  The main purpose of this paper is the study of the action that produces
Poisson-gradient systems and their multiple periodical solutions. The Section 1
establishes the basic tools.
  The section 2 underlines conditions in which the action $\phi (u) =
\displaystyle\displaystyle\int_{T_{0}}[ \displaystyle% \displaystyle{1/2}|
\displaystyle\displaystyle\frac{\partial u}{% \partial t}| ^{2}+F(t,u(t)) ]
dt^{1}\wedge >...\wedge dt^{p}$, that produces the Poisson-gradient systems, is
continuous, and some conditions in which the general action $\phi (u) =
\displaystyle\displaystyle\int_{T_{0}}L(t,u(t),
\displaystyle\displaystyle\frac{\partial u}{\partial t}(t)) dt^{1}\wedge
>...\wedge dt^{p}$ is continuously differentiable.
  The Section 3 studies the multiple periodical solutions of a Poisson-gradient
system in the case when the potential function $F$ has a spatial periodicity.

Dynamical Systems;Analysis of PDEs