二阶: second order差分: difference二阶差分变换: second-order difference transformation阶差分: difference of n-th order二阶差别图: second-order difference picture高阶差分: higher differences三阶差分: third difference; third order difference一阶差分: first difference; first order difference一阶差分法: first difference method; method of first differences一阶差分方程: first order difference equation; first-order difference equation一阶差分数列: first difference series一阶差分算子: first difference operator阶差: jump二阶: [数学] second order阶差淬火: differential quenching温度阶差: thermal taper压力阶差,压差: gradient pressure一阶差别图: first order difference picture二阶的: divalent二阶段: two-stage二阶法: second-order method二阶基: divalent radical二阶矩: second moment; secondary moment; secondarymoment二阶铃: second order fluid二阶酸: diatomic acid; dihydric acid