Graphene/Mo_2C heterostructure directly grown by chemical vapor deposition

Graphene-based heterostructure is one of the most attractive topics in physics and material sciences due to its intriguing properties and applications. We report the one-step fabrication of a novel graphene/Mo_2C heterostructure by using chemical vapor deposition(CVD). The composition and structure of the heterostructure are characterized through energydispersive spectrometer, transmission electron microscope, and Raman spectrum. The growth rule analysis of the results shows the flow rate of methane is a main factor in preparing the graphene/Mo_2C heterostructure. A schematic diagram of the growth process is also established. Transport measurements are performed to study the superconductivity of the heterostructure which has potential applications in superconducting devices.     

刍议数学“四基”下的有效教学

《义务教育阶段数学课程标准（2011）》中指出：教师要帮助学生理解和掌握基本的数学知识与技能,体会和运用数学思想与方法,获得基本的数学活动经验,也就是我们常说的“四基”．“四基”的出现给数学教学提出了更高的要求,如何围绕“四基”展开数学教学是当下要解决的重要问题．笔者从教学实践中反思和总结,归纳出以下几点方法．