2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/10704In this work we give detail consideration of the possible scenario of evolution of isolated neutron stars and determine some characteristics of X-ray pulsars from their spin period evolution (the paper containes more detailed abstract).8 pages and one PostScript figure. Presented as a poster on the NATO ASI "The many faces of neutron stars", Lipari, October 1-10, 1996Astrophysicstext