Evolution of N = 20, 28, 50 shell closures in the 20 ≤ Z ≤ 30 region in deformed relativistic Hartree-Bogoliubov theory in continuum

Magicity,or shell closure,plays an important role in our understanding of complex nuclear phenomena.In this work,we employ one of the state-of-the-art density functional theories,the deformed relativistic HartreeBogoliubov theory in continuum(DRHBc) with the density functional PC-PK1,to investigate the evolution of the N=20,28,50 shell closures in the 20 ≤Z ≤30 region.We show how these three conventional shell closures evolve from the proton drip line to the neutron drip line by studying the cha...     

对羟基苯甲醛的溴化及甲氧基取代反应液的高效液相色谱分析法

应用高效液相色谱技术，在正相硅胶柱上对时羟基苯甲醛滇化及甲氧基取代反应液进行内标法定性定量分析。流动相采用含１％冰醋酸的二氯甲烷，内标物采用对硝基苯酚，紫外检测波长为２７０ｎｍ。     

Eu2+掺杂KCaCl3晶体的生长及发光性能

通过坩埚下降法生长出不同物质的量分数Eu²⁺掺杂的KCa_1-xEu_xCl₃（x=0.005、0.01、0.02、0.03、0.05）单晶,并对晶体进行了X射线粉末衍射、热重、透过率、光致发光光谱、衰减时间、X射线激发发射光谱等测定。通过相图及结构分析,判断出该晶体为一致熔融化合物,并得出其为正交结构,晶胞参数为a=0.756 04 nm,b=1.048 23 nm,c=0.726 57 nm,空间群为Pnma（62）。在紫外光的激发下,晶体在434 nm左右有一个宽的发射峰,对应于Eu²⁺的4f⁶5d¹→4f⁷跃迁;光致衰减时间1.473 μs,晶体在X射线激发下的发光强度随Eu²⁺离子浓度增加而增强。     

Reflection Asymmetric Relativistic Mean Field Approach and Its Application to the Octupole Deformed Nucleus ^226Ra

A reflection asymmetric relativistic mean field （RAS-RMF） approach is developed by expanding the equations of motion for both the nucleons and the mesons on the eigenfunctions of the two-centre harmonic-oscillator potential. The efficiency and reliability of the RAS-RMF approach are demonstrated in its application to the well-known octupole deformed nucleus 226Ra and the available data, including the binding energy and the deformation parameters, are well reproduced.     

原子吸收法测定地下水硬度

测定水的硬度,一般采用经典的乙二胺四乙酸钠(EDTA)滴定法。其缺点是受操作条件(如滴定速度、反应液的温度等)的影响较大,在水质复杂、干扰因素较多时,干扰难以去除,滴定终点不易判别,测定误差较大。特别是测定大批水样时,取样量多,工作量大,花费时间长。考虑到北京地区地下水为Ca、MgHCO_3型,即构成地下水硬度的主要成分为钙盐和镁盐。因此本文用原子吸收(AAS)法测定钙、镁含量总和作为水的总硬度。测定了北京地区114个采样点的     

2-(4-氯代苯甲酰基)苯甲酸配合物光致发光研究

以Eu3+,Tb3+为中心离子,2-(4-氯代苯甲酰基)苯甲酸(HCBBA)为第一配体,邻菲咯啉(Phen)、三苯基氧膦(TPPO)、二苯亚砜(DPSO)为第二配体,合成了多种铕铽的二元和三元配合物,并测试其荧光效能,以研究配体的加入对中心离子发光强度的影响。结果表明,合成的配合物均发出Eu(Ⅲ)和Tb(Ⅲ)的特征荧光,但相对强度明显不同。在铕与2-(4-氯代苯甲酰基)苯甲酸根(CBBA)形成的配合物体系中,Phen和DPSO显示了较强的敏化作用,且Phen敏化效果更强,而TPPO则对配合物荧光有猝灭作用。在Tb-CBBA体系中,DPSO表现出很强的敏化作用, Phen和TPPO却对配合物荧光起猝灭作用,且TPPO猝灭效果更强。经红外推测,羧酸根均以双齿桥式与Eu3+和Tb3+配位;在3 200～3 600 cm-1出现水的弱的羟基的伸缩振动吸收峰,表明配合物中含有结晶水。     

价格一致性系统与风险偏好

本文研究了风险偏好问题.利用简单市场模型,讨论了个人风险偏好和市场风险偏好,给出了两种风险偏好的数学定义,该定义具有自然直观的经济学意义.     

无机砷甲基化研究进展

砷是一种生物活性元素。长期接触砷会导致癌症、心脏病、糖尿病等疾病的发生。无机砷甲基化是砷在动物体内的主要代谢方式,被公认为砷元素的解毒过程,因此无机砷甲基化的研究引起了科学家们的广泛关注并取得了重要进展。本文综述了近年来国内外学者及作者研究组在"砷甲基化酶","无机砷甲基化机制"及"无机砷甲基化抑制"等方面的研究进展。     

Influence of Intertube Additional Atoms on Sliding Behaviors of Double-Walled Carbon Nanotube

The effects of intertube additional atoms on the sliding behaviors of double-walled carbon nanotubes(DWCNTs) are investigated using molecular dynamics(MD) simulation method.The interaction between carbon atoms is modeled using the second-generation reactive empirical bond-order potential coupled with the Lennard-Jones potential.The simulations indicate that intertube additional atoms of DWCNT can significantly enhance the load transfer between neighboring tubes of DWCNT.The improvement in load transfer is guaranteed by the addition of intertube atoms which are covalently bonded to the inner and outer tubes of DWCNT.The results also show that the sliding behaviors of DWCNT are strongly dependent of additional atom numbers.The results presented here demonstrate that the superior mechanical properties of DWCNT can be realized by controlling intertube coupling.The general conclusions derived from this work may be of importance in devising high-performance CNT composites.     

气相色谱-氮磷检测器分析痕量磷化氢

采用柱前两次冷阱富集和气相色谱 -氮磷检测器 (GC -NPD)法 ,测定了大气环境中存在的痕量磷化氢 ;在原有的冷阱富集装置中配置温度控制仪和夹套冷阱控温 ,可在线检测并控制磷化氢的富集温度 ,并可选择不同的温度范围将其与厌氧环境中普遍存在的甲烷气体分离 ;该法的检出限为1.25×10-2pg。