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   24305篇
  免费   1033篇
  国内免费   13篇
  2020年   288篇
  2019年   286篇
  2018年   477篇
  2017年   442篇
  2016年   468篇
  2015年   304篇
  2014年   414篇
  2013年   1839篇
  2012年   741篇
  2011年   790篇
  2010年   441篇
  2009年   527篇
  2008年   695篇
  2007年   692篇
  2006年   623篇
  2005年   558篇
  2004年   551篇
  2003年   527篇
  2002年   497篇
  2001年   846篇
  2000年   853篇
  1999年   639篇
  1998年   283篇
  1997年   251篇
  1996年   230篇
  1995年   223篇
  1992年   512篇
  1991年   458篇
  1990年   514篇
  1989年   438篇
  1988年   410篇
  1987年   395篇
  1986年   408篇
  1985年   472篇
  1984年   368篇
  1983年   311篇
  1982年   243篇
  1979年   349篇
  1978年   276篇
  1977年   227篇
  1975年   315篇
  1974年   368篇
  1973年   372篇
  1972年   284篇
  1971年   257篇
  1970年   217篇
  1969年   232篇
  1968年   300篇
  1967年   264篇
  1966年   290篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The Americans with Disabilities Act (ADA) of 1990 is the most comprehensive federal civil rights law addressing discrimination against one-fifth of the American population. This article is meant to contribute to the emerging dialogue on ADA implementation by presenting information from a longitudinal investigation of employment integration and economic opportunity under the employment provisions of the ADA, set forth in Title I of the act. The broader relevance of the investigation to emerging questions under Title I law is described. Thereafter, the investigation's seven core findings are presented, and then the implications for future investigation of the ADA are examined.  相似文献   
992.
This study explores the relationship between media use and political commitment. Undergraduate participants answered an extensive political background questionnaire, which included measures of media use, perceived importance of information sources regarding the 1992 presidential election, and various political behaviors as an index of political commitment. Correlational analyses revealed that those who are more politically committed tend to select a variety of media sources regarding a presidential candidate. This study also investigated how informational and commitment variables were related to attitudes towards the major presidential candidates. Results observed for people expressing positive attitudes toward Perot are discussed in terms of the modern day “third party voter.”  相似文献   
993.
The authors examine the influence of cross-cultural training on the racial identity attitudes of 35 White graduate counselors in training (10 men and 25 women) and the impact of gender on training. A pretest-posttest comparison of responses to the White Racial Identity Attitudes Survey (WRIAS) was used. Results indicated that the cross-cultural training course (a) influenced racial identity attitudes of White counselors in training and (b) racial identity attitudes were influenced by gender.  相似文献   
994.
In a series of three experiments, subjects made risky decisions under conditions of hypothetical or real consequences. Task variations across experiments included: (1) type of risk (monetary gambles or investments of time and effort), (2) within-subject and between-subjects manipulations of consequence condition, and (3) single or multiple decisions. The hypothesis of no difference between choices in real and hypothetical consequence conditions was retained in each experiment. Supplemental analyses ruled out various “artifactual” interpretations of the null results. Discussion focused on conditions in which researchers can and cannot infer decision makers’ actual risk preferences from their responses in laboratory tasks.  相似文献   
995.
This paper situates Bogdanov in the context of social theory generally and socialist theory in particular. It outlines briefly the principal characteristics of his mature system, and assesses the strengths and weaknesses of his approach to the fundamental problems of social thought. The paper devotes particular attention to the problem of just how systems develop from less complex to more complex forms of organization, and evaluates Bogdanov’s solution to this problem against the background of populist, social democratic, and Leninist alternatives.  相似文献   
996.
The National Conference of Catholic Bishops has argued for significant government involvement in health care in order to assure respect for what they regard as the right to health care. Critics charge that the bishops are wrong because health care is not a right. In this article, it is argued that these critics are correct in their claim that health care is not a right. However, it is also argued that the premise that health care is not a right does not imply that the market is the most equitable and just system for providing health care. Natural law arguments in the tradition of Roman Catholic social teaching lead to the conclusion that a just and prosperous society has a moral obligation to provide health care even if there is no such right. Further, there are strong moral grounds for concluding that the bishops are correct in their claim that health care ought not to be considered a market commodity. It is argued that if health care ought not to be considered a commodity, then national health insurance is the best available alternative for fulfilling the social obligation to distribute health care resources justly and fairly at this time in American history. The bishops' case for government involvement can be made on the strength of the Catholic tradition in theological argumentation, independent of the claim that health care is a right.  相似文献   
997.
College students periodically experience many challenges in pursuit of their educational goals. Such experiences can have deleterious effects on subsequent motivation and performance when they are perceived as negative. Research shows that some students who experience negative events are buffered against motivational deficits, whereas others are motivationally at-risk. Several individual difference variables have been proposed to account for such diverse reactions. A longitudinal field study that involved three phases was conducted to extend this research. Phase I examined the motivational buffering effects of academic attributional style on students' performance, motivation, and emotions. Results indicated that attributional style related to students' performance, motivation, and emotions. Specifically, students who routinely made unstable and controllable attributions for negative academic events exhibited the greatest performance and motivation compared to students who typically made stable and uncontrollable attributions. Phases II and III were designed to examine the remedial benefits of attributional retraining for different attributional styles. Findings indicated that attributional retraining influenced motivation, emotions, and course grade. These results were qualified by the interaction between attributional style, attributional retraining, and time. Findings are discussed within Weiner's (1985, 1986) attribution theory. This research was based, in part, on the first author's dissertation submitted to the Department of Psychology and the Faculty of Graduate Studies of The University of Manitoba in partial fulfillment for the Degree of Doctor of Philosophy. This research was supported by a Social Sciences and Humanities Research Council of Canada (SSHRCC) doctoral fellowship, a University of Manitoba doctoral fellowship, and a SSHRCC postdoctoral fellowship to the first author. In addition, the research was also supported by a SSHRCC research grant (#410911296) to the second author. The authors gratefully acknowledge the helpful comments of Bernard Weiner, Harvey Keselman, John Adair, Rodney Clifton, and Robert Altemeyer. Also appreciated was the assistance of Verena Menec and the Higher Education Research group.  相似文献   
998.
An injection olfactometer for human psychophysical experiments is described. The olfactometer is capable of presenting, either mono- or birhinally, single odorants and binary mixtures. The pulse form of the olfactory stimulus at the exit of the olfactometer approaches a rectangular form, which makes the olfactometer well suited for olfactory reaction time measurements. Since stimulation periods are independent of the subject’s inhalation, time-intensity measurements over prolonged periods of time are possible as well. In the second part of this paper, a new technique is described for the measurement of the stimulus pulse form at the exit of the olfactometer.  相似文献   
999.
We investigated the ability of subjects to discriminate sugars with a whole-mouth forced-choice paradigm, in which a standard solution was compared with a test solution of varied concentration. Discrimination probabilities were U-shaped functions of test concentration: for 6 subjects and pairwise combinations of fructose, glucose, and sucrose, discriminability always declined to chance over a narrow range of test concentrations. At concentrations ≦ 100 mM, maltose was indiscriminable from fructose but discriminable at higher concentrations for 4 subjects. By analogy with themonochromacy of night vision, whereby any two lights are indiscriminable when their relative intensities are suitably adjusted, we call the gustatory indiscriminability of these sugarsmonogeusia. The simplest account of monogeusia is that all information about the indiscriminable sugars is represented by a single neural signal that varies only in magnitude. The discriminability of maltose from the other sugars at higher concentrations is consistent with the hypothesis that maltose also activates a second gustatory code.  相似文献   
1000.
During linear translation through a stationary environment, the pattern of optical flow generated on each retina is symmetrical when the head is aligned with the heading, but during lateral gaze the optical flow is asymmetric. We assessed whether human subjects could use the magnitude of this asymmetry to determine the direction of heading during passive translation through a 3-D environment. When allowed to move their heads in order to look in the direction of self-motion, subjects indicated their heading precisely and accurately. When the head was locked in alignment with the misaligned body, and gaze adjustments were not allowed, responses were quite precise, but showed a large bias which increased with increasing heading angle.  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