Top 16 Journals in Biochemistry & Molecular Biology in 2014, according to Journal Citation Reports
"The journal Impact Factor is the average number of times articles from the journal published in the past two years have been cited in the JCR year. The Impact Factor is calculated by dividing the number of citations in the JCR year by the total number of articles published in the two previous years. An Impact Factor of 1.0 means that, on average, the articles published one or two year ago have been cited one time. An Impact Factor of 2.5 means that, on average, the articles published one or two year ago have been cited two and a half times. The citing works may be articles published in the same journal. However, most citing works are from different journals, proceedings, or books indexed by Web of Science." - Thompson Reuters
One very useful feature of Google Scholar is its ability to allow for easily finding subsequent articles which have cited a particular article that you have located.
Step 1: When looking at search results, check for the 'Cited by X' link underneath each result. That will tell you how many subsequent articles (that Google Scholar is aware of...it's not 100% comprehensive! This is a ballpark figure) have cited this particular article.