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MOOC为学习者提供了自主学习的平台,但是高退课率一直是该领域未解决的难题。本项研究基于自主学习理论,分析了影响自主学习行为的......

Porphyrin polymers are of interest in relation to conductive materials[1, 2], catalysts for photosynthetic charge separa......

Introduction　　Panax quinquefolium L. Belongs to the Panax genus of the Araliaceae. It originates in America and Canada......

Introduction　　The heteropolyanion phase transfer chemistry created by Pope M. T. In 1984 has opened up a new field for......

In recent years, constrained-geometry group 4 metallocene catalysts have received considerable attention due to their im......