فهرس المقالات Pyran annulated hetrocyclic systems حرية الوصول المقاله صفحة الملخص نص كامل 1 - A green protocol for synthesis of pyran annulated hetrocyclic systems using Na2SO4 as an efficient catalyst Malek Taher Maghsoodlou Amin Masoumnia Mir Rasul Mousavi Nourollah Hazeri Jasem Aboonajmi Sayyed Mostafa Habibi-Khorasani Shiva Kiaee