Skip to main content

Chemical Engineering: Search tips

Principles of online searching

7 steps to effective literature searching

1.  Define your question.
Example:  Are biosurfactants effective in the clean up of oil spills?


2.  Identify the appropriate source(s) to search.
Example:  Web of Science


3.  Break down the question into its separate concepts.
Example:  Are biosurfactants effective in the clean up of oil spills?


4.  Brainstorm synonyms for each concept and use the * symbol to account for variant word endings (e.g., spill* will search for spill, spills, spilling).  You can also search each concept separately to find appropriate subject headings when available in the database; using subject headings to search will increase the relevancy of your search results. 


5.  Combine synonyms using OR and different concepts using AND.
Example:  (biosurfactant* OR rhamnolipid*) AND ((oil AND spill*) OR (petroleum AND spill*)) AND (“clean up” OR cleanup OR recovery OR bioremediat*)


6.  Apply limits.
Example:  Limit search results to English language articles published in the past 5 years.


7. Evaluate your results & modify your search strategy if necessary.
Example:  Look at the title, abstract, author keywords, and/or subject headings of a relevant result to pick out additional words or subject headings that you can use to revise your search.

Keywords vs. subject headings

Keyword Searching

  • Keyword searching occurs when you just type words in the search box (e.g., oil spills).  A database will search for your exact words anywhere in the document, usually in the title and abstract of the article. 
  • You will NOT obtain references to articles that use variations of your words (e.g., spilling of oil) or mention synonyms (e.g., petroleum spills). 
  • You can also obtain false hits, i.e., search results that happen to mention your search words somewhere in the document but are not about your topic (e.g., Chemical accidents at sea, excluding oil spills, were examined in this study).
  • Use keyword searching when subject searching (see below) is not available in the database, a subject heading is not available for your topic, or to complement subject searching when you need to perform an exhaustive literature search.


Subject Searching

  • Subject searching is available in databases that assign subject headings to articles (e.g., Compendex, Medline/PubMed). 
  • Subject headings describe what the article is about and take into account different synonyms or spellings the authors may have used.  They are selected from a controlled list of vocabulary terms.
  • For example, all references to articles about implants in Compendex are assigned the same subject heading, “Implants (surgical),” regardless of the words that authors may have used in the title and abstract, such as prosthetic implants, surgical implants, surgical implantation, etc. 
  • Use subject searching, when available, to obtain as much of the published literature on your topic as possible, as well as to increase the relevancy of your results.  Use to complement keyword searching when you need to perform an exhaustive search of the literature.

Need help? Contact:

Giovanna Badia
Email514-398-7340

Ways to increase the number of your search results:

  • Brainstorm synonyms for your concepts.
  • Remove quotes around your search terms.
  • Combine keyword and subject searching if possible to do so in the database.
  • Search another database.

Ways to decrease the number of your search results:

  • Search using subject headings if possible to do so in the database.  You will obtain articles about your topic, rather than search results that happen to mention your search terms in the title/abstract and are irrelevant.
  • To decrease the number of results from a keyword search:
    • Place quotes around search terms that you would like to appear in an article as a phrase.
    • Review your synonyms for an individual concept and remove synonyms that are too general.
    • Add an additional concept to your search strategy.
    • Search for one or more of your concepts in the title of the article.

McGill LibraryQuestions? Ask us!
Privacy notice