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11.
    
We consider a firm's production and sales decisions for an age-based product whose value increases with ageing (e.g., whisky, wine, and cheese). The firm has been selling a younger-aged product but is considering introducing a new product by setting some of its production aside to age longer (in the “maturation” process). With a fixed production capacity dictated by the “distilling” process that takes place before the maturation process, the firm needs to decide if and when to sell different aged products as partial substitutes. Specifically, the firm must decide, period by period, how much, if any, of its younger-aged product to set aside for additional ageing. Because the younger product has been selling for some time, the firm knows its market size. For the new product, we consider two scenarios in which the market size is either: (1) known (deterministic) or (2) not yet fully known (stochastic). For the deterministic market size scenario, we provide an analytic solution to the infinite horizon problem and show that the optimal fraction of production reserved for additional ageing increases and converges to a steady-state solution with a closed-form expression. Though our model is dynamic, we show that a static policy, which is easy to compute and is intuitively appealing, performs quite well. For the stochastic market size scenario, we show that a “certainty equivalence” policy is optimal under reasonable conditions, and near-optimal when these conditions do not hold. Hence the stochastic problem is effectively equivalent to the deterministic market size case. We also examine the case when the production process is subject to a deterministic yield loss and obtain similar structural results.  相似文献   
12.
    
In this study, we examine whether it is optimal to use electric vehicles (EVs) in the car sharing market and investigate the environmental impact of pulling the EVs from the market. We develop a model consisting of a profit‐maximizing car sharing company (CSC) and a population of utility‐maximizing customers. The CSC sets the number of EVs, the number of fuel vehicles (FVs), and the rental price jointly to maximize its profit. Customers decide whether to use EVs, FVs, or public transportation to complete their trips considering the rental price. We show that it is optimal to use EVs only if the charging speed, the number of charging stations, and the range of EVs are high enough. Among these three conditions, the recharging speed is the most important and the number of charging stations is more important than the range of EVs. We also find that including EVs in the car sharing market may lead to a higher total emission when ignoring customers’ other transportation choices (due to a lower rental price that results in a higher usage rate). Moreover, we consider the problem with the objective of maximizing the social welfare and find that when considering the environmental impact, governments should tax the CSC to induce a higher rental price and when ignoring this impact, they should subsidize the CSC to reduce the rental price. We demonstrate our results with the case study of Car2go. These results are in line with that the slow recharging speed may have been one of the contributing factors to that Car2go replaced EVs with FVs in San Diego.  相似文献   
13.
  总被引:1,自引:0,他引:1  
School grades, family demographics and responses to the parental authority questionnaire were assessed in 240 eighth‐grade students in the southern, central and northern parts of Tehran, Iran's capital. The result showed that poorer families with traditional values had more authoritarian attitudes toward parenting than richer families with more modern values. In contrast to the studies conducted in East Asian societies, the current study found that authoritative parenting was the style associated with the highest academic outcome. Tests of mediation and moderation effects showed that the relation between parenting style and academic outcome was independent of sociocultural context.  相似文献   
14.
    
Given the historical development of land tenure in South Africa, the aim of this article is to examine the best routes to alleviate poverty and retain sustainable agriculture in the country. First, a theoretical framework is presented that relates land tenure to sustainability, and three historical periods (pre‐colonial, colonial, and apartheid) are then considered to explain the changes in land tenure and their consequences. The progress and main limitations of post‐apartheid land reform to approach agricultural sustainability and alleviate poverty are discussed. Based on the analysis, different possibilities for future land reform are elaborated, followed by some recommendations for future land‐reform policies in South Africa.  相似文献   
15.
    
Abstract

Since 11 September 2001 Muslim Diasporas have emerged as objects of anxiety in Western societies. Underlying this (in)security-driven problematisation is the question of whether Muslims living in the West have the capacity to become fully active citizens while maintaining their religious beliefs, rituals and practices. This apprehension has prompted reactionary government programmes, particularly targeting young Muslims. Such responses fail to recognise the societal capacities that practising Muslims possess, including those informed by the ethical precepts of Islamic faith. This paper argues that it is timely to explore expressions of Islamic religiosity as they are grounded in everyday multicultural environments. The paper draws on survey data and interviews conducted with Muslims living in Melbourne, Australia. We take into consideration key variables of age and generation to highlight how young, practising Muslims enact citizenship through Islamic rituals and faith-based practices and traditions. The paper will draw from key findings to argue that these performances provide a foundation for exploring ways of ‘living’ together in a manner that privileges ethics central to Islamic faith traditions.  相似文献   
16.
    
While there has been considerable research on the analysis of extreme values and outliers by using heavy-tailed distributions, little is known about the semi-heavy-tailed behaviors of data when there are a few suspicious outliers. To address the situation where data are skewed possessing semi-heavy tails, we introduce two new skewed distribution families of the hyperbolic secant with exciting properties. We extend the semi-heavy-tailedness property of data to a linear regression model. In particular, we investigate the asymptotic properties of the ML estimators of the regression parameters when the error term has a semi-heavy-tailed distribution. We conduct simulation studies comparing the ML estimators of the regression parameters under various assumptions for the distribution of the error term. We also provide three real examples to show the priority of the semi-heavy-tailedness of the error term comparing to heavy-tailedness. Online supplementary materials for this article are available. All the new proposed models in this work are implemented by the shs R package, which can be found on the GitHub webpage.  相似文献   
17.
Abstract

The transmuted-G model is a useful technique to construct some new distributions by adding a parameter. This paper considers stochastic comparisons in the transmuted-G family with different parameters and different baseline distributions in the sense of the usual stochastic, shifted stochastic, proportional stochastic and shifted proportional stochastic orders. Also, we present a necessary and sufficient condition for existence of the moments of the transmuted-G model and then we obtain some bounds for the survival and aging intensity functions of the transmuted-G model conditioned on its parameter and its baseline distribution.  相似文献   
18.
We know that when currencies are perfect substitutes, exchange rates could become indeterminate. We show that even when currencies are less than perfect substitutes exchange rates could display volatility unrelated to economic fundamentals. With increases in currency substitution: (1) the exchange rate becomes more sensitive to changes in economic fundamentals, increasing its volatility; (2) the exchange rate could become indeterminate, and it is more likely to become so if governments pursue similar monetary policies; (3) currencies with high nominal interest rates would decline significantly and the exchange rate becomes more sensitive to changes in the supply of those currencies.  相似文献   
19.
This paper employs a multidimensional index for assessing women’s well-being in Iranian provinces using demographic and health survey macro data. Besides economic status as a traditional dimension for objective well-being, other factors such as health, education, risk, and technology as well as self-reported life satisfaction and happiness (psychological well-being) have been included as non-material well-being dimensions. We found that the values of women’s well-being are distributed unequally across the provinces. Southern provinces demonstrate the worst performances and central provinces have the best. Generally, Iranian women are in poor condition in terms of economic variables (e.g. income and participation in the job market), psychological well-being (life satisfaction), HIV literacy, use of the internet, and access to mass media. On the other hand, in recent years, they have made significant progress in education (such as the rate of literacy, high school degree), and health (safe pregnancy care and nutritional supplements).  相似文献   
20.
In spatial statistics, models are often constructed based on some common, but possible restrictive assumptions for the underlying spatial process, including Gaussianity as well as stationarity and isotropy. However, these assumptions are frequently violated in applied problems. In order to simultaneously handle skewness and non-homogeneity (i.e., non-stationarity and anisotropy), we develop the fixed rank kriging model through the use of skew-normal distribution for its non-spatial latent variables. Our approach to spatial modeling is easy to implement and also provides a great flexibility in adjusting to skewed and large datasets with heterogeneous correlation structures. We adopt a Bayesian framework for our analysis, and describe a simple MCMC algorithm for sampling from the posterior distribution of the model parameters and performing spatial prediction. Through a simulation study, we demonstrate that the proposed model could detect departures from normality and, for illustration, we analyze a synthetic dataset of CO\(_2\) measurements. Finally, to deal with multivariate spatial data showing some degree of skewness, a multivariate extension of the model is also provided.  相似文献   
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