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Finding Research Articles in PubMed and CINAHL

Limit to Type of Article


PubMed FiltersAll citations in PubMed are for journal articles. However, you may limit your retrieval based on the type of material the article represents. Click on Limits and look at the Type of Article checklist which contains a list of frequently searched publication types.


For example, limit by Randomized Controlled Trial or Clinical Trial or Meta-Analysis.




Or add Epidemiologic Studies[MeSH] to your topic search phrase.



Limit to Articles with Structured Abstracts



PubMed Structured AbstractsMany abstracts that are added to PubMed include section labels such as BACKGROUND, OBJECTIVE, METHODS, RESULTS, and CONCLUSIONS. These 'structured' abstracts appear in many different article types such as review articles, original research, and practice guidelines and facilitate skimming of citations for relevance and specific information such as research design within the Methods section.  The presence of structured abstracts in citations are a searchable feature in PubMed.  To limit to citations containing structured abstracts, include the term hasstructuredabstract in the search box.


For example: valerian AND sleep AND hasstructuredabstract

Clinical Queries




Locate PubMed clinical QueriesClinical Queries uses filters to limit retrieval to systematic reviews or research-based citations on clinical topics. The Clinical Queries link is found at the bottom of the Advanced Search screen or the PubMed home page. Enter your search terms and evidence-filtered citations will appear under Clinical Study Categories or Systematic Reviews.


Clinical Study Categories

This specialized search query with built-in research methodology search filters is intended for clinicians. Five study categories or filters are provided: etiology, diagnosis, therapy, prognosis, and clinical prediction guides. Two emphasis categories or filters are provided: broad, sensitive search (includes relevant articles but probably some less relevant) and narrow, specific search (more precise articles, with less retrieval).

NOTE: We suggest changing to Narrow scope rather than Broad.



Locate PubMed Clinical Queries


Systematic Reviews

 This feature is provided to help clinicians locate systematic reviews and similar articles. It combines your search term(s) with citations identified as systematic reviews, meta-analyses, reviews of clinical trials, evidence-based medicine, consensus development conferences, and guidelines.

The resulting retrieval in PubMed Clinical Queries can be further refined using PubMed's Limits, eg, English language, humans.



Locate PubMed Clinical Queries







Levels of Evidence

Graphic overview of the different types of references and the quality or level of evidence they provide.