Well for a researcher it is very handy to have notes with biblography . Yes you can highlight the paper but for creating a notes with link to biblographic reference is very handy when you have to describe your readings to your supervisor.
this save : http://guides.emich.edu/content.php?pid=330314&sid=2716437
Add these biblography in View-Styles-MoreSTyles and create notes, once you copy the biblography the notes will be copied as well
Also important read : http://blog.mendeley.com/tipstricks/7-ways-to-add-documents-to-mendeley/