尼泊金酯的性能及用途

尼泊金酯(即对羟基苯甲酸酯)是一类应用面较广的防腐剂,它能有效地抑制细菌、霉菌和酶的生长,而其毒性远较苯甲酸或水杨酸衍生物为小。目前已广泛用作食品、化妆品和各种药物制剂的防腐剂。尼泊金酯产品主要包括:尼泊金甲酯、     

洗发乳中羟苯甲酯和羟苯丙酯的含量测定

用高效液相色谱法测定了洗发乳中两种尼泊金酯的含量。色谱条件如下,色谱柱:hypersil C18-ODS,4.6 mm×250 mm,5um;流动相:V甲醇:V水=70:30。先对系统适用性进行考察,得到分离度大于1.5,线性相关性值大于0.999。尼泊金甲酯和尼泊金丙酯的回收率分别为97.4%和102.5%,洗发乳中尼泊金甲酯和丙酯的含量分别为0.25mg/g样品、1.74mg/g样品。结论:该方法操作简单,结果较好,能够广泛用于药品、化妆品中尼泊金酯含量的测定。     

一次性塑料餐具中尼泊金酯迁移量的测定

该文建立了RP-HPLC法快速测定一次性塑料餐具中尼泊金甲酯、尼泊金乙酯、尼泊金丙酯、尼泊金丁酯和尼泊金异辛酯迁移量的方法.优化了色谱分离和分析条件,采用Diamonsil C₁₈(150 mm×4.6 mm×5 μm)色谱柱分离,用甲醇-水体系梯度洗脱,检测波长为254 nm,流速为1.0 mL·min^-1,柱温为30 ℃.该方法的线性范围为5～1 000 ng·mL^-1(R>0.99),检出限为0.37～0.52 ng·mL^-1,重现性良好,日内及日间重复测定的相对标准偏差分别为4.0%～5.3%、4.3%～7.5%.该方法成功应用于塑料杯、塑料碗、塑料盘等一次性塑料餐具中5种尼泊金酯迁移量的测定.     

气相色谱法测定食品中多种防腐剂及抗氧化剂

目的：建立一种程序升温快速测定食品中多种防腐剂（富马酸二甲酯（DMF）、山梨酸（SA）、苯甲酸（BA）、脱氢乙酸（DHA）、尼泊金甲酯（MP）、尼泊金乙酯（EP）、尼泊金丙酯（PP）、尼泊金异丁酯（IBP）、尼泊金丁酯（BP）、尼泊金庚酯（HP））和抗氧化剂（BHA、BHT、TBHQ）。方法：样品酸化后用乙酸乙酯提取,采用HP-5色谱柱,优化色谱条件,可将上述多种防腐剂和抗氧化剂很好的分离。结果：防腐剂及抗氧化剂在8.0～500μg/mL范围内呈很好的线性,相关系数均在0.9997以上,检出限在0.8～2.5μg/mL,加标回收率为87.5%～106.7%。     

尼泊金酯类防腐剂的研究进展

介绍了尼泊金酯的性质、应用与合成方法以及国内外生产情况。     

TiPW/SiO2催化合成尼泊金酯的研究

尼泊金酯是一种高效、安全的食品防腐剂。是目前国内外应用广泛的食品添加剂之一。本文以固体杂多酸为催化剂，以对羟基苯甲酸与异丁醇为原料合成尼泊金丁酯。对酯合成的催化剂用量、醇酸配比、反应时间、带水剂等方面进行了研究。获得了最佳反应条件。此工艺简单，副反应少，产品的收率高。     

尼泊金乙酯合成的研究

本文研究了以H_2SO_4为催化剂,无水ZnCl_2为脱水剂,用对羟基苯甲酸和乙醇进行酯化反应合成尼泊金乙酯。讨论了酯化过程中,催化剂用量,反应物配比对尼泊金酯收率的影响。     

TiPW/SiO_2催化合成尼泊金酯的研究

尼泊金酯是一种高效、安全的食品防腐剂。是目前国内外应用广泛的食品添加剂之一。本文以固体杂多酸为催化剂,以对羟基苯甲酸与异丁醇为原料合成尼泊金丁酯。对酯合成的催化剂用量、醇酸配比、反应时间、带水剂等方面进行了研究。获得了最佳反应条件。此工艺简单,副反应少,产品的收率高。     

三氧化二钕催化合成尼泊金丁酯

研究了以三氧化二钕作固体催化剂合成尼泊金丁酯,通过正交实验讨论了影响催化酯化反应的各种因素,确定了该酯化反应最佳条件。催化剂用量仅为尼泊金酯重量的５％ ,醇酸摩尔比为４∶１,反应时间为４ｈ,温度为１２℃,酯收率达８１２％     

新型防霉剂富马酸二甲酯的合成及抑菌试验研究

本文讨论了以马来酸酐为原料，在复合催化剂存在下，一步合成食品及饲料新型防霉剂富马酸二甲酯的最佳反应条件，结果证明本法具有原料价廉易得，工艺流程简单、反应时间短，产率高，纯度高，甲醇损失少，易于实现工业化等优点，通过对富马酸二甲酯与苯甲酸钠，山梨酸钾，丙酸钙，尼泊金乙酯及内酯及丙酯等的抑菌效果比较，结果表明富马酸二甲酯对多种霉菌、酵母菌及细菌有较强的抑制作用。     

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.     

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     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with