"Disciplining" toddlers

My 1.5 year old has started hitting and slamming things, like cabinets and doors, or shrieking and pulling my hair when angry. He speaks in 3 to 4 word sentences and understands at least a little of what we tell him, such as "we can't do that" or "that's not safe" but even so I just don't know how to approach curbing the hitting and anger. We've tried very very very brief supervised "timeouts" (him sitting on the floor next to me in the kitchen for a minute) but I feel like it isn't helping. 
Any suggestions?