全文获取类型
收费全文 | 45884篇 |
免费 | 1740篇 |
国内免费 | 22篇 |
出版年
2019年 | 600篇 |
2018年 | 781篇 |
2017年 | 807篇 |
2016年 | 797篇 |
2015年 | 580篇 |
2014年 | 712篇 |
2013年 | 3570篇 |
2012年 | 1238篇 |
2011年 | 1398篇 |
2010年 | 878篇 |
2009年 | 903篇 |
2008年 | 1240篇 |
2007年 | 1204篇 |
2006年 | 1125篇 |
2005年 | 950篇 |
2004年 | 912篇 |
2003年 | 923篇 |
2002年 | 883篇 |
2001年 | 1560篇 |
2000年 | 1576篇 |
1999年 | 1125篇 |
1998年 | 553篇 |
1997年 | 441篇 |
1996年 | 446篇 |
1995年 | 438篇 |
1992年 | 944篇 |
1991年 | 930篇 |
1990年 | 914篇 |
1989年 | 853篇 |
1988年 | 800篇 |
1987年 | 782篇 |
1986年 | 759篇 |
1985年 | 834篇 |
1984年 | 637篇 |
1983年 | 558篇 |
1982年 | 435篇 |
1979年 | 680篇 |
1978年 | 536篇 |
1977年 | 468篇 |
1976年 | 438篇 |
1975年 | 604篇 |
1974年 | 639篇 |
1973年 | 715篇 |
1972年 | 587篇 |
1971年 | 515篇 |
1970年 | 451篇 |
1969年 | 510篇 |
1968年 | 606篇 |
1967年 | 558篇 |
1966年 | 579篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
991.
992.
The effects of tobacco smoking on responses to electrical stimulation were studied according to a Method of Limits (ML) threshold analysis and a Sensory Decision Theory (SDT) analysis. For the ML procedure, Detection Threshold (DT), Pain Threshold (PT) and Tolerance Level (TL) measures were obtained. For the SDT procedure, nonparametric estimates of capacity to discriminate between stimulus intensities (P(A)) and response criterion (B) were calculated. There was no main effect of tobacco smoking on responses to electrical stimulation. Males had consistently higher ML thresholds than females in both the NS and S condition. Males also tended to increase in DT and PT after smoking. From a comparison between the effects of smoking on ML and SDT measures it was suggested that PT is related mainly to sensory factors and TL to response factors. 相似文献
993.
In many classification problems, one often possesses external and/or internal information concerning the objects or units to be analyzed which makes it appropriate to impose constraints on the set of allowable classifications and their characteristics. CONCLUS, or CONstrained CLUStering, is a new methodology devised to perform constrained classification in either an overlapping or nonoverlapping (hierarchical or nonhierarchial) manner. This paper initially reviews the related classification literature. A discussion of the use of constraints in clustering problems is then presented. The CONCLUS model and algorithm are described in detail, as well as their flexibility for use in various applications. Monte Carlo results are presented for two synthetic data sets with appropriate discussion of the resulting implications. An illustration of CONCLUS is presented with respect to a sales territory design problem where the objects classified are various Forbes-500 companies. Finally, the discussion section highlights the main contribution of the paper and offers some areas for future research.We wish to thank C. Mallows and J. D. Carroll for some helpful technical discussion and L. Clark and D. Art for their valuable computer assistance. We also wish to thank H. Pollak, R. Gnanadesikan, and J. Kettenring for their thorough reviews of a previous draft of this paper. Finally, we acknowledge helpful comments of the editor and two anonymous reviewers. 相似文献
994.
995.
S. D. Reicher 《European journal of social psychology》1984,14(1):1-21
The paper contains a detailed study of the St. Pauls' riots of April 1980. Particular attention is paid to the limits of participation in the event and the limits of crowd action. It is argued that these limits show clear social form and cannot be explained in terms of the individualistic theories that dominate crowd psychology. Instead a model of crowd behaviour based on the social identity model is advanced to account for the observations. It is concluded that crowd behaviour is more sophisticated and creative than hitherto allowed and that the neglect of this field should be remedied. 相似文献
996.
997.
S. Wiegersma 《Memory & cognition》1984,12(2):190-194
The question of whether repetition avoidance in sequential response production depends on the phonetic or the semantic encoding of previous responses was investigated by varying the acoustic and semantic similarity among the response alternatives. The results indicated that acoustic similarity affected repetition avoidance with six alternative words and a production rate of one per second, but not with four alternative letters and a rate of one per 2 sac. Semantic similarity between words was also studied, and was not seen to affect repetition avoidance. Results were explained by means of a model in which comparisons between a memory set of admissible responses and a memory set of recent responses are made at a phonetic level of response representation. 相似文献
998.
Daniel S. Lee Julie A. Cederbaum Jordan P. Davis Michael S. Hurlburt Ferol E. Mennen 《Family process》2023,62(1):254-271
Maternal and adolescent depression are challenges that often co-occur. Many studies have drawn bivariate associations between maternal depressive symptoms, adolescent depressive symptoms, and family conflict, but few have examined reciprocal effects. Even among extant studies, there is a lack of clarity related to directionality of influence. Three competing theoretical models may explain the relationship between maternal depressive symptoms, adolescent depressive symptoms, and family conflict, and these processes may differ by adolescents’ sex. Using three time points of data from 187 diverse mother-adolescent dyads, we fit a taxonomy of autoregressive cross-lagged structural equation models to simultaneously evaluate the competing theoretical models and also examine differences by sex using multiple-group analyses. Results indicate a symptom-driven model whereby adolescent depressive symptoms predicted increases in family conflict. Sex differences were also found. For males, but not females, greater adolescent depressive symptoms predicted subsequent increases in maternal depressive symptoms, which then predicted lower family conflict—possibly indicating maternal disengagement/withdrawal. Our findings suggest addressing adolescent depressive symptoms in order to prevent family conflict and that distinctive targets for the prevention/intervention of family conflict should account for differences by adolescents’ sex. 相似文献
999.
Michael Lee Wood Grace Soelberg Jacob S. Rugh 《Journal for the scientific study of religion》2023,62(Z1):105-123
The work of W.E.B. Du Bois highlights the significance of Christian religion in Black American life. According to Du Bois, the Black Church serves as a site of self-formation and affirmation, and the White Church as a source of racist beliefs and justifications for inequality. In this paper, we expand Du Bois’ inquiry about the influence of religion with a study of Black Americans who belong to a predominantly White religion. For those whose religious experience is almost wholly within the “white world,” what role does religion play in their lives? We analyze a set of 52 public accounts by Black Americans discussing their experiences as members of the Church of Jesus Christ of Latter-day Saints (LDS). We find that for many Black LDS, membership in the LDS Church is characterized by contrast and contradiction, yielding spiritual conviction, joy, and meaningful communion on one hand, and racism and isolation on the other. We also find that Black LDS respond to these contradictions in a variety of ways. We classify these agentic responses into five types and examine the sociological significance of the observed variation. We conclude with a discussion of implications for scholarship on race and religion. 相似文献
1000.