纳米掺锑氧化锡粉末的制备和性能研究

采用阴离子交换除氯水解法和不同干燥法制备了掺锑氧化锡纳米粉末,用XRD,TEM和BET对粉末的物相、形貌、比表面积进行了表征.结果表明,用乙酸异戊酯共沸蒸馏干燥是比较有效的脱水方法,可以用来制备比表面积大(82.665 m2/g)的纳米掺锑氧化锡粉末.     

NaHSO4·H2O催化下合成乙酸异戊酯的研究

以乙酸和异戊醇为原料合成乙酸异戊酯,首次选用固体NaHSO4·H2O作催化剂通过不同的反应时间、不同用量的催化剂、不同酸醇比等对合成乙酸异戊酯的影响,找到最佳反应条件.实验成果表明,采用NaHSO4·H2O作催化剂较传统浓硫酸催化剂合成法具有缩短酯化时间、催化效率高、酯的产率较高、对环境污染较小的优点.     

乙酸异戊酯合成实验改进

本文描述了以Ｈ型离子交换树脂为催化剂，在乙酸和异戊醇近摩尔的条件下，采用一般回流酯化——共沸酯化相结合的双重酯化法合成乙酸异戊酯．该法与原来的方法相比不仅可缩短反应时间，酯的产率也提高了５％～１０％，且催化剂易分离，可重复利用     

燃烧合成超细ITO粉体

以In粒和Sn粒为原料,尿素为燃料,柠檬酸为添加剂,燃烧合成ITO(掺锡氧化铟)粉体,利用粉末X射线衍射、扫描电子显微镜对产品进行表征,并研究柠檬酸(C6H8O7)对燃烧产物的影响.结果表明,以尿素为燃料燃烧合成是制备ITO粉体的有效途径,添加剂柠檬酸能有效抑制粉体的团聚,使颗粒分散性变好,得到颗粒细小均匀的ITO粉体...     

复合固体超强酸S2O82-/Fe2O3/ZnO/ZrO2催化合成乙酸异戊酯

采用沉淀、老化、浸渍、干燥、焙烧等方法制备复合固体超强酸催化剂S2O28-/Fe2O3/ZnO/ZrO2,在该固体超强酸的催化作用下,由异戊醇和冰乙酸合成乙酸异戊酯,探讨醇酸摩尔配比、反应温度、反应时间、不同焙烧温度以及催化剂用量等条件对酯化率的影响。结果表明,此催化剂制备的最优条件为:焙烧温度为650℃,(NH4)2S2O8浸渍浓度为0.5 mol/L,焙烧时间为3 h。合成乙酸异戊酯适宜的反应条件是:反应时间50 min,原料异戊醇与冰乙酸的摩尔配比为2:1,用量为1 g,用复合固体超强酸S2O28-/Fe2O3/ZnO/ZrO2催化剂催化合成乙酸异戊酯的产率是88.5%。     

强酸性阳离子交换树脂催化下乙酸异戊酯的合成

以732型强健性阳离子交换树脂为催化剂、利用乙酸异戊酯和异戊醇可与水共沸的性质，使乙酯与异戊醇反应含成了乙酸异戊酯，收率达95%以上，此法操作方便，后处理简单，无设备腐蚀，产品收率高，质量稳定，催化剂可反复使用，环境污染轻，是乙酸异戊酯的一种理想的合成方法。     

固体超强酸S_2O_8~(2-)/TiO_2-Al_2O_3催化合成乙酸异戊酯的动力学研究

文章研究了以固体超强酸S2O82-/TiO2-Al2O3为催化剂合成乙酸异戊酯的反应,在反应温度分别为94℃﹑100℃及106℃下,测出合成乙酸异戊酯的动力学方程参数,建立了动力学方程式,并与无催化剂时酯化反应的活化能及动力学方程式进行了比较。结果表明,最佳合成条件为:醇酸摩尔比1.3∶1,催化剂用量1g,带水剂用量10mL。固体超强酸S2O82-/TiO2-Al2O3使反应活化能明显降低,是乙酸异戊酯合成的有效催化剂。     

己酸异戊酯的催化合成

以己酸和异戊醇为原料,合成了己酸异戊酯,考察了溶剂,醇酸比和反应时间对酯收率的影响,以及几种常见的无机盐和FeCl3.6H2O,Al2(SO4)3.18H2O和AlCl3.6H2O对该反应的催化活性,实验结果表明：FeCl3.6H2O对该反应有良好的催化活性,反应时间较短,并有很高的收率。     

"乙酸异戊酯"学生实验的改进

本文从环境保护的角度,对学生有机化学实验"乙酸异戊酯制备"进行了探讨、改进,将常用催化剂"浓硫酸"改变为FeCl3·6H2O,提高了产率,减少了污染,取得了满意的效果.     

共沸精馏分水酯化新装置合成乙酸异戊酯

一种带共沸精馏分水的新型酯化反应实验装置用于合成乙酸异戊酯．在树脂酸催化剂的作用下，反应转化率达到98．2％，比传统装置高2．7％，而且分水器排出废水所带出的酸仅为传统装置的25％．     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

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.     

Lower Paleozoic oil relationships within Williston Basin, Canada

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.     

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