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Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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At least 307 records · Page 17Linked to original sources
PubMed1982

A Zipfian model of an automatic bibliographic system: an application to MEDLINE.

A Zipfian model of an automatic bibliographic system is developed using parameters describing the contents of it database and its inverted file. The underlying structure of the Zipf distribution is derived, with particular emphasis on its application to work frequencies, especially with regard to the inverted flies of an automatic bibliographic system. Andrew Booth developed a form of Zipf's law which estimates the number of words of a particular frequency for a given author and text. His formulation has been adopted as the basis of a model of term dispersion in an inverted file system. The model is also distinctive in its consideration of the proliferation of spelling errors in free text, and the inclusion of all searchable elements from the system's inverted file. This model is applied to the National Library of Medicine's MEDLINE. The model carries implications for the determination of database storage requirements, search response time, and search exhaustiveness.

MEDLARS↗
PubMed1983

Automatic query formulations in information retrieval.

Modern information retrieval systems are designed to supply relevant information in response to requests received from the user population. In most retrieval environments the search requests consist of keywords, or index terms, interrelated by appropriate Boolean operators. Since it is difficult for untrained users to generate effective Boolean search requests, trained search intermediaries are normally used to translate original statements of user need into useful Boolean search formulations. Methods are introduced in this study which reduce the role of the search intermediaries by making it possible to generate Boolean search formulations completely automatically from natural language statements provided by the system patrons. Frequency considerations are used automatically to generate appropriate term combinations as well as Boolean connectives relating the terms. Methods are covered to produce automatic query formulations both in a standard Boolean logic system, as well as in an extended Boolean system in which the strict interpretation of the connectives is relaxed. Experimental results are supplied to evaluate the effectiveness of the automatic query formulation process, and methods are described for applying the automatic query formulation process in practice.

Computers↗
PubMed1983

The correlation between pertinence and rate of citation duplication in multidatabase searches.

The rate of citation duplication was examined in three databases: MEDLINE, BIOSIS, and LIFE SCIENCES COLLECTION. Duplicate citations were found to be more pertinent than unique citations. The duplicate citations came from a highly compact literature, while those from a single database were very widely scattered. The pertinent duplicated citations were more likely to be retrieved in searches that had more terms overall, had a higher percentage of thesaurus terms, and had terms which appeared in both title and abstract. These results suggest that the rate of duplication of citations in multidatabase searches may be used to rank output according to probable pertinence.

MEDLARS↗
PubMed1983

Response time variations in an online search system.

The response time characteristics of the National Library of Medicine's (NLM) ELHILL bibliographic search system are examined in this article. Transactions for a five-week period are analyzed and average response times are calculated for typical search commands, by time of day, and by file being searched. Overall, the response time of the system was found to be 2.1 seconds, a very low value. Based on statistical tests of significance applied to the data, it was concluded that response time differences can be explained in terms of the number of users on the system and not the command issued by the user nor the file the user searched.

Analysis of Variance↗
PubMed1983

An experimental comparison of the effectiveness of computers and humans as search intermediaries.

An experimental computer intermediary system, CONIT, that assists users in accessing and searching heterogeneous retrieval systems has been enhanced with various search aids. Controlled experiments have been conducted to compare the effectiveness of the enhanced CONIT intermediary with that of human expert intermediary search specialists. Some 16 end users, none of whom had previously operated either CONIT or any of the four connected retrieval systems, performed searches on 20 different topics using CONIT with no assistance other than that provided by CONIT itself (except to recover from computer/software bugs). These same users also performed searches on the same topics with the help of human expert intermediaries who searched using the retrieval systems directly. Sometimes CONIT and sometimes the human expert were clearly superior in terms of such parameters as recall and search time. In general, however, users searching alone with CONIT achieved somewhat higher online recall at the expense of longer session times. We conclude that advanced experimental intermediary techniques are now capable of providing search assistance whose effectiveness at least approximates that of human intermediaries in some contexts. Also analyzed is the cost effectiveness of current intermediary systems. Finally, consideration is given to the prospects for much more advanced systems which would perform such functions as automatic data-base selection and the simulation of human experts, and thereby make information retrieval more effective for all classes of users.

Analysis of Variance↗
PubMed1984

File maintenance of MeSH headings in MEDLINE.

This article addresses file maintenance of subject headings in the National Library of Medicine's MEDLINE, a bibliographic retrieval file which is indexed using Medical Subject Headings (MeSH), NLM's subject authority. The emphasis is class maintenance in which sets of records in MEDLINE are changed by maintenance actions which reflect yearly changes in MeSH. Specific types of maintenance action are described with examples to highlight problem areas. Class maintenance failures, checking class maintenance, and informing end-users of MeSH changes resulting in class maintenance are discussed. Technical constraints and feasibility are not analyzed in detail; rather, the approach is geared toward requirements and impact of maintenance from the standpoint of vocabulary specialists and end-users. The article concludes with a brief statement on defining file maintenance policy.

MEDLARS↗
PubMed1985

Online search patterns: NLM CATLINE database.

In this article the authors present their analysis of the online search patterns within user searching sessions of the National Library of Medicine ELHILL system and examine the user search patterns on the CATLINE database. In addition to the CATLINE analysis, a comparison is made using data previously analyzed on the MEDLINE database for the same time period, thus offering an opportunity to compare the performance parameters of different databases within the same information system. Data collection covers eight weeks and includes 441,282 transactions and over 11,067 user sessions, which accounted for 1680 hours of system usage. The descriptive analysis contained in this report can assists system design activities, while the predictive power of the transaction log analysis methodology may assists the development of real-time aids.

Cataloging↗
PubMed1988

Raising questions in clinical practice.

Answers are required by family physicians to numerous questions during a day of patient care. This study examined the number of questions that arose during one day to which family physicians did not have an answer, the library resources to which the family physicians had access and used, and the relationship between the number of questions that arose in practice and library resources or use. Volunteer family physicians (N = 87) reported a mean of 6.8 questions. When accessing libraries, physicians relied primarily on their office and home libraries. Personal libraries had fewer than ten textbooks published since 1980 and subscriptions to fewer than five journals. T-test analysis indicated that the physician with the most questions practiced in the medical school community, was a graduate of a Canadian or United States medical school, and attended a course on problem raising and solving. The number of questions did not differ by the holdings in the physician's library, the age or sex profile of the patients, the number of patients seen or the frequency with which the physician used his personal library. Medical educators and librarians should provide educational opportunities to assist family physicians develop their personal libraries, their problem solving skills and their use of modern technology to access the literature.

Alberta↗
PubMed1984

Integrating library services and continuing education.

This paper presents an innovative integration of library services and continuing education (CE). While print material is an important continuing education information source for physicians, its volume is overwhelming. Librarians have developed the use of a variety of methods, including online data bases such as MEDLINE, to simplify and expedite access to printed information. Combining a library information delivery system with formal continuing education course activities can enhance the educational potential of two popular learning methods.

Data Collection↗
PubMed1986

Information overload and how to lighten it.

The overabundance of information resources, and the inadequacy of current information retrieval methods, are considered with special reference to the scholarly record of the health sciences. Both formal and informal means for finding information, and for keeping abreast of new knowledge, are reviewed, with practical suggestions for lightening the load. Continuing educators are seen as having a special role in this process.

Abstracting and Indexing↗
PubMed1979

Retrieving information on clinical methodology.

Evidence derived from several simple searchers of the literature suggests that one interested in identifying papers which discuss the methodologies of clinical trials will have reasonable success. However, the retrieval of a meaningful methodologic duscussion of any actual trial is unlikely because very little of this information has been published. Some suggestions to remedy this deficiency are given.

Clinical Trials as Topic↗
PubMed1994

Development and impact of the Gene-Tox-Program, genetic activity profiles, and their computerized data bases.

This invited historical review traces the development and impact of two major data bases in the field of genetic toxicology. Discussed from a personal perspective are the Environmental Protection Agency (EPA) Gene-Tox Program and the EPA/International Agency for Research on Cancer Genetic Activity Profiles (GAPs) and their respective data bases. Whereas Gene-Tox was focused on the assessment of short-term tests and their role in predicting carcinogens and mutagens, GAPs and the GAP data base were designed specifically to aid in the evaluation of individual chemicals. Both data bases have been computerized. Gene-Tox is available on TOXNET and GAP is available in a personal computer format from the author. The Gene-Tox and GAP data bases appear to have had substantial impact, particularly on hazard identification activities in cancer risk assessment.

Carcinogenicity Tests↗
PubMed1986

Interaction of genetics and epidemiology in the literature.

To evaluate the extent of interaction between genetics and epidemiology in studies reported in the literature, we reviewed all the "familial/genetic" papers published in a standard epidemiology journal (American Journal of Epidemiology, AJE) and all the "epidemiology" papers published in a standard human genetics journal (American Journal of Human Genetics, AJHG) between 1966 and 1984. A variety of medline subject headings were used in this search. Computerized listings of titles, subject headings, and abstracts were reviewed. It could be shown that familial/genetic papers constituted 4.3% of all papers published in AJE and epidemiology papers constituted 16.4% of papers published in AJHG. Over time, familial/genetic studies published in AJE increased both in number and in proportion of all papers, and more family studies are using complex statistical genetic techniques. On the other hand, epidemiology papers published in AJHG did not increase in number over time, and actually decreased in relation to all papers. These papers were mostly either descriptive (eg, defining frequencies of Mendelian traits in populations) or analytical (eg, defining risk factors for chromosomal abnormalities, and other reproductive outcomes). This analysis suggests that epidemiologic methods have been widely used in the genetic literature, and that genetic methods are gaining more access to the recent epidemiology literature. Because of increasing recognition of the role of genetic factors in disease, there is a growing need to incorporate both genetic and epidemiologic methods in etiologic studies of complex disorders.

Epidemiology↗
PubMed1995

The indexing waltz.

Explore the source record for details and available documents.

Bibliography of Medicine↗
PubMed1995

Electronic surveillance of the pharmacology-toxicology literature: the need for controlled vocabularies and registry systems.

Controlled vocabularies of "preferred names" and registry systems are essential in electronic indexing, storing, searching, and retrieving the world's published literature. The most efficient and comprehensive search is accomplished by using the preferred name. Without a controlled vocabulary or a registry system, it would be necessary to remember every name that might have been used by authors since January 1966, in order to retrieve all the citations on a chemical from over 7.8 million citations currently in the National Library of Medicine's MEDLINE and its backfiles. The task of creating the list of subject descriptors that make possible the surveillance of published literature via electronic databases requires the participation of the scientific community in developing domain-specific nomenclature, drug classification, controlled vocabularies, and registry systems as well. The biological unions of the International Council of Scientific Unions and its Committee on Data for Science and Technology are major contributors to the establishment and dissemination of standards for biological terminology and nomenclature. The objectives of the IUPHAR Nomenclature Committee include the development of a rational framework for the nomenclature of receptor classes or families and a classification for therapeutic agents. This will help define rules for the characterization and classification of receptors that are stable and easy to comprehend. The International Union of Pharmacology publishes guidelines for the classification of drugs and the nomenclature of receptors and ion channels.

Abstracting and Indexing↗
PubMed1988

PDQ--a database of clinical trials and cancer treatment information.

The National Cancer Institute has developed an online clinical information system known as PDQ (Physician Data Query) to provide physicians with up-to-date information on cancer treatment and to facilitate participation in cancer clinical trials. PDQ is a major component in the National Cancer Institute's goal of reducing cancer mortality 50% by the year 2000.

Clinical Trials as Topic↗