Bear Spray can be used to deter bears at close range.
Bear Spray is available at http://www.defensedevices.com/bearpepspray.html

 

You get more power, range , OC concentration and effectiveness from these models.

http://www.defensedevices.com/bearpepspray.html or the Mace brand of bear spray http://www.defensedevices.com/mace-bear-pepper-spray.html are the best brands to get.

According to the National Park Service:

Bear spray is a non-lethal bear deterrent designed to stop aggressive behavior in bears. Capsicum, the active ingredient in bear spray is a strong irritant to the eyes, nose, mouth, throat, and lungs of bears. Bear spray has been proven to be a good defense against charging bears and has been effective in most reported cases where it has been used. Remember, no bear deterrent is 100% effective. Use proper bear encounter avoidance techniques as your first line of defense!