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Clinical and Research Support

Search Tips


Known as Boolean operators - AND, OR and NOT are used to combine search terms.

  • AND looks for both terms in the search results. Eg diet AND cancer will find articles mentioning both these terms. AND narrows your results
  • OR looks for either term in the search results  - it is inclusive. Eg diet OR cancer will find articles mentioning either of these terms. OR widens your results
  • NOT excludes terms. Eg. cancer NOT diet will find articles mentioning cancer but exclude any that also mention diet. NOT narrows your results, but should be used with caution as it can exclude useful results. For example, articles that include cancer AND diet are excluded in the example below.


These operators can be used to combine MeSH terms or keywords within a line of your search or to combine different lines. This is how you combine the separate concepts of your search.


For example, in this search the hand hygiene and hand disinfection terms are combined together,

then the results compared against guideline adherence.





  • Use the symbol to truncate words. This will find words with any ending after the . Eg surg* will find surgery, surgeries, surgeon and surgical. It is useful to ensure plurals are included.
  • can only be used for truncation at the end of words, not at the beginning.


  • Use the ? symbol to find different forms of a word. It looks for any, or no, letter. Eg wom?n will find woman or women. It is useful for international spelling. Eg p?ediatric will find paediatric or pediatric.


Proximity  (adjn)
  • Use adjn to find words within n (eg 1,,2 or 3 etc) words of each other, in any order. Eg cytology adj5 discrepancy will find discrepancy in cytology results…, cytology to determine discrepancy….. and discrepancy between histology and cytology .
  • adj ​means words have to be next to each other in the order written. Adj1 means the words have to be next to each other in any order, adj2 means 1 word between the words in any order, adj3 means 2 words between the words in any order, and so on. Linking words (known as stop words) such as and, is and of are not counted.


Nesting (brackets)

Nesting can be used to keep search items together to suit your search. These will give different results

A and B or C

(A and B) or C

A and (B or C)

All these methods can be combined.





Note that PubMed does not allow proximity searching.

In some databases the syntax may differ slightly - check the Help section for correct terminology.