Combining Sets in Advanced Search
Scope
Combining sets of results enables you to increase the precision of your search.
Requirements and Limitations
You can use Boolean operators to combine two or more sets of results by using the
R#
numbers to the left of the set.
You can also use nesting with parentheses
( )
.
You can
only
do this in the
Advanced Search
mode,
not
in
Keyword
or
Relevance
modes.
You can
not
combine the sets through the use of proximity operators.
Example
A search on
anthrax
or
smallpox
give me the first set:
R1
(Anthrax or smallpox)
View 1014 Citations; Modify Search
A search on
terrorism
give me the second set:
R2
(Terrorism)
View 565 Citations; Modify Search
A search on
"
public health
"
give me the third set:
R3
("Public health")
View 13246 Citations; Modify Search
I combine the sets as follows:
r3
and (
r2
or
r1
)
to get the fourth set:
R4 (R3 and (R2 or r1))
View 138 Citations; Modify Search
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