Reference Search Wildcards

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Reference Search Wildcards

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You may search references using the asterisk (* - match 0 or more characters) and question mark (? - match 0 or 1 character) wildcard characters.


Wildcard queries search a reference's:

  • Title
  • Abstract
  • Keywords
  • Substances/Medline Chemicals
  • CAplus Concepts
  • Medline MeSH
  • Medline Supplementary Terms

Wildcard characters can be used within a term or at the end of a term, but not at the beginning. Leading wildcard characters are not supported and are ignored in a query.

Important:

  • Wildcards contained within quotes are ignored.
  • Wildcards do not find two terms that a separated by a space (for example, water?based will find water-based but not water based).

Asterisk (*) wildcard queries return references containing:

  • An exact match that includes the asterisk.
  • The root term.
  • Terms with 0 or more additional non-space characters from the root.

Question mark (?) wildcard queries return references containing:

  • An exact match that includes the question mark.
  • The root term.
  • Terms with 0 or 1 additional non-space characters from the root.

Examples

The query Adsor* will match terms such as:

  • Adsorbents
  • Adsorbers
  • Adsorption

The query alumin?um will match terms such as:

  • Aluminum
  • Aluminium

Exceptions:

  • A term must have at least 3 non-wildcard characters for a wildcard to be searched. If a term has less than 3 non-wildcard characters, any wildcard terms will be searched literally.
  • A search query cannot contain more than 5 wildcard terms.

    _SFn-WildcardErrorMessage.png

Reference Search Wildcard Rules

Important: Synthesis of, Preparation of, Production of, and Biosynthesis of queries are currently not eligible for wildcard searching.

In order for wildcard searching to work:

  • A search term may only use 1 wildcard character (* or ?). Terms with 2 or more non-consecutive wildcards (or consecutive wildcards of differing types) are searched literally without wildcard functionality. Consecutive wildcards of the same type (* or ?) within a term are treated as one.

Examples:

    • (R*,S*,R*,S*)-2,3,6,7-Tetrachlorooctane searched literally, this will only return documents with (R*,S*,R*,S*)-2,3,6,7-Tetrachlorooctane
    • Ben*?ene searched literally as Ben*?ene
    • Ben**ene wildcard searched as Ben*ene
    • Ben??ene wildcard searched as Ben?ene
  • A search term cannot begin with a wildcard character. The wildcard character is ignored and the remaining characters are searched literally without wildcard functionality.

Examples:

    • **nzene searched as nzene, which would not return benzene
    • ?cetone searched as cetone
  • A search term ending in a wildcard character must be preceded by at least 3 characters.

Examples:

    • Ben* = valid wildcard term
    • Be* = invalid wildcard term
  • A query may not contain more than 5 valid wildcard search terms. If a query contains over 5 wildcard terms (? or * ), an error message displays. Note: Wildcard characters used in literal search terms do not count toward the limit.

Examples:

    • wat* ben? acet* car* tetra? hydro* = error message because there 6 valid wildcard terms.
    • wat* (R*,R*,R*) car* ben?ene (S*,R*,S*) acet? = valid query because there are 4 valid wildcard terms: wat*, car*, ben?ene, acet? and 2 literal searches: (R*,R*,R*), (S*,R*,S*).