Nonpartonic components in the nucleon structure functions at small Q(2) ina broad range of x

We construct a simple two-phase model of the nucleon structure functions va lid for both small and large Q(2) and in the broad range of Bjorken x. The model incorporates hadron dominance at small x and Q(2) and parton model at large Q(2). The VDM contribution is modified for small fluctuation times o f the hadronic state of the photon. With two free parameters we describe SL AG, CERN NMC, Fermilab E665 and CERN BCDMS data for both proton and deutero n structure functions. Our model explains some phenomenological higher-twis t effects extracted from earlier analyses. A good description of the NMC F- 2(p)(x) - F-2(n)(x) data is obtained in contrast to other models in the lit erature. We predict faster vanishing of the partonic component at low Q(2) than previously expected and strong Q(2) dependence of the Gottfried Sum Ru le below Q(2) approximate to 4 GeV2.