全文获取类型
收费全文 | 52104篇 |
免费 | 2085篇 |
国内免费 | 30篇 |
出版年
2020年 | 583篇 |
2019年 | 737篇 |
2018年 | 1059篇 |
2017年 | 1060篇 |
2016年 | 1110篇 |
2015年 | 743篇 |
2014年 | 909篇 |
2013年 | 4522篇 |
2012年 | 1653篇 |
2011年 | 1798篇 |
2010年 | 1046篇 |
2009年 | 1067篇 |
2008年 | 1639篇 |
2007年 | 1610篇 |
2006年 | 1419篇 |
2005年 | 1285篇 |
2004年 | 1266篇 |
2003年 | 1143篇 |
2002年 | 1183篇 |
2001年 | 1752篇 |
2000年 | 1649篇 |
1999年 | 1262篇 |
1998年 | 663篇 |
1997年 | 571篇 |
1996年 | 512篇 |
1995年 | 516篇 |
1994年 | 495篇 |
1993年 | 516篇 |
1992年 | 1008篇 |
1991年 | 953篇 |
1990年 | 940篇 |
1989年 | 849篇 |
1988年 | 812篇 |
1987年 | 800篇 |
1986年 | 803篇 |
1985年 | 853篇 |
1984年 | 667篇 |
1983年 | 576篇 |
1982年 | 469篇 |
1979年 | 653篇 |
1978年 | 485篇 |
1976年 | 446篇 |
1975年 | 589篇 |
1974年 | 619篇 |
1973年 | 594篇 |
1972年 | 539篇 |
1971年 | 473篇 |
1968年 | 539篇 |
1967年 | 540篇 |
1966年 | 475篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
231.
We obtain in this paper a representation of the formulae of extensions ofL
by generalized quantifiers through functors between categories of first-order structures and partial isomorphisms. The main tool in the proofs is the back-and-forth technique. As a corollary we obtain the Caicedo's version of Fraïssés theorem characterizing elementary equivalence for such languages. We also discuss informally some geometrical interpretations of our results. 相似文献
232.
233.
It has been proposed that a principal cause of the agrammatism of some Broca's aphasics is that such patients, unlike normal subjects, are unable to make use of a special retrieval mechanism for closed-class ("function") words (D. C. Bradley, 1978, Computational distinctions of vocabulary type, Unpublished Ph.D. thesis; D. C. Bradley, M. F. Garrett, & E. B. Zurif, 1980. In D. Caplan (Ed.), Biological studies of mental processes). The main evidence for the existence of such a mechanism consisted of two observations: (1) the recognition of open-class words was observed to be frequency-sensitive, but that of closed-class words was not; and (2) lexical decisions for nonwords which began with open-class words were delayed, whereas there was no such interference for nonwords which began with closed-class words. However, the first of these observations has proved nonreplicable (e.g., B. Gordon & A. Caramazza, 1982, Brain and Language, 15, 143-160, 1983, Brain and Language, 19, 335-345; J. Segui, J. Mehler, W. Frauenfelder, & J. Morton, 1982, Neuropsychologia, 20, 615-627), and in the present paper, three lexical decision experiments are reported in which it is found that, when certain confounding variables are controlled, nonwords which begin with closed-class words are subject to interference. Moreover, contrary to a suggestion of Kolk and Blomert (1985, Brain and Language, 26, 94-105) the interference is independent of the presence of closed-class items in the lexical decision word list. It seems, then, that closed-class words are not qualitatively different from open-class words with respect either to frequency sensitivity or to nonword interference, and in consequence, the above proposed explanation of agrammatism is left without major empirical support. 相似文献
234.
After thermal cauterization of the area postrema in rats the absence of conditioned taste aversion to sucrose paired with lithium chloride (0.15 M, 3.3 ml/kg) was used as a pharmacologic/behavioral index of area postrema damage. In a subsequent experiment the effects of area postrema lesions on three measures proposed as species-relevant measures of motion sickness were studied, using off-vertical rotation at 150 degrees/s for either 30 or 90 min. Lesions of area postrema did not alter postrotational suppression of drinking or amount of defecation during motion. The initial acquisition of conditioned taste aversion to a novel cider vinegar solution paired with motion was not affected by lesioning of the area postrema, but these taste aversions extinguished more slowly in lesioned rats than in sham-operates or intact controls. Results are discussed in terms of proposed humoral factors which may induce motion sickness and in light of recent data on the role of the area postrema in similar measures in species possessing the complete emetic reflex. 相似文献
235.
D L Fisher S A Duffy C Young A Pollatsek 《Journal of experimental psychology. Human perception and performance》1988,14(2):253-266
Effects of load (i.e., the number of stimuli in the display) have been observed in multiple-frame studies using a consistent mapping of stimuli to responses (e.g., Fisher, 1982, 1984). In a series of four experiments, it is shown that these effects are not the consequence of differences across the high- and low-load conditions in either decision noise or peripheral masking. Additionally, it is shown that of two modes of limited capacity (a limited-channel and divided-capacity model) considered as possible explanations of load effects in tasks where subjects are required to locate a target, only one--the limited-channel model--is consistent with the results from all three location tasks. Finally, it is argued that the limited-channel model predicts not only the behavior observed in the four consistent-mapping experiments reported in this article but also the behavior observed in several related consistent-mapping tasks (Kleiss & Lane, 1986; Shiffrin & Gardner, 1972). 相似文献
236.
237.
The purpose of the present study was to determine whether the sex role orientations of male and female collegiate athletes were more similar in team sports than in individual sports. It was predicted that females in masculine-oriented team sports (basketball and volleyball) would exhibit sex role orientations more similar to those of their male counterparts than would females in individual sports (track/field and swimming). To test this notion the S. L. Bem (The Measurement of Psychological Androgyny, Journal of Consulting and Clinical Psychology, 1974, 42, 155–167) Sex Role Inventory was administered to 381 athletes from 37 National Collegiate Athletic Association institutions. The median-split procedure (S. L. Bem, On the Utility of Alternative Procedures for Assessing Psychology Androgyny, Journal of Consulting and Clinical Psychology, 1977, 45, 196–205) was used to classify subjects as masculine, feminine, androgynous, or undifferentiated. Separate Gender × Sex Role Orientation chi square tests were performed on the frequency data of team and individual sport athletes. The results indicated no significant differences in the sex role orientations of male and female team sport performers, with the greatest proportion (66%) having a masculine (33%) or androgynous (33%) orientation. For individual sports there was a significant difference in the sex role orientations of males and females. The highest proportion of females were classified as feminine (37%) and the lowest proportion were classified as masculine (11%). Individual sport males were somewhat evenly distributed among the four sex role orientation categories, with the highest proportion classified as undifferentiated (36%). It was concluded that sex role orientation of elite female athletes may be associated with the male appropriateness of the sport in which they participate. 相似文献
238.
The present study examined the effect of facial attractiveness and gender on raters' evaluations of and explanations for managerial performance. Results showed attractiveness to be a potential liability for both males and females. Good performance of attractive females was more likely than that of others to be attributed to luck or bias, while that of attractive males was viewed as occurring with little effort. In addition, the poor performance of attractive individuals was blamed on lack of effort (females) or lack of ability (males). Implications of these findings are discussed.An earlier version of this paper was published in the 1986 Proceedings of the Southern Management Association. 相似文献
239.
This paper has two objectives: (1) to develop a more complex measure of work involvement than that typically used, and (2) to correlate this measure with selected lifestyle/family and work variables. The data were drawn primarily from a 1981 survey of 110 female graduates of a large Midwestern university who completed their undergraduate degrees in 1967. Respondents were categorized as high, moderate, or low on a work involvement index based on four variables: work continuity, work status, current or most recent occupation, and educational achievement. Findings in the area of lifestyle/family suggest that high work-involved women are more likely to be single and to marry later when they do marry, less likely to have children, and less likely to perceive conflicts between marriage/relationships and/or children and a career. Findings in the area of work suggest that high work-involved women are significantly more likely to work in male-dominated occupations and to earn salaries of $20,000 or more. High work-involved women are also significantly more likely to be supervisors, to report that most of the people in their work group or branch are below them in rank/position, to be working with all or predominantly men, to have men above them in rank, and to have experienced sex discrimination on the job. In the area of job satisfaction, the differences by work involvement are not as pronounced. High work-involved women are significantly more likely to be employed and not job hunting — one measure of job satisfaction. However, they are no more or less likely than moderate or low work-involved women to perceive their job as a compromise with what they expected or to report overall job satisfaction. Some directions for future research are discussed.Environmental Strategies, Inc.Preparation of this report was supported, in part, by the Providence College Fund to Aid Faculty Research. Thanks are due to the staff of The Henry A. Murray Research Center of Radcliffe College for access to the 1970 questionnaires, to Sharon R. Jenkins for data processing consultation, and to the anonymous reviewers for their helpful suggestions. 相似文献
240.
Lawrence A. Kurdek 《Sex roles》1988,18(11-12):727-738
Negative attitudes toward homosexuals were assessed in 103 heterosexual college students. On the average, 17% of the sample agreed or strongly agreed with each of 40 negative statements about homosexuals. Cronbach's alpha and a principal components analysis indicated that the attitude scale was unidimensional. Methodological improvements were made in the assessment of the correlates of negative attitudes toward homosexuals. Such attitudes were inversely related to age, academic performance, and the use of principled moral reasoning. They were positively related to traditional attitudes toward men, women, and the equality of men and women. Compared to females, males' attitudes toward homosexuals were more negative, and their attitudes toward men, women, and the equality of men and women were more traditional. However, the correlates of negative attitudes toward homosexuals were similar for males and for females. It was concluded that negative attitudes toward homosexuals are part of a larger belief system regarding conventional social order. 相似文献