(Sections of this document downloaded from STN reprinted by permission of CAS)
Medline is a bibliographic database produced by the U.S. National Library of Medicine (NLM). The database covers the biomedical literature, the records of which appear in Index Medicus, Index to Dental Literature, and International Nursing Index. The vast majority of Medline bibliographic records are references to journal articles, and approximately 50% of the records contain abstracts (no abstract for pre-1975 records). CAS Registry Numbers (RN) are present in the file dating from 1980 forward. The majority of Medline records are in English.
Medline provides summaries of articles from over 3,900 journals which taken together cover all areas of biomedicine. The database extends back to 1966 and is updated monthly. Full text articles (including images or graphics) are included for over 60 of the journals, from 1995 (15 of them from 1993). Records and articles can be viewed online and downloaded.
The Medline database is different from the other databases with which you are already familiar (LCA, CA). Medline is a relational database. In addition to the fields contained in "normal" databases, relational databases also have one or more Thesauri. As used here, a Thesaurus is a comprehensive list of subject headings.
Each record in Medline is assigned a set of controlled terms (/CT) that describe its contents. These terms are called Medical Subject Headings or MeSH terms. The Thesaurus is a hierarchical listing of all of these terms (a huge subject outline). You can use the Expand Command to search through the Thesaurus in order to find all of the subject headings that apply to your subject.
The Thesaurus helps you to design your search strategy by allowing you to walk up (broader subject headings, /BT) and down (narrower subject headings, /NT field specifier) the outline. There are 3 thesauri in medline, the controlled terms thesaurus (/CT), the Tree Number and descriptor class thesaurus (/MN field specifier), and the compound thesaurus (/CN field specifier). For our purposes, the first two thesauri can be considered to be the same. We will use /CT because it will avoid confusion when we go searching for records related to a particular CT.
The main database is accessed by STN (via STN Express) in the file Medline. This file is actually fairly cheap, but we receive no discount for searches conducted in that file. There is a FREE (except for connect time) learning file, LMedline, and that is the file that was used to prepare this document.
It should be noted that search strategies that give reasonable number of records in LMedline will likely be too broad in the full Medline file. So you will have to modify/narrow an LMedline strategy if you plan to use it in Medline.
Introduction
Overview
Designing a Search Strategy in LMedline
Topic Strategy Design - using the Thesaurus
Narrower Terms
Tree number (MN) - a outlining asideBroader Terms
Chemical Names
Refining the Strategy
Display, Editing Results, and Printing
Entering LMedline
About LMedline
Commands in LMedline
Search Command in Medline
Search Fields
Expand Command in Medline
Thesaurus in Medline
Relationship Codes (RCodes) in Medline
Display Formats
Medline is one of the cheaper STN database files in which one can perform searches. As such it is a good addition to your literature searching repertoire.
=> help costs
STN International Fees and Prices Effective January 1, 1999
MEDLINE File U.S.
------------ Dollars
-------
Connect Hour Fee (per hour) 30.00
SDI Search Fee (1)
Weekly. . . . . . . . 6.00
Monthly . . . . . . . 6.00
Format Display and Print Fees (per answer)
BIB or CBIB . . . . . 0.12
ABS . . . . . . . . . 0.05
IND . . . . . . . . . FREE
ALL . . . . . . . . . 0.17
TRIAL or SAM . . . . . FREE
HIT or KWIC . . . . . Variable, depending on displayed fields
OCC . . . . . . . . . FREE
Individual Field Display and Print Fees
AB or AU or SO . . . . . 0.05
All other fields. . . . . FREE
Offline Print Fee
(additional per answer) . 0.16
SDI FREQUENCY:WEEKLY/MONTHLY
(1) All SDI search fees include up to 20 (twenty) SDI prints
delivered offline, by electronic mail, or by fax. Additional
SDI prints are charged at the list prices above. Online
display of SDI answers are charged at the list prices above.
If you are displaying information by specifying individual fields,
you will be charged the price for the least expensive combination
that contains all of the fields you request.