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1.
在已获得的C6 0 分子取向几率与温度关系的基础上 ,考虑C6 0 晶体两种最优取向构成的双能级系统 ,探讨了C6 0 晶体的各种热力学函数在 2 6 0K温度下的表现形式 .着重分析了 87K附近二阶相变两侧热力学函数的变化规律 .根据已报道的C6 0 晶体在有序相两端点温度 87K和 2 6 0K的取向分布实验结果 ,将较高能级分子取向 (38°)的几率转化成分数值 1 6和 3 8.由热力学基本原理 ,得到了两端点温度的 38°取向分子的三维排列结构 ,并对其随温度的转变作了初步的探讨 .  相似文献   

2.
利用内耗方法分别对淬火态和时效态Au7Cu5Al4合金的相变过程进行了研究,分析了2种状态马氏体相变的差异.结果表明:淬火态与时效态Au7Cu5Al4合金的马氏体相变开始温度分别为-2.7和13.8 °C;根据驰豫内耗峰信息得出其晶界驰豫激活能分别为131.5和93.0 kJ/mol,反映了时效前后Au7Cu5Al4合金有序度的差异,即淬火态Au7Cu5Al4合金母相在室温下主要为B2结构,而时效态合金为L21有序结构.  相似文献   

3.
用固体核磁共振研究热失水壳聚糖的结构变化   总被引:4,自引:0,他引:4  
用13C CP/MAS NMR方法通过测定13C的驰豫时间(T1)和旋转坐标系下1H的驰豫时间(T1ρ)研究了壳聚糖热处理前后的结构变化,结果发现与含水壳聚糖相比,热失水壳聚糖所有位置的碳的驰豫时间均延长,在三个无水壳聚糖样品中C2,6的T1值依次升高,表明了与C2相连的氨基和与C6相连的羟基的运动受到了束缚,这是由于氨基与羟基之间形成氢键所致,分子链排列的规整性增加,大分子之间的作用力增强,导致了热处理后壳聚糖溶解速度下降。  相似文献   

4.
指出了由极值动力学所导出的活化能为Ngai由实验结果推导的表观活化能,对无序材料的玻璃相变温度区表现出的时间与温度关联性的分析发现:伸展指数的温度行为导致了VFT方程;介电驰豫的减慢来源于伸展行为和因子的温度行为,指出了标度理的适用条件为伸展指数不随温度而变化;提出了伸展指数函数由单一单元的衰减引起;von Schweidler函数由多个单元的共同衰减引起。  相似文献   

5.
本文提出凝聚态物质驰豫的一个简单的分维时间模型,理论研究表明,凝聚态物质内的反常驰豫是由于绝热近似遭破坏的结果,且需要引入三个不同时间标度描述间断驰豫过程替代连续驰豫过程.本文提出模型不仅能很自然给出持续指数型驰豫exp[-(t/τ)β],而且能解释实验中观测到β的标度行为.  相似文献   

6.
利用旋涂法制备了一种偶氮类化合物掺杂有机聚合物薄膜,并对其吸收谱、厚度、折射率、进行了测量,采用二次谐波产生的方法的方法对全光极化后薄膜的二阶非线性光学特性进行了研究.实验结果表明,随着薄膜厚度和生色团含量的增加其二阶非线性增强.这与聚合物薄膜中含有较高浓度的分散红1有关.对极化饱和后的驰豫情况进行了分析,发现不同厚度薄膜的驰豫速度不同.这是由于薄膜中偶氮分子含量越多,分子间相互作用越强,导致驰豫时间增长.  相似文献   

7.
从理论上研究了在多原子分子材料中,由激光感生的热致折射率光栅及其驰豫效应。并利用简并四波混频实验,观察了多原子分子液晶的热致折射率光栅和它的驰豫行为,讨论了有关的物理机制  相似文献   

8.
在双能级模型及凝聚态物质的低频涨落,耗散和驰豫行为的统一理论基础上,研究了非晶合金Fe50Ni30B20于480K退火2h以后,在250-350K范围的磁后效谱,计算得到红外发散指数n=0.11,特征驰豫时间τ∞=2.8×10^-17S.在驰豫峰温处,计算的表观激活能E为1.7eV,此结果与实验很好地一致。计算结果表明,对此非晶合金,磁后效是由于B原子跳跃引起Fe-B,Ni-B原子对的局域重排而导  相似文献   

9.
用重整化群方法分析了存在表面驰豫效应时表面生长的动力学行为,得到了相应的标度指数x与z、驰豫时间τ的函数关系,结果表明,随着驰豫效应的增强,会使生长表面有化并有利于稳定生长阶段的形成。  相似文献   

10.
利用线性近似方法推导了具有e指数关联噪声的单模激光增益模型的光强关联函数和关联时间,分析讨论了光强关联函数随时间的演化特征及各种参数对光强关联时间的影响。研究表明:a.噪声间的负关联使得光强关联函数随时间演化具有两种形式,即单调衰减和出现负极值;b.噪声间的负关联使激光的驰豫过程变快,而正关联则慢化了激光的驰豫过程;c.光强关联时间随泵噪声强度变化的一个明显特征是存在一个峰(谷)值。  相似文献   

11.
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.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
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.  相似文献   

13.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

14.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

15.
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。  相似文献   

16.
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.  相似文献   

17.
Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.  相似文献   

18.
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-  相似文献   

19.
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-  相似文献   

20.
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  相似文献   

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