固定电位络合滴定法测定朱砂中硫化汞含量

基于溶液中Hg2+Br-各组分的分布系数在Br平衡浓度一定的条件下为常数,建立了固定电位络合滴定法测定朱砂中硫化汞含量的新方法.该方法采用HAc-NaAc缓冲溶液和KNO3为总离子强度调节缓冲剂、氯离子选择性电极为指示电极、饱和甘汞电极为参比电极,用KBr溶液滴定至固定电位286mV(vs.SCE),使用标准曲线法计算硫化汞含量.在选定条件下,消耗的KBr溶液体积与Hg的物质的量呈良好的线性关系,相关系数0.99997.用于朱砂中硫化汞的测定,相对标准偏差0.04%～0.08%,与传统络合滴定法比较,相对误差-0.07%～0.05%.该方法无需确定的化学计量点和已知滴定剂的浓度,方法简便准确,适合于朱砂中硫化汞含量的测定.     

固定电位络合滴定法测定朱砂中硫化汞含量

基于溶液中Hg2+Br-各组分的分布系数在Br平衡浓度一定的条件下为常数,建立了固定电位络合滴定法测定朱砂中硫化汞含量的新方法.该方法采用HAc-NaAc缓冲溶液和KNO3为总离子强度调节缓冲剂、氯离子选择性电极为指示电极、饱和甘汞电极为参比电极,用KBr溶液滴定至固定电位286mV(vs.SCE),使用标准曲线法计算硫化汞含量.在选定条件下,消耗的KBr溶液体积与Hg的物质的量呈良好的线性关系,相关系数0.99997.用于朱砂中硫化汞的测定,相对标准偏差0.04%～0.08%,与传统络合滴定法比较,相对误差-0.07%～0.05%.该方法无需确定的化学计量点和已知滴定剂的浓度,方法简便准确,适合于朱砂中硫化汞含量的测定.     

腐殖质与Ca~(2+)、Mg~(2+)、Co~(2+)、Ni~(2+)的络合作用及其在农业中的应用

用电位滴定法研究腐殖酸FA和HA与金属离子(Ca2+、Mg2+、Co2+、Ni2+)的络合作用,发现它们与金属离子形成的络合物比较稳定,在溶液中的络合形成常数可通过作图法获得 随着溶液中金属离子浓度的增大,络合形成常数减小,同时发现FA与金属离子的络合形成常数比HA的大 腐殖酸是土壤肥力高低的一个重要标志,在农业应用中具有重要作用     

黄原酸钾的电位滴定法测定

报道了以银电极为指示电极，饱和甘汞电极为参比电极，在丙酮一氨水介质中，用硝酸银电位滴定法测定黄原酸钾的含量，滴定终点敏锐，方法简便、准确，相对标准偏差低于0.50%(n=5)。     

腐殖酸与Cu2+、Zn2+、Fe3+的络合作用

用电位滴定法研究了腐殖酸与Cu^2 、Zn^2 、Fe^3 的络合作用．它们的络合形成常数可通过作图法获得．随着溶液中金属离子浓度的增大，络合形成常数减小．同时发现络合形成常数FA大于HA；Cu^2 和Fe^3 大于Zn^2 ．     

海水中钙的电位滴定

钙离子选择性电极为指示电极,饱和甘汞电极作参比,用硼砂盐缓冲液控制ＰＨ,以ＥＧＴＡ为滴定剂进行电位滴定,与现行用ＧＨＡ为指示剂,ＥＧＴＡ为滴定剂的络合滴定法相比,可减小络合滴定中目测终点的人为误差,故测量精度优于０．０８％。     

铀酰—酒石酸—二元羧酸的混合络合物

本文用电位滴定法研究了铀酰—酒石酸—二元羧酸(丙二酸、丁二酸、戊二酸、已二酸)的络合平衡,测定了在25±0.1℃,μ=0.1(KCLO_4)时的三元混合络合物的平衡常数,计算了溶液中各物种的平衡浓度.     

电位滴定法测定锡基合金中的铅

报告了用铅离子选择性电极为指示电极,电位滴定法测定锡基合金中铅的新方法.在测定体系中加入过量的EDTA标准溶液络合铅,再用Pb（NO3）2标准溶液滴定过量的EDTA.电位实跃明显,方法简便、快速,结果准确可靠.加标回收率达99.95%100.02%.     

用铜离子选择性电极电位滴定法测人发和尿液中的铜

本文以铜离子选择性电极作指示电极,用Trien作滴定剂,就电位滴定法对人发和尿中铜(Ⅱ)的测定条件、发样处理以及干扰实验进行了探讨.本法简便快速,结果与原子吸收法基本一致,其相对偏差小于5%,人发中铜的测定回收率在96.2-106.8%之间.     

电位滴定法测定食品中的氯化钠

本文应用电位滴定法测定食品中的氯化钠含量,以银电极作为指示电极,以双盐桥饱和甘汞电极作为参比电极,用硝酸银标准溶液作为滴定剂,采用二次微商法确定滴定终点。该法的加标回收率为98.54％～101.06％。     

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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