基于认识化学正向价值的教学实践——以“二氧化碳*”为例

模拟大型科普求真类节目《是真的吗？》创设学习氛围;通过基于生活生产实际的“日常灭火可否用N₂代替CO₂”“深海捕获CO₂可否调控温室效应”“石油采矿业中,向油井下注射1吨CO₂可否增产原油3~5吨”“用石灰水可否保鲜鸡蛋”等4个核心问题及3个真假难辨的小问题,引导学生从化学的正向视角深刻认识二氧化碳的性质;利用移动磁贴板设计板书,引导学生经历并建构结构化知识体系。     

CT检查参数对腰椎管狭窄症的诊断价值及与疗效、腰椎功能改善的相关性分析

选取我院60例腰椎管狭窄症(LSS)患者作为研究组,同期健康者60例作为对照组,探究CT检查参数对LSS的诊断价值及与疗效、腰椎功能改善的相关性。结果显示,研究组椎管面积、硬膜囊面积、椎管矢径、椎管横径、侧隐窝矢径、侧隐窝角小于对照组(P<0.05);CT各参数联合诊断LSS的AUC值大于任一参数单独诊断;疗效优良患者术后3个月椎管面积、硬膜囊面积、椎管矢径、侧隐窝矢径、侧隐窝角大于治疗前及非优良患者(P<0.05);经偏相关性分析发现,CT检查参数与疗效显著相关(P<0.05)。说明LSS疗效、腰椎功能改善情况与椎管面积、硬膜囊面积、椎管矢径等关系密切,CT检查对指导临床完善手术方案有重要意义。     

Analyzing Anisotropic Exchange in a Pentanuclear Os2Ni3 Complex

Spin Hamiltonian parameters of a pentanuclear Os Ni cyanometallate complex are derived from ab initio wave function based calculations, namely valence-type configuration interaction calculations with a complete active space including spin-orbit interaction (CASOCI) in a single-step procedure. While fits of experimental data performed so far could reproduce the data but the resulting parameters were not satisfactory, the parameters derived in the present work reproduce experimental data and at the same time have a reasonable size. The one-centre parameters (local matrices and single-ion zero field splitting tensors) are within an expected range, the anisotropic exchange parameters obtained in this work for an Os−Ni pair are not exceedingly large but determine the low-T part of the experimental χT curve. Exchange interactions (both isotropic and anisotropic) obtained from CASOCI have to be scaled by a factor of 2.5 to obtain agreement with experiment, a known deficiency of such types of calculation. After scaling the parameters, the isotropic Os−Ni exchange coupling constant is cm⁻¹ and the D parameter of the (nearly axial) anisotropic Os−Ni exchange is ⁻¹, so anisotropic exchange is larger in absolute size than isotropic exchange. The negative value of the isotropic J (indicating antiferromagnetic coupling) seemingly contradicts the large-temperature behaviour of the temperature dependent susceptibility curve, but this is caused by the negative g value of the Os centres. This negative g value is a universal feature of a pseudo-octahedral coordination with configuration and strong spin-orbit interaction. Knowing the size of these exchange interactions is important because Os(CN) is a versatile building block for the synthesis of / magnetic materials.     

湿法脱硫浆液中Hg2+的还原机制研究

针对燃煤电厂湿法脱硫浆液中Hg²⁺易被还原的特性,研究Hg²⁺在模拟湿法脱硫系统中的迁移机制,考察了浆液温度、pH值以及SO₃^2-、Cl^-、Ca²⁺、Mg²⁺浓度等因素对Hg²⁺还原性能的影响。结果表明,Hg²⁺还原率随着浆液中SO₃^2-浓度的增大而降低;pH值对Hg²⁺的还原呈先增加后降低的趋势,在pH值为5.5时还原率最高;温度的升高不利于浆液中稳定的二价汞盐络合物存在,导致Hg²⁺还原率增加;Ca²⁺、Mg²⁺以及Cl^-浓度的增加有利于形成稳定化合物,从而抑制Hg²⁺的还原。     

化学计量研究进展

叙述了化学计量的特点、作用和重要性及其研究内容,探讨了标准物质量值传递系统及实现标准物质量值溯源性的途径,阐述了建立化学测量溯源性的重要性、困难性、复杂性及基本设想和途径,并对化学计量中物质的量“摩尔”进行了简要论述。     

Periodic precipitation of cobalt(II) oxinate in agar gel: factors influencing the flocculation

The influence of concentration, ageing and pH of the gel medium on the periodic precipitation of cobalt oxinate in agar gel is reported. The results are explained on the basis of Shinohara’s revised flocculation theory. The flocculation value (F) increases with increase in the gel concentration whereas it decreases with increase in ageing and pH of the gel. The raise in temperature of the gel increases the solubility of the sparingly soluble substance and hence theF value. The effect of additives on the periodic precipitation of cobalt (II) oxinate is reported.     

Boundary integral equation methods in the theory of elasticity of hemitropic materials: A brief review

The theory of elasticity of hemitropic materials has recently been the object of rigorous mathematical analysis. In particular, the potential method and the theory of pseudodifferential equations have been used in studying the solvability in various function spaces of the main boundary value and transmission problems, in smooth and in Lipschitz domains. The main features and results of this boundary integral equations approach are briefly reviewed here.     

Singular and nonsingular first-order initial value problems

Under barrier strip type arguments we investigate the existence of global solutions to the initial value problem x^′=f(t,x,x^′), x(0)=A, where the scalar function f(t,x,p) may be singular at x=A.     

单位圆周上多解析函数的Riemann边值问题(英文)

本文研究了单位圆周上具不同回子的Riemann边值问题的可解性.利用转化法,得到了可解条件和解的表达式,将现有的相同冈了的情况作为特例.     

On solvability of boundary value problems for higher order nonlinear hyperbolic equations

In the rectangle Ω=[0,a]×[0,b] for the nonlinear hyperbolic equation

the boundary value problems of the type

are considered, where and are linear bounded functionals.Sufficient conditions of solvability and unique solvability of the general problem and its particular cases (Nicoletti type, Dirichlet, Lidstone and Periodic problems) are established.