全文获取类型
收费全文 | 560篇 |
免费 | 24篇 |
出版年
2023年 | 5篇 |
2021年 | 4篇 |
2020年 | 11篇 |
2019年 | 5篇 |
2018年 | 14篇 |
2017年 | 14篇 |
2016年 | 19篇 |
2015年 | 12篇 |
2014年 | 15篇 |
2013年 | 85篇 |
2012年 | 28篇 |
2011年 | 28篇 |
2010年 | 11篇 |
2009年 | 13篇 |
2008年 | 8篇 |
2007年 | 22篇 |
2006年 | 18篇 |
2005年 | 11篇 |
2004年 | 14篇 |
2003年 | 10篇 |
2002年 | 14篇 |
2001年 | 11篇 |
2000年 | 13篇 |
1999年 | 10篇 |
1998年 | 8篇 |
1997年 | 7篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 9篇 |
1991年 | 5篇 |
1990年 | 12篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1987年 | 12篇 |
1986年 | 4篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1980年 | 6篇 |
1979年 | 6篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1975年 | 7篇 |
1974年 | 5篇 |
1973年 | 9篇 |
1971年 | 5篇 |
1970年 | 6篇 |
1969年 | 5篇 |
1968年 | 6篇 |
1966年 | 6篇 |
排序方式: 共有584条查询结果,搜索用时 15 毫秒
111.
Motion in depth results in radial optic-flow patterns. Forward motion results in radially expanding patterns, whereas backward motion generates contracting patterns. Radial optic-flow patterns are typically represented with a positive speed gradient, ie zero speed at the point of fixation, and maximum speed at the periphery. However, the actual speed profile in such a stimulus will depend upon the relative depth of objects in the scene. Using large-field stimuli (82 deg diameter) we determined relative sensitivities to radial expansion and contraction patterns and also to various types of speed gradients: positive, negative, random, and flat. We found that, even when large-field stimuli are used, observers are more sensitive to radially contracting patterns than to expanding patterns. Sensitivity to the positive speed gradient was not consistently different from either the negative or random gradients. Sensitivity to the flat gradient depended upon the speed of the stimuli. The finding of greater sensitivity to radial contraction is discussed in terms of the functional requirements involved in the use of optic-flow signals in maintaining balance. On the basis of the present findings, the utility of comparing psychophysical results based on thresholds against physiological data based on suprathreshold stimuli is also discussed. 相似文献
112.
Suicide deaths are often viewed as sudden and unexpected. Research examining bereavement responses to suicide are generally set within this conceptual framework. Twenty-two parents were interviewed about their bereavement experience following the suicide death of a young adult son or daughter. Data analyzed using narrative methods revealed the concept of preparedness. Three distinct preparedness narratives were identified, termed turbulent-relief, tragedy, and reflective plots. The data presented here highlights the way in which these different situations influence the resultant grief. Understanding preparedness for suicide assists in explaining the variety of grief responses in parents bereaved in this manner. 相似文献
113.
The neural consequences of semantic richness: when more comes to mind, less activation is observed 总被引:1,自引:0,他引:1
Some concepts have richer semantic representations than others. That is, when considering the meaning of concepts, subjects generate more information (more features, more associates) for some concepts than for others. This variability in semantic richness influences responses in speeded tasks that involve semantic processing, such as lexical decision and semantic categorization tasks. It has been suggested that concepts with richer semantic representations build stronger attractors in semantic space, allowing faster settling of activation patterns and thus faster responding. Using event-related functional magnetic resonance imaging, we examined the neural activation associated with semantic richness by contrasting activation for words with high and low numbers of associates in a semantic categorization task. Results were consistent with faster semantic settling for words with richer representations: Words with a low number of semantic associates produced more activation than words with a high number of semantic associates in a number of regions, including left inferior frontal and inferior temporal gyri. 相似文献
114.
Enriching the environment of alphaCaMKIIT286A mutant mice reveals that LTD occurs in memory processing but must be subsequently reversed by LTP
下载免费PDF全文
![点击此处可从《Learning & memory (Cold Spring Harbor, N.Y.)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Parsley SL Pilgram SM Soto F Giese KP Edwards FA 《Learning & memory (Cold Spring Harbor, N.Y.)》2007,14(1-2):75-83
alphaCaMKII(T286A) mutant mice lack long-term potentiation (LTP) in the hippocampal CA1 region and are impaired in spatial learning. In situ hybridization confirms that the mutant mice show the same developmental expression of alphaCaMKII as their wild-type littermates. A simple hypothesis would suggest that if LTP is a substrate for learning, then enriching the environment should cause learning-dependent changes in wild-type mice that have LTP. Such changes would not be seen in LTP-deficient alphaCaMKII(T286A) mutants. Excitatory synaptic currents in CA1 neurons, recorded with patch clamp in brain slices, revealed that enrichment induces an increase in glutamate release probability and a decreased miniature current amplitude. Confocal microscopy also showed dendritic spine density to be reduced. However, contrary to the hypothesis above, these enrichment-induced changes occur only in the mutant mice and are not detectable in wild-type littermates. We suggest that enrichment induces alphaCaMKII-independent changes in both wild-type and mutant mice. Such changes may be subsequently reversed in wild-type animals via alphaCaMKII-dependent mechanisms, such as LTP. Reversal of plasticity has long been hypothesized to be essential for the hippocampus to maintain its role in memory processing. The inability to reverse plasticity in alphaCaMKII(T286A) mutant mice would then result in impairment of spatial learning. 相似文献
115.
116.
Edwards MC Gardner ES Chelonis JJ Schulz EG Flake RA Diaz PF 《Journal of abnormal child psychology》2007,35(3):393-404
This study evaluated the validity and classification utility of the Conners' Continuous Performance Test (CCPT) in the assessment of inattentive and hyperactive-impulsive behaviors in children. Significant, positive correlations between the CCPT parameters and behavioral ratings of ADHD behaviors were hypothesized. In addition, it was hypothesized that the CCPT parameters would perform better than a random test (chance) and show fair to moderate utility of classification across the different indices. Participants were 104 children between 6 and 12 years of age who were referred for evaluation of attention problems. The first hypothesis was not supported. There were no significant, positive correlations between the CCPT parameters and parent and teacher ratings of inattentive and hyperactive-impulsive behaviors. The second hypothesis was only partially supported. The CCPT Overall Index and the Omission Errors (84th percentile cutoff) performed better than a random test; however, the utility of the CCPT Overall Index only ranged from poor to slight. Receiver operating characteristic analyses showed the accuracy of the CCPT to be low. The implications and limitations of this study and future research directions are discussed. 相似文献
117.
Examined the free-field interaction of 32 mother-child dyads who volunteered to participate in a 1-hr home observation. Observers coded mother instructions, child compliance, and child prosocial approaches plus mothers' social attention as potential reinforcers for the children's compliance and social approaches. Herrnstein's matching law was used to analyze covariations between mothers' attention and the children's 2 responses. This analysis was followed by correlational and sequential probability analyses to determine linkages between these 2 child responses and the children's willingness to obey their mothers' instructions. Results showed consistent matching between mothers' social attention and the children's production of prosocial approaches and acts of compliance. An index of the proportions of these 2 responses also covaried with the children's compliance probabilities, and the prosocial approach component was the direct covariate. These findings are discussed within an interactional synchrony framework in which children's willingness to obey their mothers is influenced by opportunities for the dyad to engage each other in specific forms of social interaction. 相似文献
118.
119.
120.