全文获取类型
收费全文 | 201657篇 |
免费 | 8654篇 |
国内免费 | 162篇 |
出版年
2020年 | 2809篇 |
2019年 | 3468篇 |
2018年 | 3878篇 |
2017年 | 4297篇 |
2016年 | 4861篇 |
2015年 | 3952篇 |
2014年 | 4829篇 |
2013年 | 23526篇 |
2012年 | 5595篇 |
2011年 | 4992篇 |
2010年 | 4379篇 |
2009年 | 4997篇 |
2008年 | 4991篇 |
2007年 | 4708篇 |
2006年 | 4986篇 |
2005年 | 4836篇 |
2004年 | 4275篇 |
2003年 | 3856篇 |
2002年 | 3719篇 |
2001年 | 4570篇 |
2000年 | 4379篇 |
1999年 | 3981篇 |
1998年 | 2946篇 |
1997年 | 2754篇 |
1996年 | 2666篇 |
1995年 | 2496篇 |
1994年 | 2443篇 |
1993年 | 2418篇 |
1992年 | 3351篇 |
1991年 | 3107篇 |
1990年 | 2994篇 |
1989年 | 2800篇 |
1988年 | 2798篇 |
1987年 | 2774篇 |
1986年 | 2794篇 |
1985年 | 2963篇 |
1984年 | 2917篇 |
1983年 | 2641篇 |
1982年 | 2501篇 |
1981年 | 2467篇 |
1980年 | 2306篇 |
1979年 | 2765篇 |
1978年 | 2448篇 |
1977年 | 2320篇 |
1976年 | 2159篇 |
1975年 | 2415篇 |
1974年 | 2529篇 |
1973年 | 2513篇 |
1972年 | 2036篇 |
1968年 | 1966篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
851.
Rats were allowed to forage in a simulated natural environment made up of eight food sources (patches) each containing a fixed number of pellets. Two of the eight contained an extra supply of peanuts. The peanut patches were signaled by an olfactory/visual cue located at the bottom of the ladder leading to the patch. In successive phases the number of sessions per day, height of the patches, and availability of peanuts were manipulated. Subjects showed evidence of discrimination learning under these conditions, although the degree of discriminatory behavior varied as a function of environmental manipulations. Assessment of behavior within foraging sessions showed that subjects systematically changed their patterns of utilization of patches across time. Sampling or exploration, as well as food reinforcement, seem implicated in these results. 相似文献
852.
Jeffrey S. Levin Ph.D. M.P.H. C. David Jenkins Ph.D. Robert M. Rose M. D. 《Journal of religion and health》1988,27(4):267-278
In a study of air traffic controllers, religious differences are found in the way Type A behavior is associated with several health status indicators. Associations between the Jenkins Activity Survey (JAS) and physical illness incidence, health-promotive behavior, diastolic and systolic blood pressure, subjective distress and impulse control problems, and alcohol consumption are examined by religious attendance, religious affiliation, and change in affiliation. Findings confirm that Type A does not vary significantly by religion. However, there are several significant findings between Type A and various health indicators. Type A is associated with illness incidence, overall and more strongly in several religion, subgroups. Type A and alcohol consumption are related positively in Protestants and converts, and negatively in churchgoing Catholics. Type A is related to impulse control problems in churchgoing Protestants and to subjective distress in churchgoing Catholics. Finally, in individuals with weak or no religious ties, Type A is associated with lower blood pressure. This last finding suggests that in some people (for example, the irreligious or unchurched), the coronary-prone behavior pattern may have cardiovascular effects which are salutary in at least one respect.The authors wish to thank Dr. Kyriakos S. Markides and Laura A. Ray for their assistance with this study. Address requests for reprints to Dr. Levin at the Institute of Gerontology, 300 North Ingalls, Ann Arbor, MI 48109. 相似文献
853.
Magnitude estimation and sensory matching 总被引:2,自引:0,他引:2
L E Marks 《Perception & psychophysics》1988,43(6):511-525
854.
855.
856.
A general model is developed for the analysis of multivariate multilevel data structures. Special cases of the model include repeated measures designs, multiple matrix samples, multilevel latent variable models, multiple time series, and variance and covariance component models.We would like to acknowledge the helpful comments of Ruth Silver. We also wish to thank the referees for helping to clarify the paper. This work was partly carried out with research funds provided by the Economic and Social Research Council (U.K.). 相似文献
857.
Human motor learning is often measured by error scores. The convention of using mean absolute error, mean constant error, and variable error shows lack of desirable parsimony and interpretability. This paper provides the background of error measurement and states criticisms of conventional methodology. A parsimonious model of error analysis is provided, along with operationalized interpretations and implications for motor learning. Teaching, interpreting, and using error scores in research may be simplified and facilitated with the model. 相似文献
858.
Body-frame size is an important factor in determining an optimal body weight for a given height. Previous studies have indicated that many individuals incorrectly estimate their body-frame size, and, as a result, incorrectly assess their ideal weight. The present study investigated the accuracy of estimation of body-frame size as a function of sex and actual frame size. The subjects were 66 men and 52 women participating in a community adult fitness program. Data indicated that medium-framed individuals were the most accurate in their estimations of body-frame size. Also, women were twice as likely to be accurate as were men. These results are interpreted to mean that most people assume they are medium-framed and that there is a sex difference in the way body-frame size is estimated. 相似文献
859.
In this pilot study, 20 middle-school-age children classified as emotionally handicapped were administered Forms L and M of the Peabody Picture Vocabulary Test--Revised in test-retest fashion. Pearson correlations for Form L were .90, for Form M, .69, and these dependent correlations were significantly different from each other. As triennial school psychological evaluations typically contain tests which have been administered previously, e.g., WISC-R, WRAT-R, we suggest that psychologists use caution when using Form M to test or retest the receptive vocabulary of emotionally handicapped or disturbed middle-school-age children. 相似文献
860.
Cutoff scores are used in a variety of settings to help managers make personnel decisions. Although cutoff scores are used widely, information about their derivation and appropriate use is scattered in the legal, psychometric, and professional literatures. The purpose of this paper is to analyze critically and to integrate these diverse literatures, to summarize what is known and what is unknown about the use and misuse of cutoff scores. Alternative methods are examined in relation to legal precedents set by the courts, to psychometric principles, and to the various sets of professional guidelines. Directions for future research are suggested, and we conclude with a set of recommendations regarding acceptable professional practice in this area. 相似文献