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Suspended graphene devices are successfully fabricated by using a novel PMMA/MMA/PMMA tri-layer resist technique. The gap between graphene and dielectric substrate can be easily controlled by the thickness of the bottom PMMA layer, and no wet-etching with hazardous hydrofluoric acid is involved in our fabrication process. Electrical characterizations on suspended graphene devices are performed in vacuum when in-situ current annealing directly leads to a significant improvement on transport properties of graphene, i.e., the increase of carrier mobility with the reduction of width of Dirac peak. Our results make a new opportunity to study intrinsic properties of graphene. 相似文献
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闹牛山铜矿床次火山岩及与成矿的关系 总被引:4,自引:0,他引:4
论述了闹牛山铜矿床的地质特征,着重阐明铜矿床受火山机构、次火山岩,隐爆角砾岩控制,并将隐爆系统角砾岩划分为隐爆角砾岩,隐爆震碎热液角砾岩和隐爆破裂隙带三种类型。讨论了火山岩岩石化学、稀土元素特征;次火山岩,隐爆系统然砾岩与成矿关系,硫同位素特征,爆裂温度特征,并提出了闹牛山铜矿为与次火山岩有关的浅成中低温热液矿术。 相似文献
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河北省如期完成了5000多个有效矿业权的实地核查工作,为了全面掌握矿业权分布情况,对核查成果进行了较为系统的分析。按照矿种、经济类型、行政区划等对探矿权分析,按照矿种、行政区、发证类别、经济类型、开采方式等多角度对采矿权进行分析。通过分析,不但摸清了河北省矿产资源家底,而且对于今后矿政管理及矿产资源规划有重要意义。 相似文献
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