Abstract :
We present a model for the parton distribution in nuclei based on the assumption that the nuclear Fermi motion fully accounts for the collective motion of partons in nuclear medium. The presence of the Fermi motion changes the nucleon rest energy in the deep inelastic region and consequently the nucleon structure function inside a nucleus. The sea parton distributions are described by the modified virtual pion cloud of nucleon in such a way that the nuclear energy-momentum sum in the deep inelastic region is saturated. Very good agreement with the experimental data including nuclear Drell-Yan experiments has been obtained.