超声强化合成可生物降解原料乙交酯的研究

研究了超声催化强化作用在合成可生物降解原料乙交酯的过程中对收率和纯度的影响.以氯乙酸为原料通过超声波催化强化作用合成羟基乙酸,并以辛酸亚锡为引发剂,采用多步减压脱水反应成功地合成可生物降解原料乙交酯.研究了催化剂用量、脱水温度和裂解温度对乙交酯收率的影响,得到了较为理想的合成条件.通过对图谱及数据分析,总结出了合成乙交酯的最佳工艺参数.     

硫酸铁催化合成氯乙酸异戊酯的研究

以硫酸铁为催化剂,正己烷为带水剂催化合成氯乙酸异戊酯,对反应过程中的酸醇摩尔比、反应时间、催化剂用量及催化剂重复使用等因素对反应收率的影响进行了考察,寻求氯乙酸异戊酯的最佳合成条件.结果显示,当酸醇摩尔(以0.1 mol为基准)比为1:1.3,催化剂用量为0.5 g,反应时间为0.5 h,带水剂正己烷为15 ml,反应温度100～110℃的条件下,氯乙酸异戊酯的收率可达到93.0%.该研究为氯乙酸异戊酯的工业合成提供了理论依据.     

固体氯化亚锡催化合成氯乙酸丁酯的研究

以氯化亚锡为催化剂催化成化合成了氯乙酸丁酯，实验结果表明，此催化剂催化活性好，可缩短酯化时间，简化后处理，酯化率和酯的纯度较高．     

氯乙酰氯的合成与气相色谱分析方法

介绍了氯乙酰氯的性质、应用以及合成方法。开发了以氯乙酸为原料，用亚硫酰氯进行氯化反应，“一锅法”合成氯乙酰氯，并且提高了产品纯度和收率。将氯乙酰氯乙醇醇解转化成酯，进行气相色谱定量分析。     

十八水硫酸铝催化合成氯乙酸异戊酯

以Al2SO4318H2O为催化剂,氯乙酸和异戊醇反应合成了氯乙酸异戊酯,研究了醇酸物质的量比、催化剂的用量、带水剂的用量、催化剂反复使用次数及反应时间等因素对酯化率的影响.结果表明:Al2SO4318H2O对氯乙酸异戊酯的合成具有良好的催化活性,当氯乙酸为0.10mol,异戊醇为0.14mol,催化剂的用量为反应物总重量的1.5%,带水剂环己烷的用量为7mL,反应时间1.5h,反应温度105~118℃时,酯化率可达96.5%.     

硫氢酸钠催化合成氯乙酸异丙酯

以硫酸氢钠作为催化剂合成氯乙酸异丙酯,研究了醇酸摩尔比、催化剂种类、催化剂用量、带水剂种类以及带水剂用量对合成氯乙酸异丙酯的酯化反应的影响.在醇酸摩尔比1.2/1、催化剂用量1.0%(以酸的摩尔数计量)、反应时间2.5 h、反应温度为回流温度以及10 mL环已烷作为带水剂的反应条件下,酯化率可达97.1%.     

SnCl4·5H2O催化合成氯乙酸丁酯

报道了用SnCl4@5H2O作催化剂合成氯乙酸丁酯,最佳合成条件为正丁醇、氯乙酸及催化剂的摩尔比为210.005,反应时间2.5 h.该方法酯化率为97.5%,收率为93.6%,反应时间短,无腐蚀,无污染.     

羧甲基淀粉的合成及其药用性能

以木薯淀粉为原料,以环氧氯丙烷为交联剂、氯乙酸为醚化剂复合变性合成适用于药片崩解剂的羧甲基淀粉,并对其崩解性能进行了研究.本品在常温下即可快速吸水膨胀而不糊化.原料最佳质量配比为淀粉:环氧氯丙烷:氯乙酸:氢氧化钠=6:0.85:1:0.90.     

2-氯苯氧乙酸的催化合成研究

利用十六烷基三甲基溴化铵催化氯乙酸和2-氯苯酚合成2-氯苯氧乙酸,十六烷基三甲基溴化铵具有较高的催化活性,可以加快合成2-氯苯氧乙酸.反应过程考察了2-氯苯酚与氯乙酸摩尔比、催化剂用量、反应时间、反应温度对产率的影响以及催化剂的重复使用性能.反应的最佳条件为:在85℃下,2-氯苯酚和氯乙酸的摩尔比为1:4,催化剂质量为...     

硫酸高铈催化合成氯乙酸丙酯

以硫酸高铈催化氯乙酸与丙醇酯化反应合成了氯乙酸丙酯.较适宜的反应条件为：氯乙酸50mmol,n（氯乙酸）：n（丙醇）=1：1.5,ω（催化剂）=2.7%,环己烷2.0mL,于95℃～110℃反应2h,酯化率达到97.35%.     

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