共查询到19条相似文献，搜索用时 140 毫秒
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急性白血病相关基因的文本挖掘分析 总被引：2，自引：0，他引：2
从PubMed检索1966年到2005年9月6日间白血病与基因关系的相关文献3 529篇.经编程处理生成主题词词篇矩阵并进行聚类.通过聚类树图可将所提取的主题词/副主题词分成13类,经对比原始文献进行验证,全部29种基因中只与ALL相关的有3种, 占10.34%;只与AML相关的有8种,占27.59%.特异的可用于鉴别ALL和AML的基因有11种,占37.93%.通过主题词的共现关系进行聚类可以基本实现发现基因与疾病之间的联系,但该方法所获得的相关基因较少,不利于对疾病与基因关系的全面了解. 相似文献
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分析MeSH在PubMed、中国生物医学文献数据库、中国医院知识资源总库和万方医学网中的应用,总结出MeSH在医学信息检索中的三种应用机制,即直接使用主题词检索、实现自然语言或分类号向主题词的转换以及利用主题词等级范畴表进行知识导航,进而提出加强中文主题词表和中文一体化医学语言系统的构建与研究的建议。 相似文献
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组配标引是在词表中选择两个及两个以上有形式逻辑关系的词,按照特定规则组成的一组标引词串,用以满足文献多层次、多途径检索的需要。概念组配是文献标引的关键环节。根据参与组配的主题词之间的逻辑关系,概念组配可分为交叉组配、限定组配和联结组配3种基本类型。在实际组配标引工作中,编目员应避免因对新词表不熟悉造成检索词语构成混乱,避免因主题概念转换错误造成粗标、漏标和错标,避免因未遵循专指性标引规则造成切题不当,减少组配标引失误。 相似文献
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非控主题词,也称自由词,是指词表未收、可随需要增补、不作为正式标引检索用词、但可实际用于检索,具有较大的识别功能的词。非控主题词属于自然语言范畴,其专指度一般高于词表中的正式词。在CNMARC(中国机读目录格式)中,610字段反映非控主题词。 相似文献
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本文拟从数据库的选择、检索途径、检索词的输入、主题词检索、逻辑运算、限制字段检索、检索结果的显示等七个方面将CbmWin与CBMdisc和Winspirs进行比较,以探讨CbmWin这一检索软件的优点及不足之处. 相似文献
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MEDLINE是医学界最常用的外文文献书目数据库,其发展演变情况复杂、检索平台品种繁多.文章回顾了其发展演变过程,并从数据范围、记录构成、检索规则、主题词检索、结果输出、个性化服务等方面比较SilverPlatterMEDLINE、Ovid-Medline和PubMed三个版本的异同,试图让读者对MEDLINE有一个更为全面的了解. 相似文献
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浅谈《中文科技期刊论文数据库》检索技巧 总被引：1，自引：0，他引：1
《中文科技期刊论文数据库》（以下简称《科技库》）,是国内自行研制的系统检索中文科技文献的一个重要的光盘版的检索工具,检索途径有：主题词、分类号、著者、刊名、篇名、复合式６种。在检索文献中,如果用户提出的检索词是一些反映文献主题内容的自由词,通常我们都通过主题词──这个检索途径为读者检索。笔者最近发现,在使用《科技库》检索中文科技文献中,有时篇名检索比主题词检索所得到的文献更令读者感到满意,或者说,篇名检索的查准率高于主题词检索的查准率。 有这样一个例子,本校材料系一用户要求检索一课题：内燃机缸体… 相似文献
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利用数据库特色功能提高查新检索质量研究 总被引：2，自引：0，他引：2
利用数据库特色功能,从结构检索、信息分析及号码检索三个方面研究了提高查新检索质量的方法.研究表明,对一些课题,利用数据库提供的特色功能可以提高查新检索结果的全面性和相关性.对结构检索,选择合适的基本结构成为提高检索质量的关键;号码检索与词检索共同使用、利用合适的信息分析词都可以有效地提高查新检索质量. 相似文献
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在向文献数据库发送检索提问后,用户检索到的往往是数量众多且线性排列的文献记录,如何进一步分类这些文献记录以方便用户使用是信息检索领域的重要课题之一。本文以一个比较狭小的主题(脊髓损伤)为文献查询提问,探索利用原数据库中提供的论文主题相似性信息对检索到的文献记录进行聚类的方法,并对每个类别赋予类别标签。本文①利用生物医学权威文献数据库Medline,分别检索PubMed中有关脊髓损伤的部分文献(源文献),实际操作中我们抽取近两年发表的有关脊髓损伤的1906篇文献中前50篇;②利用PubMed中的相关文献功能分别检索出源文献的相关文献(共5108篇),筛选出频次较高的相关文献(出现频次大于或等于5次,共31篇);③形成源文献和相关文献的关联矩阵,根据该矩阵对来源文献进行聚类分析;④分别采用人工分析和主题词的向量空间模型算法提取各类的文献内容或类标签,初步评价分类结果的正确性。经过基于相似性的聚类分析,可以将脊髓损伤的源文献分为3个大类,对比人工分析和主题词向量空间模型方法对来源文献的内容提取,二者基本相符。就本文研究涉及的主题而言,利用文献数据库中提供的论文相关性信息对检索结果进行再次分类的方法是可行的。 相似文献
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知识检索中自然语言控制机制研究 总被引：6，自引：0，他引：6
情报检索过程中,对自然语言进行词汇控制是可行方法.借助各种技术和措施揭示词间的语义关系,词汇控制至少可以实现查询词的自动转换、一定程度的查询扩展、关联检索、排歧检索等,提高检索的语义性、知识性、智能性,提高查全率和查准率.参考文献12. 相似文献
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《Journal of Web Librarianship》2013,7(4):309-331
Perhaps the greatest power of folksonomies, especially when set against controlled vocabularies like the Library of Congress Subject Headings, lies in their capacity to empower user communities to name their own resources in their own terms. This article analyzes the potential and limitations of both folksonomies and controlled vocabularies for transgender materials by analyzing the subject headings in WorldCat records and the user-generated tags in LibraryThing for books with transgender themes. A close examination of the subject headings and tags for twenty books on transgender topics reveals a disconnect between the language used by people who own these books and the terms authorized by the Library of Congress and assigned by catalogers to describe and organize transgender-themed books. The terms most commonly assigned by users are far less common or non-existent in WorldCat. The folksonomies also provide spaces for a multiplicity of representations, including a range of gender expressions, whereas these entities are often absent from Library of Congress Subject Headings and WorldCat. While folksonomies are democratic and respond quickly to shifts and expansions of categories, they lack control and may inhibit findability of resources. Neither tags nor subject headings are perfect systems by themselves, but they may complement each other well in library catalogs. Bringing users’ voices into catalogs through the addition of tags might greatly enhance organization, representation, and retrieval of transgender-themed materials. 相似文献
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P F Cranefield 《Bulletin of the Medical Library Association》1967,55(2):129-134
Present day programs of computerized information retrieval overvalue the importance of retrieving "facts" without either attaching a scale of importance to the material with which they deal or ordering information in any way which corresponds to the order of human thought. The limitations of classification by subject heading become especially apparent when a body of information becomes, through new insight, pertinent to a new area of thought. That body of information thereby acquires new subject headings: thus one sees that the system of retrieval by subject heading can never serve to aid fundamental discovery. The dangers of the present approach lie in their devaluation of traditional methods. Critical reviews are devalued, personal knowledge of the literature is devalued, and a false impression is created that knowledge is the same thing as retrievable information. This diminishes respect for that sort of personal organization of knowledge which alone can serve creative insight. 相似文献
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《Cataloging & classification quarterly》2013,51(1):35-44
Pattern indexing is an attempt at combining standardized and free indexing. In contrast to prevailing indexing methods, notably precoordinated ones, pattern indexing also takes into consideration the terminological and information retrieval habits in certain displines of science. It is based on patterns consisting of subject categories reflecting the conceptual and methodological framework of a given discipline. These categories provide structured sets of standardized subject headings. To allow for flexibility and adequacy, these headings may be complemented by free indexing terms. Pattern indexing is intended to mend opaque catalog structures and terminological uncertainties of topical subject headings in common precoordinated indexing practice. Pattern indexing is discussed in the context of literary scholarship. 相似文献
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This paper investigates the effectiveness of using MeSH® in PubMed through its automatic query expansion process: Automatic Term Mapping (ATM). We run Boolean searches based on a collection of 55 topics and about 160,000 MEDLINE® citations used in the 2006 and 2007 TREC Genomics Tracks. For each topic, we first automatically construct a query by selecting keywords from the question. Next, each query is expanded by ATM, which assigns different search tags to terms in the query. Three search tags: [MeSH Terms], [Text Words], and [All Fields] are chosen to be studied after expansion because they all make use of the MeSH field of indexed MEDLINE citations. Furthermore, we characterize the two different mechanisms by which the MeSH field is used. Retrieval results using MeSH after expansion are compared to those solely based on the words in MEDLINE title and abstracts. The aggregate retrieval performance is assessed using both F-measure and mean rank precision. Experimental results suggest that query expansion using MeSH in PubMed can generally improve retrieval performance, but the improvement may not affect end PubMed users in realistic situations. 相似文献
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Objective:There are no existing validated search filters for the group of 37 Organisation for Economic Co-operation and Development (OECD) countries. This study describes how information specialists from the United Kingdom''s National Institute for Health and Care Excellence (NICE) developed and evaluated novel OECD countries’ geographic search filters for MEDLINE and Embase (Ovid) to improve literature search effectiveness for evidence about OECD countries.Methods:We created the draft filters using an alternative approach to standard filter construction. They are composed entirely of geographic subject headings and are designed to retain OECD country evidence by excluding non-OECD country evidence using the NOT Boolean operator. To evaluate the draft filters’ effectiveness, we used MEDLINE and Embase literature searches for three NICE guidelines that retrieved >5,000 search results. A 10% sample of the excluded references was screened to check that OECD country evidence was not inadvertently excluded.Results:The draft MEDLINE filter reduced results for each NICE guideline by 9.5% to 12.9%. In Embase, search results were reduced by 10.7% to 14%. Of the sample references, 7 of 910 (0.8%) were excluded inadvertently. These references were from a guideline about looked-after minors that concerns both OECD and non-OECD countries.Conclusion:The draft filters look promising—they reduced search result volumes while retaining most OECD country evidence from MEDLINE and Embase. However, we advise caution when using them in topics about both non-OECD and OECD countries. We have created final versions of the search filters and will validate them in a future study. 相似文献
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Rehabilitation professionals need access to current journal literature for research and patient care. Using the American Journal of Occupational Therapy, subject headings from the MEDLINE and NAHL files are compared to determine coincidence and numbers of headings. Based on the study findings, an information retrieval plan is suggested that librarians may use in assisting rehabilitation personnel in effective use of Index Medicus, Cumulative Index to Nursing and Allied Health, and their online counter-parts. 相似文献
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本研究对MEDLINE中生物体类文献中高频主要主题词进行共词聚类分析,获取主题词之间的关联规则,利用UMLS语义关系进行结构化表达.从MEDLINE中选取<中华医学杂志>上的生物体类文献作为测试集,由专家人工抽取关系,与共词聚类得到的关联规则进行比较.利用共词聚类分析对生物体类主题词关系的挖掘及评价分析,为文本知识发现提供了一种新的尝试. 相似文献