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基于MATLAB的OFDM系统仿真 总被引：1，自引：0，他引：1
正交频分复用调制技术（OFDM Orthogonal Frequency Division Multiplexing）是由多载波调制（MCM）发展而来。文章讨论了OFDM的基本原理、建立了正交频分复用系统的数学仿真模型,用MATLAB语言实现了整个系统的计算机仿真并给出了参考设计程序。最后分析了不同的信道条件和调制体制下,系统的误码率特性。 相似文献
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介孔分子筛MCM-41对铅离子吸附性能研究 总被引：1，自引：0，他引：1
采用十六烷基三甲基溴化铵(CTAB)作模板剂,正硅酸乙脂(TEOS)为硅源,氨水(NH3.H2O)为碱性介质的条件下在常温下快速合成出了介孔分子筛MCM-41。采用X射线衍射(XRD)对合成样品进行了表征,XRD结果表明合成的MCM-41具备高的结构规整度。将该MCM-41作为吸附剂,对水中铅离子的吸附进行了研究。实验结果表明:MCM-41用量、吸附时间、吸附温度和pH值均影响其对铅离子的吸附率;其吸附动力学符合准二级动力学方程式;其等温吸附行为可以用Langmuir等温线来描述。 相似文献
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Tóshiko Takahashi-I?iguez Enrique García-Hernandez Roberto Arreguín-Espinosa María Elena Flores 《Journal of Zhejiang University. Science. B》2012,13(6):423-437
Vitamin B12 is an organometallic compound with important metabolic derivatives that act as cofactors of certain enzymes, which have been grouped into three subfamilies depending on their cofactors. Among them, methylmalonyl-CoA mutase (MCM) has been extensively studied. This enzyme catalyzes the reversible isomerization of L-methylmalonyl-CoA to succinyl-CoA using adenosylcobalamin (AdoCbl) as a cofactor participating in the generation of radicals that allow isomerization of the substrate. The crystal structure of MCM determined in Propionibacterium freudenreichii var. shermanii has helped to elucidate the role of this cofactor AdoCbl in the reaction to specify the mechanism by which radicals are generated from the coenzyme and to clarify the interactions between the enzyme, coenzyme, and substrate. The existence of human methylmalonic acidemia (MMA) due to the presence of mutations in MCM shows the importance of its role in metabolism. The recent crystallization of the human MCM has shown that despite being similar to the bacterial protein, there are significant differences in the structural organization of the two proteins. Recent studies have identified the involvement of an accessory protein called MMAA, which interacts with MCM to prevent MCM’s inactivation or acts as a chaperone to promote regeneration of inactivated enzyme. The interdisciplinary studies using this protein as a model in different organisms have helped to elucidate the mechanism of action of this isomerase, the impact of mutations at a functional level and their repercussion in the development and progression of MMA in humans. It is still necessary to study the mechanisms involved in more detail using new methods. 相似文献
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介绍了项目教学法在单片机教学及实训中的应用。在单片机教学及实训中采用项目教学法,有利于激发学生的学习兴趣,提高学生分析问题、解决问题的能力,有利于进一步提高学生的动手能力和综合能力,从而提高教学质量。 相似文献
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[目的/意义] 基于实证调查分析,探究大学生数学建模团队信息行为特征、信息行为模型及其影响因素,为提高大学生数学建模团队信息素养和创新能力提供科学参考。[方法/过程] 以大学生数学建模团队为研究单元,通过对数学建模团队信息行为的参与式观察和深度访谈获取个案数据,主要采用话语分析法和归纳性内容分析法对数据进行挖掘分析。[结果/结论] 大学生数学建模团队以电子信息需求为主,信息查寻以专业数据库为主、搜索引擎为辅;主要通过全文或关键词检索方式来进行文献检索;通过结果分享模式实现团队合作信息查寻;偶遇信息利用对问题解决和数学模型质量起重要作用;大学生数学建模团队信息行为有其一般行为模型。 相似文献
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将铜稳定、均匀分散在MCM 41型中孔材料的结构中 ,可充分发挥铜活性中心的催化活性。特定条件下 ,采用季铵盐类模板剂 ,在正硅酸乙酯 (TEOS)的水解聚沉时 ,向材料的结构中引入金属铜源 ,成功合成了分子自组装Cu MCM 41型分子筛。经XRD、FT IR、ED、HTEM、TG DTA分析 ,证实了样品属多晶态纳米材料 ,铜的骨架含量及脱模条件如焙烧温度、焙烧时间 ,对材料结构的稳定性及中孔有序度均有较大影响。 相似文献
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