No, you need to be bringing the bar down to your chest.

While some will say it is bad for your shoulders, the reality is you need to going full ROM just like on all other exercises.

Partial reps will mean if your chest is ever stretched beyond that half range of motion, you could INJURE yourself.

If you stimulate the entire chest, you will be able to make better gains and build a bigger, fuller chest.

Related Questions:

1. Should I use full range of motion even if it hurts?
2. How will training in full range of motion (ROM) benefit my workouts?