  We study the positive, regular, radially symmetric solutions to the nonlinear
biharmonic equation $\Delta^2 \phi = \phi^p$. First, we show that there exists
a critical value $p_c$, depending on the space dimension, such that the
solutions are linearly unstable if $p<p_c$ and linearly stable if $p\geq p_c$.
Then, we focus on the supercritical case $p\geq p_c$ and we show that the
graphs of no two solutions intersect one another.
