全文获取类型
收费全文 | 55027篇 |
免费 | 2261篇 |
国内免费 | 25篇 |
出版年
2020年 | 608篇 |
2019年 | 690篇 |
2018年 | 1052篇 |
2017年 | 1015篇 |
2016年 | 1089篇 |
2015年 | 822篇 |
2014年 | 951篇 |
2013年 | 5157篇 |
2012年 | 1586篇 |
2011年 | 1692篇 |
2010年 | 1056篇 |
2009年 | 1013篇 |
2008年 | 1477篇 |
2007年 | 1368篇 |
2006年 | 1219篇 |
2005年 | 1037篇 |
2004年 | 1036篇 |
2003年 | 1046篇 |
2002年 | 992篇 |
2001年 | 1788篇 |
2000年 | 1745篇 |
1999年 | 1286篇 |
1998年 | 590篇 |
1997年 | 551篇 |
1996年 | 643篇 |
1995年 | 603篇 |
1994年 | 592篇 |
1993年 | 586篇 |
1992年 | 1209篇 |
1991年 | 1086篇 |
1990年 | 1111篇 |
1989年 | 1010篇 |
1988年 | 982篇 |
1987年 | 948篇 |
1986年 | 959篇 |
1985年 | 944篇 |
1984年 | 834篇 |
1983年 | 693篇 |
1979年 | 739篇 |
1978年 | 580篇 |
1975年 | 694篇 |
1974年 | 736篇 |
1973年 | 751篇 |
1972年 | 735篇 |
1971年 | 643篇 |
1970年 | 579篇 |
1969年 | 596篇 |
1968年 | 710篇 |
1967年 | 600篇 |
1966年 | 592篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
241.
The present experiments were designed to teach pigeons to discriminate two locations represented by color photographs. Two sets of photographs were taken at two distinctive locations on a university campus. These sets represented several standpoints at each location. For the true-discrimination group, pictures from the two locations were differentially associated with reward; for the pseudodiscrimination group, half of the views from each location were arbitrarily but consistently associated with reward. The former group acquired the discrimination much more rapidly. These birds also showed good transfer to new views from the standpoints used in training and to a new standpoint at each location not used in training. In a second experiment, another group of pigeons could terminate any training trial by pecking an “advance” key. Three of 4 subjects used this option to reduce the duration of trials in which pictures from the negative location were presented. These data suggest that pigeons can integrate views shown in pictures into a “concept” of a location. The method used here may be the experimental analogue of a common, natural process by which animals learn to identify locations. 相似文献
242.
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
243.
244.
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
245.
246.
247.
K Friemert 《Psychiatrie, Neurologie, und medizinische Psychologie》1988,40(11):671-677
Basing on the author's experiences during his study stay at the Serbsky All-Union Research Institute for General and Forensic Psychiatry in Moscow a report is given about the theoretical foundations and the carrying-out of forensic-psychiatric expert-opinions in the field of penal as well as civil law in the U.S.S.R. Some peculiarities in comparison with the practice in the G.D.R. are taken in special account. 相似文献
248.
Visual cognitive differences between hearing (N = 16) and deaf (N = 32) high-school and middle-school students were studied. Visual tasks were presented on a microcomputer and response latencies were collected. Significant differences were noted between the deaf and normal groups but not between total communication deaf and oral deaf students. These differences support the hypothesis that deaf students prefer a visual cognitive strategy. Implications for educating the deaf are discussed. 相似文献
249.
S Martin K Housley H Mccoy P Greenhouse F Stigger M A Kenney S Shoffner V Fu M Korslund F G Ercanli-Huffman 《Perceptual and motor skills》1988,67(3):879-884
The Rosenberg Self-esteem Scale was administered to 550 14- and 16-yr.-old (+/- 6 mo.) girls. Self-esteem scores were categorized by weight and weight by height. Scores on the Quetelet Index for obesity were correlated with self-esteem scores. Mean self-esteem of the low- and middle-weight by height group was significantly higher than the mean of the high-weight by height group. In analyzing weight alone, the self-esteem of the middle-weight group was significantly higher than the self-esteem of the high-weight group. The correlation of the obesity index and self-esteem indicated that as weight increased self-esteem decreased. 相似文献
250.