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1.
使用原子-键电负性均衡模型(ABEEM),计算了一些任意选取的有机大分子的电荷分布和分子电负性。计算结果很好地重复了相应的从头计算结果,但却更加快捷、省时,展示了原子-键电负性均衡模型的广阔应用前景。  相似文献   

2.
对于任意分子A-B(A、B表示原子或基团),建立了一个由Pauling电负性估算原子部分电荷的新经验公式: ?? 式中X_A和X_B表示原子或基团的电负性. 计算了40多种化合物中原子的部分电荷,结果与文献值一致.  相似文献   

3.
在密度泛函理论和电负性均衡原理的理论框架下 ,发展了直接用于计算原子及键电荷分布的原子 键电负性均衡方法的σπ模型 ,本文应用此模型计算了氨基酸和一些较大多肽分子的电荷分布 .  相似文献   

4.
讨论了键合原子内壳层结合能和它的分子环境的关系。报导了从XPS实测数据得到的表征分子环境影响的若干基团参数值和基团电负性。  相似文献   

5.
多氯联苯醚(PCDEs)的QSPR研究   总被引:2,自引:0,他引:2  
以类原子的形式处理多氯联苯醚苯环上的基团(CH和CCl),构建分子的距离矩阵,以分子基团的均衡电负性对原子进行着色建立行矩阵,结合分子的距离矩阵和行矩阵,同时考查分子的相互间的作用情况,建立分子的结构参数——拓扑距离电负性指数.通过计算化合物的拓扑距离电负性指数(TDEI),以107种PCDEs理化性质的实验值为建模样本,建立了PCDEs的定量结构/性质相关(QSPR)模型,相关性良好.最后对107种PCDEs的三个理化性质进行了预测.  相似文献   

6.
在许多复杂的分子中,一些基团(取代基)的作用相当于一个原子的行为,因此,在复杂的体系中,通常采用基团电负性的慨念。基团电负性在研究有机化合物的结构和性质中是一个重要的参数。人们在这方面已做了许多工作,文献中报导的基团电负性值不少于十套。本文试以核磁共振谱的质子化学位移值为依据,建立一套基于实验数据的基团电负性值。  相似文献   

7.
运用中性基团中原子的价层轨道能和“假原子”近似,建立了一个新的计算中性基团电负性的公式。运用该式,运用该式,计算了270个中性基团的电负性,计算结果与国内外新近的几套基团电负性颇为一致。  相似文献   

8.
一个异核双原子氯化物分子键长的经验公式   总被引:1,自引:1,他引:0  
试用元素电负性、原子价电子数和主量子数为参数建立一个简便公式,用以计算异核双原子氯化物分子键长。用该式计算一些常见异核双原子氯化物分子的键长,方法简单,结果与实验值颇为一致。  相似文献   

9.
根据Klopman和Iczqowski等关于“原子的一些性质在分子中仍然得以保留”的研究结果,运用Sanderson电负性均衡原理,并借用Ichikawa加权调和平均电负性模型和Parr等的离子电负性计算公式,将密度泛函理论离散变分方法对抗肿瘤多酸的计算结果融入Reed分子参数计算中,建立了包含研究对象三维构象信息的Reed分子参数计算新方法.用该法计算得到的抗肿瘤多酸阴离子的分子片参数,能恰当地与Anderson型和Linqvist型多酸的抗肿瘤活性关联.  相似文献   

10.
以密度泛函理论和电负性均衡原理为基础 ,应用原子 键电负性均衡方法中的σπ模型下得到的分子的整体硬度 ,解释和预测含磷分子的Diels Alder反应 ,并对一些含磷有机分子的稳定构型进行了讨论  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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