Isoscaling of projectile-like fragments

In this paper, the isotopic and isotonic distributions of projectile fragmentation products have been simulated by a modified statistical abrasion--ablation model and the isoscaling behaviour of projectile-like fragments has been discussed. The isoscaling parameters \alpha and \beta have been extracted respectively, for hot fragments before evaporation and cold fragments after evaporation. It looks that the evaporation has stronger effect on \alpha than \beta. For cold fragments, a monotonic increase of \alpha and |\beta| with the increase of Z and N is observed. The relation between isoscaling parameter and the change of isospin content is discussed.