  The purpose of this paper is to give a characterization of the structure of
non-autonomous attractors of the problem $u_t= u_{xx} + \lambda u -
\beta(t)u^3$ when the parameter $\lambda > 0$ varies. Also, we answer a
question proposed in [11], concerning the complete description of the structure
of the pullback attractor of the problem when $1<\lambda <4$ and, more
generally, for $\lambda \neq N^2$, $2 \leq N \in \mathbb{N}$. We construct
global bounded solutions , "non-autonomous equilibria", connections between the
trivial solution these "non-autonomous equilibria" and characterize the
$\alpha$-limit and $\omega$-limit set of global bounded solutions. As a
consequence, we show that the global attractor of the associated skew-product
flow has a gradient structure. The structure of the related pullback an uniform
attractors are derived from that.
