Stem from these reasons, the paper made a detailed description about the retention of HPAM in porous media.

出于上述理由，本文对HPAM在多孔介质中的滞留作出了详细的阐述。

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Barclays believes the main reasons for these declines stem from poor ore grades being mined as well as disruptions in the form of strikes, with some pipeline cuttings, and poor weather.

FORBES: Analysts Look For Decline In 2011 Global Copper-Mine Production