In a broad sense, research is the gathering of facts and information on a particular topic. The goal of research is to further the body of knowledge in a field.
In the field of science, research is a methodical study undertaken to answer a question or prove a hypothesis, and includes an interpretation of the findings.
Often, these studies are published as articles in scientific journals. Articles can be accessed via individual journals (in print or online), or in databases, which contain mass collections of articles from many different journals.
You may need resources for conducting primary, or secondary research, or both!
Primary Resources: Contain original information like studies, clinical trials, reports, dissertations, technical reports and data that hasn't been interpreted. They don’t summarize, grade, or appraise the studies/data (you do that yourself). Advanced search skills for efficient retrieval are required.
Secondary (Filtered) Resources: Contain research that has been evaluated, summarized and/or synthesized such as literature (or systematic) review articles, textbooks and some clinical databases.
Are there databases with both?
Many databases, like PubMed, contain both primary and secondary research. Cochrane, has mainly secondary research (review articles), but also includes abstracts of randomized controlled trials. In most databases, there are ways to limit to primary or secondary research by using limits or filters.