As far I am aware, the only way to provide artificial gravity is to spin the body of the spaceship. Given that the human body readjusts itself to gravity again, weightlessness may be the lesser evil than radiation poisoning and running out of oxygen.
What rate of spin would generate artificial gravity?
Acceleration is V^2/R, where V is the linear speed at the rotating end a distance R from the axis of rotation. Earth 1G is approximately 10 m/sec^2. Choose your poison.