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   3411篇
  免费   74篇
管理学   578篇
民族学   26篇
人才学   5篇
人口学   228篇
丛书文集   18篇
理论方法论   366篇
综合类   28篇
社会学   1698篇
统计学   538篇
  2023年   26篇
  2021年   16篇
  2020年   58篇
  2019年   90篇
  2018年   81篇
  2017年   103篇
  2016年   97篇
  2015年   77篇
  2014年   86篇
  2013年   568篇
  2012年   116篇
  2011年   104篇
  2010年   100篇
  2009年   91篇
  2008年   116篇
  2007年   97篇
  2006年   108篇
  2005年   137篇
  2004年   89篇
  2003年   100篇
  2002年   94篇
  2001年   81篇
  2000年   56篇
  1999年   69篇
  1998年   58篇
  1997年   41篇
  1996年   39篇
  1995年   35篇
  1994年   57篇
  1993年   49篇
  1992年   39篇
  1991年   48篇
  1990年   46篇
  1989年   37篇
  1988年   36篇
  1987年   40篇
  1986年   25篇
  1985年   45篇
  1984年   40篇
  1983年   36篇
  1982年   34篇
  1981年   19篇
  1980年   16篇
  1979年   19篇
  1978年   20篇
  1977年   18篇
  1976年   18篇
  1975年   17篇
  1974年   17篇
  1973年   14篇
排序方式: 共有3485条查询结果,搜索用时 15 毫秒
81.
Modelling udder infection data using copula models for quadruples   总被引:1,自引:0,他引:1  
We study copula models for correlated infection times in the four udder quarters of dairy cows. Both a semi-parametric and a nonparametric approach are considered to estimate the marginal survival functions, taking into account the effect of a binary udder quarter level covariate. We use a two-stage estimation approach and we briefly discuss the asymptotic behaviour of the estimators obtained in the first and the second stage of the estimation. A pseudo-likelihood ratio test is used to select an appropriate copula from the power variance copula family that describes the association between the outcomes in a cluster. We propose a new bootstrap algorithm to obtain the p-value for this test. This bootstrap algorithm also provides estimates for the standard errors of the estimated parameters in the copula. The proposed methods are applied to the udder infection data. A small simulation study for a setting similar to the setting of the udder infection data gives evidence that the proposed method provides a valid approach to select an appropriate copula within the power variance copula family.  相似文献   
82.
83.
Implementation of adaptive clinical trial designs raises challenges with regard to the processes by which accruing trial data is analyzed, reviewed, and acted upon. In line with current monitoring conventions, it should be viewed that inappropriate knowledge of interim results can raise concerns regarding maintaining trial integrity and interpretability of results. Here we discuss issues related to these processes in adaptive trials, and point out distinctions versus other more familiar monitoring situations. One topic involves the composition of the group of individuals who will have access to interim results in order to recommend adaptations. We discuss operational models for data review by this group; one question addressed is whether in adaptive trials a role in this process for a representative of the study sponsor could at times be warranted, and might be justified if adequate protections are in place. Another issue involves whether adaptations made based upon interim data can convey to observers an amount of information about the results, which could rise to a level of concern. We consider whether different types of adaptations might be more or less problematic with regard to this issue, and recommend steps that might be considered to mitigate this concern.  相似文献   
84.
85.
The paper posits an intervention in current debates around 'method making' in the social sciences, drawing on the experience of undertaking an ethnographic study of a community mental health team in East London. Theoretical recourse is made to the process philosophy of A.N. Whitehead and to the enduring provenance of the problem of 'suggestion' in the history of medicine and psychology. These offer rich and provocative theoretical resources with which to rethink the interpenetration of subject and object and 'feeling' and 'finding'. Whitehead's work provides a general philosophical framework whereby the ongoing subjective experience of the researcher can no longer be sharply demarcated from the 'data' encountered. Meanwhile the adoption of a 'register of suggestion' opens up insights into the inevitably selective and singular character of any given methodological procedure. It maintains the importance of affective factors at the forefront of analysis, and brings into focus the parts played by indeterminacy and risk in the research event.  相似文献   
86.
Analyses of data from the 2000 US Census show that the gender pay gap differs by sector of employment and according to the part of the earnings distribution that is considered. The gender pay differential in the private sector in the US does not display either the glass ceiling or sticky floor effects that have been reported for many other countries. The government sector is, however, characterized by a distinct sticky floor effect in the female–male pay differential. Regardless of the sector of employment, females have lower hourly rates of pay than men across the entire earnings distribution.
Paul W. MillerEmail:
  相似文献   
87.
Three‐ to 4‐month‐old and 6‐ to 7‐month‐old infants were administered an infant version of the Face Dimensions Test that has been used with adults (e.g., Bukach, Le Grand, Kaiser, Bub, & Tanaka, 2008). Infants were familiarized with a photograph of a woman's face and then tested with the familiar face paired with a face differing in the (a) distance separating the eyes (a configural/eyes change), (b) distance between the nose and mouth (configural/mouth change), (c) size of the eyes (featural/eyes change), and (d) size of the mouth (featural/mouth change). Infants were shown to be more sensitive to (a) configural than featural change, and (b) change around the eyes versus the mouth. Implications for the development of face processing are discussed.  相似文献   
88.
The importance of informal care provided inside the household (co-residential care) is widely acknowledged in policy circles. However, the factors that determine the likelihood and scale of provision are not fully understood. A two-part model (2PM) is used to investigate both participation and levels of provision. Random effects dynamic panel specifications are employed. Results show that co-residential informal care competes with other time demanding activities, such as childcare and employment. Wealthier individuals are less likely to be caregivers, whereas wealthier households have a higher tendency towards caregiving. Evidence of both substitution and complementarity is found between formal and informal care. Informal care and health status are significantly related, with carers more likely to report worse General Health Questionnaire scores than non-carers. Finally, significant dynamic effects are observed with the continuance of the provision of informal care being more likely than the initiation of such activity, while heavy commitment in the past increases the hours provided in the current period.
Emmanouil MentzakisEmail:
  相似文献   
89.
Research conducted in Canada and the United States shows that the age of arrival of immigrant children, language spoken in the home, and ethno‐racial origin have consequences for English language acquisition and academic attainment. So far, however, the degree to which these factors have consequences for academic achievement at the post‐secondary level has scarcely been studied. In this study, it is found that the communication skills of university students who are the sons and daughters of immigrants, independent of length of time in Canada, are not as high as those of native‐born English‐speaking Canadians. Moreover, all else being equal, independent of length of time in the country, the university GPAs of immigrant and non‐European origin groups are generally lower than those of native‐born Canadians. Findings such as these suggest the presence of social and cultural processes at the family, community, and educational system level that continue to disadvantage identifiable groups of post‐secondary students.  相似文献   
90.
International policy now constantly advocates a need for populations to engage in more physical activity to promote health and to reduce society’s health care costs. Such policy has developed guidelines on recommended levels and intensity of physical activity and implicitly equates health with well-being. It is assumed that individual, and hence social welfare will be enhanced if the activity guidelines are met. This paper challenges that claim and raises questions for public policy priorities. Using an instrumental variable analysis to value the well-being from active leisure, it is shown that the well-being experienced from active leisure that is not of a recommended intensity to generate health benefits, perhaps due to its social, recreational or fun purpose, has a higher value of well-being than active leisure that does meet the guidelines. This suggests rethinking the motivation and foundation of existing policy and perhaps a realignment of priorities towards activity that has a greater contribution to social welfare through its intrinsic fun and possibly social interaction.  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