Search on Medline

Nieves Gonzalez Ramon ni.gonzalez.ramon at wxs.nl
Fri Mar 3 14:27:32 EST 2000


MEDLINE
Several interfaces allow the search on MEDLINE. Not willing to be
exhaustive I selected a sample of them:

1) Biomednet search interface.

http://www.biomednet.com/db/medline/advanced

This one offers a separate help window, independent from the search one
and giving brief but accurate info of the capabilities and a friendly
interface with menu choice of search fields.

a) Near operator for searching words in close proximity to each other.
Inside a phrase search, you can use the * to represent the possible
occurrence of intervening words. This is also known as ordered proximity
searching, as the words must still occur in the same order as they are
present in the phrase.
 e.g. 1 -Drosophila *1 homeotic- searches for the term "Drosophila"
followed by "homeotic" with no more than one intervening word. Items
retrieved include phrases such as "In Drosophila, most homeotic genes
are..." and "Drosophila homeotic genes are usually expressed...".
e.g. 2 -acetylation *5 histones- searches for "acetylation" followed by
"histones" with no more than 5 intervening words, and will match phrases

such as "acetylation of various Xenopus histones".

b) Wildcards Two symbols are available
* matches any number of characters including none. e.g. sul*ur matches
sulphur; sulfur. e.g. catheter* matches catheters; catheterisation;
catheterization; catheterise etc.
? matches exactly one character. e.g. sulf?nyl matches sulfonyl or
sulfinyl.
Using unnecessary wildcards may slow down response time. Consider using
stemming instead.

c) Stemming allows you to retrieve a group of words having the same word
root. For example, when stemming is switched on infection will also
match infect, infectious, infecting etc.
If the stemming checkbox is checked, stemming will be applied to all
query terms. If not, then + can be used after an individual word to
indicate that that word should be stemmed.
e.g. fluorescence+ and calcium produces around 50% more hits than
fluorescence and calcium
 Stemming is a faster alternative to wildcards, but, as with wildcards,
it cannot be used inside phrases.

d) Soundex matching
If you append the symbol $ to a search term, it will be matched using
soundex phonetic matching technology, to include similar sounding words.

e.g. stevenson$:au will match 'stevenson', 'stephenson' and 'stephens'
The soundex matching algorithm puts very loose constraints on what are
regarded as "similar" names, so it is most useful as an additional
constraint on an query rather than as a primary search mechanism itself.




2) The new version of PUBMED (launched on the web 4 months ago), with a
lot more of improved tools than the precedent one:

http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?db=PubMed

 This new version of PubMed with pull-down menus that display
- Field limits, indexes
- HISTORY of search queries  and combination of them (typing each query
as #1, #2 and combining with the Boolean AND; OR ;NOT always in capital
letters).
- Hyperlinks to the FULL TEXT document. Depending on the publisher the
article will be of free access or on subscription.
- Allows "saving a search query" in the format of an URL, so that it can
be resent to get updates of your frequently used searches.

3) Internet Grateful Med (IGM) searches MEDLINE using the retrieval
engine of NLM's PubMed system.

 http://igm.nlm.nih.gov/

Additionally it contains other Databases:
MEDLINE, AIDSLINE, AIDSDRUGS, AIDSTRIALS, BIOETHICSLINE, ChemID,
DIRLINE, HealthSTAR, HISTLINE, HSRPROJ, OLDMEDLINE, POPLINE, SDILINE,
SPACELINE, TOXLINE.
- Also allows "saving a search query" in the format of an URL.

Regards








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