空穴是一种粒子

空穴是本征激发或受主杂质激发时存在于半导体晶体内的一种粒子,它具有与正电子相同的有效质量、电荷量和动量。在一定条件下,它可以和电子组成气体及液体浮动于固态半导体内。     

隧道温室效应产生及防治

超长隧道内由于通风设备限制，必然会留下一部分不可交换的空气，这些空气在大流量车辆交溶穿梭过程中，尾气污染、内燃机热量散发及不问断车流对隧道内空气切割产生的能量和隧道内照明热量等。在一段时间内及特定环境条件下的积累必然会产生被人忽视的“隧道温室效应”。“隧道温室效应”环境下的有害气体与其它环境条件下的有害气体不同，由于温室作用关系，它对不同体质驾驶人员在较短时间内会产生一定的生理影响，使人产生头昏、心慌、眼发黑及诱发其它疾病，降低驾驶人员的控制能力，从而引发隧道内交通事故。     

基于系统动力学的国家战略物资储备控制模型及应用

基于系统动力学原理和方法,在分析国家战略物资储备控制机理和各要素间的因果关系的基础上,建立了战略物资储备控制系统动力学仿真模型,利用VENSIM仿真平台对模型进行模拟,得出了在不同影响因素条件下的战略物资库控制的运行规律,分析了不同要素对战略物资储备控制的影响。     

"标准状况"与"标准状态"不能混用

在许多科技书报刊中 ,常出现把“标准状况”和“标准状态”两个不同的概念混为一谈的情况。甚至对这两个概念作随心所欲的解释 :把“标准状态”2 98 15Ｋ( 2 5℃ )和 10 1 32 5ｋＰａ条件 ,说成“标准状况” ;而把“标准状况”2 73 15Ｋ (即 0℃ )和 10 1 32 5ｋＰａ条件说成是“标准状态”。在科技领域常遇到气体方面的问题 ,而气体的体积又是随温度和压强的变化而变化的 ,因此 ,表示某气体的体积时 ,就必须说明该气体所处的温度和压力条件。为了便于比较不同气体的体积 ,规定 2 73 15Ｋ(即 0℃ )和 10 1 32 5ｋＰａ条件为“标准状况” ,并…     

档案缺氧保护方法简介

档案的许多退化过程，如颜料和染料的褪色、铁锈的产生、昆虫与霉菌的生长等，都与氧气有关。如果没有氧气，这些退化反应将不会发生。因此，为了预防或延缓档案的退化过程，必要时应对档案进行缺氧处理。早在二十世纪八十年代我国的档案保护工作就开始思考采用物理方法保护档案，如填充CO2或N2气体保护档案方法，其原理就是在装有档案的密封袋中充人一定浓度的CO2或N2气体，将空气中的O2气体排除，造成缺氧的环境。这种档案保护方法在原理上是正确的，但它有一定操作难度，如密封袋的气密性不理想，CO2和N2气体气源不能随时得到等。这些局限性致使缺氧保护档案的物理方法多年来难于在我国推广应用。     

电子文件与纸质档案保护差异

纸张的耐久性取决于纤维素的性质,尽管纤维素在一定的条件下:如高温、高湿、酸、酶、氧化剂等作用下,可发生水解和氧化反应,但只要我们在档案保护过程中,注意排除发生两大化学反应所需要的条件,就可以使纸质档案的寿命达到上百年甚至上千年.     

论民族文献的科学布局

由于我国55个少数民族的文献在一定的历史条件下产生于一定的自然范围 ,客观条件上限制了其与外部的交流 ,本文就如何在新的历史条件下最大程度地发挥它的作用 ,为我国西部大开发、为民族地区的经济发展服务做了初步的探讨 ,指出了它的必要性、重要性和可行性     

气体爆炸效果的计算机模拟仿真

协调、配合应用ＡＬＩＡＳ软件集成的粒子效果和相关功能模块能够创造出非常壮观的气体爆炸的动画效果（见本文首图）。本文仅涉及粒子和动力学参数和选项的设定。一、设定粒子发射源及参数和选项１、通过ｗｈｄｏｗｓ／Ｍｕｌｔｉ-ｌｉｓｔｅｒ／Ｅｄｉｔ／Ｎｅｗ　Ｌｉ?..     

论市场经济条件下的党报改革

<正>在计划经济条件下,党报基本上形成了"官办—官订—官看"的模式,人民群众自费订阅党报的极少。在社会主义市场经济条件下,党报"宣传舆论工具"的性质虽然没有变化,但它却在许多方面和过去有了不同,其中最显著的一点是:报纸的商品性大大增强了。所谓商品性,最基本的表现形式就是买卖关系。其实,报纸的商品性是早已有之的,长期以来所以没有引起我们的足够重视,这是计划经济条件下官办、官订的缘故。既然商品性是报纸基于市场经济条件下的显著特点,那么,它就为报纸改革提出了新的课题。     

洗澡水应去余氯

氯是一种黄绿色的气体,具有强烈的刺激性。氯气的作用很广,水厂常用液氯进行杀菌消毒。氯气吸入人体时能与呼吸道粘膜和肺泡表面的水分迅速反应,生成盐酸,对局部组织发生烧灼和刺激作用。严重     

Do you know where your information is in the homeland security era?

Why should we care about our information? As we enter the era of homeland security, one can see a new premium being placed on the role of information to fight terrorism while the policies related to government information practices are in a state of flux. Exactly how these policies are evolving is not always clear. Yet, the decisions being made now will likely have a lasting impact for years to come. In an attempt to better understand dynamics underlying these changes, a number of questions regarding the use, control, and protection of personal and public information are posed in this introduction to the symposium issue. We also review some of the major themes examined in greater detail by the contributors to the symposium. These issues include the role of e-government in homeland security, the emphasis on information sharing, the emergence of new information classification categories, the growth of data mining, and the eroding sense of privacy. While a number of reasons can be offered to justify one policy alternative over another, we conclude that the importance of these issues suggests that they are best debated and implemented during a time not under duress when decisions made in the heat of the moment can lead to unintended consequences.     

Palestinian media landscape: Experiences,narratives, and agendas of journalists under restrictions

This study aims to increase our understanding of the dynamics of the Palestinian media and the conditions and circumstances in which they work, including both the conflict with Israel and the internal political strife within Palestinian society. It is based on the use of qualitative research methods and was conducted in two stages. First, we performed a mapping of Palestinian media outlets. Data on these Palestinian media outlets were collected online from the West Bank-based Palestinian Authority’s Ministry of Information website, the Gaza-based Hamas government’s Ministry of Information website, and statements published by Palestinian media outlets on their websites describing their affiliation and ownership. Second, to gain a more in-depth understanding of the dynamics and experience of practicing journalism in a situation of asymmetrical conflict, semistructured in-depth interviews were conducted with 25 professional local Palestinian journalists working for local media outlets in the Gaza Strip, the West Bank, and East Jerusalem. Through this study we aim to learn more about how groups shape and express their narratives and agendas through the media when restricted by the conditions, pressures, and limitations of asymmetrical conflict.     

数字信息资源共享动力机制研究

数字信息资源共享动力机制,是指能够促使图书馆数字信息资源共享活动持续发展而形成的复杂的动力系统。它包括内部动力和外部动力两大要素。内部动力包括馆长、馆员要素;外部动力包括读者监督、图书馆评估、图书馆法、信息技术与标准、经费等要素。当前应建立并完善读者监督、图书馆评估、图书馆法等动力机制。图1。参考文献10。     

中国政府网“一带一路”新闻话题挖掘分析

[目的/意义]探究中国政府网"一带一路"相关新闻的话题内容及热度变化，呈现"一带一路"倡议主题及动态，明确不同时期的倡议重点，为相关研究提供参考。[方法/过程]构建基于LDA模型的新闻话题内容的基本框架，限定2015-2017年"一带一路"相关新闻数据，利用LDA模型进行话题抽取，根据文档与话题的概率分布计算，分析各主题在不同时间段的热度演化。[结果/结论]抽取得出30个细分话题，归纳为政策沟通、设施联通、贸易畅通、资金融通、民心相通、"一带一路"对我国经济的影响和政府工作7大类。其中，政策沟通类在全时间段上热度最高，贸易畅通和"一带一路"对我国经济的影响两类话题紧随其后。"进出口"等细分话题的热度不断上升，"改革与转型"等细分话题的热度则有下降，体现了官方媒体新闻内容及其关注度随时间而变化的特点。     

Transforming travel and border controls: Checkpoints in the Open Society

Prior concerns regarding terrorism resulted in a rush to legislate. Now terrorism is not the only issue in the new security agenda, and we appear to have stopped rushing our legislative processes. Yet, policies are still emerging with a lack of public discourse and legislative deliberation. This article reviews two such policies: access to personal information held by airlines and new border practices that include the collection and processing of biometrics. By looking at the negotiations between the U.S. and the European Commission on passenger name records (PNR), the debates in Canada regarding the collection of passenger information, and the deployment of the US-VISIT system, we identify a number of policy dynamics. We can see within these dynamics of policy formation some essential ingredients for discourse and deliberation, which may inform future debates. In particular, this article argues that we may inform policy by looking at the international, regulatory, legal, and technological dynamics of policy.     

全球新型抗生素专利技术及市场研究

新型抗生素是人类临床医疗中使用最广泛的一类药物,本文以新型抗生素药物专利分析和市场状况为主要切入点,通过对全球新型抗生素领域的专利申请趋势、区域分布、重要申请人、技术分布、上市和停研率以及研发热度进行研究,进而为我国政府部门及相关企业机构的研发提出相应的决策参考和对策建议。     

“二十一条”外交事件中袁世凯政府新闻策略及传播效果考察

国内学术界从传播的视角对袁世凯政府在二十一条外交事件中的反应及新闻策略在整个过程中的运用方面研究很少。本文拟对袁世凯政府二十一条密约从泄露到交涉时期的新闻与外交互动进行全面考察,从而认识袁世凯对新闻媒体和新闻舆论的操控与利用。     

Leadership and institutional design in collaborative government digitalisation: Evidence from Belgium,Denmark, Estonia,Germany, and the UK

Large-scale government digitalisation projects require collaborative approaches for their successful development and implementation. To shed light on these collaboration dynamics, the interplay between two integral parts of collaborative projects: the project rules, procedures, and structures (collectively known as institutional design) and the leaders managing these projects is studied. In doing so, the paper provides empirically grounded insights into the management of collaborative government digitalisation projects. Taking an institutional perspective, and the strategic-relational approach (SRA), we examine the extent to which institutional design constraints leadership behaviours, and under what conditions leaders begin to adjust and/or challenge these design features adding to the knowledge of managing digitalisation of government. To this end, we present a five-country case study of national digitalisation projects across Europe. Our results show that while clear institutional design features such as established rules, project structures, and standard operating procedures are essential at the initial stages of the projects, leaders' skills in understanding and tailoring these features are critical to handle project-related problems and moving forwards towards implementation. This underscores the importance of examining projects taking an SRA approach and the need to understand leadership behaviour in the context of the structures in which it is embedded.     

润湿反转技术在气液转换时稳定井壁机理研究

川西地区实施气体钻井过程中钻遇水层时被迫转换为常规钻井液,而钻井液体系转换时,泥页岩地层在气体钻进时产生大量微裂缝使得钻井液滤液浸入从而导致井壁失稳,给后续钻井带来复杂情况。针对川西地区气体钻井过程中气液转换时井壁垮塌失稳等问题,分析了井壁失稳的原因,介绍了润湿反转技术在气液转换时稳定井壁的机理。     

CONSOLIDATION OF PAINTED WOODEN ARTIFACTS

Abstract

Wood, particularly in the presence of excessive moisture, deteriorates due to action of biological agents and sunlight. Decay manifests itself not only in impairment of physical strength but also in discoloration. Protection of the paint during consolidation by impregnation and polymerization, albeit difficult, is possible. Details of a home-built 23 cm-diameter and 48 cm-long chamber for vacuum impregnation are given. The permeating methylmethacrylate monomer solution used with good results contained bis-4-t-butylcyclohexyl peroxidicarbonate as catalyst, and pyridine as activator in addition to methylmethacrylate polymer, which reduced the rate of heat generation by the reaction. Polymerization induced by gamma irradiation also yielded satisfactory results. Case histories of three artifacts are described.