Boolean search operators AND, OR, NOT, and SAME may be used to combine terms
in order to broaden or narrow retrieval.
Case does not matter when using Booleans. For example, SAME, Same, and same
returns the same results.
Use AND to find records containing all terms separated by the operator.
Use SAME to find records where the terms separated by the operator appear in
the same sentence. A sentence is defined as:
- the title of an article;
- a sentence in the abstract; or
- a single address.
Using the SAME operator instead of AND is a good way to narrow your search.
Use OR to find records containing any of the terms separated by the operator.
Use NOT to exclude records containing certain words from your search.
Search Order Precedence
If you use different operators in your search, the search is processed according
to this order of precedence:
copper OR lead AND algae finds all records in which both lead AND algae
are present as well as all records in which the word copper is present.
(copper OR lead) AND algae finds all records in which the word algae
is present together with either copper or lead.
Use of Parentheses
Use parentheses to override operator precedence. The expression inside the
parentheses is executed first.
(cadmium AND gill*) NOT Pisces finds records containing both cadmium
and gill (or gills), but excludes records containing the word Pisces
(honey bee* OR honeybee* OR Apis mellifera) SAME danc* find records
containing any one of the words or phrases in parentheses (for example, honey bee, honey bees, honeybee, honeybees, Apis mellifera) in the same sentence as any word beginning
with danc (for example, dance, dances, dancing).
Beverage AND bottle finds records containing
Beverage AND bottle AND beer finds records
containing all three terms.
Beverage SAME bottle finds records in which
these two terms must appear in the same sentence.
Beverage OR bottle finds records containing
either beverage or bottle (or both).
Beverage NOT bottle finds records containing
beverage but excludes records containing bottle.