Have a look at REF-N-WRITE scientific paper writing tool. This tool allows you to import text from previous papers relevant to the subject area in MS word. While you are writing your paper, you can just search for similar statements from other authors and inherit their vocabulary and language to improve your paper. It also comes with a library of academic phrases that you can readily use to polish your paper. Here is the link for the site.
First, I suggest that you have a look at the journal you are trying to get your paper published in. See if they tend to use the active or the passive in their papers and modify your expressions accordingly. Louis Rosocha 's suggestions are great.