水溶性壳聚糖制备工艺的研究

以甲壳素为原料通过碱液法制备水溶性壳聚糖,通过控制加热温度及反应时间,来控制脱乙酰度的大小.并对脱乙酰后的壳聚糖进行脱乙酰度测试和红外表征,得出了反应时间、反应温度、反应试剂用量、取代度、溶解性能对壳聚糖反应的影响.结果表明控制反应温度在100℃,反应时间4小时,反应次数3次,氢氧化钠溶液浓度50%时,所得的壳聚糖脱乙酰度最高.并推导出壳聚糖酯化的最佳反应条件使其溶解性能得到有效改善.     

制备脱乙酰甲壳素的研究

从虾蟹壳中提取甲壳素,利用甲壳素脱乙酰基制取壳聚糖并对甲壳素和壳聚糖粉末的制备条件进行优选.实验结果表明,先用4%的稀盐酸脱去钙质,反应时间8h,反应温度80℃,后用浓度为50%的浓氢氧化钠脱去乙酰基,反应时间4h,反应温度90℃,可以制得平均脱乙酰度为90.05%的高脱乙酰度的可溶性粉末状壳聚糖.     

甲壳素的脱乙酰化反应

研究了甲壳素的脱乙酰化反应时,碱溶液浓度、反应时间和反应温度等各种因素对反应产物的脱乙酰度、粘度和红外吸收光谱的影响。结果表明,随溶液中氢氧化钠浓度、反应温度和反应时间增加,甲壳素的脱乙酰化作用增加。甲壳素经一次反应的脱乙酰化度不超过90％。在较低温度和较短时间得到的壳聚糖在稀酸溶液中的粘度较高。     

基于数据挖掘的蟹壳壳聚糖提取工艺

以蟹壳为原料,结合数据挖掘技术,利用箱式图、斯皮尔曼相关性和冗余分析等方法进行统计,选择确定甲壳素脱乙酰过程中的反应条件。在此基础上,为了证明此次基于数据挖掘的壳聚糖提取条件设计的合理性,设计了不同反应条件对壳聚糖脱乙酰度影响的响应面实验。结果表明：最优提取工艺条件为氢氧化钠质量浓度0.5 kg/L、反应温度110℃、反应时间6 h,该条件下脱乙酰度达到89.53%,壳聚糖性能达到商品壳聚糖的要求。实验数据符合数据挖掘的统计结果,可以为研究人员提供参考。     

壳聚糖化学改性条件的探讨

探讨了如何控制在均相条件下以高脱乙酰度的壳聚糖为主要原料,在乙酸水溶液-乙醇-吡啶介质中实现壳聚糖N位乙酰化反应的问题;制备了脱乙酰度为50%左右,具有良好水溶性的壳聚糖;重点研究了乙酰酐的用量、反应时间、反应温度、溶剂对脱乙酰度的影响.结果表明:乙酰酐用量与壳聚糖的摩尔比在2.0左右,温度为40℃,溶剂为乙醇时产物的脱乙酰度接近50%,反应时间为3小时.     

非质子溶剂法制备羧甲基壳聚糖

研究了一种制备羧甲基壳聚糖的新方法——非质子溶剂法,即以壳聚糖为原料,在碱性条件下以1,4-二氧六环为溶剂和氯乙酸发生亲核取代.探讨了不同碱度、投料比、温度、时间及催化剂用量等反应因素对制备高取代度羧甲基壳聚糖的影响.结果表明:在碱浓度为35%、反应温度50℃、投料比1∶6、反应时间6 h、催化剂用量5%时,产品达到最佳取代度为2.23,优于文献上的水溶剂法和醇水混合溶剂法.此外还对羧甲基壳聚糖进行了红外光谱和X-衍射表征。     

正交试验优化乙酰水杨酸合成工艺

目的:研究乙酰水杨酸合成工艺的影响因素,探索乙酰水杨酸合成实验的最佳条件.方法:采用正交试验,考察水杨酸和乙酸酐的物质的量比(A)、反应温度(B)、反应时间(C)和催化剂浓硫酸的用量(与水杨酸用量的体积质量比)(D)四个因素对乙酰水杨酸产率的影响.结果:乙酰水杨酸合成的最佳条件为A_1B_3C_1D_1,即水杨酸和乙酸酐物质的量比为1︰2,反应温度为80℃,反应时间为8 min,催化剂用量为1%.结论:在此工艺条件下,乙酰水杨酸产率可达76.3%(以水杨酸的投料量计算).     

壳聚糖微球树脂的制备及应用

以甲壳素为原料 ,采用正交试验法确定制备高脱乙酰度和高交联度的壳聚糖树脂的工艺条件 .当温度、碱浓度和反应时间分别为 70℃ ,12 .5 0 mol· L-1和 4 h时 ,可得脱乙酰度 94 %、粘度80 0 m Pa· s的壳聚糖 .在交联剂浓度为 1.0 mol· L-1、壳聚糖用量为 2 g和交联时间为 2 h的条件下 ,可获交联度为 93%的微球树脂 .研究壳聚糖树脂对染料废水及印染废水的吸附脱色条件 ,其对单一染料废水的吸附率可达 85 %以上 .高交联度树脂的吸附率优于低交联度树脂的吸附率 ,交联后的壳聚糖微球树脂 ,具有适用于较广 p H范围的优点     

不同脱乙酰度壳聚糖对活性FM黑的吸附性能研究

以壳聚糖为吸附剂,研究了其对活性FM黑染料的吸附性能.探讨了温度、时间、介质pH值、壳聚糖脱乙酰度以及用量对壳聚糖吸附活性FM黑的影响.结果表明,随着壳聚糖脱乙酰度的增大,壳聚糖的吸附能力随之增强;壳聚糖用量增加,吸附能力先增强后减弱;介质的pH在4～7范围内,对活性FM黑染料废水的吸附性能较好,在中性条件下达到最强;温度对吸附性能的影响较小.由此得出在壳聚糖脱乙酰度为97%、用量为0.006 0g、温度为25℃、反应时间为50min、活性FM黑质量浓度为30mg/L、体积为100mL、介质的pH为7的条件下,吸附量达到273.23mg/g.且其吸附行为满足Langmuir等温式.     

壳聚糖荧光标记反应研究

 以壳聚糖-海藻酸钙微球在体检测为研究背景,建立壳聚糖的荧光标记方法.以荧光素异硫氰酸酯(FITC)作为标记化合物,采用紫外-分光光度计在447nm下检测标记在壳聚糖上的FITC,通过m(FITC,μg)/m(壳聚糖,g)表征壳聚糖的荧光标记效率.考察壳聚糖溶液pH值、浓度、反应时间以及壳聚糖分子量、脱乙酰度对壳聚糖荧光标记反应的影响.结果表明:选取相对分子质量20万、脱乙酰度95%的壳聚糖配制成0.01g/mL的溶液,在pH₁₀的条件下与荧光素反应5h将制得标记效率为117.4μg/g的荧光壳聚糖.建立了一种稳定有效的壳聚糖荧光标记方法,为荧光标记壳聚糖-海藻酸钙微球提供了技术支持.     

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