全文获取类型
收费全文 | 8087篇 |
免费 | 226篇 |
学科分类
社会科学 | 8313篇 |
出版年
2021年 | 51篇 |
2020年 | 93篇 |
2019年 | 138篇 |
2018年 | 175篇 |
2017年 | 260篇 |
2016年 | 215篇 |
2015年 | 157篇 |
2014年 | 187篇 |
2013年 | 1402篇 |
2012年 | 304篇 |
2011年 | 229篇 |
2010年 | 184篇 |
2009年 | 168篇 |
2008年 | 198篇 |
2007年 | 191篇 |
2006年 | 143篇 |
2005年 | 208篇 |
2004年 | 187篇 |
2003年 | 226篇 |
2002年 | 233篇 |
2001年 | 232篇 |
2000年 | 200篇 |
1999年 | 191篇 |
1998年 | 147篇 |
1997年 | 112篇 |
1996年 | 127篇 |
1995年 | 104篇 |
1994年 | 93篇 |
1993年 | 104篇 |
1992年 | 132篇 |
1991年 | 120篇 |
1990年 | 113篇 |
1989年 | 101篇 |
1988年 | 114篇 |
1987年 | 111篇 |
1986年 | 102篇 |
1985年 | 125篇 |
1984年 | 94篇 |
1983年 | 105篇 |
1982年 | 71篇 |
1981年 | 77篇 |
1980年 | 74篇 |
1979年 | 78篇 |
1978年 | 77篇 |
1977年 | 50篇 |
1976年 | 43篇 |
1975年 | 58篇 |
1974年 | 47篇 |
1973年 | 40篇 |
1972年 | 43篇 |
排序方式: 共有8313条查询结果,搜索用时 587 毫秒
1.
2.
3.
Cathy W. S. Chen Hong Than-Thi Mike K. P. So 《Journal of Statistical Computation and Simulation》2019,89(2):191-210
This paper proposes a new hysteretic vector autoregressive (HVAR) model in which the regime switching may be delayed when the hysteresis variable lies in a hysteresis zone. We integrate an adapted multivariate Student-t distribution from amending the scale mixtures of normal distributions. This HVAR model allows for a higher degree of flexibility in the degrees of freedom for each time series. We use the proposed model to test for a causal relationship between any two target time series. Using posterior odds ratios, we overcome the limitations of the classical approach to multiple testing. Both simulated and real examples herein help illustrate the suggested methods. We apply the proposed HVAR model to investigate the causal relationship between the quarterly growth rates of gross domestic product of United Kingdom and United States. Moreover, we check the pairwise lagged dependence of daily PM2.5 levels in three districts of Taipei. 相似文献
4.
Carlos J. Pérez-González Arturo J. Fernández 《Journal of Statistical Computation and Simulation》2019,89(13):2489-2504
An accurate procedure is proposed to calculate approximate moments of progressive order statistics in the context of statistical inference for lifetime models. The study analyses the performance of power series expansion to approximate the moments for location and scale distributions with high precision and smaller deviations with respect to the exact values. A comparative analysis between exact and approximate methods is shown using some tables and figures. The different approximations are applied in two situations. First, we consider the problem of computing the large sample variance–covariance matrix of maximum likelihood estimators. We also use the approximations to obtain progressively censored sampling plans for log-normal distributed data. These problems illustrate that the presented procedure is highly useful to compute the moments with precision for numerous censoring patterns and, in many cases, is the only valid method because the exact calculation may not be applicable. 相似文献
5.
This study investigated the risk factors associated with the occurrence of child physical and psychological abuse in South Korea based on the ecological theory of child maltreatment. A subsample of 3‐ to 18‐year‐old children from “A Study on the Current State of Child Abuse and Neglect,” a nationally representative study on child abuse and neglect, was utilized for secondary data analysis. The sample was divided into two age groups (third graders in elementary school and below and fourth graders and above). We utilized hierarchical logistic regression for each age group separately to analyze the data. The variables at each level of the system (i.e., ontogenic development, microsystem, and exosystem) were entered into the model in sequential order. The results showed the common risk factors for both age groups are the caregiver's experience of abuse in childhood, the child's problem behavior, exposure to domestic violence, community size, and informal social control. The child's age was also significant in both groups but in the opposite direction. Social support was a significant predictor for the younger age group only, while the caregiver's level of education was significant for the older age group only. Implications for future research and practice are discussed based on the study results. 相似文献
6.
The emerging digital transformation in the twenty‐first century is rapidly and significantly changing the business landscape. The fast‐changing activities, expectations and new modes of collaboration suggest it is time to review the current theoretical insights from strategic alliance (SA) research, which are based on assumptions from a different era. We therefore aim to stimulate multidisciplinary debate and theoretical reflections to better understand emerging paradoxes and challenges that contemporary firms face in the formation, evolution and dissolution of strategic alliances. Specifically, we offer alternative visions of SA research and suggest fresh applications or supplements of existing theoretical perspectives and research methods that can better address the research questions emerging from an era of digital transformation. 相似文献
7.
Politics and Scientific Expertise: Scientists, Risk Perception, and Nuclear Waste Policy 总被引:2,自引:0,他引:2
To study the homogeneity and influences on scientists'perspectives of environmental risks, we have examined similarities and differences in risk perceptions, particularly regarding nuclear wastes, and policy preferences among 1011 scientists and engineers. We found significant differences ( p 0.05)in the patterns of beliefs among scientists from different fields of research. In contrast to physicists, chemists, and engineers, life scientists tend to: (a)perceive the greatest risks from nuclear energy and nuclear waste management; (b)perceive higher levels of overall environmental risk; (c)strongly oppose imposing risks on unconsenting individuals; and (d)prefer stronger requirements for environmental management. On some issues related to priorities among public problems and calls for government action, there are significant variations among life scientists or physical scientists. We also found that–independently of field of research–perceptions of risk and its correlates are significantly associated with the type of institution in which the scientist is employed. Scientists in universities or state and local governments tend to see the risks of nuclear energy and wastes as greater than scientists who work as business consultants, for federal organizations, or for private research laboratories. Significant differences also are found in priority given to environmental risks, the perceived proximity of environmental disaster, willingness to impose risks on an unconsenting population, and the necessity of accepting risks and sacrifices. 相似文献
8.
Sandra G. Turner Carol P. Kaplan Luis Zayas Ruth E. Ross 《Child and Adolescent Social Work Journal》2002,19(5):357-374
Epidemiological data show high rates of suicide attempts among adolescent Latinas. Few studies have addressed the psychosocial, cultural and family correlates of suicide attempts among this age group of a rapidly growing population. The authors studied 31 adolescent Hispanic females who were receiving mental health services; 14 girls had attempted suicide in the previous five years and 17 had never attempted suicide. The two groups of girls did not differ significantly with respect to demographic profiles, levels of depression, family type, acculturation, or self-esteem. However, as hypothesized, the mutuality between girls and their mothers was lower among suicide attempters. Maladaptive coping skills of withdrawal and wishful thinking were more commonly used by attempters, and non-attempters used emotional regulation and problem-solving more frequently. Findings are discussed within the context of the empirical and theoretical literature and implications for practice are considered. 相似文献
9.
Abstract In recent years, church burnings in the South have attracted a great deal of attention. Many commentators have charged that they are a product of strained race relations throughout the South, and particularly of severe racial tensions in Southern rural areas. In this study we evaluate these claims. We begin by mapping the spatial coordinates of recorded church burnings from 1990 to 1997, and find that church arsons indeed are concentrated in the South. Church burnings, however, are a more urban phenomenon than popular media accounts would suggest. Our analysis then explores the influence of contextual factors (population and locale, racial composition and inequality, so‐cioeconomic conditions, local religious ecology, and patterns of reported crime) on church burnings in counties located in the study region. Logistic regression models confirm that church arsons are most likely to occur in small metropolitan statistical areas (MSAs) and non‐MSA counties containing a city of at least 10,000 residents. Church burnings also are especially likely in counties with a higher percentage of black residents, a larger number of churches relative to the rest of the state, and a higher arson rate. We conclude by discussing the implications of these findings for future research and public policy. 相似文献
10.
Using data from a national survey of pharmacists who are members of the American Pharmaceutical Association, we examine the
union voting intentions of employee pharmacists. We find that union instrumentality regarding professionalism is a primary
predictor of union voting intent among these employees. In addition, this predictor mediates the relationship between the
level of professionalism at a pharmacist’s current employment situation and his or her expected union vote. Also important
to union voting intent are respondent beliefs about union instrumentality regarding pecuniary issues, prior union experience,
as well as overall job satisfaction. Implications for employers, unions, and researchers are drawn.
We thank Mary Graham, Jann Skelton, Paul Swiercz, Terry Thomason, and participants at the Seventh Bar-gaining Group Conference
at Michigan State University for their comments on earlier versions of this paper. This research was made possible by a grant
from the American Pharmaceutical Association. 相似文献