TY - JOUR T1 - 7 TT - 7 JF - jsci JO - jsci VL - 1371 IS - 4 UR - http://jsci.khu.ac.ir/article-1-1277-fa.html Y1 - 1991 SP - 0 EP - 0 KW - 7 N2 - 7 M3 ER -