Boolean Operators

Boolean operators define the relationships between words or groups of words.

Use To
AND    Narrow search and retrieve records containing all of the words it separates.
OR Broaden search and retrieve records containing any of the words it separates. The | can be used instead of 'or' (e.g., 'mouse | mice | rat' is equivalent to 'mouse or mice or rat').
NOT Narrow search and retrieve records that do not contain the term following it.
( ) Group words or phrases when combining Boolean phrases and to show the order in which relationships should be considered: e.g., '(mouse or mice) and (gene or pseudogene)

Note: Search queries containing several operators search in the following order:

( )

To ensure that a search containing different operators performs as you intend, use parentheses: e.g., 'calder and (painting not (sculpture or mobiles))'.

Note: Depending on how the Boolean Operator AND is used with the Keyword Field (KW) results may be slightly different. Remember the keyword field automatically searches the Abstract(AB), Descriptor (DE), and TItle (TI) fields together. If a database has the Identifier(ID) field that field is also searched.

For example: KW=(nasa and mir) is processed as

TI=(nasa and mir) or AB=(nasa and mir) or DE=(nasa and mir) or ID=(nasa and mir)

KW=(nasa) and Kw=(mir) is processed as

(TI=(nasa) or AB=(nasa) or DE=(nasa) or ID=(nasa)) and (TI=(mir) or AB=(mir) or DE=(mir) or ID=(mir))

Proximity Searching

Proximity searches limit the number of words between your search terms.

Use To
No Operator Find words as a phrase, e.g., life stage transitions retrieves records containing the three words immediately adjacent to one another and in the same order.
WITHIN "X" Find words within a specified radius, e.g., carbon within 3 fiber retrieves records that contain carbon and fiber in any order and within a three word radius of one other. Any number may be used to determine the proximity radius.
NEAR Find words within 10 words of each other, e.g., (women near violence) retrieves records that contain women and violence in any order and within a 10 word radius of one other. Note: near is the same as within 10.
BEFORE Finds words in a relative order, e.g., social before security. Note: adjacency is not implied.
AFTER Finds words that contain words in the relative order specified with the after expression, e.g., scope after science. Note: adjacency is not implied.

Note: Use double quotes " " to search for "near", "before", or "after" as a term or part of a phrase, e.g., "near" death experience.

Wildcard Symbols

Wildcard symbols can expand the scope of your search.

Use For
* Truncation. This expands a search term to include all forms of a root word, e.g., patent* retrieves patent, patents, patentable, patented, etc.
* Multi-character wildcard for finding alternative spellings. Use to indicate an unlimited number of characters within a word, e.g., behavi*r retrieves behaviour or behavior.
? Single-character wildcard for finding alternative spellings. The ? represents a single character; two ?? represent two characters; three ??? represent three characters, and so on. Use within or at the end of a word, e.g., wom?n finds woman as well as women, and carbon fib?? finds carbon fiber or carbon fibre.

Note: Only words with characters equal to the number of ?'s present are retrieved, e.g., cell? retrieves cells and cello but not cell. Three characters are required before truncation, therefore h*ophilia will not function in our database.

Tip: When looking for singular and plural forms of short words that have a common root, such as cell, the truncation symbol may retrieve too many irrelevant words, while the wildcard symbol may retrieve too few words. In such a case, do not use wildcards and instead OR together the forms of the word you want, e.g., cell or cells.