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   238篇
  免费   11篇
管理学   31篇
民族学   2篇
人口学   16篇
理论方法论   17篇
综合类   2篇
社会学   120篇
统计学   61篇
  2023年   2篇
  2022年   3篇
  2021年   5篇
  2020年   6篇
  2019年   21篇
  2018年   17篇
  2017年   20篇
  2016年   14篇
  2015年   6篇
  2014年   9篇
  2013年   31篇
  2012年   48篇
  2011年   7篇
  2010年   7篇
  2009年   10篇
  2008年   4篇
  2007年   6篇
  2006年   7篇
  2005年   1篇
  2004年   4篇
  2003年   1篇
  2002年   4篇
  2001年   1篇
  1999年   2篇
  1998年   1篇
  1996年   4篇
  1995年   2篇
  1993年   1篇
  1991年   2篇
  1980年   1篇
  1978年   1篇
  1975年   1篇
排序方式: 共有249条查询结果,搜索用时 31 毫秒
91.
Over the last few decades radio has becomeone of the primary means of mass communication in Latin America, able to reach euen the remotest rural populations because of the transistor. Colombia, where ninety-one percent of the homes in the seven largest cities have at least one radio, has also been heavily impacted by this modern technological phenomenon, Elssy Bonilla de Ramos focuses on radio advertising as a means of characterizing the relationship between radio and the Colombian economic sector. She argues that private companies who own most of the country's stations and networks influence programming and advertising in order to widely promote products which they produce. She believes that in many cases these products are not necessary to the consumers'well-being but are advertised in a way to make them more desirable. The authorgives a brief history of commercial radio in Colombia during the last fifty years, stating that early in its development programming underwent significant changes in order to capture an expanded audience. Comedy, sports, news, soap operas, classical and popular music, and quiz shows soon dominated the airways to the exclusion of programming that could play a role in the political, social and economic development of the country. She contends that industries that owned radio were intent on training for consumption and she uses a week's sample of programming and advertising to illustrate her point.  相似文献   
92.
In this study, we present findings of the Portuguese national prevalence study, “Aging and Violence,” the purpose of which was to estimate the prevalence of abuse and neglect of older people in family settings over a 12-month period and examine the relationship between abuse and sociodemographic and health characteristics. Through a telephone survey of a representative probability sample (N = 1,123), we evaluated 12 abusive behaviors and demographic data. Overall, 12.3% of older adults experienced elder abuse in family settings. The prevalence rates of specific types were as follows: psychological, 6.3%; financial, 6.3%; physical, 2.3%; neglect, 0.4%; and sexual, 0.2%. Logistic regression was employed to determine the relationship between abuse and covariates. The study suggests that education level, age, and functional status are significantly associated with abuse. Accurate estimates of the prevalence of elder abuse and understanding of victim and perpetrator characteristics are fundamental to designing effective strategies for prevention and intervention.  相似文献   
93.
This paper presents a new Metropolis-adjusted Langevin algorithm (MALA) that uses convex analysis to simulate efficiently from high-dimensional densities that are log-concave, a class of probability distributions that is widely used in modern high-dimensional statistics and data analysis. The method is based on a new first-order approximation for Langevin diffusions that exploits log-concavity to construct Markov chains with favourable convergence properties. This approximation is closely related to Moreau–Yoshida regularisations for convex functions and uses proximity mappings instead of gradient mappings to approximate the continuous-time process. The proposed method complements existing MALA methods in two ways. First, the method is shown to have very robust stability properties and to converge geometrically for many target densities for which other MALA are not geometric, or only if the step size is sufficiently small. Second, the method can be applied to high-dimensional target densities that are not continuously differentiable, a class of distributions that is increasingly used in image processing and machine learning and that is beyond the scope of existing MALA and HMC algorithms. To use this method it is necessary to compute or to approximate efficiently the proximity mappings of the logarithm of the target density. For several popular models, including many Bayesian models used in modern signal and image processing and machine learning, this can be achieved with convex optimisation algorithms and with approximations based on proximal splitting techniques, which can be implemented in parallel. The proposed method is demonstrated on two challenging high-dimensional and non-differentiable models related to image resolution enhancement and low-rank matrix estimation that are not well addressed by existing MCMC methodology.  相似文献   
94.
Companies are currently choosing to integrate logics and systems to achieve better solutions. These combinations also include companies striving to join the logic of material requirement planning (MRP) system with the systems of lean production. The purpose of this article was to design an MRP as part of the implementation of an enterprise resource planning (ERP) in a company that produces agricultural implements, which has used the lean production system since 1998. This proposal is based on the innovation theory, theory networks, lean production systems, ERP systems and the hybrid production systems, which use both components and MRP systems, as concepts of lean production systems. The analytical approach of innovation networks enables verification of the links and relationships among the companies and departments of the same corporation. The analysis begins with the MRP implementation project carried out in a Brazilian metallurgical company and follows through the operationalisation of the MRP project, until its production stabilisation. The main point is that the MRP system should help the company's operations with regard to its effective agility to respond in time to demand fluctuations, facilitating the creation process and controlling the branch offices in other countries that use components produced in the matrix, hence ensuring more accurate estimates of stockpiles. Consequently, it presents the enterprise knowledge development organisational modelling methodology in order to represent further models (goals, actors and resources, business rules, business process and concepts) that should be included in this MRP implementation process for the new configuration of the production system.  相似文献   
95.
In this article, we establish strong consistency of the ridge estimates using extended results for the strong consistency of the least squares estimates in multiple regression models which discard the usual assumption of null mean value for the errors and only requires them to be i.i.d. with absolute moment of order r (0 < r ? 1).  相似文献   
96.
Some bootstrap and boosting methods for problems related to classification are introduced in this article. The first method chooses better boosting weights by using a bootstrap search algorithm. The second method is a good way to define a classification frontier. A new formulation for boosting in linear discriminant analysis is given. Since in this new formulation the uncertainty is represented by the weighted covariance matrix, it is more appropriate from the conceptual point of view. Simulation results show that the proposed methods perform well in data analysis.  相似文献   
97.
The construction of some wider families of continuous distributions obtained recently has attracted applied statisticians due to the analytical facilities available for easy computation of special functions in programming software. We study some general mathematical properties of the log-gamma-generated (LGG) family defined by Amini, MirMostafaee, and Ahmadi (2014 Amini, M., S. M. T. K. MirMostafaee, and J. Ahmadi. 2014. Log-gamma-generated families of distributions. Statistics 48:91332.[Taylor &; Francis Online], [Web of Science ®] [Google Scholar]). It generalizes the gamma-generated class pioneered by Risti? and Balakrishnan (2012 Risti?, M. M., and N. Balakrishnan. 2012. The gamma exponentiated exponential distribution. Journal of Statistical Computation and Simulation 82:1191206.[Taylor &; Francis Online], [Web of Science ®] [Google Scholar]). We present some of its special models and derive explicit expressions for the ordinary and incomplete moments, generating and quantile functions, mean deviations, Bonferroni and Lorenz curves, Shannon entropy, Rényi entropy, reliability, and order statistics. Models in this family are compared with nested and non nested models. Further, we propose and study a new LGG family regression model. We demonstrate that the new regression model can be applied to censored data since it represents a parametric family of models and therefore can be used more effectively in the analysis of survival data. We prove that the proposed models can provide consistently better fits in some applications to real data sets.  相似文献   
98.
This paper investigates the relationship between country-risks (or conflicts) within countries and electricity production. The determinants of electricity production have been neglected in the literature that favours the relationship between energy consumption, growth and development, and despite of the major challenges on electricity supply systems. We empirically establish that weighted conflict index, as well as sub-items as anti-government demonstrations, government crises and riots negatively influence electricity production per capita, after controlling for income per capita. Country conflicts affect electricity production mostly in the long-run. Our results imply that conflicts may affect electricity production substantially and consequently the economy as a whole. Policy should emphasize the institutional framework to avoid conflicts within countries in order to secure electricity production.  相似文献   
99.
Social touch is essential for physical and emotional well-being. However, different meanings can be attributed to physical contact during social interactions and may generate bonding or avoidant behaviors. This personal and unique experience is not usually taken into account in health and social care services. The aim of this study is to produce a valid and reliable European Portuguese version of the Social Touch Questionnaire (STQ, Wilhelm et al. in Biol Psychol 58:181–202, 2001. doi: 10.1016/S0301-0511(01)00113-2). The STQ is a self-report questionnaire for adolescents and adults measuring behaviors and attitudes towards social touch. The original version was translated into European Portuguese using a forward-back translation process and its feasibility was examined. To evaluate the psychometric properties, a total of 242 Portuguese university students participated in the study (21.3 ± 3.8 years). The STQ was considered feasible, showed adequate internal consistency (Cronbach’s α = .734), and the test–retest correlation with the STQ items demonstrated a high concordance between the tests over a two-week interval (ICC = .990; n = 50). Validity tests were performed, comparing the total score of the STQ with that of the anxiety and avoidance subscales of the Social Interaction and Performance Anxiety and Avoidance Scale (SIPAAS). A very significant conceptual convergence was confirmed between the STQ and with the SIPAAS-Anxiety (r = .64; p < .0001) and with the SIPAAS-Avoidance (r = .59; p < .0001). The exploratory factor analysis, with Promax rotation, revealed 3 factors: dislike of physical touch, liking of familiar physical touch and liking of public physical touch (Cronbach’s alphas ranged from .68 to .75). Psychometric properties confirmed the adaptation of the STQ to the Portuguese culture. It is a reliable and valid self-report questionnaire and it appears to be a useful tool to assess behaviors and attitudes towards social touch.  相似文献   
100.
Adolescence is a relevant life stage in which to study a global well-being measure, health-related quality of life, in order to analyse the impact of important determinants in adolescents' health-related quality of life (e.g., the quality of family relationships). This study aimed to examine the impact of several family dimensions (parental affection, parental promotion of autonomy, family activities, adolescent disclosure, parental solicitation and parental knowledge) on adolescents' health-related quality of life. Additionally, this study investigated whether demographic variables (adolescents' gender and age) influenced health-related quality of life and moderated the relationship between family dimensions and health-related quality of life. The sample was composed of 14,825 adolescents, aged 13–14, 15–16, and 17–18, from the 2006 edition of Spain's Health Behaviour in School-aged Children study. The results showed that parental promotion of autonomy, family activities and especially parental affection were the most important dimensions influencing health-related quality of life. Boys reported higher health-related quality of life than girls, and younger adolescents reported higher health-related quality of life than older adolescents. The discussion explains how the aforementioned family dimensions encourage better health-related quality of life in adolescents.  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