EDTA络合滴定钙镁指示剂的改进

工业生产和控制中钙镁测定多采用EDTA络合滴定分析.在实际测定中,我们发现钙指示剂-萘酚绿B于pH=12时,EDTA络合滴定钙;以及酸性铬蓝K-铬黑T-萘酚绿B为指示剂于pH=10时,EDTA络合滴定钙镁合量均具有广泛的适应性.曾用于白云石、石灰石、烧结矿、啤酒中的钙镁测定,取得满意结果.并对指示剂的变色机理作了初步探讨.     

活性炭废水中钙镁离子含量测定方法研究

以EDTA为络合剂,络合活性炭废水中的钙、镁离子,通过指示剂显色变化,测定钙、镁离子含量;以乙酸铵为交换剂,交换活性炭废水中的钙、镁离子,交换出的钙、镁离子直接用乙炔火焰—原子吸收分光光度法测定。     

芦荟中钙和镁含量的检测

在萘酚绿B-KOH和铬黑T-乙二胺-KOH底液中,用线性扫描极谱法做电流-电压曲线,测定芦荟中的钙和镁.钙和镁分别在-0.602和-0.966 V左右的峰形较好.在相应的底液中,根据介质浓度、酸度及干扰离子对测定结果的影响,确定了各种因素的合理操作范围.此法测定钙和镁的线性范围,分别为5-500mg/L和1-40 mg/L,其回收率分别为99.10%和99.92%.     

芦荟中钙和镁含量的检测

在萘酚绿B-KOH和铬黑T-乙二胺-KOH底液中,用线性扫描极谱法做电流-电压曲线,测定芦荟中的钙和镁.钙和镁分别在-0.602和-0.966 V左右的峰形较好.在相应的底液中,根据介质浓度、酸度及干扰离子对测定结果的影响,确定了各种因素的合理操作范围.此法测定钙和镁的线性范围,分别为5-500mg/L和1-40 mg/L,其回收率分别为99.10%和99.92%.     

甘薯样品中钙和镁的快速测定

介绍了在室温下用 1mol·L- 1 盐酸直接浸提甘薯样品 ,并用络合滴定法测定钙和镁含量的方法。研究了试验条件和共存离子的干扰。对 4种样品 ,分别重复 5次测定其含量 ,平均变异系数钙为 0 .5 88% ,镁为2 .0 2 8% ,测定结果与常规的干灰化法测定结果比较 ,平均RSD钙为 0 .173% ,镁为 0 .40 6 %。该方法简便、快速、实用。也可应用于蔬菜样品的分析     

间氯偶氮安替比林双波长分光光度法同时测定钙和镁的研究

本文着重研究了用间氯偶氧安替比林作为显色剂,在 pH=10的硼砂缓冲溶液中,以三乙醇胺作为掩蔽剂,用双波长分光光度法同时测定钙和镁的新方法。测定钙选用655nm—587nm 作为波长对,测定镁选用600nm—674nm 作为波长对,有效地消除了钙镁之间的相互干扰。钙和镁的量均在5—30μg/25cm~3范围内符合比耳定律。提出的方法具有简便快速的特点,用于水样中钙和镁的同时测定,结果与原子吸收法测定值基本一致,回收率也令人满意。     

流动注射分光光度法同时快速测定水泥及其原材料中高低含量的钙和镁

本文提出用流动注射光度法测定水泥及其原材料中高低含量的钙、镁。以EGTA标准溶液掩蔽高钙含量样品中的部份钙,并将其掩蔽部份加入结果计算;以缓冲剂氨—氯化铵和CTMAB退色的显色剂二甲酚橙的混和液为载流;于570,590nm处同时测定钙,镁络合物的吸光系数和样品吸光度,通过联立方程组求解结果。同时快速测定了样品中从高到低含量的钙和镁。进样频率为120样/小时;样品测定的查对百分偏差为钙(0.24％～3％),镁12.6～4％)(视样品种类和含量高低而定)。     

分光光度法同时分析环境水样中钙镁含量

本文将计算数学与分光光度法相结合,采用酸性铬蓝K为显色剂在氨性条件下(pH10)对水样中的钙、镁含量进行了测定,用反推矩阵计算法计算钙、镁各自浓度,方法简单有效.     

多波长数据线性回归光度法同时测定钙和镁

本文研究了酸性铬蓝K体系用于同时测定钙和慎的显色条件，借助多波长线性回归法处理数据，提出光度测定钙和镁的简便方法，免去了分离手续。应用于三个水样中钙、镁含量的测定，结果满意。     

酸碱滴定法测定蛋壳中钙镁总量的改进

在高中化学实验中,利用酸碱滴定法测定蛋壳中钙镁总量,是鉴定蛋壳元素组成的有效手段。与此同时,酸碱滴定法主要化学反应原理是利用酸类物质溶解蛋壳中的钙元素和镁元素,进而通过判断消耗的碱溶液的数量,来判断蛋壳中的钙镁总量。针对这样的情况,该文将对酸碱滴定法测定蛋壳中钙镁总量的方法进总结研究,并对如何利用酸碱滴定法,改进蛋壳中钙镁总量测定效果的方式方法进行探索研究。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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