不同脱乙酰度和分子质量的壳聚糖的抑菌性能

通过壳聚糖的抑茵实验和几种壳聚糖最低抑茵浓度的测定,比较了相同脱乙酰度不同分子质量以及分子质量相近但脱乙酰度不同的壳聚糖对金黄色葡萄球菌、枯草杆菌、大肠杆菌和假单胞菌的抑茵性能．结果表明：脱乙酰度相同、分子质量为400～800ku的壳聚糖,其抑茵能力随分子质量的增加而增强;而分子质量相近（均在430ku左右）、脱乙酰度不同（分别为68．4％,75．3％,83．6％和93．7％）的壳聚糖对上述4种细菌的抑茵能力差别不大;在pH值为5．5～6．0左右的条件下,壳聚糖具有最强的抑茵能力;实验条件下的壳聚糖对4种细菌都有较强的抑制作用,总体看来,壳聚糖对金黄色葡萄球菌的抑制作用最强,而对大肠杆菌的抑制作用相对较弱;实验条件下的壳聚糖对上述4种细菌的抑制作用普遍比苯甲酸钠强．     

壳聚糖的脱乙酰度、分子量和浓度对微囊制备和特性的影响（英文）

用不同规格的壳聚糖与海藻酸钠和羧甲基维素钠制备了各种微囊．研究了壳聚糖的脱乙酰度、分子量及溶液浓度对微囊形成和特性的影响．确定了微囊制备的最佳参数,并发现壳聚糖的分子量在一定范围内对微囊通透性无影响而脱乙酰度显著地影响微囊通透性．降低壳聚糖的脱乙酰度可明显增加微囊的通透性,而不影响微囊机械强度．这种微囊制备方法简便、通透性可调,在多种生物活性物质的固定化及药物缓释方面具有重要应用前景     

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.     

多波长线性回归—紫外分光光度法测定壳聚糖的脱乙酰度

以不同浓度的N－乙酰基－D－葡萄糖胺溶液在200，202，203nm处的吸光度值对波长作图得到线性关系良好的1组直线，其斜率与对应溶液的浓度成正比，线性范围为0.0025-0.0400mg/mL，回归方程为k=-2.252c-0.0027,相关系数r=0.99995(n=6)。不同批号壳聚糖样品测定结果的相对标准偏差0.20%-0.52%(n=5)，回收率在100.2%-101.6%之间。本法解决了单波长紫外分光光度法中共存物吸收干扰问题，并简化了紫外一阶导数法中导数值的求法。实验结果表明，该法测定壳聚糖的脱乙酰度准确度高，重现性好，试样无须特殊处理，适用于可溶性壳聚糖脱乙酰度的测定。     

胶体滴定法测定壳聚糖脱乙酰度

采用胶体滴定法测定壳聚糖的脱乙酰度,考察了壳聚糖溶液pH值、溶液浓度、指示剂用量、不同溶剂和离子强度等因素对胶体滴定的影响,并与电位滴定和1H NMR法相比较,希望寻找一种简便、快速和准确测定壳聚糖脱乙酰度的方法.结果表明:胶体滴定法可作为测定壳聚糖脱乙酰度的优选方法.     

用壳聚糖对织物进行改性的探讨

用不同浓度，不同脱乙酰度的壳聚糖溶液对不同织行进行浸轧处理，并测定了织物的各种性能，实验结果表明，各种织物经过壳聚糖溶液处理后，其上染率，折皱回复角，硬挺度和拒水性都有所提高，纤维素纤维织物的强度有所下降，蛋白质维生素织物的强度则有所上升，壳聚糖的脱乙酰度对织物的性能有一定影响。     

壳聚糖阻垢效果研究

研究了不同脱乙酰度的壳聚糖对ＣａＣＯ３水样的阻垢效果,以及壳聚糖的浓度,水样Ｃａ＾２＋浓度,溶液温度,ＰＨ恒温时间等对阻垢率的影响,并探讨了壳聚糖与丙烯酸共聚的阻垢效果。     

蜚蠊壳聚糖的快速制备方法研究

研究微波方法快速制备蜚蠊壳聚糖的实验条件，运用L9(3^4)正交实验法，将碱浓度、时间、微波加热温度、料液比在三个不同水平上进行优选实验，得出最佳制备条件为45％的NaOH，温度100℃，时间30min，壳聚糖脱乙酰度可达84．9％．此工艺比常规方法时间短，得率较高．     

微波半干一步法制备壳聚糖的研究

报道了以脱钙虾壳为原料,用ＮａＯＨ溶液浸润然后在微波作用下一步脱去乙酰基和蛋白质制备壳聚糖;研究了影响乙酰基产物粘度的因素;在适当条件下脱钙虾在微波作用下反应１５ｍｉｎ,可制得脱乙酰度６０％－７０％,粘度５３．６ｍＰａ．ｓ的壳聚糖,与传统方法相比简化了工艺流程,缩短了反应时间１０－９０倍,节约了能耗。     

高脱乙酰度、低粘度壳聚糖的研制

利用相转移催化剂与均匀设计探讨了高脱乙酰度、低粘度壳聚糖的制备方法，找出了最佳工艺条件，在最佳工艺条件下得到了粘度为２６．６ｍＰａ．ｓ，脱乙酰度为９９．４％的壳聚糖。     

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