催化褪色光度法测定痕量铁的研究

研究了在稀 H2 SO4 介质中 ,痕量铁催化 H2 O2 氧化甲基红褪色反应 ,建立了一种高灵敏、高选择性测定痕量铁的新方法 .检出限为 5 .0× 1 0 - 7g/L,线性范围 0 .0 μg/1 0 m L～0 .4μg/1 0 m L,用于食品中铁的测定 ,结果令人满意     

RP-HPLC法测定北五味子中6种木脂素类成分

采用RP-HPLC法同时测定北五味子中6种木脂素类成分.色谱柱为Agilent ZORBAX SBC18(5μm,4.6×150 mm),流动相为甲醇-水溶液梯度洗脱,检测波长为254 nm,柱温为25℃.结果表明:五味子甲素在40.4~600.0μg/m L(r=0.999 8)、五味子乙素在42.0~420.0μg/m L(r=0.9999)、五味子丙素在15.8~118.8μg/m L(r=0.999 5)、五味子醇甲在10.0~160.0μg/m L(r=0.9999)、五味子醇乙在15.5~388.0μg/m L(r=0.999 5)、五味子酯甲在16.3~408.0μg/m L(r=0.999 9)范围内峰面积与对照品质量浓度呈良好的线性关系(n=6).6种成分的加样回收率均高于98%,RSD值小于3%本方法简便,准确,快速,重现性好,可用于北五味子中有效成分的定量分析.     

新指示反应催化光度法测定痕量钴(Ⅱ)的研究

本法基于钴 ( )对高碘酸钾氧化孔雀绿有催化作用 ,提出一种灵敏地测定痕量钴 ( )的新方法。该方法线性范围在 0～ 0 .0 32μg/m L ,检测限为 2 .1× 10 - 10 g/m L。测定出反应表现活化能 Ea=37.94K J/m ol。此法用于茶叶、维生素 B12 中钴的测定 ,结果满意     

荷移反应测定可可碱的研究及其应用

研究了可可碱与氯冉酸的荷移反应 ,确定了荷移反应的最佳条件 .在乙醇介质中 ,可可碱与氯冉酸在室温下可生成 1∶ 1的π-π型荷移络合物 ,其最大吸收波长为 31 8nm,表观摩尔吸光系数为 ε=1 .57× 1 0 5L·mol-1· cm-1 ,可可碱的浓度在 0 μg/ m L～ 1 .1 5μg/ m L 范围内与其吸光度呈线性关系 ,回收率为 98.3%～ 1 0 1 .1 % ,相对标准偏差为 0 .6%～ 1 .0 9%     

HPLC法同时测定饲料添加剂中的双乙酸钠、丙酸钙、山梨酸钾和苯甲酸钠

建立了同时测定饲料添加剂中的双乙酸钠、丙酸钙、山梨酸钾和苯甲酸钠4种防腐剂的HPLC方法.使用Hypersil ODS C18反相色谱柱(5μm;250×4.6 mm),0.02 mol/L KH2PO4-甲醇(65∶35,V/V)为流动相,标准和样品的p H值为2.5,流速为1.0 m L/min,检测波长为214 nm.柱温为25℃.结果表明:双乙酸钠在30~1 000μg/m L浓度范围内峰面积与浓度线性关系良好,平均回收率为91.8%;丙酸钙在50~2 000μg/m L浓度范围内线性关系良好,平均回收率为87.5%;苯甲酸钠在3~300μg/m L浓度范围内线性关系良好,平均回收率为92.3%;山梨酸钾在4~400μg/m L浓度范围内线性关系良好,平均回收率为83.4%.双乙酸钠、丙酸钙、苯丙酸钠和山梨酸钾的检出限分别为6.3μg/m L,11.8μg/m L,0.1μg/m L和0.2μg/m L.     

RP-HPLC法同时测定通窍鼻炎片中5种成分

建立RP-HPLC法同时测定通窍鼻炎片中花椒毒酚、水合氧化前胡素、白当归素、欧前胡素和异欧前胡素的含量。Agilent TC-C18色谱柱(4.6 mm×250 mm,5μm),流动相为0.2%甲酸水(A)—乙腈(B),梯度洗脱(0~42 min,22%B;43~72 min,50%B);柱温30℃;进样量50μL,流速1.0 m L/min;检测波长为254 nm。花椒毒酚在0.163~5.216μg/m L(r2=0.999 8),水合氧化前胡素在0.699~22.356μg/m L(r2=0.999 5),白当归素在0.375~11.988μg/m L(r2=0.999 8),欧前胡素在1.617~51.744μg/m L(r2=0.999 3),异欧前胡素在0.869~27.784μg/m L(r2=0.999 8)质量浓度范围内与峰面积具有良好的线性关系,平均回收率均大于95%。该方法准确可靠,可行性及重复性良好,可作为通窍鼻炎片的质量控制方法。     

~1Rh(Ⅲ)对鲁米诺-H_2O_2-Cu(Ⅱ)化学发光抑制作用的研究及其测定

研究 Rh( )对 Lu- H2 O2 - Cu( )化学发光体系的抑制作用 ,提出在贵金属混合物中测定微量 Rh( )的新方法 :在 p H=1 2 .40～ 1 2 .6 0的碱性溶液中 ,微量 Rh( )可抑制 ( 2 .5～ 7.5)× 1 0 -3 mol/ L Lu- ( 1～ 4)× 1 0 -2 mol/ L H2 O2 - Cu( ) (与待测 Rh在同一数量级 )体系的化学发光 ,线性范围 0 .1～ 1 0μg/ m L Rh( ) ,相对标准偏差 2 % ,检出限 0 .0 4 μg/ m L Rh( ) ,已用于 7种贵金属人工混合试液和 Pt- Rh合金中 Rh的测定 .     

水中痕量铅的氢化物原子荧光测定

提出了以酸性重铬酸钾碱性铁氰化钾为氧化剂的铅氢化物发生体系 .采用断续流动氢化物发生器 ,对原子荧光法测定痕量铅的条件进行了系统研究 .以 2 0g/L柠檬酸钠为干扰抑制剂 ,考察了共存元素的干扰情况 .在最佳测试条件下 ,测得铅的检出限 ( 3σ)为 0 .2 1μg/L ,相对标准偏差 ( ρ(Pb) =2 5μg/L ,n =11)为 1.2 % .对水中痕量铅进行分析 ,回收率为 97.5%～ 10 5.0 % ,结果令人满意 .     

基于火焰原子吸收光谱法的苯甲酸阿格列汀中残留钯测定

建立了一种基于火焰原子吸收光谱法测定残留钯的方法:苯甲酸阿格列汀原料药经前处理后,直接用火焰原子吸收光谱法进行测定.结果显示,残留钯元素的标准曲线线性范围在0~1.6μg/m L,相关系数为0.9997,方法回收率在94.8%~104.6%之间,检出限为0.03μg/m L,重复性RSD=3.45%(n=5).方法操作简便、迅速,有较好的准确度与精密度,可适用于苯甲酸阿格列汀中残留钯的测定.     

聚乙二醇辛基苯基醚增敏光度法测定茶叶中铅的含量

采用聚乙二醇辛基苯基醚增敏光度法测定茶叶中铅的含量.在邻苯二甲酸氢钾-氢氧化钠缓冲溶液中,铅与甲基百里酚蓝反应生成蓝色配合物,非离子表面活性剂聚乙二醇辛基苯基醚的加入大大提高了测定的灵敏度.分别研究了增敏剂用量、显色剂用量、缓冲溶液酸度、显色时间、反应温度对吸光度的影响.结果表明,最佳反应条件为p H=6.2的邻苯二甲酸氢钾-氢氧化钠缓冲溶液2 m L,0.5 g·L-1甲基百里酚蓝溶液4 m L,2 g·L-1的聚乙二醇辛基苯基醚1 m L,室温(25℃)下反应3 min.配合物的最大吸收波长为608 nm.铅(Ⅱ)含量在0-5.6μg·m L-1范围内符合朗伯-比尔定律,标准曲线的线性回归方程为:A=0.034 8 C(μg·m L-1)+0.158 9,相关线性系数为R2=0.999 7,由线性回归方程可得表观摩尔系数为1.8×104L·mol-1·cm-1.测得样品的相对标准偏差(RSD)为2.45%-3.59%(n=3),加标回收率为95.2%(n=3).国标规定茶叶中铅含量不超过5μg·g-1,实验测得茶叶中铅含量为65.28μg·g-1,严重超标.     

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