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961.
Cluster analysis refers to a family of methods for identifying cases with distinctive characteristics in heterogeneous samples and combining them into homogeneous groups. This approach provides a great deal of information about the types of cases and the distributions of variables in a sample. This paper considers cluster analysis as a quantitative complement to the traditional linear statistics that often characterize community psychology research. Cluster analysis emphasizes diversity rather than central tendency. This makes it a valuable tool for a wide range of familiar problems in community research. A number of these applications are considered here, including the assessment of change over time, network composition, network density, person-setting relationships, and community diversity. A User's Guide section is included, which outlines the major decisions involved in a basic cluster analyses. Despite difficulties associated with the identification of optimal cluster solutions, carefully planned, theoretically informed application of cluster analysis has much to offer community researchers.
Editor's note: Dr. Edward Seidman served as action editor for this article while serving as Associate Editor for Methodology. 相似文献
962.
In this study the authors explored the relationship between counselor trainee anger-proneness and anger discomfort and trainees' reactions to an angry client. A total of 38 of trainees viewed and gave their reactions to a videotape of an angry client-actress. There were two dependent variables in the study: discomfort with and anger toward the client. Trainee anger-proneness and anger discomfort scores were positively and significantly related to discomfort with and anger toward the client. Implications for future research and training are discussed. 相似文献
963.
Monkeys performed a visual search task for food reward. Green square targets were embedded in 3 × 3 arrays of colored forms. In distinct-feature arrays, all nontarget stimuli were red diamonds, whereas in shared-feature arrays, some nontarget stimuli shared either form (red square) or color (green diamond) with the target. Reaction time was slower for shared-feature arrays and linearly related to the number of shared-feature distractors. Errors were more common in shared-feature arrays, and shared-feature distractors were mistaken for targets more frequently than distinct-feature distractors. Event-related local field potentials were recorded from implanted transcortical electrodes. Significant task-related differences were obtained from association cortex, but not from projection cortex. Results are discussed in terms of the relative contribution of inferotem-poral, 相似文献
964.
Mark and Todd (1983) reported an experiment in which the cardioidal strain transformation was extended to three dimensions and applied to a three-dimensional (3-D) representation of the head of a 15-year-old girl in a direction that made the transformed head appear younger to the vast majority of their subjects. The experiments reported here extend this research in order to examine whether subjects are indeed detecting cardioidal strain in three dimensions, rather than detecting changes in head slant or making 2-D comparisons of the shape of the occluding contour. Three-dimensional surfaces were obtained by measuring a real head manually (Experiment 1) and with a laser scanner (Experiment 2), and transformed to different age levels using the 3-D strain transformation described by Mark and Todd (1983). There were no statistically significant differences in the accuracy with which relative age judgments could be made in response to pairs of profiles, pairs of 3/4 views, or pairs of mixed views (profile plus 3/4 view), suggesting that subjects can indeed extract the cardioidal strain level of the head in three dimensions. However, an additional effect that emerged in these studies was that judgments were crucially affected by the instructions given to subjects, which suggests that factors other than cardioidal strain are important in making judgments about rich data structures. 相似文献
965.
Summary In the awake, behaving cat, we have compared response of striate cortex neurons to informative and to noninformative stimuli. A cat pressed a pedal in response to a flashed pattern repeated every 10 s, receiving a reward if the press was within a 0.5–1.5-s post-stimulus window. There were three trial types: 50% of the trials had only the initial informative flash, 25% had an additional physically identical, but unrewarded, flash 500 ms after the first, and 25% had an unrewarded flash 3–5 s after the informative flash. Cats learned to respond only to the rewarded flashes. Neurons were divided into two categories: 27 neurons defined as primary showed an early burst of firing 30–70 ms after stimulus onset, and 17 did not. The distinction was arbitrary, since all cells were exposed to the same stimulus. For stimuli preceding a pedal press, stimulus-synchronized histograms of primary neurons had a smaller early burst and more firing before and after it. Response-synchronized histograms showed an abrupt decrease in firing shortly before the pedal press. The effects were stronger for primary cells in the stimulus-synchronized data and stronger for non-primary cells in the response-synchronized data. 相似文献
966.
Pigeons were exposed to continuous and partial reinforcement (25%) schedules in an autoshaping procedure. The number of trials and/or pairings per session were equated across two factorial group sets and all groups were trained for a fixed total number of acquisition trials (192). When acquisition was analyzed as a function of reinforcements delivered, the groups receiving fewer number of trials per session acquired the response faster, independently of the percentage of reinforced trials. Moreover, the number of reinforcements to satisfy an acquisition criterion was a monotonic function of the number of trials per session but not of the schedule. The results are discussed in relation to the neocontinuity and the scalar expectancy theories. 相似文献
967.
A statewide study of adolescents' attitudes toward division of labor in the home was conducted to determine if adolescents are becoming more egalitarian in their approach to sex roles. This investigation attempted to examine adolescents' attitudes toward household tasks based on gender and maternal employment. A survey-research design was employed to collect data on 893 students in grades 7 to 12 as part of a larger study to develop a profile of today's adolescents. In general, the findings indicated that adolescents' attitudes were still somewhat traditional. Although some variations in sex-role performance of tasks were evident between males and females and students with employed and unemployed mothers, these differences were not significant. 相似文献
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