The reaction rate is limited by the concentration gradient of oxygen in the sample.
反应速率受试样中氧浓度梯度的限制。
The change of the mass concentration gradient of uranium metal is obviously regular.
铀金属质量浓度梯度变化规律明显；
The change of the mass concentration gradient of uranium metal is obviously regular.
铀金属质量浓度梯度变化规律明显；
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