Connecting terms with AND requires all terms to appear in the same article.
Connecting terms with OR results in articles that include one term, a combination of terms, or all of the terms.
Keep in mind that search is not a linear process -- you will need to test and revise as you go. Terms that seem good may not find good results, or your topic may be too broad or too narrow.
Before starting your database search, think about terms that can be used to describe the key concepts in your research question. Start your search with terms that you think make sense. When you find citations that are highly relevant to your research, take a closer look at those records. Examine those records for two types of terms that you can use in your search: subject headings and keywords.
Subject headings and keywords have different advantages and disadvantages. Keywords can retrieve new articles that do not yet have subject headings assigned to them. You can also use keywords to capture alternative spellings. Subject headings, however, will help you find highly relevant articles, and may mitigate the need to search for synonyms.
When you conduct your search, consider whether it makes sense to use keywords, subject headings, or both.
See "Documenting Your Search" to learn how to keep track of useful terms.
Many databases allow you to filter your search. You can usually find filters are on the left-hand side of your results page. Based on your selection criteria, you may want to filter your results based on:
If you're searching different databases for information, keep in mind that you may need to adjust your search terms for each database. For instance, the equivalent subject heading for "Heart, Artificial" in PubMed is "Heart, Mechanical" in CINAHL. Additionally, because CINAHL is an allied health and nursing database, you will find specialized subject headings such as "Toileting" in CINAHL that you won't find in PubMed.
Keywords are more likely to stay consistent across databases.