EXCLUSIVE: The girls are rising on The Big Bang Theory this season. The CBS comedy — which just upped costar Melissa Rauch to a full-fledged series regular — has rewarded Mayim Bialik with a similar bump. The former Blossom star made her debut as Sheldon’s quasi-girlfriend in last season’s finale and returned this fall on a recurring basis. Like Rauch, Bialik’s new deal is for this season only and — unlike the show’s central quintet — doesn’t call for her to appear in all episodes produced. Still, her promotion brings the number of female regulars on Big Bang to 3, improving the balance between the sexes on the comedy series which has 4 male regulars. Michael Ausiello will be contributing to Deadline.com and Movieline.com as he preps for the January launch of a new TV-centric website.