BibDesk Help: 6.2 Syntax for Entrez Searching

Syntax for Entrez Searching

Entrez databases use a search syntax closer to natural language than does z39.50 databases. Enter key words, and the Entrez server will generate a custom set of search results based on its retrieval algorithms. Note that when searching PubMed for personal author names, `,' should not be entered between first names and last initials, and that first initials (as opposed to first names) are typically used, as in `wright s' or `fisher ra'.

For more focused searching, Entrez allows terms to be combined using Boolean operators. According to the Entrez documentation, available at Boolean Operators, these must be entered as follows.

`AND:'	Combine two search terms together to find all documents that contain BOTH terms.
`OR:'	Combine two search terms together to find all documents that contain EITHER term.
`NOT:'	Combine two search terms together to find all documents that contain search term 1 BUT NOT search term 2.

The Entrez search rules and syntax for using Boolean operators are:

Boolean operators AND, OR, NOT must be entered in UPPERCASE (e.g., promoters OR response elements).
Entrez processes all Boolean operators in a left-to-right sequence. The order in which Entrez processes a search statement can be changed by enclosing individual concepts in parentheses. The terms inside the parentheses are processed first as a unit and then incorporated into the overall strategy. For example, the search statement: `g1p3 AND (response element OR promoter)' is processed by Entrez by OR-ing the terms `response element OR promoter' first and then AND-ing the resulting set of `documents with g1p3'.

Another way in which searches can be focused in PubMed is by the use of extensions to the search terms. For instance, to search for `random genetic drift' in the MeSH terms field only, enter the following:

random genetic drift [hm]

into the search field. Note that the extension appears in brackets after the search key (`random genetic drift,' in this case).

Other useful extensions include the following.

Extension	Meaning
au	Author
1au	First author
lastau	Last author name
la	Language (use the first three letters of the language's name, but note that "ja" means "japanese".)
sh	MeSH Subheadings
dp	Publication date in YYYY/MM/DD format. Month and day are optional.
ti	Title
tiab	Title or abstract

Complete documentation of the extensions is provided at Search Field Description and Tags.