High pressure X-ray diffraction study of CdAl2Se4 and Raman study of AAl2Se4 (A=Hg, Zn) and CdAl2X4 (X=Se, S)

We report the results of an X-ray diffraction study of CdAl₂Se₄ and of Raman studies of HgAl₂Se₄ and ZnAl₂Se₄ at room temperature, and of CdAl₂S₄ and CdAl₂Se₄ at 80 K at high pressure. The ambient pressure phase of CdAl₂Se₄ is stable up to a pressure of 9.1 GPa above which a phase transition to a disordered rock salt phase is observed. A fit of the volume pressure data to a Birch-Murnaghan type equation of state yields a bulk modulus of 52.1 GPa. The relative volume change at the phase transition at ∼9 GPa is about 10%. The analysis of the Raman data of HgAl₂Se₄ and ZnAl₂Se₄ reveals a general trend observed for different defect chalcopyrite materials. The line widths of the Raman peaks change at intermediate pressures between 4 and 6 GPa as an indication of the pressure induced two stage order-disorder transition observed in these materials. In addition, we include results of a low temperature Raman study of CdAl₂S₄ and CdAl₂Se₄, which shows a very weak temperature dependence of the Raman-active phonon modes.     

Full-relativistic calculation of electronic structure of Zr2AlC and Zr2AlN

We have employed a full-relativistic version of an all-electron full-potential linearized-augmented plane-wave method in the local density approximation to investigate the electronic structure of nanolaminate Zr₂AlX (X=C and N). The Zr 4d electrons are treated as valence electrons. We have investigated the lattice parameters, bulk moduli, band structures, total and partial densities of states and charge densities. It is demonstrated that the strength and electrical transport properties in these materials are principally governed by the metallic planes.     

论峡江地区“烧龙”与“烧畬”的区别和联系

唐宋时期峡江地区“击鼓焚山”的民俗活动是远古时代尚巫之风的残存,其目的是为烧龙祈雨以禳除旱灾;而“烧畬下种”则是自远古“刀耕火种”传承下来的一门农耕技术,但由于“占卜伺雨”的仪式亦使它带上了一些巫风色彩。二者既有明显的区别又有一定的联系。     

对市场营销专业课程整合改革的探讨

专业课程整合是教学改革的一个十分重要的内容。课程整合也是21世纪高等职业教育课程体系和教学方法改革的主要趋势之一，是当今 世界科学技术日益综合渗透的反映。是高等职业教育与社会实践和社会发展密切结合的结果。     

知识经济的可持续发展刍议

知识经济被视为实现可持续发展的必由之路，但它本身也有个可持续发展的问题。知识经济本质上是人的经济，它淡化了经济发展对天然资源的依赖关系，强化了对人自己创造的知识资源的依赖性，使得科技和教育的发展成为实现其可持续发展的关键；同时，处理和运用知识的手段和能力是知识转化为资源的重要环节，高科技产业的发展也因之成为其必要的条件；知识经济又是商品化经济，知识产权的保护等措施是保证知识生产和再生产顺利进行的环境支持。     

产品数据管理（PDM）在制造业中的应用与发展

在计算机技术快速发展的今天，许多企业的软件使用者和领导者开始体会到新技术带来的效益和进一步发展的必要性，认为到企业信息化的基础是产品数据管理（PDM）从PDM的产生、特点、结构、应用和发展等方面，详细地介绍了PDM的功能及其地位，以及在实施中要注意的事项。     

相对性原理与空间对称

本文分析了相对性原理与空间对称性的关系 ,指出物理规律不变性的破坏必然是时空空间的均匀性、对称性的破坏     

A Novel Biomass Supported Na2CO3 System for Flue Gas Desulfurization

The breakthrough and stoichiometric SO2 adsorption efficiencies of a biomass supported Na2CO3 system (80 wt %Na2CO3/straw) have reached 48.9% and 80.6% respectively at a desulfurization temperature of 80℃.     

R-拟连续模的不可分分解

设R是环,M是R-拟连续左R-模.如果R关于形如l（m）,m∈M的左理想满足升链条件,则M可写成一致子模的直和.