MEDLINE (Medical Literature Analysis and Retrieval System Online, or
MEDLARS Online) is a bibliographic database of life sciences and
biomedical information. It includes bibliographic information for
articles from academic journals covering medicine, nursing, pharmacy,
dentistry, veterinary medicine, and health care.
MEDLINE also covers
much of the literature in biology and biochemistry, as well as fields
such as molecular evolution.
Compiled by the United States National Library of
MEDLINE is freely available on the
Internet and searchable via PubMed
and NLM's National Center for Biotechnology Information's Entrez
1.1 Initial development of MEDLARS
1.2 MEDLARS Online
5 Inclusion of journals
7 See also
MEDLARS (Medical Literature Analysis and Retrieval System) is a
computerised biomedical bibliographic retrieval system. It was
launched by the National Library of
Medicine in 1964 and was the first
large scale, computer based, retrospective search service available to
the general public.
Initial development of MEDLARS
Since 1879, the National Library of
Medicine had published Index
Medicus, a monthly guide to medical articles in thousands of journals.
The huge volume of bibliographic citations was manually compiled. In
1957 the staff of the NLM started to plan the mechanization of the
Index Medicus, prompted by a desire for a better way to manipulate all
this information, not only for
Index Medicus but also to produce
subsidiary products. By 1960 a detailed specification was prepared and
by the spring of 1961 a request for proposals was sent out to 72
companies to develop the system. As a result, a contract was awarded
to the General Electric Company. The computer (a Minneapolis-Honeywell
800) which was to run MEDLARS was delivered to the NLM in March 1963,
Frank Bradway Rogers (Director of the NLM 1949 to 1963) said at
the time "..If all goes well, the January 1964 issue of Index Medicus
will be ready to emerge from the system at the end of this year. It
may be that this will mark the beginning of a new era in medical
MEDLARS cost $3 million to develop and at the time of its completion
in 1964, no other publicly available, fully operational electronic
storage and retrieval system of its magnitude existed. The original
computer configuration operated from 1964 until its replacement by
MEDLARS II in January 1975.
In late 1971, an online version called
MEDLINE ("MEDLARS Online")
became available as a way to do online searching of MEDLARS from
remote medical libraries. This early system covered 239 journals
and boasted that it could support as many as 25 simultaneous online
users (remotely logged-in from distant medical libraries) at one
time. However, this system remained primarily in the hands of
libraries, with researchers able to submit pre-programmed search tasks
to librarians and obtain results on printouts, but rarely able to
interact with the NLM computer output in real-time. This situation
continued through the beginning of the 1990s and the rise of the World
In 1996, soon after most home computers began automatically bundling
efficient web browsers, a free public version of
instigated. This system, called PubMed, was offered to the general
online user in June, 1997, when
MEDLINE searches via the Web were
demonstrated, in a public ceremony, by Vice President Al Gore.
The database contains more than 26 million records from 5,639
selected publications covering biomedicine and health from 1950 to
the present. Originally the database covered articles starting from
1965, but this has been enhanced, and records as far back as 1950/51
are now available within the main index. The database is freely
accessible on the
Internet via the
PubMed interface and new citations
are added Tuesday through Saturday. For citations added during
1995-2003: about 48% are for cited articles published in the U.S.,
about 88% are published in English, and about 76% have English
abstracts written by authors of the articles. The most common topic in
the database is Cancer with around 12% of all records between
1950-2016, which have risen from 6% in 1950 to 16% in 2016. 
Medical Subject Headings (MeSH) for information
retrieval. Engines designed to search
MEDLINE (such as
PubMed) generally use a
Boolean expression combining MeSH terms, words
in abstract and title of the article, author names, date of
PubMed can also find articles similar to
a given one based on a mathematical scoring system that takes into
account the similarity of word content of the abstracts and titles of
MEDLINE added a "publication type" term for “randomized controlled
trial” in 1991 and a MESH subset “systematic review” in
MEDLINE functions as an important resource for biomedical researchers
and journal clubs from all over the world. Along with the Cochrane
Library and a number of other databases,
evidence-based medicine. Most systematic review articles published
presently build on extensive searches of
MEDLINE to identify articles
that might be useful in the review.
MEDLINE influences researchers in
their choice of journals in which to publish.
Inclusion of journals
More than 5,500 biomedical journals are indexed in MEDLINE. New
journals are not included automatically or immediately. Selection is
based on the recommendations of a panel, the Literature Selection
Technical Review Committee, based on scientific scope and quality of a
journal. The Journals Database (one of the
contains information, such as its name abbreviation and publisher,
about all journals included in Entrez, including PubMed.
PubMed usage has been on the rise since 2008. In 2011, PubMed/MEDLINE
was searched 1.8 billion times, up from 1.6 billion searches in the
A service such as
MEDLINE strives to balance usability with power and
comprehensiveness. In keeping with the fact that MEDLINE's primary
user community is professionals (medical scientists, health care
MEDLINE effectively is a learned skill;
untrained users are sometimes frustrated with the large numbers of
articles returned by simple searches. Counterintuitively, a search
that returns thousands of articles is not guaranteed to be
comprehensive. Unlike using a typical
Internet search engine, PubMed
MEDLINE requires a little investment of time. Using the
MeSH database to define the subject of interest is one of the most
useful ways to improve the quality of a search. Using MeSH terms in
conjunction with limits (such as publication date or publication
type), qualifiers (such as adverse effects or prevention and control),
and text-word searching is another. Finding one article on the subject
and clicking on the "Related Articles" link to get a collection of
similarly classified articles can expand a search that otherwise
yields few results.
For lay users who are trying to learn about health and medicine
topics, the NIH offers MedlinePlus; thus, although such users are
still free to search and read the medical literature themselves (via
PubMed), they also have some help with curating it into something
comprehensible and practically applicable for patients and family
PubMed - explore PubMed/
MEDLINE with Gene Ontology
HubMed - an alternative interface to the
PubMed medical literature
eTBLAST - a natural language text similarity engine for
other text databases.
Twease - an open-source biomedical search engine
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