英汉语篇粘连手段差异及其对中国学生英文写作的影响

英汉语篇粘连手段存在着诸多的差异,本文从词汇手段、语法手段和结构手段三方面对英汉语篇粘连手段的异同进行分析,旨在找出造成中国学生英语写作欠连贯的原因,并指出在写作教学中可以尝试通过语言对比教学等来帮助学生提高英语写作水平。     

关于农业结构调整和区域布局问题的理论和方法

加入WTO ,农业的发展面临全新的国际环境 ,如何进行农业结构调整使地区布局更加合理 ,是我国当前农业发展过程中一个亟待解决的问题。本文从区域分工、技术要素与产品周期等理论和定性、定量方法两个方面对农业结构调整和区域布局问题做较全面的综述     

Multilevel models for longitudinal data

Summary.  Repeated measures and repeated events data have a hierarchical structure which can be analysed by using multilevel models. A growth curve model is an example of a multilevel random-coefficients model, whereas a discrete time event history model for recurrent events can be fitted as a multilevel logistic regression model. The paper describes extensions to the basic growth curve model to handle auto-correlated residuals, multiple-indicator latent variables and correlated growth processes, and event history models for correlated event processes. The multilevel approach to the analysis of repeated measures data is contrasted with structural equation modelling. The methods are illustrated in analyses of children's growth, changes in social and political attitudes, and the interrelationship between partnership transitions and childbearing.     

‘Wallbanking’, innovativeness and computer attitudes: 25–40-year-old ATM-users on the spot

Attitudes towards ‘wallbanking’ (making use of banking services through an Automated Teller Machine (ATM)) and self-reported frequency of wallbanking have been related to attitudes towards innovations and towards computers. The investigation also included the perception of advantages as well as disadvantages of wallbanking, factors that determine one's choice of a bank, man-machine problems related to the use of an ATM, and demographic factors. Using a sample of 201 respondents in the age range of 25 to 40 years, structural equation modeling revealed that wallbanking attitudes have a major influence on the frequency of using ATMs. The innovativeness attitude ‘New is wasteful’ also showed a clear negative link with the frequency of wallbanking. On the other hand, the relationship between computer attitudes and the frequency of using ATMs had to be rejected. Income and education proved to have an indirect link with the frequency of wallbanking, which refines other research findings. These results may reflect specific financial management characteristics of the age group under investigation.     

二乙酸甲胺磷合锰的合成研究

甲胺磷是一种广谱性有机磷杀虫剂，甲胺磷的金属配位化合物具有生物活性、作为农药缓释剂，本文研究了二乙酸甲胺磷合锰配位化合物的合成方法、分子的组成、磁性、电子自旋、配合物的成键情况等．     

The Effect of Veteran Status on Mortality among Older Americans and its Pathways

This research examines excess mortality among American veterans age 70 years or older during a two-to-three year interval from 1993/94 to the end of 1995. Using a structural hazard rate model, we analyzed data on a sample of respondents age 70 or over from the Survey of Asset and Health Dynamics among the Oldest Old (AHEAD). We found that at age 70, older veterans have a slightly higher death rate than their nonveteran counterparts, implying a mortality crossover right before this age. Such excess mortality among veterans increases considerably with age, when other factors are held equal. The direct and indirect effects of veteran status on mortality by means of physical and mental health mostly perform in opposite directions, and such effects vary greatly in magnitude and direction as a function of age. The intervening effects of physical and mental health status decrease substantially with increasing age. Many of the mechanisms inherent in the excess mortality among older veterans are not captured by variations in their health status, especially among the oldest-old. A more extensive study on this topic is urgently needed.     

Structural probability bounds for the strong Pareto law

By using the structural density function (Fraser 1979, Ch. 7) of the parameters of a Pareto distribution, the structural distribution function of the strong Pareto law is derived. Its fractiles have been evaluated numerically for special cases, and the results are displayed through graphs from which structural one-sided probability bounds may be found. It is shown that these graphs may also be used to find structural tolerance bounds for the Pareto distribution.     

Smoothing Time Series with Local Polynomial Regression on Time

Time series smoothers estimate the level of a time series at time t as its conditional expectation given present, past and future observations, with the smoothed value depending on the estimated time series model. Alternatively, local polynomial regressions on time can be used to estimate the level, with the implied smoothed value depending on the weight function and the bandwidth in the local linear least squares fit. In this article we compare the two smoothing approaches and describe their similarities. Through simulations, we assess the increase in the mean square error that results when approximating the estimated optimal time series smoother with the local regression estimate of the level.     

Testing for abrupt breaks in variance structures with smooth changes

Abstract

We investigate the problem of testing for variance breaks in the case where the variance structure is assumed to be smoothly time-varying under the null. Since the classical tests are aimed to detect any change in the variance, they are not able to distinguish between smooth non constant variance and abrupt breaks. In this paper a new procedure for detecting variance breaks taking into account for smooth changes in the variance under the null is proposed. The finite sample properties of the test we introduce are investigated by Monte Carlo experiments. The theoretical outputs are illustrated using U.S. macroeconomic data.