硫酸钛催化合成乙酸异戊酯

研究了硫酸钛催化下的乙酸异戊酯的合成．酯化率高达98％以上,酯化条件如下：异戊醇0．2mol,乙酸0．22mol,反应时间1h,硫酸钛的用量为反应物总质量的1．5％。     

纳米型复合磷钨酸催化合成肉桂酸异戊酯

以纳米型复合杂多酸H3PW12O40／SiO2为催化剂,以肉桂酸和异戊醇为原料,来合成肉桂酸异戊酯．结果表明：纳米复合磷钨酸是合成肉桂酸异戊酯的良好催化剂;适宜的工艺条件为：酸醇物质的量比为1：2．5,催化剂用量为0．6g／0．05mol肉桂酸,回流时间为3h,酯化率可达96．2％．     

硫酸钛催化合成乙酸异戊酯

研究了硫酸钛催化下的乙酸异戊酯的合成.酯化率高达98%以上,酯化条件如下异戊醇0.2mol,乙酸0.22mol,反应时间1h,硫酸钛的用量为反应物总质量的1.5%.     

硫酸铈铵催化合成乙酸异戊酯的研究

以硫酸铈铵为催化剂，乙酸和异戊醇为原料，合成乙酸异戊酯。考察了醇酸摩尔比，催化剂用量，反应时间诸因素对产品收率的影响。实验表明：硫酸铈铵是合成乙酸异戊酯的良好催化剂，在醇酸摩尔比为1．8：1；催化剂用量为1．5g；反应时间3．0h的优化条件下，乙酸异戊酯的收率可达91．4％。     

对甲苯磺酸催化合成肉桂酸异戊酯

肉桂酸异戊酯是一种重要的高级香料,具有可可香味,广泛用于食品和日用化工等领域.合成肉桂酸异戊酯的传统方法是以硫酸为催化剂直接酯化生产肉桂酸异戊酯,硫酸同时具有酯化、脱水和氧化作用,产生一系列副反应,后处理繁杂,产品质量差,收率低,污染环境,同时硫酸对设备具有严重腐蚀,使产品成本升高.因此,国内外都在探索代替浓硫酸的新型催化剂.笔者将对甲苯磺酸用于催化合成肉桂酸异戊酯,取得较满意结果.     

微波辐射硫酸钛催化合成肉桂酸甲酯

采用微波常压法,以硫酸钛为催化剂,由肉桂酸与甲醇酯化合成肉桂酸甲酯。实验表明最佳反应条件为:0.02mol肉桂酸、0.25mol甲醇和反应物料总质量3.2%的硫酸钛,微波功率640w,辐射25m in,肉桂酸甲酯的产率达91.2%.     

微波法催化合成水杨酸异戊酯

研究了利用微波辐射技术，在对甲苯磺酸的催化下以水杨酸和异戊醇合成水杨酸异戊酯的反应，探讨了原料配比、反应时间、催化剂用量、微波功率等参数对酯化率的影响．在适宜工艺条件下，酯化率可达97％以上、     

微波辐射下乙酸异戊酯合成条件研究

在微波辐射下，以SO4^2-／TiO2固体超强酸为催化剂合成乙酸异戊酯。最佳反应条件是：乙酸和异戊醇的摩尔比为1：2．0，催化剂用量为1．5g。微波输出功率为729W，反应时间为12min。在此反应条件下，乙酸的酯化率为94．7％，产品收率为89．7％。     

微波辐射对甲苯磺酸催化合成丙酸异戊酯

在常压、微波辐射条件下,以对甲苯磺酸为催化剂,以丙酸和异戊醇为原料,合成了丙酸异戊酯。实验结果表明：催化剂对甲苯磺酸的用量为0．25 g,丙酸的用量为0．2 mol,异戊醇的用量为0．60 mol,微波辐射功率为750 W,辐射回流时间为12 min,酯化率可达96．6%。与常规加热方法相比,具有反应速度快、转化率高等优点。     

四氯化锡催化合成马来酸二异戊酯

四氯化锡能够代替硫酸作为酯化催化剂．研究了利用五水四氯化锡催化，由马来酸酐与异戊醇反应合成马来酸二异戊酯，讨论了其影响因素，当马来酸酐、异戊醇和四氯化锡的物质的量比为1：4：0．086，回流分水60min，酯收率达96．7％，并且催化合成了马来酸二正丁酯，马来酸二异丁酯和马来酸二正戊酯．     

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.     

Design and analysis of generic LBS application developing platform

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.     

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