study were to test single versus multiple cognitive deficit models of dyslexia (reading disability) at the level of individual cases and to determine the clinical utility of these models for prediction and diagnosis of dyslexia. To accomplish these goals, we tested five cognitive models of dyslexia--two single-deficit models, two multiple-deficit models, and one hybrid model--in two large population-based samples, one cross-sectional (Colorado Learning Disability Research Center) and one longitudinal (International longitudinal Twin Study). The cognitive deficits included in these cognitive models were in phonological awareness, language skill, and processing speed and/or naming speed. To determine whether an individual case fit one of these models, we used two methods: 1) the presence or absence of the predicted cognitive deficits, and 2) whether the individual's level of reading skill best fit the regression equation with the relevant cognitive predictors (i.e., whether their reading skill was proportional to those cognitive predictors.) We found that roughly equal proportions of cases met both tests of model fit for the multiple deficit models (30-36%) and single deficit models (24-28%); hence, the hybrid model provided the best overall fit to the data. The remaining roughly 40% of cases in each sample lacked the deficit or deficits that corresponded with their best-fitting regression model. We discuss the clinical implications of these results for both diagnosis of school-age children and preschool prediction of children at risk for dyslexia.  相似文献   
145.
It has been shown that the brain has its own intrinsic renin-angiotensin system (RAS) and angiotensin-(1-7) (Ang-(1-7)) is particularly interesting, because it appears to counterbalance most of the Ang II effects. Ang-(1-7) exerts its biological function through activation of the G-protein-coupled receptor Mas. Interestingly, hippocampus is one of the regions with higher expression of Mas. However, the role of Ang-(1-7)/Mas axis in hippocampus-dependent memories is still poorly understood. Here we demonstrated that Mas ablation, as well as the blockade of Mas in the CA1-hippocampus, impaired object recognition memory (ORM). We also demonstrated that the blockade of Ang II receptors AT1, but not AT2, recovers ORM impairment of Mas-deficient mice. Considering that high concentrations of Ang-(1-7) may activate AT1 receptors, nonspecifically, we evaluate the levels of Ang-(1-7) and its main precursors Ang I and Ang II in the hippocampus of Mas-deficient mice. The Ang I and Ang II levels are unaltered in the whole hipocampus of MasKo. However, Ang-(1-7) concentration is increased in the whole hippocampus of MasKo mice, as well as in the CA1 area. Taken together, our findings suggest that the functionality of the Ang-(1-7)/Mas axis is essential for normal ORM processing.  相似文献   
146.
Exercise induces brain function adaptations and improves learning and memory; however the time window of exercise effects has been poorly investigated. Studies demonstrate an important role for cyclooxygenase-2 (COX-2) pathway function in the mechanisms underlying memory formation. The aim of present work was to investigate the effects of treadmill exercise on aversive memory and COX-2, PGE(2) and E-prostanoid receptors contents in the rat hippocampus at different time points after exercise has ended. Adult male Wistar rats were assigned to non-exercised (sedentary) and exercised (running daily for 20min, for 2weeks) groups. The inhibitory avoidance task was used to assess aversive memory and the COX-2, PGE(2) and E-prostanoid receptors (EP1, EP2, EP3 and EP4) levels were determined 1h, 18h, 3days or 7days after the last training session of treadmill exercise. The step down latency in the inhibitory avoidance, COX-2 and EP4 receptors levels were acutely increased by exercise, with a significant positive correlation between aversive memory performance and COX-2 levels. Increased EP2 content decreased PGE(2) levels were observed 7days after the last running session. The treadmill exercise protocol facilitates inhibitory avoidance memory and induces time-dependent changes on COX-2 pathways function (COX-2, PGE(2) and EP receptors).  相似文献   
147.
The central role of perceived control in the development of anxiety disorders is proposed by several theoretical models. The main objective of the present study was to examine the relation between perceived control and anxiety in Portuguese school-age children. To accomplish this objective we developed the Portuguese short form of the Anxiety Control Questionnaire for Children (ACQ-C, Weems, 2005; Pereira & Barros, 2010), whose psychometric studies are presented. The sample comprised 238 children, aged 8 to 15 years, from the general population attending Portuguese schools. Children completed measures of perceived control (ACQ-C) and their anxiety (Screen for Child Anxiety Related Emotional Disorders--Revised, SCARED-R). The psychometric studies indicate good psychometric characteristics of the Portuguese ACQ-C short form, in particular a high internal consistency (a = .85) and an adequate temporal stability (r = .60, p = .002). Results show a significant negative association between perceived control and anxiety symptomatology, providing partial support for models that assign a central role to control beliefs in explaining the development of anxiety disorders. These results also suggest the importance of considering the perception of control as a prime target for preventive actions and intervention aimed at reducing anxiety in school aged children.  相似文献   
148.
Affiliative stimuli are pleasant and highly biologically relevant. Affiliative cues are thought to elicit a prosocial predisposition. Here affiliative and neutral pictures were exposed prior to a reaction time task which consisted in responding to a visual target. Half the participants responded with finger-flexion, a movement frequently involved in prosocial activities. The other half responded with finger extension, a less prosocially compatible movement. Results showed that under the exposure to affiliative pictures, as compared to neutral ones, participants who used finger flexion were faster, while those using finger extension were slower. Performance benefits to the task, when flexing the finger, together with performance costs, when extending it, indicate the relevance of movement compatibility to the context. These findings put forward a possible link between affiliative primers and motor preparation to facilitate a repertoire of movements related to prosocial predispositions including finger flexion.  相似文献   
149.
Misinformation has negative effects in the accuracy of eyewitnesses' reports. We investigated whether those negative effects could be reduced when participants are allowed to decide how many answers to include in their answers, that is, to regulate the plurality option. Participants watched a slideshow and received misinformation through a narrative. In the recognition memory test, participants had to select, out of five alternatives, one (single) and then three alternatives (plural answer) and to indicate which one they preferred to report if they were in a courtroom. Perceived likelihood ratings were also collected. Results showed that the regulation of the plurality option increased accuracy even in the presence of misinformation and highlighted the importance of the perceived likelihood ratings in the decision to select a single or plural answer. In general, the results suggest that better testimonies could be obtained if witnesses are given some control over their answers. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
150.
This paper aims to untangle the relationship between income and subjective well-being. To accomplish this, we investigate how subjective well-being is affected by two financially-related determinants that have not been investigated before or scarcely so. Specifically, we research the impact on subjective well-being of how people are coping with their present income as well as of their borrowing constraints. The results indicate that both variables determine subjective well-being and that they mediate the effects of other variables, namely income, which is not directly related to well-being. Additionally, they signal that income matters to the extent to which it contributes to meeting the desired consumption needs and eases borrowing constraints. Such mediating effects thus contribute to explain how income affects subjective well-being. We also inspect differences in life satisfaction responsiveness to perceived income adequacy and borrowing constraints in certain groups of individuals, and find that the subjective well-being of individuals in a more fragile financial position is particularly responsive to the alleviation of borrowing constraints.  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