Google is now tracking the metrics of journals. They chose the h5 factor, which is basically the h factor taking into account the last 5 years. The search function works with keyword, as you can guess. So if you search for materials science journal with the keyword “materials”, you will only get results of journals whose name include “materials”, and skip journals like Nanoletters, ACS Nano or other ones.
If you click on the h5 link, you get a list of the top cited paper for that journal, neat. The 2007 graphene paper in Nature Materials of Geim and Novoselov is already cited >5600 times. Holy cow.