当前搜索引擎不足及改进建议

搜索引擎已经成为人们获取信息的一个重要手段，对搜索引擎技术的研究也日益增多，如何能有效弥补现有技术的缺陷，更合理地满足用户需求变化越来越重要。本文从信息时效性方面提出对现有“超链分析”技术改进的必要性，并结合现有的过分优化网站行为和结果输出方式进一步提出了改进策略。     

A validated search assessment tool: assessing practice-based learning and improvement in a residency program

Objective:

The objective of this study was to validate an assessment instrument for MEDLINE search strategies at an academic medical center.

Method:

Two approaches were used to investigate if the search assessment tool could capture performance differences in search strategy construction. First, data from an evaluation of MEDLINE searches from a pediatric resident''s longitudinal assessment were investigated. Second, a cross-section of search strategies from residents in one incoming class was compared with strategies of residents graduating a year later. MEDLINE search strategies formulated by faculty who had been identified as having search expertise were used as a gold standard comparison. Participants were presented with a clinical scenario and asked to identify the search question and conduct a MEDLINE search. Two librarians rated the blinded search strategies.

Results:

Search strategy scores were significantly higher for residents who received training than the comparison group with no training. There was no significant difference in search strategy scores between senior residents who received training and faculty experts.

Conclusion:

The results provide evidence for the validity of the instrument to evaluate MEDLINE search strategies. This assessment tool can measure improvements in information-seeking skills and provide data to fulfill Accreditation Council for Graduate Medical Education competencies.

Highlights

• The University of Michigan MEDLINE Search Assessment tool can be used to assess search skills in residency education.
• Five elements were identified as critical elements in the development of an effective MEDLINE search strategy: inclusion of all search concepts, appropriate use of Medical Subject Headings, appropriate use of search limits, successful combination of all concepts, and search efficiency.

Implications

• This validated assessment tool can serve as an effective means to measure improvements in residents'' information-seeking skills and provide data to fulfill Accreditation Council for Graduate Medical Education competencies.

     

Literature searching for social science systematic reviews: consideration of a range of search techniques

Background: Literature for a systematic review on the student experience of e‐learning is located across a range of subject areas including health, education, social science, library and information science. Objectives: To assess the merits and shortcomings of using different search techniques in retrieval of evidence in the social science literature. Methods: A conventional subject search was undertaken as the principal method of identifying the literature for the review. Four supplementary search methods were used including citation searching, reference list checking, contact with experts and pearl growing. Results: The conventional subject search identified 30 of 41 included references; retrieved from 10 different databases. References were missed by this method and a further 11 references were identified via citation searching, reference list checking and contact with experts. Pearl growing was suspended as the nominated pearls were dispersed across numerous databases, with no single database indexing more than four pearls. Conclusions: Searching within the social sciences literature requires careful consideration. Conventional subject searching identified the majority of references, but additional search techniques were essential and located further high quality references.     

Output-sensitive autocompletion search

We consider the following autocompletion search scenario: imagine a user of a search engine typing a query; then with every keystroke display those completions of the last query word that would lead to the best hits, and also display the best such hits. The following problem is at the core of this feature: for a fixed document collection, given a set D of documents, and an alphabetical range W of words, compute the set of all word-in-document pairs (w, d) from the collection such that w ∈ W and d ∈ D. We present a new data structure with the help of which such autocompletion queries can be processed, on the average, in time linear in the input plus output size, independent of the size of the underlying document collection. At the same time, our data structure uses no more space than an inverted index. Actual query processing times on a large test collection correlate almost perfectly with our theoretical bound.

网络信息资源检索策略与方法

国内外众多网站都开辟了有关于检索策略与方法的专栏，本汇集一些具有代表性的网站，以使网络用户系统地学习到网络信息检索方法和技巧。     

纸质文献与电子文献比较研究

数字图书馆和现代通信技术结合形成的网络环境,使文献的载体从传统的纸本印刷发展到电子化、网络化.这不仅极大地改变了读者使用文献资源的方式,而且还给教学科研带来了高效、方便的信息服务.然而电子文献并不能完全取代纸质文献,纸质文献在电子文献的冲击下也在努力寻求生存与发展.两种载体文献优势互补,将形成长期并存的局面.     

Google学术搜索引擎与跨库检索系统的功能对比

文章介绍了两种数字资源整合利用的方法--Google中文学术搜索引擎和Cross-Search跨库检索系统,并将它们各自的功能进行了对比.     

How users search and what they search for in the medical domain

The internet is an important source of medical knowledge for everyone, from laypeople to medical professionals. We investigate how these two extremes, in terms of user groups, have distinct needs and exhibit significantly different search behaviour. We make use of query logs in order to study various aspects of these two kinds of users. The logs from America Online, Health on the Net, Turning Research Into Practice and American Roentgen Ray Society (ARRS) GoldMiner were divided into three sets: (1) laypeople, (2) medical professionals (such as physicians or nurses) searching for health content and (3) users not seeking health advice. Several analyses are made focusing on discovering how users search and what they are most interested in. One possible outcome of our analysis is a classifier to infer user expertise, which was built. We show the results and analyse the feature set used to infer expertise. We conclude that medical experts are more persistent, interacting more with the search engine. Also, our study reveals that, conversely to what is stated in much of the literature, the main focus of users, both laypeople and professionals, is on disease rather than symptoms. The results of this article, especially through the classifier built, could be used to detect specific user groups and then adapt search results to the user group.     

搜索引擎的性能评价

在信息飞速增长的网络环境下，对有用信息的查找变得越来越困难，搜索引擎便应运而生，并逐渐发展壮大。论文以用户为导向构建层次分析模型，借此对搜索引擎的评价作简要探讨。     

Efficient distributed selective search

Simulation and analysis have shown that selective search can reduce the cost of large-scale distributed information retrieval. By partitioning the collection into small topical shards, and then using a resource ranking algorithm to choose a subset of shards to search for each query, fewer postings are evaluated. In this paper we extend the study of selective search into new areas using a fine-grained simulation, examining the difference in efficiency when term-based and sample-based resource selection algorithms are used; measuring the effect of two policies for assigning index shards to machines; and exploring the benefits of index-spreading and mirroring as the number of deployed machines is varied. Results obtained for two large datasets and four large query logs confirm that selective search is significantly more efficient than conventional distributed search architectures and can handle higher query rates. Furthermore, we demonstrate that selective search can be tuned to avoid bottlenecks, and thus maximize usage of the underlying computer hardware.     

语义检索研究综述

随着语义网技术的发展,语义检索的研究已成为热点领域。本文首先分析了传统网络检索技术的局限性。然后在对若干研究与应用调研的基础上,对当前语义检索的研究进行了综述,详细分析了目前的两类语义检索研究：语义支持的检索及语义网检索,对语义网检索更进一步分析了其三种不同的研究方向：语义网文档检索、实例检索、关系检索。     

Coverage-based search result diversification

Traditional retrieval models may provide users with less satisfactory search experience because documents are scored independently and the top ranked documents often contain excessively redundant information. Intuitively, it is more desirable to diversify search results so that the top-ranked documents can cover different query subtopics, i.e., different pieces of relevant information. In this paper, we study the problem of search result diversification in an optimization framework whose objective is to maximize a coverage-based diversity function. We first define the diversity score of a set of search results through measuring the coverage of query subtopics in the result set, and then discuss how to use them to derive diversification methods. The key challenge here is how to define an appropriate coverage function given a query and a set of search results. To address this challenge, we propose and systematically study three different strategies to define coverage functions. They are based on summations, loss functions and evaluation measures respectively. Each of these coverage functions leads to a result diversification method. We show that the proposed coverage based diversification methods not only cover several state-of-the-art methods but also allows us to derive new ones. We compare these methods both analytically and empirically. Experiment results on two standard TREC collections show that all the methods are effective for diversification and the new methods can outperform existing ones.     

Identifying the effective evidence sources to use in developing Clinical Guidelines for Acute Stroke Management: lived experiences of the search specialist and project manager

Background: The Australian National Stroke Foundation appointed a search specialist to find the best available evidence for the second edition of its Clinical Guidelines for Acute Stroke Management. Objective: To identify the relative effectiveness of differing evidence sources for the guideline update. Methods: We searched and reviewed references from five valid evidence sources for clinical and economic questions: (i) electronic databases; (ii) reference lists of relevant systematic reviews, guidelines, and/or primary studies; (iii) table of contents of a number of key journals for the last 6 months; (iv) internet/grey literature; and (v) experts. Reference sources were recorded, quantified, and analysed. Results: In the clinical portion of the guidelines document, there was a greater use of previous knowledge and sources other than electronic databases for evidence, while there was a greater use of electronic databases for the economic section. Conclusions: The results confirmed that searchers need to be aware of the context and range of sources for evidence searches. For best available evidence, searchers cannot rely solely on electronic databases and need to encompass many different media and sources.     

吴中文献展览会推进地方文献建设述略

1937年,在馆长蒋吟秋先生的主持下,苏州图书馆举办了近代史上一次有名的吴中文献展览会.展览会所征集的文献分为五大类,除少数为公立图书馆所藏外,绝大多数为私人收藏品.展览会引来各界人士参观,展品中尤以乡贤遗物和地方典籍最为引人瞩目.本次展览会的召开,反映了吴中文化特色,推进吴中学术传统,凸显乡土文献在弘扬区域文明中的重要作用.