I hope anyone blocking ads decides to register, or unblock ads. They have a helpful banner that pops up when you visit the site using an ad blocker, that directs you to a page[1] that very nicely explains that while they appreciate your cjoice, they use ads to fund the site, and provide a couple alternative ways to help them. One of those is to register, which they say allows browsing with less ads (I'm not sure if the implication is you'll register and then turn off the ad-blocker, but it seems to me to be clearly offered as an alternative).

In any case, they've very clearly set expectations.

1: http://phys.org/help/adblock/