First hitting probabilities for semi-Markov chains and estimation

We first consider a stochastic system described by an absorbing semi-Markov chain (SMC) with finite state space, and we introduce the absorption probability to a class of recurrent states. Afterwards, we study the first hitting probability to a subset of states for an irreducible SMC. In the latter case, a non-parametric estimator for the first hitting probability is proposed and the asymptotic properties of strong consistency and asymptotic normality are proven. Finally, a numerical application on a five-state system is presented to illustrate the performance of this estimator.     

论技术使用的三种情境

技术使用的情境实际上是人类使用者通过技术的使用所建构出来的一个实践语境和社会境域。随着使用者主要使用的技术所展现出来的不同历史形态,技术使用也展现出三种面貌的情境———经验型技术使用情境、实体型技术使用情境以及知识型技术使用情境。     

论地区教学资源在高校“中国近现代史纲要”教学中的挖掘和利用——以四川凉山民族地区为例

充分挖掘和利用地区教学资源并运用于高校＂中国近现代史纲要＂课程教学,是增强教学实效性的重要途径。四川凉山彝族地区＂一步跨千年＂的社会变迁历史、红军长征过凉山的历史、独特的民族文化等丰富全面的社会实践教学资源,是增强大学生＂三个选择＂政治认同的优质教学素材。充分挖掘、整合这些优质教学资源,探索对其利用的有效形式,对增强＂纲要＂课程教学实效性能起较好作用。     

螯合树脂富集—AAS测定水中六价铬、总铬的研究

树脂富集——AAS法对水中六价铬、总铬的测定消除了二苯碳酰二肼分光光度法的测定干扰和化学试剂不稳定的问题,称取2.5g干重树脂装填充到　ф8×70mm离子交换树脂柱内,用1.5mol/L　HNO3洗脱后直接进入原子吸收光谱仪测定,方法的检出限0.002mg/L,精密度 RSD小于3%,操作简便,易于推广。     

Parents' time use: A 1967–1986 comparison

The purpose of this article is to report the different time allocations of parents with an infant in 1967 and in 1986 in order to observe changes in household production, childcare, and total obligatory activities. The sample is a subset of 84 families from a 1967 study of two-parent families and from 108 families from a study of first-time parents in 1986.Multivariate analysis of covariance is used to indicate the effects of variables such as age, education, and employment of the parents as well as appropriate interaction terms before allowing the factor of sample year to allow for variance. The effect for sample year then is adjusted for other variables in the sample. Significant differences in time use, all other variables held constant, are observed in mothers' time in childcare, in household production, and in total obligatory activities. Fathers' time in childcare and in total obligatory activities significantly increase. Implications for family well-being are drawn.     

分词在科技英语中的用法

本文着重讨论了分词在科技英语中的各种用法 ,为科技知识的普及和科技文章的写作提供了一定的依据     

Children's Influence on Internet Access at Home: Adoption and use in the family context

In this study, an integrated quantitative and qualitative research design was employed. From over 900 telephone interviews a typology of family types based on possession of media appliances was constructed, then divided into 'traditional' (low media density), 'intermediate' (average media density) and 'multimedia' (high media density) families. This typology was then used as a basis for selecting thirty-eight families for in-depth interviews. Of these, thirty-one contained children and it is these that form the basis for this article. The results of the family interviews indicate that children are a very important factor in the acquisition and use of the Internet. It was apparent from our interviews that Internet access and use become major issues in family discussions and conflicts - both between parents and children and between siblings.     

《诗经》与《左传》意动用法之比较

本文主要从主观意念的表达法、意动用法及其特点三个方面进行比较 ,阐明《诗经》与《左传》在这方面的同异 ,并说明意动用法在较早的史料中并不多见。     

行业报采编人员利用网络寻找“信息源”的方式

行业报注重信息资源整合和关注新闻“第二落点”的特点为其采编人员利用网络媒体寻找、挖掘信息提供了可能。本文从专业网站、网络专题、社区和论坛几个方面论述了行业报记者利用网络寻找信息源的方法。     

Some Problems in Forecasting Population for Government Planning Purposes

Some governments rely on centralized, official sets of population forecasts for planning capital facilities. But the nature of population forecasting, as well as the milieu of government forecasting in general, can lead to the creation of extrapolative forecasts not well suited to long-range planning. This report discusses these matters, and suggests that custom-made forecasts and the use of forecast guidelines and a review process stressing forecast assumption justification may be a more realistic basis for planning individual facilities than general-purpose, official forecasts.