symmetric derivative

• 对称导数

symmetric derivative的用法和样例：

例句

1. The derivative of the step is the impulse.
   阶梯的导数就是脉冲。
2. Progress in the studies on new derivative atomic spectrometry was reviewed.
   摘要本文评介了导数测量技术在原子光谱分析中的应用研究进展。