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1.
用M,M,P,q,n等分子参数表征链烷烃的分子大小、取代参量和相邻取代基的相互作用,并以其为独立变量,通过回归方法建立模型预测链烷烃的某些物理化学性质,85种链烷烃的沸点、标准生成焓、标准熵、标准自由能以及1-9个碳原子链烷烃的气化焓、摩尔体积、摩尔折光度的预测表明该模型的原理简单、方法实用.为预测链烷烃物理化学性质提供了可靠的手段。  相似文献   

2.
基于核磁共振现象定义了一个新的拓扑指数1R,研究了链烷烃的标准熵与1R及碳原子得到数N的相关性.对比发现,157个链烷烃标准熵的计算值与实验值非常吻合,分析得到的方程可用于链烷烃标准熵的估算与预测.  相似文献   

3.
改进的连接性指数用于链烷烃热力学性质与沸点研究   总被引:1,自引:0,他引:1  
基于邻接矩阵和碳原子特征值 ti 建立新的连接性指数 m Q,其中 0 Q对链烷烃异构体具有很强的区分能力 .0 Q,N (烷烃中碳原子数 )与 85种链烷烃的标准生成焓、标准熵、标准生成自由能和沸点关联 ,相关系数多在 0 .998以上 ,属于良好模型 .与 Randic的 1χ比较 ,0 Q具有良好的结构选择性和性质相关性  相似文献   

4.
拓扑指数xz和路径数P1、P3、P4是表征烷烃分子大小、支化度和形状等结构特征的重要参量.据此,本文将xz、P1、P3、P4作为独立参量,用多元线性模型系统地研究了烷烃结构-性质的定量关系,预测了含2~9个碳原子烷烃的原子化焓、标准生成焓、汽化焓、摩尔体积、摩尔折射度、正常沸点、密度、溶解度等10项物理化学性质.计算方法简单,结构意义明确,结果令人满意  相似文献   

5.
厦门港微表层中烷烃富集规律的研究   总被引:3,自引:0,他引:3  
用气相色谱法测定厦门港微表层和次表层海水中烷烃的含量.微表层直链烷烃含量范围从未检出至4.1μg/L/检出的支链烷烃含量为0.16~2.6μg/L;次表层直链烷烃含量范围从未检出至2.7μg/L,检出的支链烷烃含量为0.03~1.4μg/L 微表层对烷烃的富集系数(EF)为1.0~21.直链烷烃的EF值春季较大;支链烷烃的EF值一般小于同碳数的直链烷烃,植烷例外.根据获得的实验结果,对影响烷烃的含量分布及其EF值的诸因素进行了探讨。  相似文献   

6.
在对文献中发表的22种脂肪酸甲酯和16种脂肪酸乙酯的液相黏度实验数据进行收集的基础上,建立了脂肪酸酯类物质的自由体积理论黏度模型,并得到了模型的参数。结果表明,对脂肪酸甲酯而言,实验值和计算值的最大偏差小于5.5%(其中脂肪酸链的碳原子数与不饱和键数之比为20∶1和22∶1的除外),对脂肪酸乙酯,最大偏差小于4.0%(其中脂肪酸链的碳原子数与不饱和键数之比为18∶1和18∶2的除外)。分析发现,模型参数与酯类相对分子质量之间存在一定的规律,获得了其定量关系,使得所建立的模型具有了预测同类物质黏度的功能。将预测模型计算结果和实验值进行比较发现,对38种脂肪酸酯类,黏度总体平均相对偏差小于1%,可以满足实际工程的需要。  相似文献   

7.
在对文献中发表的22种脂肪酸甲酯和16种脂肪酸乙酯的液相黏度实验数据进行收集的基础上,建立了脂肪酸酯类物质的自由体积理论黏度模型,并得到了模型的参数。结果表明,对脂肪酸甲酯而言,实验值和计算值的最大偏差小于5.5%(其中脂肪酸链的碳原子数与不饱和键数之比为20:1和22:1的除外),对脂肪酸乙酯,最大偏差小于4.0%(其中脂肪酸链的碳原子数与不饱和键数之比为18:1和18:2的除外)。分析发现,模型参数与酯类相对分子质量之间存在一定的规律,获得了其定量关系,使得所建立的模型具有了预测同类物质黏度的功能。将预测模型计算结果和实验值进行比较发现,对38种脂肪酸酯类,黏度总体平均绝对相对偏差小于1%,可以满足实际工程的需要。  相似文献   

8.
通过微机拟合曲线,给出了1-溴代正烷烃表面张力与碳原子数及温度的定量关系:σT(n)=(3.785n+17.791)×10-27.424+n-(8.271n-2.480)×10-5-1.292+nT.对式中系数的物理意义、表达形式以及公式计算结果的可靠性进行了分析讨论  相似文献   

9.
改进的UNIFAC-SRK法预测汽液平衡   总被引:1,自引:0,他引:1  
链烷烃分子结构非常相似,可以认为链烷烃溶液是无热体系,因此其超额吉布斯自由能可以假设为零,由此可以得到不含能量项的简化Vidal混合规则.这一改进混合规则和原来的Vidal混合规则一起构成改进的UNIFAC-SRK模型。同时,根据Nelder-Mead扩展单形求极值法估算出了23对新的基因交互作用参数.利用估算出的基因参数对43个二元汽液平衡体系的泡点压力和汽相组成进行了预测,大部分体系的泡点压力和汽相组成预测平均偏差都低于5.0%、  相似文献   

10.
对45种烷烃的0阶到4阶分子连接性指数进行主成分分析,将得到的4个主成分变量作为贝叶斯、正则化神经网络的输入特征参数,对烷烃的密度进行预测.预测结果与实验值的相关系数为0.996,预测标准偏差为0.0028.因此,人工神经网络可以作为预测烷烃密度的有效手段.  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.
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   

18.
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   

19.
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   

20.
<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  相似文献   

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