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1、平顶山学院 2008 届本科生毕业论文 HPGe 谱仪系统死时间校正方法的实验研究 王某某HPGe 谱仪系统死时间校正方法的实验研究摘 要摘要不要写成综述，一般要包含目的、方法、结果、结论这四大要素。特别是要把所做的主要工作、重要数据体现出来。字数不宜太少，建议 300 字以上。关键词：HPGe 谱仪；死时间；校正因子Experimental study on the method of deadtimecorrection For HPGe spectrometer systemAbstract英文摘要一定要复合语法结构规范，杜绝使用翻译工具现象。 correction for HPGe s
2、pectrometer system was given.The relation between the percent deadtime and the correction of counting rate losses for HPGe spectrometer system was found by using a strong source. Therefore ,the activity measurement can be finished at very high count rate,with this spectrometer.Keywords：HPGespectrome
3、ter; deadtime; coefficient of correction注意：如果摘要内容较多，一页排不下，则中文摘要（含关键词）单独占一页，英文摘要（含关键词）单独占一页。如下所示：注意标题上边有一空行小二号黑体/Times New Roman，加粗，居中，段前 1.5 行，段后1.5 行。小四号宋体/ Times New Roman，1.5 倍行距。 四号黑体，加粗，居中，段前0 行，段后 1 行。小四号黑体，加粗不要写成“关键字”小五号宋体/ Times New Roman小四号宋体/ Times New Roman 小三号字，Arial Black，居中，段前1.5 行，段后
4、1.5 行。标题两行间距 30磅四号字，Arial Black，居中，段前 0 行，段后 1 行。小四号字，Times New Roman，1.5 倍行距（如果内容较多可适当减小行距，以美观为标准）小四号字，Arial Black 小四号字，Times New Roman英文状态下的分号，且后有一空格首字母不需大写，除非是专有名词分号平顶山学院 2008 届本科生毕业论文 HPGe 谱仪系统死时间校正方法的实验研究 王某某-取代甲苯定向硝化的理论研究摘 要运用密度泛函理论(DFT), 研究了吸电子氟基和供电子羟基在取代甲苯的 -H 以后, 其邻、间、对各位次进行硝化反应的速控步骤, 在 B3L
5、YP/6-311G*水平上, 计算了该速控步骤基元反应各反应驻点(反应物、过渡态和中间体)的优化几何、电子结构和能量性质, 并首次给出了目标硝化反应速控步骤的 IR 谱学的动态特征及解析, 从微观层面上验证了反应坐标 CN 的形成和 CH 的断裂是非协同的, 从而无一级动力学同位素效应的实验事实. 通过对目标硝化反应速控步骤的微观动态计算, 验证了氟基对甲基定位的影响. 氟基的电负性大, 吸电子能力强, 取代甲苯的 -H 以后对硝酰阳离子的进攻有抑制作用, 活化能较取代前高, 但比较苄基氟各位次硝化活化能的相对大小得知, CH2F 仍为邻、对位定向基团. 而供电子羟基取代甲苯的 -H 以后,
6、则对硝酰阳离子的进攻有促进作用, 因而各反应驻点络合物的稳定化能较 -H 取代前甲苯的有所增大, 且邻、对位硝化的活化能较间位低, 故CH2OH 为邻、对位定位基. 但对位因硝化活化能低, 反应放热多, 空间位阻小, 为亲电试剂 NO最有利的进攻位；而邻位则因羟基取代甲苯 -H 后多了 2 一个氧原子, 增大了邻位进攻的空间位阻, 使得其络合物的能量比相应对位的高.关键词： 苄基氟；苄醇；-取代；取代基效应；速控步骤注意上下标平顶山学院 2008 届本科生毕业论文 HPGe 谱仪系统死时间校正方法的实验研究 王某某Theoretical Study on Selectivity for Nit
7、ration of-Substituted Toluene with NitroniumAbstractThe rate-determining steps of isomeric ortho, meta and para nitrations of benzyl alcohol and benzyl fluoride have been theoretically investigated at B3LYP/6-311G* level. Stationary points of the step involving reactant, transition state and interme
8、diate complexes were successfully located and characterized without any restriction on the internal coordinates. Their molecular geometries, electronic structures, IR spectra, and the FMO symmetries of two initial aromatic compounds and the nitronium ion have 2NObeen studied. The vibrational shifts
9、of CN and CH stretches from TS to INT at the rate-determining step of target aromatic nitrations show up that the formation of CN and the cleavage of CH are not con-cerned but stepwise to provide an explanation, on a microscopic scale, for the experimental fact of the absence of kinetic isotopic eff
10、ect in the nitration process for the first time. Also, the influence of introduced fluorine on the orientation effect was figured by calculating the microscopic and kinetic properties of the rate-determining step of concerned aromatic nitrations. The attack to the benzyl 2NOfluoride was deactivated
11、because of high electronegativity and strong electron withdrawal of fluorine atom. The activation energy after -substitution of methyl group by a fluorine atom became higher. Yet the CH2F group was still an ortho-para directive, since the activation energies of ortho and para nitrations were relativ
12、ely lower than that of meta nitration. Contrarily, the introduction of electron-donating substituent OH onto the methyl accelerated the attack. Consequently the stabilization energies of complexes were droped even 2NOlower than before the -substitution occurred. The activation energies of ortho and
13、para nitrations, however, were also quite lower than the energy of meta nitration. Therefore, the CH2OH is an ortho-para directing group. Compared to the ortho, the para position is the most favorable due to the to approach, for its low steric hindrance effect and high 2NOexothermicity. Attack at or
14、tho, however, became even more crowd since one more O atom has been introduced after the -substitution onto the methyl group. Hence, the energy of ortho nitrobenzyl alcohol complex is higher than the energy of para one.Keywords：benzyl fluoride; benzyl alcohol; -substitution; substituent effect; rate-determining step 注意上下标分子式不要用斜体
