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291.
292.
Abstract

Objective: To compare the extent to which information efficacy (confidence for acquiring useful information) and media literacy skills predict knowledge and self-efficacy for preventing or treating the health threat of influenza. Participants: A random-sample survey of 1,379 residential students enrolled at a northwestern public university was conducted in fall 2009. Methods: Students accessed an Internet survey through a link provided in an e-mail. Results: Students who self-diagnosed correctly demonstrated higher levels of media literacy skills than those who self-diagnosed incorrectly. Among those who self-diagnosed incorrectly, the only predictor of knowledge was accessibility of information sources; low accessibility was associated with reduced knowledge. Information efficacy predicted self-efficacy for both groups. Conclusions: The results illustrate the limitations of information efficacy in the absence of media literacy skills. To decrease health risks, college health practitioners should promote media literacy while also ensuring easy access to high-quality information.  相似文献   
293.
Abstract

Objective: The authors examine the dynamics and the impact of all-campus events on pH1N1 spread at Bates College in fall 2009, with comparisons to 3 other campuses. Participants: Students (N = 285) presented or called in to the Bates Health Center with symptoms consistent with influenza-like illness. Methods: Health Center staff at Bates collected data on the outbreak; data from other colleges are from Web sites and journal articles. Data were analyzed using a mathematical model for influenza. Results: Bates held 2 vaccine clinics mid-outbreak. The data are consistent with the hypothesis that the vaccine clinics may have altered routine student interactions, facilitating transmission of pH1N1 among students who otherwise might not have encountered each other. Conclusion: The vaccine clinics, held when vaccine became available, were too late to halt transmission. The disruptions to campus rhythms due to the vaccine clinics may instead have contributed to pH1N1 spread.  相似文献   
294.
The Shapiro–Wilk statistic and modified statistics are widely used test statistics for normality. They are based on regression and correlation. The statistics for the complete data can be easily generalized to the censored data. In this paper, the distribution theory for the modified Shapiro–Wilk statistic is investigated when it is generalized to Type II right censored data. As a result, it is shown that the limit distribution of the statistic can be representable as the integral of a Brownian bridge. Also, the power comparison to the other procedure is performed.  相似文献   
295.
The proportional hazards model is the most commonly used model in regression analysis of failure time data and has been discussed by many authors under various situations (Kalbfleisch & Prentice, 2002. The Statistical Analysis of Failure Time Data, Wiley, New York). This paper considers the fitting of the model to current status data when there exist competing risks, which often occurs in, for example, medical studies. The maximum likelihood estimates of the unknown parameters are derived and their consistency and convergence rate are established. Also we show that the estimates of regression coefficients are efficient and have asymptotically normal distributions. Simulation studies are conducted to assess the finite sample properties of the estimates and an illustrative example is provided. The Canadian Journal of Statistics © 2009 Statistical Society of Canada  相似文献   
296.
“科学主义”概念主要指仿照自然科学的程序来构建理论。结构现实主义在理论构建过程中表现出了强烈的科学主义倾向,尤其体现在其研究假设中。沃尔兹的科学主义倾向存在一定的局限性,但总体而言,其理论还是较好地满足了科学主义的要求,这种构建理论的方式有着重大意义,它对整个西方国际关系理论的发展都具有深远影响。  相似文献   
297.
This paper introduces a counterfactual technique to estimate net emigration from Norwegian birth cohorts from 1846 to 1900. A main finding is that despite strong fluctuations in annual emigration, the percentage reduction of each cohort due to emigration was surprisingly stable for all cohorts from 1846 to 1886, with net emigration of about 30% for males and about 20% for females. Estimating an econometric model of annual male gross emigration by single years of age 15–60 in the period 1870–1914, we find that previous net emigration from a cohort reduces later gross emigration from the same cohort. The estimations also give some justification for attributing this to selectivity of emigration, in the sense that only a certain proportion of each cohort were potential migrants. Received: 1 October 1997/Accepted: 23 March 2000  相似文献   
298.
Early twentieth century observers argued that recent American immigrants were inferior, and in particular less skilled, than the old. I estimate wage equations for 1909 allowing for different effects by nationality and for different characteristics on arrival. I then apply the estimated wage differentials to the immigrant composition to measure the effect of changing composition on immigrant earnings. Finally I ask how immigrant earning power changed relative to that of native Americans. I conclude that immigrant “quality” in terms of earnings did decline due to shifting composition but these effects are very small compared with those reported in studies of the post-second World War period. Received: 1 September 1997/Accepted: 6 June 1998  相似文献   
299.
We investigate the asymptotic behavior of a nonparametric M-estimator of a regression function for stationary dependent processes, where the explanatory variables take values in some abstract functional space. Under some regularity conditions, we give the weak and strong consistency of the estimator as well as its asymptotic normality. We also give two examples of functional processes that satisfy the mixing conditions assumed in this paper. Furthermore, a simulated example is presented to examine the finite sample performance of the proposed estimator.  相似文献   
300.
Tree‐based methods are frequently used in studies with censored survival time. Their structure and ease of interpretability make them useful to identify prognostic factors and to predict conditional survival probabilities given an individual's covariates. The existing methods are tailor‐made to deal with a survival time variable that is measured continuously. However, survival variables measured on a discrete scale are often encountered in practice. The authors propose a new tree construction method specifically adapted to such discrete‐time survival variables. The splitting procedure can be seen as an extension, to the case of right‐censored data, of the entropy criterion for a categorical outcome. The selection of the final tree is made through a pruning algorithm combined with a bootstrap correction. The authors also present a simple way of potentially improving the predictive performance of a single tree through bagging. A simulation study shows that single trees and bagged‐trees perform well compared to a parametric model. A real data example investigating the usefulness of personality dimensions in predicting early onset of cigarette smoking is presented. The Canadian Journal of Statistics 37: 17‐32; 2009 © 2009 Statistical Society of Canada  相似文献   
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