  We present a multiphase model for the evolution of elliptical galaxies.
Diffuse gas, molecular clouds, stars and remnants are taken into account.
Cloud--cloud collisions and stimulated processes are the main causes of star
formation. The occurrence of winds driven by Supernovae is considered, and the
evolution of the system is computed also after the first wind, allowing for
further star formation from the restored gas. The evolution of the abundances
of 15 elements or isotopes is followed with detailed stellar nucleosynthesis.
Stellar lifetimes are taken into account and a new IMF has been adopted. The
gas removal due to the Supernovae explosions depends on the galactic mass and
the presence of dark matter; the subsequent wind episodes are crucial to the
intergalactic gas enrichment. Good agreement is obtained for current SNs rates,
Star Formation Rate and gas masses when compared to the available data.
