  By studying the nonperturbative contribution to the
Dokshitzer-Gribov-Lipatov-Altarelli-Parisi and Gribov-Levin-Ryskin equation, it
is found that (i) the nonperturbative contribution suppresses the evolution
rate at the low $Q^2$, small-x region; (ii) the nonperturbative contribution
weakens the shadowing effect. The method in this paper suggests a smooth
transition from the low $Q^2$ ("soft"), where nonperturbative contribution
dominates, to the large $Q^2$ ("hard") region, where the perturbative
contribution dominates and the nonperturbative contribution can be neglected.
  PACS numbers:12.38.Aw, 13.60.Hb
