PubMed is a freely available database developed by the National Center for Biotechnology Information (NCBI). Subject coverage includes:
PubMed includes access to MEDLINE® and to citations for selected articles in life science journals not included in MEDLINE. PubMed also provides access to additional relevant Web sites and links to the other NCBI molecular biology resources.
PubMed Clinical Queries allows you to find critically appraised information indexed in MEDLINE. PubMed uses a broad definition of systematic reviews. It includes systematic reviews, meta-analyses, reviews of clinical trials, evidence-based medicine, consensus development conferences, and guidelines.
You are also able to find original clinical studies using the Search by Clinical Study section of this interface.
Note: When reviewing original studies you need to critically appraise all material to determine the relative value of the study to your needs.