BaTiO3式半导体陶瓷的晶界效应

针对一固定的低电阻率ＰＴＣ配方，在实验手段允许的范围内，以及在能保证瓷体半导化的温度范围内波动时，改变ＰＴＣ瓷片的烧成温度、保温时间和冷却速度，均未实现由ＰＴＣ效应向晶界层电容效应的转变；通过涂敷受主氧化物进行热处理，并且热处理温度较低低时就能实现由ＰＴＣ效应的向晶界层电容效应的转变，基于本实验的现象和数据，对解释ＰＴＣ效应的Ｈｅｙｗａｎｇ模型，Ｄａｎｉｅｌｓ钡空位模型和较为普遍公认的晶界层电容器     

低密度聚乙烯／氯化聚乙烯／炭黑复合导电体系…

研究了低密度聚乙烯（ＬＤＰＥ）／氯化聚乙烯（ＣＰＥ）／炭黑复合导电体系在室温到１４０℃温度范围内电阻对温度的依赖性。根据复合体系的形态结构提出了一种能够解释体系电阻率的正温度系数（ＰＴＣ）和负温度系数（ＮＴＣ）效应形成的新模型，该模型表明ＰＴＣ效应是由ＬＤＰＥ熔融时发生的晶相向非晶相的转变以及热膨胀共同引起，ＮＴＣ效应主要与炭黑粒子在高温下发生的附聚效应有关。此外还研究了各组分含量和热处理对ＰＴＣ     

聚乙烯—炭黑复合材料PTC特性的研究

主要研究了两种炭黑和不同聚乙烯对聚乙烯炭黑复合材料的电导及ＰＴＣ特性的影响，测量了复合体系的伏安特性．试验结果表明，使用炭黑Ｂ时复合材料的ＰＴＣ特性不明显，复合体系的电导机理主要为隧道效应．用相变模型可以较好地解释ＰＴＣ和ＮＴＣ现象．     

Ca^2＋掺杂对PTCR元件电性能的影响

研究了Ｃａ＾２＋取代Ｂａ＾２＋后对ＰＴＣＲ材料电性能的影响，发现随着Ｃａ＾２＋含量的增加，ＢａＴｉＯ３系ＰＴＣＲ样品的平均晶粒直径单调下降，耐电压性能单调上升。Ｃａ＾２取代量在一定范围内，常温电阻率变化不大，但超过一定值后，常温电阻率急剧上升，这种现象与晶界缓冲效应有关。     

炭黑／橡胶涂层复合材料导电性能的研究

本研究了橡胶／炭黑复合材料体系的导电性能。实验指出，其电阻率随温度的变化呈不同强度的正温度系数（ＰＴＣ）效应，讨论了不同炭黑粒子填充率，橡胶基体的性质，炭黑的结构及表面性质，加工工艺和硫化条件等对室温电阻率及ＰＴＣ效应的影响。     

偶联剂对正温度系数高分子材料性能的影响

研究了偶联剂对正温度系数（ＰＴＣ）高分子材料性能的影响,发现偶联剂Ｊ１、Ｊ２在中低温时有较好的分散效果,但高温时较差;耐高温的偶联剂Ｊ３在高温时有更好的分散效果,从而使高分子ＰＴＣ材料有较好的高温性能,但在中低温时稳定性较差,另外,辐照交联可以很好地增加材料的ＰＴＣ强度和降低负温度效应（ＮＴＣ）。从理论上对实验现象进行了定性分析。     

Co-Ag/Ag多层膜的巨磁电阻效应

用离子束溅射法制备了６个系列的ＣｏｘＡｇ１００－ｘ／Ａｇ颗粒多层膜,对其巨磁电阻随成分及Ａｇ层和Ｃｏ—Ａｇ层厚度的变化规律进行了研究．当Ａｇ层厚度改变时,ＧＭＲ有一峰值,且随着Ｃｏ含量增加,峰值向层厚增加的方向位移,当Ｃｏ—Ａｇ层厚度改变时,Ｃｏ含量较高的样品的磁电阻在ｄｍ＝２．０ｎｍ附近有一个极大值,而Ｃｏ含量较低的样品在ｄｍ６．０ｎｍ范围是单调上升的．用磁层间静磁相互作用的反铁磁耦合模型对上述现象加以解释．还研究了Ｃｏ４５Ａｇ５５／Ａｇ多层膜样品的退火效应．     

PrCo5的磁晶各向异性起源

用单粒子点电荷模型研究了ＰｒＣｏ５的磁晶各向异性，特别是计算了磁晶各向异性常数随温度的变化，计算结果表明：晶场和屏蔽因子对磁晶各向异性能有较大影响，而交换相互作用对各向异性能影响较小．同时，理论分析的结果也解释了实验上观察到的ＰｒＣｏ５由易锥面磁化转向易轴磁化的现象     

退火对C60膜结构及PPC效应的影响

研究了退火前后Ｃ６０膜的ＰＰＣ效应。结果表明，随着高温退火温度的升高，Ｃ６０膜的结果由非晶相向多晶相转变，同时其ＰＰＣ效应减弱，基于以上实验事实，对上述结果给出了合理的理论解释。     

超突变结变容管C－V曲线拐点存在条件的研究

根据改进的超突变结变容管掺杂分布模型所得到的电容电压方程，对电容变化比较大时变容管的Ｃ－Ｖ曲线可能出现拐点这一现象进行了深入的研究，得出了产生拐点的条件，从而给出了理论上的解释．     

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.     

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     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

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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