Keyword searching in the PubMed interface is fine, but you may want to use MeSH (Medical Subject Headings) to create a more precise search (with fewer irrelevant results to screen).  To use MeSH:

1. Search the MeSH Database link in the "Explore" column below and to the right of the PubMed search box, or
2. Find assigned Mesh terms at the bottom of every article record if the journal is indexed for MEDLINE.

Here's an example of a simple PubMed MeSH hierarchy:

Once you have search results in PubMed (whether you use MeSH to construct your search or not), use the "Publication Date" filter to select the timespan you want.  Use the "Article Type" filter to limit to Randomized Controlled Trials or other article types. If you don't see the option you want, use the "Additional filters" button to add the option you want to the Filters sidebar.

Check the Advanced search to see how your search is interpreted. The search below will search for (multicenterstudy[Filter] OR randomizedcontrolledtrial[Filter]). If you are looking for articles that are both multicenter and RCT you will need to adjust your search to (multicenterstudy[Filter] AND randomizedcontrolledtrial[Filter])

In considering your selection of an article from your search results, look up the full journal name -- from the PubMed abbreviation and check that the journal is currently indexed for MEDLINE.

Then consult Journal Citation Reports for the impact factor rating and other information regarding how highly cited the journal is compared to other journals covering your subject:

--------------------------