  Based upon the general supercharges which involve not only generators C_j of
the Clifford algebra C(4,0) with positive metric, but also operators of third
order, C_j C_k C_l, the general form of N=4 supersymmetric quantum mechanics
(SSQM), which brings out the richer structures, is realized. Then from them, an
one-dimensional physical realization and a new multi-dimensional physical
realization of N=4 SSQM are respectively obtained by solving the constraint
conditions. As applications, N=4 dynamical superconformal symmetries, which
possess both the N=4 supersymmetries and the usual dynamical conformal
symmetries, are studied in detail by considering two simple superpotentials k/x
and \omega x, and their corresponding superalgebraic structures, which are
spanned by eight fermionic generators and six bosonic generators, are
established as well.
