To apply the property of negative integer exponents, we use the rule that states:
\[ a^{-n} = \frac{1}{a^n} \]
In this case, we have \( 9^{-23} \).
Applying the property:
\[ 9^{-23} = \frac{1}{9^{23}} \]
Thus, the expression with positive exponents only is:
\[ \frac{1}{9^{23}} \]