Please reason step by step, and put your final answer within \boxed{}.
Given a function $f(x)$ defined on $\mathbb{R}$ which satisfies $f(m + n) = f(m)f(n)$ for any real numbers $m$ and $n$, and $0 < f(x) < 1$ when $x > 0$, find the solution set for the inequality $f(x^2) \cdot f(2x - 3) > 1$.
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