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排序方式: 共有132条查询结果,搜索用时 15 毫秒
1.
Summary.  When evaluating potential interventions for cancer prevention, it is necessary to compare benefits and harms. With new study designs, new statistical approaches may be needed to facilitate this comparison. A case in point arose in a proposed genetic substudy of a randomized trial of tamoxifen versus placebo in asymptomatic women who were at high risk for breast cancer. Although the randomized trial showed that tamoxifen substantially reduced the risk of breast cancer, the harms from tamoxifen were serious and some were life threaten-ing. In hopes of finding a subset of women with inherited risk genes who derive greater bene-fits from tamoxifen, we proposed a nested case–control study to test some trial subjects for various genes and new statistical methods to extrapolate benefits and harms to the general population. An important design question is whether or not the study should target common low penetrance genes. Our calculations show that useful results are only likely with rare high penetrance genes.  相似文献   
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Social Indicators Research - The heterogeneous economic results of divorce have received limited attention. The current study analyzes such consequences from an intersectionality perspective, where...  相似文献   
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We show that the Lagrange multiplier (LM) unit root test exhibits size distortions when a break in the innovation variance exists but is ignored. We develop a modified LM unit root test that is based on a generalized least-squares transformation of the original series. The asymptotic null distribution of the new modified LM unit root test is derived. Finite-sample simulation evidence shows that the modified LM unit root test maintains its size and has reasonable power against the trend stationary alternative.  相似文献   
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Decision analysis tools and mathematical modeling are increasingly emphasized in malaria control programs worldwide to improve resource allocation and address ongoing challenges with sustainability. However, such tools require substantial scientific evidence, which is costly to acquire. The value of information (VOI) has been proposed as a metric for gauging the value of reduced model uncertainty. We apply this concept to an evidenced‐based Malaria Decision Analysis Support Tool (MDAST) designed for application in East Africa. In developing MDAST, substantial gaps in the scientific evidence base were identified regarding insecticide resistance in malaria vector control and the effectiveness of alternative mosquito control approaches, including larviciding. We identify four entomological parameters in the model (two for insecticide resistance and two for larviciding) that involve high levels of uncertainty and to which outputs in MDAST are sensitive. We estimate and compare a VOI for combinations of these parameters in evaluating three policy alternatives relative to a status quo policy. We find having perfect information on the uncertain parameters could improve program net benefits by up to 5–21%, with the highest VOI associated with jointly eliminating uncertainty about reproductive speed of malaria‐transmitting mosquitoes and initial efficacy of larviciding at reducing the emergence of new adult mosquitoes. Future research on parameter uncertainty in decision analysis of malaria control policy should investigate the VOI with respect to other aspects of malaria transmission (such as antimalarial resistance), the costs of reducing uncertainty in these parameters, and the extent to which imperfect information about these parameters can improve payoffs.  相似文献   
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Business Model Design: An Activity System Perspective   总被引:2,自引:0,他引:2  
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This study focuses on Poland and Israel, both commonly classified as ethnic nation-states, and aims to question the expression of ethnic–civic dichotomy in return-migration policies. Policy documents in each country were analysed and complemented by interviews with policymakers and representatives from relevant organizations. Our analysis reveals that, although there are differences in their policies toward returning residents and in the related programmes in both countries, Israeli and Polish policies include both ethnic and civic components. Therefore, our study supports Joppke's (2005) argument that there is no purely civic or ethnic nationalism and there can be no purely civic or ethnic nation. We show that the proportion of ethnic and civic elements may change over time; thus, our findings contribute to the growing literature pointing to the dynamic nature of nationalism.  相似文献   
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Few measures parallel the robust depth offered in the existing multidimensional and ecologically informed theories of resilience. This study sought to evaluate the test–retest reliability, construct, and predictive validity of the individual, family, and community resilience resource profile (IFCR-R). The IFCR-R measures a family’s access to resilience resources and protective factors across multiple ecological levels. Confirmatory factor analysis was used with a sample of n?=?810 low-income families. And 159 families completed multiple time point measures for test–retest reliability and predictive validity evaluation. Results of this study support the proposed multidimensional ecological structure of the IFCR-R and found that the IFCR-R offers an acceptable test–retest reliability and predictive validity for outcomes of mental and physical health.  相似文献   
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Using relative utility curves to evaluate risk prediction   总被引:2,自引:0,他引:2  
Summary.  Because many medical decisions are based on risk prediction models that are constructed from medical history and results of tests, the evaluation of these prediction models is important. This paper makes five contributions to this evaluation: the relative utility curve which gauges the potential for better prediction in terms of utilities, without the need for a reference level for one utility, while providing a sensitivity analysis for misspecification of utilities, the relevant region, which is the set of values of prediction performance that are consistent with the recommended treatment status in the absence of prediction, the test threshold, which is the minimum number of tests that would be traded for a true positive prediction in order for the expected utility to be non-negative, the evaluation of two-stage predictions that reduce test costs and connections between various measures of performance of prediction. An application involving the risk of cardiovascular disease is discussed.  相似文献   
10.
This study interviewed adolescents conceived using sperm donation to examine their experiences of contacting and meeting ‘same‐donor offspring’ (i.e. donor‐conceived offspring raised in different families who share the same donor), their motivations for this contact, and how they make meaning of these relationships. This in‐depth qualitative study involved semi‐structured interviews with 23 young people aged 12–19 years (mean = 14 years). Interviewees were motivated by curiosity about their biological relations and by wanting to extend their family. Contact with same‐donor offspring was described as being either normal/neutral or as a unique experience that was integrated into their identity. This study highlights the importance of contact between same donor offspring, particularly during adolescence, a developmental stage associated with identity formation. The findings have important policy implications as they suggest that donor‐conceived individuals may benefit from contact with others conceived using the same donor prior to the age of 18 years.  相似文献   
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