Extensions to the STAIRS Study—Empirical Evidence for the Hypothesised Ineffectiveness of Boolean Queries in Large Full-Text Databases

The STAIRS study conducted by Blair and Maron in the mid-80's is a milestone in the history of IR evaluation. Blair and Maron made strong conclusion about the inadequacy of free-text searching large databases, and their study has been widely referred in the literature to justify the problems of effectiveness in IR systems. However, some critics of the study have plausibly pointed out that the ineffectiveness conclusions were not solidly based on empirical data.This paper introduces a new theoretical and empirical approach to study the problems of high recall searching in large databases and reports the results of a case experiment. The findings verify some of the hypothetical conclusions introduced in the STAIRS study, and expands the picture of falling performance. It is shown that low precision in high recall searching is unavoidable in exact-match Boolean searching since even major concepts are often expressed implicitly in relevant documents. The author suggests that the problem could be reduced in facet-based best-match searching.     

关于短跑运动员服用甲壳素影响运动能力的研究

观察了我院田径队短跑组运动员服用甲壳素(C hitin)前后,机体在激烈运动后血乳酸浓度、血细胞形态、超氧化物歧化酶及最大摄氧量的变化。实验表明:通过服用甲壳素短跑运动员在运动过程中血乳酸浓度有显著的降低;成熟红细胞形态有更圆润、保满的趋势;最大摄氧量有提高;谷胱甘肽有所升高、乳酸脱氢酶、丙二醛有所下降,运动员的运动能力有所提高。     

基于用户信息需求的元搜索引擎的构建

针对当前网络搜索引擎未能较多地关注用户需求、查全率与查准率不高、彼此间不兼容的缺陷,提出建立基于用户需求的元搜索引擎,并分析其基本原理,给出其基本结构,讨论其运行机制和关键技术。指出基于用户需求的元搜索引擎可使网络信息资源在一定程度上结构化,实现网络信息资源的自组织,提高网络信息检索的查全率和查准率.     

The IR Has Two Faces: Positioning Institutional Repositories for Success

This article describes the ongoing efforts at University of Nevada, Las Vegas (UNLV) Libraries to evolve the role of the institutional repository (IR) and to effectively position it within the context of the Libraries’ collections, research support, and scholarly communication services. A major component of this process is re-examining the fundamental aims of the IR and aligning it to the Libraries and the campus strategic goals. The authors situate UNLV Libraries’ experience within the context of the current literature to provide background and reasoning for our decision to pursue two, at times conflicting, aims for the IR: one for scholarly communication and another for research administration.     

世界主义的价值诉求——国际关系规范理论的视角

世界主义是一种具有悠久传统的哲学理念,它主张世界是一个单一的共同体,所有人皆为其中的平等成员。近年来随着国际关系规范理论的复兴,世界主义再次走向前台。在当前全球化的背景下,面对国际政治、经济秩序的重大变迁,一系列关乎人类命运问题的显现,以个人主义的价值前提和全球共同体的道德理想为基础,世界主义在人权的普遍性、全球范围的分配正义和世界主义民主等不同领域都表达了自己的道德诉求。然而,作为一种普遍性的价值目标,其在具体实施过程中可能产生的负面影响同样不容忽视。     

两道循环效率题的启示

由两道循环效率题的解答，总结计算循环效率时应注意的两个问题。     

一类Henstock可积而非Lebesgue可积的函数

通过讨论(L)积分、(IR)积分及(H)积分三者的关系,给出一类(H)可积而非(L)可积的函数.     

红外光谱法确认辽宁三地区苹果中黄烷醇类化合物

黄烷醇基本结构为C6·C3·C6型化合物 ,具有一定的抗癌活性 .其衍生形成的多酚类化合物对人体具有较强的抗衰老作用 ,它广泛存在于各种水果及一些植物中 .本文利用红外光谱法对辽宁三地区不同种类苹果的提取物进行了分析、比较 ,结果是辽南地区的苹果黄烷醇类化合物的含量少于辽西地区的苹果黄烷醇类化合物的含量 ,富士苹果的黄烷醇类化合物的含量高于国光苹果的黄烷醇类化合物的含量 ,为进一步研究开发提供了依据     

数控系统中的干扰抑制

介绍了数控系统中的干扰抑制。从电网干扰抑制、数字信号线干扰抑制、模拟信号干扰抑制方面,对感性负载加吸收电路来抑制瞬态噪声作了详细说明,可避免干扰造成的数控系统的“软”故障。     

高校人才引进工作中存在的问题及对策分析

人才是高校发展的宝贵资源，当前，人才竞争愈演愈烈，高校应从实际出发分析人才引进工作中存在的问题，建立人才引进的新机制，确保人才引进工作良性发展。