BEFORE TKOF, THE PLT WAS BRIEFED ON FLT PRECAUTIONS FOR IFR & SNOW; HOWEVER, HE WAS NOT ADZD OF ICING CONDS IN CLOUDS & PRECIP ABOVE THE FREEZING LVL TO 18,000' AS CAUTIONED IN THE CURRENT AREA FORECAST. WHILE CLIMBING AFTER TKOF, HE ENCTRD CLOUDS & 'SOME LIGHT ICING' BTN 5500' & 6000'. HE CONTD AN EN ROUTE CLIMB UNTIL IN THE CLEAR AT ABOUT 10,000'. DRG THE CLIMB, PREDOMINANTLY RIME ICE & SOME MIXED ICE ACCUMULATED ON THE WINDSHIELD & WINGS. DRG DSCNT TO THE DESTN, SIMILAR ICING CONDS WERE ENCTRD UNTIL THE ACFT WAS IN THE CLEAR AT APRX 4600'. THE PLT THEN FLEW IN VFR CONDS TO CLEAR HIS WINDSHIELD. ESTIMATING ABT 1/4' OF ICE ON THE WINGS, THE PLT BEGAN A TURN TO FINAL AT APRX 600' TO 700' AGL WITH A 10 KT SAFETY MARGIN (90 KTS). HOWEVER, DRG THE TURN, THE ACFT STALLED. THE PLT STATED HE APPLIED CORRECTIVE ACTION, BUT THE ENG DID NOT RESPOND TO APPLICATION OF FULL THROTTLE. BEFORE RECOVERING, THE ACFT STRUCK THE GND & SLID APRX 300' TO A STOP. AFTER THE ACDNT, ICE WAS FND ON THE WINGS WHICH WAS APRX 3/4' THICK AT THE LEADING EDGES.