6.
\(f\)\((\)\(x\)\()=\log \)\({\,\!}_{a}\)\((\)\(x\)\({\,\!}^{2}-\)\(ax\)\(+3)(\)\(a\)\( > 0\)且\(a\)\(\neq 1)\)满足对任意的\(x\)\({\,\!}_{1}\),\(x\)\({\,\!}_{2}\),当\(x\)\({\,\!}_{1} < \)\(x\)\({\,\!}_{2}\leqslant \dfrac{a}{2} \)时,\(f\)\((\)\(x\)\({\,\!}_{1})-\)\(f\)\((\)\(x\)\({\,\!}_{2}) > 0\),则实数\(a\)的取值范围为 ( ).