改进的沾滴法测量缓蚀剂预膜厚度

分析了传统沾滴法测量预膜厚度存在的问题,对原有的方法进行了改进,使用自制实验装置采用改进后的沾滴评价法测试分析了不同材质、不同管径管件的平均预膜厚度。结果表明,不同材质的管材表面吸附能力不同,导致管件平均预膜厚度相差较大,其中铜管的平均预膜厚度最大(0.05mm左右),碳钢管的平均预膜厚度最小(0.013mm左右);而管径对管件平均预膜厚度的影响很小。实验所得结果与同位素示踪法测定膜厚结果较吻合,从而说明改进后的沾滴评价法是一种室内评价管件平均预膜厚度的有效方法。     

近十年陕北耕地资源变化与粮食安全分析

该文以包括榆林市和延安市的陕北地区为研究对象,对陕北地区1996～2006年耕地动态变化与粮食生产情况进行分析研究。选择最小人均耕地面积和压力指数模型法,在分析陕北地区1996～2006年间耕地、人口、粮食动态变化的基础上,总结了该区域最小人均耕地面积和耕地压力的变化特点:陕北地区最小人均耕地面积的平均值是0.219hm2,耕地压力指数的平均值K是1.389。K值远大于1,因此耕地压力较大。在以上基础上提出了保障陕北地区耕地动态平衡与粮食安全生产的一些建议。     

Back to literacy

One of the seminal works in the development of British cultural studies was Richard Hoggart's The Uses of Literacy , in which he presents a vision of working class communities in the 40 years since the First World War. To do this he drew particularly on his experiences of Hunslet in South Leeds. In this paper we revisit South Leeds 40 years on to examine continuities and changes in the community as evidenced through people's leisure and compare this with Hoggart's analysis. To do this we have drawn on census and other official statistics and our own observation and interviews in the field. In order to interpret today's communities in South Leeds we make use of theoretical developments in the interim. We suggest that in what Bauman (1997) refers to as ‘two nations society mark two’ people try to reinvent community and it is through leisure in particular that this is evidenced. We therefore conclude that any attempt to understand ‘community’ at the millennium must place leisure centre stage.     

Development Regimes in the City Fringe: The Case of Discover Islington,London

There is a growing recognition of the importance of inter-organisational collaborations, or partnerships, for tourism development at various geographical and sectoral levels. Academic studies of the phenomenon are, in part, a reflection of the increasing number and forms of partnership arrangements being established in a range of settings to develop tourism. This paper examines a particular case of inter-organisational collaboration for local tourism development for the London inner city fringe. Established in 1991, Discover Islington provides an illustration of an agency involving representation from diverse stakeholders with an interest in tourism within a single administrative district. The agency has been innovative in its approach to local tourism development in the inner city fringe, but it is confronted by issues that may affect its longer-term viability. The perspectives and experiences of the partners represented on the Board of Discover Islington are pertinent to the study of comparable collaborative arrangements for local tourism development in other urban fringe contexts. The analysis is based on interviews with Board members and their policy and strategy documents within a theoretical framework that draws on regime theory. Implications for other inner city fringe tourism development partnerships are offered in the conclusion of this paper.     

Using proxies for the short rate: when are three months like an instant?

The dynamics of the unobservable short rate are frequently estimateddirectly using a proxy. We examine the biases resulting fromthis practice (the 'proxy problem'). Analytic results show thatthe proxy problem is not economically significant for single-factoraffine models. In the two-factor affine model of Longstaff andSchwartz (1992), the proxy problem is only economically significantfor pricing discount bonds with maturities of more than fiveyears. We also describe two different numerical procedures forassessing the magnitude of the proxy problem in a general interestrate model. When applied to a nonlinear single-factor model,they suggest that the proxy problem can be economically significant.     

大学生应确立终身体育意识

培养终身体育意识和能力,是我国学校体育发展的最终目标。本文从大学生终身体育意识的确立与人的发展;体育兴趣对终身体育意识的形成;高校体育与终身体育发展等多种因素,提出了:宣传体育时尚培养体育兴趣;大学生体育消费意识;从需要的角度出发确立教材内容,逐步建立终身体育教育体系的基本发展对策。     

资源型城市土地资源与矿产资源冲突问题分析

我国资源型城市的发展遇到难题,破解这一难题是当前的重大任务.引起资源型城市发展困难的一个原因就是土地资源与矿产资源的冲突.因此,资源对土地的补偿是恢复土地生产力和资源型城市发展的一个重要方面.在对资源开发的同时,应对土地的破坏作出必要适当的补偿.     

不完全合同理论视角下渐进性创新的逆向研发外包组织模式、技术溢出与创新能力研究

既有研发外包组织理论主要基于技术优势企业视角,关注如何治理技术溢出等交易成本,忽视了缺少专利和隐性知识的企业进行渐进性创新时最优研发外包组织选择。基于不完全合同视角,从企业对研发中激励代理方努力与降低渐进性创新的不完全替代性成本之间的权衡出发,分析委托方如何合作、并购、委托以及新建研发等组织最优选择。结果表明,当委托方技术水平较低时,最优组织将需要给代理方更多控制权以激励其努力,相反,委托方则保留更多控制权以降低不完全替代性成本。委托方市场规模通过影响代理方的私人收益降低不完全替代性成本,使得委托方愿意放弃控制权以激励代理方努力。新建研发可以看作是委托方通过承担更多时间和风险成本,从而降低不完全替代性成本。在不同组织形式中,委托方对研发投入的积极性是不同的,这决定了委托方通过研发外包获得的技术溢出效应和企业创新能力。