They used to have a better paywall where Google's spider could see the results to index but if you went there - even from Google's cache you couldn't. I suspec

They used to have a better paywall where Google's spider could see the results to index but if you went there - even from Google's cache you couldn't. I suspect Google cracked down on this so they had to unblock the results. The block is in place for a few scientific journals, they must have worked out some deal with google to protect their content.