2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/47274We present very simple non-integral relations between deep inelastic structure functions $F_L$, $F_2$ and the gluon distribution at small $x$ based on perturbative QCD which are useful for the phenomenological analysis of data at low $x$. As an application we extract the deep inelastic scattering cross-sections ratio $R= σ_L/σ_T$ in the range $10^{-4} \leq x \leq 10^{-2}$ from $F_2$ HERA data.Latex (6 pages), 1 ps fig., sprocl, psfig; contribution to Madrid low x Workshop (Miraflores de la Sierra, Spain, June 18-21 1997), to appear in the proceedingsHigh Energy Physics - Phenomenologytext