  The nonlinear ballistic conductance of three-dimensional quantum
microconstrictions, which contain magnetic impurities, is investigated. The
nonlinear part of the conductance, which is due to the interaction of electrons
with magnetic impurities is obtained. The analytical results have been analyzed
numerically. It is shown that intensity of the Kondo anomaly in the conductance
as the function of the applied voltage depends on the diameter of the
constriction and the positions of impurities.
