天然高分子材料——甲壳素和壳聚糖及其衍生物

壳聚糖是甲壳素脱乙酰后的产物，是自然界中存在的唯一碱性多糖．甲壳素、壳聚糖及其衍生物由于具有生物活性、良好的生物相容性、完全可降解性及无毒性等优点而在众多领域中都有广泛的应用．并且，它们的应用领域还在进一步的得到开发，有广泛的应用前景,论述了甲壳素、壳聚糖及其衍生物在治污、医药、农业、食品、生物及日用化学品等领域中的应用，并对它们的未来应用前景进行了展望．     

壳聚糖在水处理中的应用

壳聚糖是天然聚合物甲壳素脱乙酰化产物,是一种具有重要开发研究价值的天然生物多糖资源。这里主要介绍了壳聚糖及其作为吸附剂、絮凝剂在水处理中的应用,指出开发壳聚糖作为新型水处理材料具有广阔的应用前景。     

甲壳素、壳聚糖免疫调节及抗肿瘤研究进展

甲壳素广泛存在于甲壳纲动物虾、蟹及昆虫的甲壳和植物细胞壁中,是一种天然高分子多糖.壳聚糖是甲壳素脱乙酰后的产物,是自然界中存在的唯一碱性多糖.甲壳素和壳取糖都是人类在开发和利用废弃物过程中开发出来的瑰宝.文章综述了甲壳素和壳聚糖的结构和性能,以及甲壳素和壳聚糖在免疫和抗肿瘤方面应用的研究进展.纵观了甲壳素和壳聚糖在保健食品及药品方面的应用现状及前景.     

甲壳素--21世纪的绿色材料

甲壳素是从虾蟹外壳提炼出的天然高分子氨基多糖聚合物。甲壳素和其脱乙酰衍生物甲壳胺独特的成膜与可纺性能为医疗、纺织提供了又一新型绿色材料。甲壳素类奇妙的生物活性已为保健食品赢得“第六生命要素”的誉称。这里介绍甲壳素研究简史、性能、制作方法、应用范围和今后发展方向。     

方兴未艾的甲壳素产业

有人说:“21世纪多糖的研究最有希望的是甲壳素。”有人说:“从来没有一种物质像甲壳素这样,被如此广泛的研究和应用。”更有人说:“20世纪是塑料的世纪,21世纪是甲壳素的世纪。”日本平均每3天就有一份申请甲壳素应用专利的报告。全世界从事甲壳素产业化开发的企业已达数千家,其年销售额超过20亿美元……那么,甲壳素是什么东西?它对人类社会的发展与进步真的有那么大的作用吗?     

甲壳素／壳聚糖的改性及其衍生物的应用

综述了甲壳素／壳聚糖的化学改性及其衍生物的应用,指出甲壳素／壳聚糖的研究和应用前景更为广阔．     

甲壳素在离子液体中的溶解与改性

自人类发现甲壳素以来,一直致力于甲壳素在各领域功能的开发,时至今日,甲壳素的各类性能仍存在很大研究价值.作为自然界当中仅有的一个带正离子电荷的纤维素,甲壳素以其自身独特的性质吸引了广泛关注,本文从对甲壳素在离子液体中的溶解与改性进行研究,为甲壳素及其经脱乙酰化后的壳聚糖的各类应用提供借鉴.     

壳聚糖对果蔬和鲜花的保鲜功能和应用

壳聚糖是甲壳素经化学处理脱乙酰基后的产物,是惟一的碱性天然多糖,在各个领域都有广泛的应用。本文综述了壳聚糖的保鲜原理以及在食品保鲜、切花保鲜上的应用。     

甲壳素/壳聚糖及衍生物在印染废水处理中的应用

在介绍甲壳素、壳聚糖及衍生物来源、结构、性质以及制各方法和工艺基础上，重点综述了近年来国内外利用甲壳素壳聚糖及其衍生物处理印染废水的研究现状与应用进展。     

甲壳素及其衍生物概述

甲壳素及其衍生物是近年来在功能性食品、生物制药及环保领域发展起来的研究热点，素有“人体第六生命要素”、“软黄金’’之美誉．介绍了甲壳素及其衍生物的制造过程、国外该产业发展状况，展望了我国该产业开发应用前景．     

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.     

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     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the