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   67379篇
  免费   2816篇
  国内免费   31篇
  70226篇
  2020年   852篇
  2019年   1019篇
  2018年   1427篇
  2017年   1424篇
  2016年   1516篇
  2015年   1082篇
  2014年   1335篇
  2013年   6136篇
  2012年   2414篇
  2011年   2433篇
  2010年   1488篇
  2009年   1530篇
  2008年   2125篇
  2007年   2084篇
  2006年   1960篇
  2005年   1681篇
  2004年   1687篇
  2003年   1650篇
  2002年   1559篇
  2001年   2139篇
  2000年   2000篇
  1999年   1537篇
  1998年   792篇
  1997年   715篇
  1996年   759篇
  1995年   695篇
  1994年   681篇
  1993年   656篇
  1992年   1228篇
  1991年   1144篇
  1990年   1108篇
  1989年   1054篇
  1988年   1009篇
  1987年   958篇
  1986年   970篇
  1985年   1041篇
  1984年   869篇
  1983年   749篇
  1982年   586篇
  1981年   583篇
  1979年   839篇
  1978年   660篇
  1977年   567篇
  1976年   563篇
  1975年   688篇
  1974年   775篇
  1973年   782篇
  1972年   656篇
  1971年   601篇
  1968年   634篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
871.
A general latent variable model is given which includes the specification of a missing data mechanism. This framework allows for an elucidating discussion of existing general multivariate theory bearing on maximum likelihood estimation with missing data. Here, missing completely at random is not a prerequisite for unbiased estimation in large samples, as when using the traditional listwise or pairwise present data approaches. The theory is connected with old and new results in the area of selection and factorial invariance. It is pointed out that in many applications, maximum likelihood estimation with missing data may be carried out by existing structural equation modeling software, such as LISREL and LISCOMP. Several sets of artifical data are generated within the general model framework. The proposed estimator is compared to the two traditional ones and found superior.The research of the first author was supported by grant No. SES-8312583 from the National Science Foundation and by a Spencer Foundation grant. We wish to thank Chuen-Rong Chan for drawing the path diagram.  相似文献   
872.
The marriage role expectations of female university students enrolled in an introductory marriage and family course at the University of Kentucky in 1961 (N=72), 1972 (N=58), 1978 (N=115), and 1984 (N=81) were compared. The 1972 group was found to be significantly more egalitarian than the 1961 group in overall marriage role expectations and on all subscales except authority. The 1978 and 1984 groups were significantly more egalitarian than the 1961 group on overall marriage role expectations and on all seven of the subscales: authority, homemaking, child care, personal characteristics, social participation, education, and employment and support. The 1978 group was significantly more egalitarian than the 1972 group only on authority and homemaking, with no significant differences on the other five subscales or on overall role expectation score. The 1984 group was significantly more egalitarian than the 1972 group only on authority, homemaking, and child care, and was slightly (not satistically significant) more traditional on personal characteristics and social participation. There were no significant differences between the 1978 and 1984 groups on overall expectation or on any of the subscales. In fact, the 1984 group was slightly more traditional on homemaking, personal characteristics, social participation, employment and support, and overall expectations. The data from this study showed the greatest gain in egalitarian trends to be between 1961 and 1972, with a continuation of the trends at a somewhat slower rate of change between 1972 and 1978, and a discontinuation of the trend toward more egalitarian expectations between 1978 and 1984.The data were collected in February 1961, January 1972, September 1978, and September 1984. Special acknowledgement and appreciation are expressed to Jessie Ringo (retired), University of Kentucky, for making the 1961 data available for this study.  相似文献   
873.
The representation of nonuniform motion: induced movement   总被引:2,自引:0,他引:2  
N J Wade  M T Swanston 《Perception》1987,16(5):555-571
Induced motion occurs when there is a misallocation of nonuniform motion. Theories of induced motion are reviewed with respect to the model for uniform motion recently proposed by Swanston, Wade, and Day. Theories based on single processes operating at one of the retinocentric, orbitocentric, egocentric, or geocentric levels are not able to account for all aspects of the phenomenon. It is therefore suggested that induced motion is a consequence of combining two different types of motion signals: one provides information by registering the motion with respect to the retina, orbit, and egocentre; the other provides information only on the relational motions between the pattern elements. Simple rules are given for defining a frame of reference for the relational motion process, which can result in a reallocation of the motion signals. It is proposed that the two signals in combination are weighted differentially, with the greater influence coming from the relational signals. Procedures for determining the weighting factors are described, and predictions from the model are examined.  相似文献   
874.
After inducing hostility toward a confederate by threatening subjects' self-esteem, subjects were then given the opportunity either to deliver shocks (Experiment 1) or to withhold rewards (Experiment 2) from their confederate. Physiological measures were taken prior to the hostility induction, shortly after the induction and, finally, after the opportunity to aggress. Measures of individual differences relating to aggressive behavior were also considered. While the experimental manipulation was the best predictor in the ‘withholding rewards’ condition, measures of dissipation-rumination tendencies and emotional vulnerability were the best predictors in the ‘shock administration’ condition. In both conditions, systolic blood pressure seemed to reflect differences in arousal as a function of the hostility induction procedure, while subjects in the withhold rewards procedure also showed a decrease in systolic pressure after having an opportunity to aggress toward the confederate. It was concluded that not only is the withholding of rewards a more ethically acceptable procedure than shock administration, but it is also more likely to reflect experimental rather than individual difference affects.  相似文献   
875.
In a study of recognition memory for pictures, we observed an asymmetry in classifying test items as "same" versus "different" in left-right orientation: Identical copies of previously viewed items were classified more accurately than left-right reversals of those items. Response bias could not explain this asymmetry, and, moreover, correct "same" and "different" classifications were independently manipulable: Whereas repetition of input pictures (one vs. two presentations) affected primarily correct "same" classifications, retention interval (3 hr vs. 1 week) affected primarily correct "different" classifications. In addition, repetition but not retention interval affected judgments that previously seen pictures (both identical and reversed) were "old". These and additional findings supported a dual-process hypothesis that links "same" classifications to high familiarity, and "different" classifications to conscious sampling of images of previously viewed pictures.  相似文献   
876.
The term pioneer is used for girls aspiring to male-dominated careers. This longitudinal study assesses the career choices of 68 middle-class girls during childhood (8–13 years, Phase I) and again during adolescence (13–18 years, Phase II), and investigates the relation between pioneering career choice and personal and family characteristics. Subjects were originally selected for exposure vs nonexposure to exogenous hormones during pregnancy. In childhood, pioneers were somewhat older, were more often persistent tomboys, had higher IQs, and had parents with higher educational attainment. In adolescence, paternal education was the only variable that showed the same relation to career choice. Adolescent girls who had wanted to get married at the time of the childhood assessment were now less likely to choose pioneering careers. Adolescent pioneers also had higher educational aspirations than nonpioneers and less likely anticipated being married within ten years than nonpioneers. A number of statistically borderline relationships were also observed: pioneers had somewhat fewer older brothers than nonpioneers, less often came from homes in which traditional femininity was stressed, and more frequently had mothers who had worked outside the home throughout their daughters' school years than mothers of nonpioneers. Prenatal exposure to exogenous sex hormones was not related to career choice during either childhood or adolescence.  相似文献   
877.
878.
Previous experimental investigation of the effects of repeating an unfamiliar stimulus suggests that mere exposure breeds attraction (e.g., Zajonc, 1968). On the other hand, correlational work with naturally occurring stimuli such as names, music, or landscapes suggests that there is also an overexposure effect: the preference function does rise with familiarity at first but then reaches a turning point and diminishes. The study (N=72) demonstrates this inverted-U relationship in an experimental setting. The stimuli were synthetic nonsense speech, permitting exact control of exposure durations and interstimulus intervals. The critical factors for demonstrating the effect are probably (1) the inclusion of a large number of repetitions, and (2) blocked repetition of each stimulus in a homogeneous sequence not interspersed with other more or less frequent stimuli.  相似文献   
879.
880.
A social skills training program was evaluated with emotionally disturbed adolescent inpatients. The targeted social skills required an action or reaction within six skill areas. The program was adapted from a commercially available social skills training game that features the use of response specific feedback, self-monitoring, individualized reinforcers, and individualized performance criteria. A peer conducted the baseline and posttraining sessions while the training was conducted by an adult who had no previous interactive history with the subjects. A multiple baseline design across groups demonstrated that the program increased appropriate responding in all skill areas and that these effects generalized during the posttraining peer conducted sessions. A generalization test indicated that the subjects used their newly learned skills with a novel adult outside the training setting. The program appears quite applicable to emotionally disturbed adolescents since it targets skills in a variety of areas and employs standardized procedures to enhance replicability.  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