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   247篇
  免费   56篇
  国内免费   20篇
  323篇
  2024年   1篇
  2023年   3篇
  2022年   5篇
  2021年   5篇
  2020年   3篇
  2019年   13篇
  2018年   10篇
  2017年   12篇
  2016年   17篇
  2015年   6篇
  2014年   22篇
  2013年   39篇
  2012年   3篇
  2011年   12篇
  2010年   6篇
  2009年   6篇
  2008年   11篇
  2007年   10篇
  2006年   9篇
  2005年   9篇
  2004年   13篇
  2003年   7篇
  2002年   12篇
  2001年   8篇
  2000年   6篇
  1999年   7篇
  1998年   4篇
  1997年   7篇
  1996年   1篇
  1995年   3篇
  1994年   4篇
  1993年   1篇
  1992年   2篇
  1991年   7篇
  1990年   1篇
  1989年   4篇
  1987年   4篇
  1986年   3篇
  1985年   2篇
  1983年   4篇
  1982年   2篇
  1981年   5篇
  1980年   2篇
  1979年   2篇
  1978年   5篇
  1976年   2篇
  1975年   3篇
排序方式: 共有323条查询结果,搜索用时 0 毫秒
71.
A theory of justice for the basic structure of society may constrain though not directly govern colleges. The principle of "equal opportunity" commonly applied to jobs either does or does not apply to varsity opportunities. If it applies, it interdicts sex discrimination but, one fallacious argument notwithstanding, it states no obligation to expend resources on new teams. If it does not apply, an analogue of Rawls's difference principle may appropriately constrain inequalities between the sexes. In either case the preferences of a majority of the sex affected by any inequality are pivotal in fashioning any tenable distributive policy. Those preferences are neglected by a government policy that assimilates equal opportunity to equality of (i) the ratio of male:female varsity athletes and (ii) the ratio of male:female students. It is argued that such policy rests on affirming the consequent. Its effects include misallocations of resources and overvaluation of athletics. It is argued that what should approximately be equal is competitive access, the ratio of available positions to aspirants, for each sex. Two versions of a principle of equal competitive access are proposed, the recommended one of which pertains to teams whose net consumption of resources is positive.  相似文献   
72.
The possibility of obtaining locally optimal solutions with categorical data is pointed out for the original version of OSMOD development by Saito and Otsu. A revision of the initialization strategy in OSMOD is suggested, and its effectiveness in diminishing this possibility is demonstrated.  相似文献   
73.
Probabilistic multidimensional scaling: Complete and incomplete data   总被引:1,自引:0,他引:1  
Simple procedures are described for obtaining maximum likelihood estimates of the location and uncertainty parameters of the Hefner model. This model is a probabilistic, multidimensional scaling model, which assigns a multivariate normal distribution to each stimulus point. It is shown that for such a model, standard nonmetric and metric algorithms are not appropriate. A procedure is also described for constructing incomplete data sets, by taking into consideration the degree of familiarity the subject has for each stimulus. Maximum likelihood estimates are developed both for complete and incomplete data sets. This research was supported by National Science Grant No. SOC76-20517. The first author would especially like to express his gratitude to the Netherlands Institute for Advanced Study for its very substantial help with this research.  相似文献   
74.
Critical examination is made of the recent controversy over the value of Monte Carlo techniques in nonmetric multidimensional scaling procedures. The case is presented that the major relevance of Monte Carlo studies is not for the local minima problem but for the meaningfulness of the obtained solutions.  相似文献   
75.
In the continuous response (CR) task, the subject is given the name of a familiar category and must respond with category examples within a fixed time limit. The response sequence and the interresponse times are the measured variables. A general model is proposed for performance in the CR task. The time taken to generate a response is identified with the shortest search time from among a set of simultaneous search processes. Each response has a generation probability that is a function of the parameters governing the search process durations. Data involving the category states in the United States are used to test the model. The model accounts for the performance of nearly all individuals in these data.This article is based on a dissertation completed at the University of California-Berkeley in partial fullfillment of the requirements for the Ph.D. degree in psychology. Portions of the article were presented at the joint meeting of the Psychometric and Classification Societies (June 1984) and at the meeting of the Society for Mathematical Psychology (August 1984). The authors wish to thank Barbara Mellers, Juliet Schaffer, Steve Palmer, and Eleanor Rosch for helpful comments.  相似文献   
76.
On the distinction between open and closed economies.   总被引:4,自引:3,他引:1  
Open and closed economies have been assumed to produce opposite relations between responding and the programmed density of reward (the amount of reward divided by its cost). Experimental procedures that are treated as open economies typically dissociate responding and total reward by providing supplemental income outside the experimental session; procedures construed as closed economies do not. In an open economy responding is assumed to be directly related to reward density, whereas in a closed economy responding is assumed to be inversely related to reward density. In contrast to this predicted correlation between response-reward relations and type of economy, behavior regulation theory predicts both direct and inverse relations in both open and closed economies. Specifically, responding should be a bitonic function of reward density regardless of the type of economy and is dependent only on the ratio of the schedule terms rather than on their absolute size. These predictions were tested by four experiments in which pigeons' key pecking produced food on fixed-ratio and variable-interval schedules over a range of reward magnitudes and under several open- and closed-economy procedures. The results better supported the behavior regulation view by showing a general bitonic function between key pecking and food density in all conditions. In most cases, the absolute size of the schedule requirement and the magnitude of reward had no effect; equal ratios of these terms produced approximately equal responding.  相似文献   
77.
Pigeons were presented a series of keylight time periods (separated by blackouts) during which two response keys were lit, one by blue light and the other either by orange or green. Blue-key responses changed the color on the other key. Orange-key responses sometimes produced food during the first half of a time period; green-key responses sometimes produced food during the second half. In three experiments, the probability of a green-key response increased as a function of elapsed time. Experiment 1 compared performance when the duration of the keylight periods was varied across a wide range. Discrimination of performance was similar across the range of durations. Experiment 2 varied both relative reinforcement rate and the local reinforcement rate for orange-key and green-key responses. These manipulations produced changes in response bias but not discrimination sensitivity. Experiment 3 varied the local temporal placement of reinforcers within time periods and demonstrated that choice behavior was affected by differential reinforcement at different points during the time periods. The results were consistent with previous research on duration discrimination that used psychophysical trials procedures.  相似文献   
78.
Power of the likelihood ratio test in covariance structure analysis   总被引:4,自引:0,他引:4  
A procedure for computing the power of the likelihood ratio test used in the context of covariance structure analysis is derived. The procedure uses statistics associated with the standard output of the computer programs commonly used and assumes that a specific alternative value of the parameter vector is specified. Using the noncentral Chi-square distribution, the power of the test is approximated by the asymptotic one for a sequence of local alternatives. The procedure is illustrated by an example. A Monte Carlo experiment also shows how good the approximation is for a specific case.This research was made possible by a grant from the Dutch Organization for Advancement of Pure Research (ZWO). The authors also like to acknowledge the helpful comments and suggestions from the editor and anonymous reviewers.  相似文献   
79.
等级图形加工半球偏侧化的发展   总被引:2,自引:1,他引:2       下载免费PDF全文
以往的研究显示,大脑对等级视觉信息的加工有半球偏侧化的现象,左半球有加工局部特征的优势,右半球有加工整体的优势。本研究采用2年级、4年级、6年级和成人4个年龄组的被试,对等级复合图形中的靶子做选择判断,通过单侧呈现来考察整体-局部加工的大脑功能偏侧化发展。结果发现反应时发展呈现从局部优先到整体优先的过程,半球偏侧化发展呈现从无偏侧化到左侧呈现较右侧呈现更强的整体优先。发展的转折点可能在4~6年级(约9岁~12岁)之间。  相似文献   
80.
Despite a long history of vigilance research, the role of global and local feature discrimination in vigilance tasks has been relatively neglected. In this experiment participants performed a sustained attention task requiring either global or local shape stimuli discrimination. Reaction time to local feature discriminations was characterized by a quadratic trend over time-on-task with performance levels returning to initial levels late in the task. This trend did not occur in the global shape discrimination task. Functional near-infrared spectroscopy (fNIRS) was utilized in this study as an index of cerebral activation. In both tasks there was increased right hemisphere relative to left hemisphere oxygenation and right hemisphere oxygenation increased with time-on-task. Left hemisphere oxygenation, however, decreased slightly in the global task, but increased significantly in the local task as task duration increased. Indeed, total oxygenation, averaging both right and left, increased more with time-on-task in the local discrimination task. Both the performance and physiological results of this study indicate increased utilization of bilateral cerebral resources with time-on-task in the local, but not the global discrimination vigil.  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