see,there no such syntax that can use for that, but there is advance search button just under the google search bar in which one can put the specific words, and categories, this is for all users.
You can use the Affilorama SEO toolbar . This is a Firefox browser add-on that will show you which links are no follow and do follow in any webpage you visit. But really, searching for do follow blogs can take up much of your time that can be better spent participating in blogs and forums. Most blogs and forums are no follow these days anyway due to spam. Hope that helps. Have a good day!