羟基乙酸均聚物PGA的合成及表征

以实验室合成的羟基乙酸二聚体乙交酯为原料，经乙交酯开环聚合合成高相对分子质量的聚羟基乙酸，对乙交酯在不同催化剂作用下的开环聚合成的均聚物进行了研究．结果表明，单体结晶次数、催化剂浓度、聚合时间等条件是影响聚合物特性黏度系数的重要因素．合成了满足要求的聚乙交酯，并提供了合理的工艺流程．     

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.     

聚乙交酯公斤级生产途径探索

探索聚乙交酯的工业生产途径,以氯乙酸为原料,与氢氧化钠成盐后在真这下热解制得乙交酯单体,纯化后进行开环聚合成成功地获得了高相对分子质量聚乙交酯,研究了取乙交酯的制备以及催化剂和引发剂用量对聚合反应的影响,以苯酚／1,1,2,2－甲氯乙烷（m/m＝1：1）作溶剂,在30℃下测定了聚乙交酯溶液的特性粘数。结果表明,合成出的聚乙交酯特性粘数[η]在0．64－1．36dL/g之间可调。     

有机硅改性聚氨酯预聚体的制备及表征

以聚己二酸乙二醇酯、甲苯-2．4二异氰酸酯、二元醇、羟基硅油为主要原料，合成有机硅改性聚氨酯密封剂预聚体。用红外光谱法对其结构进行表征，同时测定预聚体的物理性能。结果表明．合成的聚氨酯密封剂预聚体受环境温度、空气湿度影响小，存放时间长，因此提高了密封胶力学性能。     

基于传统催化剂作用下L-丙交酯的合成分析

L-丙交酯是制备高的相对分子质量聚左旋乳酸PLIA的重要原料，其纯度和成本的高低决定了高的相对分子质量PLLA的质量和价格，以L-乳酸水溶液为原料，采用SnCl2或Zn为催化荆，经齐聚及解聚两步反应合成了L-丙交酯，光学纯度可达99％，研究了齐聚物相对分子质量、催化剂用量、齐聚反应温度、时间及解聚温度等因素与丙交酯收率及纯度的关系，选定合成的最佳条件为：采用SnCl2为催化荆，用量0．5％，脱水8h，齐聚温度和解聚温度分别低于170℃和220℃，所得丙交酯收率最高达93．2％。     

聚叔碳酸乙烯酯-乙酸乙烯酯-乙烯乳液及其乳液聚合制备的研究

一、引言当前聚乙酸乙烯酯乳液使用量大,广泛应用于胶粘剂、涂料、建筑、织物加工、纸张加工等许多方面。由于聚乙酸乙烯乳液采用聚乙烯醇为保护胶体,而聚乙烯醇自身带有大量的亲水基团羟基,聚乙酸乙烯酯在碱性条件下又易水解,使分子链上带上羟基或羧基,形成了聚乙酸乙烯酯乳液自身固有的缺陷,如耐水性、耐候性、耐碱性差等,限制其使用。     

固体氯化亚锡催化合成脂肪酸烯丙醇酯

采用固体氯化亚锡为催化剂，催化合成脂肪酸烯丙醇酯．实验结果表明，此催化剂可几十倍的缩短酯化时间，提高酯的收率，是脂肪酸和烯丙酸酯化较好的催化剂．我们得到的甲酸、乙酸、丙酸、丁酸、戊酸烯丙醇酯的收率分别为：６２．４９％、７０．５０％、７０．３１％、７４．０２％、７１．００％．     

有机氨钙催化合成乙交酯ε-己内酯AB型嵌段共聚物

以有机配体氨钙为催化剂，采用分段加入聚合单体的方法，先合成具有活性的PCL，然后用PCL作为大分子引发剂，引发了乙交酯和ε-己内酯的开环聚合，形成了一系列乙交酯和ε-己内酯的AB型嵌段共聚物．用核磁、GPC、DSC及黏度法对嵌段共聚物进行了表征，确定了嵌段共聚物的结构．研究了嵌段共聚物的热力学性能和结晶性．     

聚酯类可吸收型医用缝合线的单体——乙交酯及丙交酯的合成

可吸收型医用缝合线是一种能经受生物组织反应,经降解后被人体吸收的高分子材料。本文以α-羟基酸为原料合成了聚酯类可吸收型缝合线的单体:乙交酯和丙交酯,测定了它们的IR,NMR,MS以及DSC图谱。利用中间产物的质谱讨论了交酯生成的反应途径。运用DSC图谱以及加热红外光谱讨论了α-乙交酯、β-乙交酯的稳定性,得到α-乙交酯较为稳定的结论。     

复合催化剂Hβ沸石／TiO2催化合成乙酸辛酯

采用复合催化剂Hβ沸石／TiO2合成了乙酸辛酯。确定反应的最佳条件为：酸醇物质的量比1：1．1、催化剂用量3．0g／mol乙酸、催化剂中TiO2的质量百分比10％、环己烷用量20mL／mol乙酸、反应时间3．5h。与其它单一固体酸催化剂比较，复合催化剂的催化性能更优越，乙酸的转化率更高。     

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