15℃硼酸锂-硼酸钾-硼酸镁-水体系相平衡与相图

采用等温溶解平衡法研究四元体系硼酸锂-硼酸钾-硼酸镁-水15℃时固液相平衡,测定了体系溶解度和平衡液相的密度、折光率.研究发现:该体系15℃稳定相图中包含一个共饱点(L+Li2B4O7·3H2O+K2B4O7·4H2O+Mg2B6O11·15H2O),其液相组成为w(Li2B4O7)1.31％、w(K2B4O7)10....     

热解法制备碱式碳酸镁

以盐湖水氯镁石氨法一次沉镁后的母液经碳酸氢铵二次沉镁得到的复盐MgCO3·(NH4)2CO3·H2O为原料,采用热解法制备碱式碳酸镁.研究液固比、Mg2 用量、预氨量、热解温度和热解时间对产品质量的影响.研究结果表明:在液固比为6,Mg2 实际用量与理论用量的摩尔比为1：1,热解温度为90～100 ℃,预氨量为0.2 mL/g复盐和热解时间为4.0 h的工艺条件下得到的碱式碳酸镁质量达到HG/T 2959-2000标准,该工艺可作为盐湖水氯镁石制备碱式碳酸镁的有效方法.     

Mg4Nb2O9/Ag 共烧微波介质陶瓷性能研究

采用固相法,制备了Mg4Nb2O9微波介质陶瓷,研究了银粉与Mg4Nb2O9陶瓷粉体的化学兼容性和微波介电性能.通过X射线衍射谱(XRD)、扫描电镜(SEM)等分析测试手段,对材料的晶相组成、显微结构进行了研究.采用V2O5、Li2CO3复合掺杂来降低Mg4Nb2O9陶瓷的烧结温度,以便能够与银粉匹配共烧.结果表明,1.5%V2O5和1.5%Li2CO3(VLi)共掺杂可使925℃烧结无第二相生成.该陶瓷良好的整体微波介电性能可用于微波材料.     

微波合成四钛酸钾晶须

采用微波加热工艺,以K_2CO_3和TiO2为原料合成了K_2Ti_4O_9晶须。通过X射线衍射和扫描电子显微镜对材料的相组成及微观形貌进行表征,研究K_2O和TiO_2物质的量比、微波加热温度及保温时间对合成K_2Ti_4O_9晶须物相及形貌的影响。研究结果表明:n(K_2O)∶n(TiO_2)为1∶3.0时,850℃微波加热15 min合成的K_2Ti_4O_9晶须,大小均匀,直径0.5~1.0μm,长25~40μm,长径比大于30。与常规加热相比,合成温度降低了150℃,同时大大缩短了工艺周期。     

BaCu(B2O5)的合成及其对CLST陶瓷烧结性能的影响

分别采用固相反应法和共沉淀结合固相反应法合成了BaCu(B2O5)粉体,并研究了所合成BaCu(B2O5)粉体对CLST陶瓷的烧结性能的影响规律.结果表明:以BaO、CuO和B2O3为原料,BaO和B2O3先反应生成BaB2O4,进一步与CuO反应生成BaCu(B2O5).适当延长煅烧时间,有利于BaCu(B2O5)的...     

Ni-Zn共掺对(Mg0.95Ca0.05)TiO3陶瓷介电性能的影响

采用固相反应法制备(Mg0.95Ca0.05)TiO3陶瓷,探讨Ni-Zn共掺对(Mg0.95Ca0.05)TiO3陶瓷物相组成、微观结构和介电性能的影响。研究结果表明:复合添加NiO和ZnO,可在一定程度上抑制第二相MgTi2O5的产生,并能有效地降低烧结温度至1 300℃。当NiO和ZnO添加总量(质量分数)为2%,w(NiO)/w(ZnO)为0.5%:1.5%时,陶瓷在1 300℃烧结获得最佳介电性能:介电常数εr=20.39,7.67 GHz时的介电损耗tanδ=2.01×10-4,频率温度系数τf=-1.72×10-6/℃。     

水热法合成超细硫酸钙晶须

以CaSO4.2H2O为原料,采用水热法合成了超细硫酸钙晶须.以扫描电镜作为分析超细硫酸钙晶须直径的手段,得出制备超细硫酸钙晶须的最优工艺条件为反应温度120℃、料浆初始pH值9.8~10.1、料浆质量分数5%、原料粒度18.1μm.在此条件下,制备出了平均直径为0.19μm,长径比为98的超细硫酸钙晶须产品.得出的结论对超细硫酸钙晶须的工业化生产具有重要的指导意义.     

自蔓延冶金法制备硼粉的基础研究

提出采用自蔓延冶金法制备硼粉的新工艺·计算知B2O3 Mg反应体系的绝热温度(Tad)为2604K,对B2O3 Mg反应体系的相关反应进行了热力学分析,确定了采用自蔓延模式的可行性·差热分析(DTA)表明反应体系850～930℃放热峰的表观活化能为903 75kJ·mol-1,反应级数为n=1·X射线衍射分析表明燃烧产物主要由MgO,Mg3B2O6和B2O3等相组成,确定了燃烧产物的浸出条件以及三步浸出方案·光谱分析及化学分析表明硼粉纯度可达92 43%,平均粒度为0 5～0 8μm·     

V2O5和Li2CO3共掺杂对Mg4Nb2O9陶瓷烧结行为及微波介电性能的影响

采用固相法，制备了Mg4Nb2O9（MN）微波介质陶瓷，研究了V2O5和Li2CO3共掺杂对MgaNb2O9陶瓷烧结行为、相结构、显微结构和微波介电性能的影响．结果表明，采用1．5％V2O5和1．5％Li2CO3共掺杂，能够将Mg4Nb2O9（135O℃）陶瓷的烧结温度降至925℃，且有助于Mg4Nb2O9单相的形成．3．0％（V2O5，Li2CO3）共掺杂样品在925℃空气中烧结5h可获得良好的微波介电性能（介电常数为13．7，品质因数为77975GHz）．     

A位取代对ZnO-0．5SiO2陶瓷烧结特性和介电性能的影响

采用常规固相反应法,以ZnO-0.5SiO2体系为基体成分,研究了A位取代ZnO-0.5SiO2陶瓷的烧结特性和介电性能的影响规律.结果表明:Mg在一定范围内A位取代ZnO-0.5SiO2中的Zn可形成(Zn1-x,Mgx)2SiO4固溶体,x(Mg)最大固溶度不超过0.5.当取代量超过固溶度后,出现Mg2SiO4和Mg2SiO3相.x(Mg)≤0.5,陶瓷介电常数变化不大,品质因子较高;x(Mg)＞0.5时,陶瓷介电常数增大,品质因子急剧下降.研究还揭示了(Zn1-x,Mgx)2SiO4(x=0.1～0.3)陶瓷在1 275℃烧结具有良好的介电性能,其介电常数为6.19～6.23,品质因子为48 000～53 000 GHz,频率温度系数为-50×10-6～-60×10-6/℃.     

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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