  Applying a constant voltage to superconducting nanowires we find that its
IV-characteristic exhibits an unusual S-behavior. This behavior is the direct
consequence of the dynamics of the superconducting condensate and of the
existence of two different critical currents: j_{c2} at which the pure
superconducting state becomes unstable and j_{c1}<j_{c2} at which the phase
slip state is realized in the system.
