TY JOUR TI MARKET ANALYSIS OF THE RYAZAN REGION MEAT INDUSTRY USING MICHAEL PORTER'S COMPETITIVE FORCES MODEL KW Porter's Five Forces model KW industry structure analysis KW competitive advantage KW Ryazan Oblast meat market KW capital intensity KW vertical integration KW buyer power KW entry barriers KW product differentiation KW price competition JO INTERNATIONAL AGRICULTURAL JOURNAL AU Afanasyeva, Y.S. AU Kostrova, Y.B. AU Shibarshina, O.Y. PY 2026 IS 9 PB Electronic science