In this paper, that the formula of cannot be tenable is pointed out because of the component of the momentum functor not always satisfying the self-adjointness in the curvilinear coordinate system.

指出由于在曲线坐标系中，动量算符的分量不一定满足自伴性，因而公式不能成立。

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In this paper, we get the self-adjointness of the product operators generated by different two differential expressions by operator theory and matrix calculation.

此前对微分算子的积算子自伴的研究主要集中于由同一个对称微分算式生成的两个或多个微分算子积的自伴问题上，取得了一些成果。

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