is adblock a specific service or do you mean adblockers in general ?
you could tie an "onload" command to an image in the ad
<a href=sponsor.html><img src=adimage.jpg onload=showpage();></a>
the showpage function would show the page , i.e. if the ad image doesnt load the page wont be displayed, or you could hide/show a div container that holds a message like "sorry you cant view our page with adblockers enabled , please disable your adblocker to view this page"