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   85篇
  免费   1篇
管理学   5篇
人口学   22篇
理论方法论   6篇
综合类   1篇
社会学   32篇
统计学   20篇
  2023年   1篇
  2022年   1篇
  2021年   1篇
  2020年   2篇
  2019年   2篇
  2018年   1篇
  2017年   5篇
  2016年   3篇
  2015年   1篇
  2013年   19篇
  2012年   3篇
  2011年   2篇
  2010年   4篇
  2009年   3篇
  2008年   2篇
  2007年   3篇
  2006年   1篇
  2005年   3篇
  2004年   2篇
  2003年   3篇
  2002年   1篇
  1999年   1篇
  1998年   1篇
  1997年   1篇
  1996年   2篇
  1995年   1篇
  1994年   1篇
  1992年   1篇
  1991年   1篇
  1990年   2篇
  1989年   1篇
  1982年   2篇
  1981年   1篇
  1978年   1篇
  1972年   1篇
  1970年   1篇
  1969年   1篇
  1967年   1篇
  1966年   2篇
  1964年   1篇
排序方式: 共有86条查询结果,搜索用时 15 毫秒
21.
Many clinical research studies evaluate a time‐to‐event outcome, illustrate survival functions, and conventionally report estimated hazard ratios to express the magnitude of the treatment effect when comparing between groups. However, it may not be straightforward to interpret the hazard ratio clinically and statistically when the proportional hazards assumption is invalid. In some recent papers published in clinical journals, the use of restricted mean survival time (RMST) or τ ‐year mean survival time is discussed as one of the alternative summary measures for the time‐to‐event outcome. The RMST is defined as the expected value of time to event limited to a specific time point corresponding to the area under the survival curve up to the specific time point. This article summarizes the necessary information to conduct statistical analysis using the RMST, including the definition and statistical properties of the RMST, adjusted analysis methods, sample size calculation, information fraction for the RMST difference, and clinical and statistical meaning and interpretation. Additionally, we discuss how to set the specific time point to define the RMST from two main points of view. We also provide developed SAS codes to determine the sample size required to detect an expected RMST difference with appropriate power and reconstruct individual survival data to estimate an RMST reference value from a reported survival curve.  相似文献   
22.
We consider a two-stage voluntary provision model where individuals in a family contribute to a pure public good and/or a household public good, and the parent makes private transfers to her own child. We show not only that Warr’s neutrality holds, regardless of the different timings of parent-to-child transfers, but also that there is a continuum of Nash equilibria which individuals’ contributions and parental transfers are indeterminate, although the allocation of each’s private consumption and total public good provision is uniquely determined. Furthermore, impure altruism or productivity difference in supplying public goods may not break our results above.  相似文献   
23.
This study introduces a novel framework for building company bankruptcy models and a methodology for assessing the vulnerability of industrial economic activities. We consider the identification of bankruptcy as a classification problem and assume that bankruptcy criteria differ across industries. We build highly accurate industry bankruptcy models by constructing separate models for each industry. We also propose a method of analyzing the vulnerability of industrial economic activities in various countries and industries using new indicators we call “expected potential loss,” which we obtain using the predicted likelihood of bankruptcy and company information. (JEL G0, C0)  相似文献   
24.
Despite the significant financial and human resources invested in child protection services (CPS), it is unknown whether these services are effective in preventing recurrence of child physical abuse and neglect. This paper reviews available studies evaluating the effectiveness of these interventions and identifies methodological limitations and factors that may contribute to these limitations. We searched databases to identify randomised controlled trials published in peer‐reviewed journals in the past five decades that evaluated interventions to reduce recurrence of physical abuse and neglect. We outlined ten methodological standards that are important for rigorous testing of psychosocial interventions and applied them in critically appraising identified studies. Thirteen randomised controlled trials were reviewed. This review identified methodological limitations (e.g. small sample size, lack of standardisations, contamination) that made it difficult to draw reliable conclusions as to the effectiveness of interventions. Field‐specific factors that contributed to methodological limitations (e.g. heterogeneity of sample, multiple family problems, psychosocial nature of interventions) were identified and recommendations were provided for improvement. It was concluded that it is possible to implement high‐quality trials that are ethical and feasible in the child welfare field. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   
25.
Owing to equal and increased opportunities for education and employment, today's trend in Japanese marriages is characterized by late and less frequent marriage. This paper discusses unavoidable diversity in rural families to point out the anticipated consequences of aging in rural areas and to discuss limitations in current public social care policies. Specifically, the averaged proportion of never-married and single persons at ages 45 to 49 and 50 to 54 in legally recognized depopulated cities, towns, and villages in Japan is calculated to illustrate the expected diversity in families in rural depopulated areas. It also illustrates the need for future studies to develop better social care policies for increasing numbers of single caregivers and single elders.  相似文献   
26.
In this paper we analyze the effect of inequality on school enrollment, preferred tax rate and expenditure per student in developing countries; when parents can choose between child labor, public schooling or private schooling. We present a model in which parents make schooling decisions for their children, weighing the utility benefit of having a child with formal public or private education versus the forgone income from child labor or household work. Parents vote over the preferred tax rate to finance freely provided public education. The utility benefit of an educated child is proportional to expenditure per student, so that there is congestion in public school. We find that when parents can send their children to work or to private school, high inequality leads to exit from public education at both ends of the income distribution. Thus high inequality reduces the support for public education, leading to a low tax rate and expenditure per student. Exit from public education results in both high child labor and a large fraction of students attending private school. In fact there is a threshold level of inequality above which there is no longer support for public education. In addition we explore the implications for the design of foreign aid. The results suggest that foreign aid policies should focus on promoting school attendance rather than increasing school resources, as the later policy might be offset by a reduction in the recipient country’s fiscal effort, with little impact on outcomes.   相似文献   
27.
Generalizing methods of constructions of Hadamard group divisible designs due to Bush (1979), some new families of semi-regular or regular group divisible designs are produced. Furthermore, new nonisomorphic solutions for some known group divisible designs are given, together with useful group divisible designs not listed in Clatworthy (1973).  相似文献   
28.
Summary A record of simulated removal trapping of 50 samples drawn fromN=50 under a design has been considered as to how it does contribute to practical censuses of small mammals. It follows that, for ordinary-density populations so far experienced, the removal census based on the theory may frequently lead to quite wrong estimates from single-plot data by the simplest method, and that the maximum likelihood method is doubtless better, but even this method may produce right estimates in about half of the cases, their standard error being of limited availability. Therefore pooling of data from many plots are desirous for such populations.  相似文献   
29.
In Japan, accurately assessing and targeting gambling urges is important for the treatment of gambling disorder because people are constantly exposed to external triggers that elicit gambling urges. However, a valid measure that assesses gambling urges has not been adequately established. Therefore, the purpose of this study was to examine the psychometric properties of the Japanese version of the Gambling Urge Scale (GUS-J), which is a well-known valid 6-item instrument in English-speaking countries. Two hundred and thirty-nine participants completed questionnaires, 86 of which met the criteria for a probable gambling disorder. As with the original GUS, the GUS-J was demonstrated to be a one-factor model that accounted for 63.82% of the total item variance, with all items demonstrating loadings of .40 or higher. With regard to reliability, the GUS-J showed good internal consistency (α = .88). Furthermore, validity based on evidence of relationships with other variables, especially convergent and concurrent validity of the GUS-J, were supported by several analyses that examined hypotheses based on previous findings. In conclusion, this study showed that the GUS-J has good psychometric properties as an assessment tool for gambling urges in Japanese people and it will be useful for future clinical practice and research.  相似文献   
30.
Within a population of the web-building spiderAgelena limbata, the weight of the first instar nymphs ranged from 1.187 to 6.559 mg. Both intraclutch and interclutch variation were recorded. The mean weights were different among clutches and the coefficients of variation within a clutch ranged from 3.3 to 29.2%. Variation in the nymphal weight was certainly derived from variation in the egg weight because there was a high correlation between the two weights. Factors affecting interclutch variation in nymphal weight were examined by multiple regression analysis. Nymphal weight was positively correlated with the body size and food conditions of female parents, and negatively correlated with the clutch size. Among these three factors, the food conditions of female parents had the largest apparent effect on the interclutch variation. The results suggest that females with larger body size and more food produce larger offspring, and that there is a trade-off between offspring size and clutch size. Heavier nymphs had larger body size (carapace width) and may have larger energy reserves. Heavier nymphs survived experimental starvation for a significantly longer period.  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