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   73599篇
  免费   3038篇
  国内免费   25篇
  2020年   728篇
  2019年   930篇
  2018年   1267篇
  2017年   1274篇
  2016年   1363篇
  2015年   1023篇
  2014年   1197篇
  2013年   5542篇
  2012年   2236篇
  2011年   2356篇
  2010年   1511篇
  2009年   1468篇
  2008年   2110篇
  2007年   2180篇
  2006年   1945篇
  2005年   1757篇
  2004年   1606篇
  2003年   1501篇
  2002年   1646篇
  2001年   2431篇
  2000年   2399篇
  1999年   1824篇
  1998年   871篇
  1997年   772篇
  1996年   790篇
  1993年   685篇
  1992年   1526篇
  1991年   1400篇
  1990年   1405篇
  1989年   1270篇
  1988年   1229篇
  1987年   1174篇
  1986年   1249篇
  1985年   1260篇
  1984年   1077篇
  1983年   972篇
  1982年   713篇
  1981年   688篇
  1979年   1118篇
  1978年   808篇
  1975年   915篇
  1974年   1004篇
  1973年   1081篇
  1972年   896篇
  1971年   851篇
  1970年   745篇
  1969年   802篇
  1968年   1007篇
  1967年   922篇
  1966年   774篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
972.
Three-way metric unfolding via alternating weighted least squares   总被引:6,自引:3,他引:3  
Three-way unfolding was developed by DeSarbo (1978) and reported in DeSarbo and Carroll (1980, 1981) as a new model to accommodate the analysis of two-mode three-way data (e.g., nonsymmetric proximities for stimulus objects collected over time) and three-mode, three-way data (e.g., subjects rendering preference judgments for various stimuli in different usage occasions or situations). This paper presents a revised objective function and new algorithm which attempt to prevent the common type of degenerate solutions encountered in typical unfolding analysis. We begin with an introduction of the problem and a review of three-way unfolding. The three-way unfolding model, weighted objective function, and new algorithm are presented. Monte Carlo work via a fractional factorial experimental design is described investigating the effect of several data and model factors on overall algorithm performance. Finally, three applications of the methodology are reported illustrating the flexibility and robustness of the procedure.We wish to thank the editor and reviewers for their insightful comments.  相似文献   
973.
Combinatorial data analysis: Association and partial association   总被引:4,自引:0,他引:4  
A combinatorial data analysis strategy is reviewed that is designed to compare two arbitrary measures of proximity defined between the objects from some set. Based on a particular cross-product definition of correspondence between these two numerically specified notions of proximity (typically represented in the form of matrices), extensions are then pursued to indices of partial association that relate the observed pattern of correspondence between the first two proximity measures to a third. The attendant issues of index normalization and significance testing are discussed; the latter is approached through a simple randomization model implemented either through a Monte Carlo procedure or distributional approximations based on the first three moments. Applications of the original comparison strategy and its extensions to partial association may be developed for a variety of methodological and substantive tasks. Besides rank correlation, we emphasize the topics of spatial autocorrelation for one variable and spatial association between two and mention the connection to the usual randomization approach for one-way analysis-of-variance.  相似文献   
974.
Studied problems of identification, using a meta-contrast design. The first stimulus (A) was always the word ME. In experiment 1 , the second stimulus (B) depicted an aggressor and a victim facing each other. The subliminal A was flashed either on the victim or the aggressor or completely withheld. In experiment 2 , B showed two persons standing against different backgrounds: an open horizon or a closed room. It was assumed that the subject would be "forced" to identify with that figure in B on which A was flashed. Subjects in experiment 1 were 18 psychiatric patients and in experiment 2 , 32 professional artists. The results showed that the subliminal manipulation had been effective: e.g., when led by A to identify with the aggressor, projective-sensitive and borderline subjects were confused and even reported perceptual difficulties; when led to identify with the open side, highly creative artists, as opposed to less creative ones, reported more positive impressions of the B theme.  相似文献   
975.
976.
977.
978.
979.
Flicker fusion frequencies of 48 healthy controls and of 35 alcoholics were measured to detect possible associations between flicker fusion and signs of nonspecific brain damage, the aim of the study. FFF was statistically significantly lower in patients addicted to alcohol than in healthy subjects. Lower flicker fusion frequencies were associated with the severeness of organic psychosis as rated psychopathologically. The hypothesis that addiction to alcohol is a sign of diffuse, nonspecific, organic brain damage was discussed.  相似文献   
980.
On the basis of surveys completed by 105 male participants in a popular marathon, a multiple regression analysis was conducted to identify the variables contributing significantly to the prediction of final time. Overall prediction was successful, with R = .896, and training pace was the most important factor in the equation, speedier workouts being associated with faster marathon times. Final time was also related positively to best 10-km race time in the previous 12 mo. and repression-sensitization (faster runners being more sensitized), and negatively to maximum number of training miles in a single week, number of previous marathons completed, and number of days of training lost through illness or injury. Contrary to expectations, locus of control was not related to final time. Only 27% of the runners had lost training time through injury, but a discriminant analysis showed that, compared to those who had avoided this problem, the injured were younger, rested less, ran less in the week prior to the marathon, ran a slightly longer long run but ran it earlier before the race, and ran fewer runs of 20 miles or more. It is suggested that researchers should study the repression-sensitization variable and investigate injury in runners preparing for a marathon.  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