微波消解-火焰原子吸收法连续测定三氯苯肼中的铬、铁含量

采用微波消解-火焰原子吸收法,利用金属离子混合标液进行标准曲线测定,实现了2,4,6-三氯苯肼中微量铬和铁的快速连续测定.结果表明:混合标准溶液中铬的标准曲线为:A=0.087+0.028C,相关系数r=0.999 4;铁回归方程为A=0.048 8+0.127 6C,相关系数r=0.998 1.用该法测得三氯苯肼试样中的铬、铁含量分别为3.170 mg/L、1.620 mg/L;相对标准偏差分别为1.02%和1.79%;平均加标回收率为101%和99%.     

动力学分光光度法测定食品中的痕量铁

介绍了一种动力学分光光度测定痕量铁的方法.在pH=4.70的HAc-NaAc介质中,Fe(Ⅲ)对H2O2氧化番红花T的反应具有强烈的催化作用,使溶液颜色褪去.该溶液最大吸收波长为520 nm,铁含量在3.08×10-6～2.80×10-5 g/L范围内遵从比尔定律,表观摩尔吸光系数为5.6×105 L.mol-1.cm-1,回归方程为:ΔA=5.6×105 CFe(Ⅲ)+0.02(C的单位为mol.L-1),相关系数γ=0.9999,检出限为3.16×10-6 g/L,同时也研究了多种干扰离子对测定的影响,该方法应用于测定食品如大米、面粉中的痕量铁取得了满意的结果.     

表面活性剂-火焰原子吸收法测定人发中的微量铁

研究了用表面活性剂十二烷基硫酸钠测定铁的火焰原子吸收法 ,摸索了测定条件 ,在 1 mol/ L盐酸介质中 ,选定合适的仪器工作条件 ,铁含量 0 .0 2～ 0 .2 mg/ L范围内符合比尔定律 ,检出限量铁浓度为 1 .8mg/ L.经实际样品分析 ,变异系数不大于 3.6% ,样品加标回收率为 98%～ 1 0 2 % .     

电位溶出法测定多维元素片铜、铁、锌含量

目的 测定多维元素片中锌、铜、铁含量.方法 样品经微波消解,用微分电位溶出法测定.结果 与结论在pH 2.5 HCl底液中测定Cu,浓度范围在0.25～200μg/L,r=0.999 1,平均回收率为97.3%,RSD为1.7%;在0.05 moL/L邻苯二甲酸氢钾(pH 4.0)+4.3×10-4mol/L CdY溶液中测定Fe和zn,本法对Zn,浓度范围在0.16-75μg/L,r=0.997 7,平均回收率为104.1%,RSD为2.7%;对Fe,浓度范围为2～7μg/L,r=0.997 7,平均回收率为105.5%,RSD为1.8%.     

2,4-二氯苯基荧光酮测定食品中的微量铁

研究了在表面活性剂TritonX-100的存在下,显色剂2,4-二氯苯基荧光酮(DCIPF)与铁形成三元胶束络合物的反应条件.在pH=4.40的HCl-(CH2)6N4缓冲介质中,在表面活性剂TritonX-100存在下,铁与DCIPF形成组成比为1∶4的络合物,其最大吸收峰位于570nm处,表观摩尔吸光系数为ε=1.30×105L·mol-1·cm-1,铁含量在0～0.4μg/mL范围内符合比耳定律,大多数常见的阳离子不干扰铁的测定,此方法用于小麦粉、大米粉标样中铁的测定,结果满意.     

Fe(Ⅲ)-茜素红-PVPK-30体系分光光度法测定微量铁

研究 p H值为 4 .5的 NH4 Ac- HAc缓冲液中 ,在表面活性剂 PVPK- 30存在下 ,铁 ( )与茜素红生成可溶性有色络合物的显色反应条件。络合物最大吸收波长在 6 0 0 nm,表观摩尔吸光系数 ε6 0 0 =2 .93× 10 4 L.mol- 1 .cm- 1 ,铁的浓度在 0～ 1mg/ L范围内符合比耳定律。把拟定的分析方法用于发样和水样中微量铁的测定 ,获得满意结果     

以磷酸为掩蔽剂的铁(Ⅱ)-邻二氮菲分光光度法间接测定雪莲果中维生素C含量

利用维生素C定量将铁(Ⅲ)还原为铁(Ⅱ),铁(Ⅱ)与邻二氮菲发生显色反应,多余的铁(Ⅲ)用磷酸溶液掩蔽.结果表明,在pH=4.0的溶液中,维生素C的线性范围为0～12.8μg.mL-1,表观摩尔吸收系数ε=2.03×104L.mol-.1cm-1,加标回收率为97.3%～98.5%,变异系数为1.1%.该方法简便、准确、灵敏,是测量新鲜雪莲果中维生素C的一种有效方法.     

磺基水杨酸差示分光光度法测定不同含量的研究及应用

研究了用磺基水杨酸显色,差示分光光度法测定不同含量铁的方法.在pH?1.80—3.00的缓冲介质中,铁与磺基水杨酸生成紫红色络合物,表观摩尔吸光系数ε490为1.7×103?L*mol-1*cm-1,铁含量在4.00—28.00?mg*L-1(或16.00—40.00?mg*L-1)范围内符合比耳定律.该法简便快速,选择性好,准确度高,测定范围广,适用于地质样、钢样中常量特别是高含量铁的测定.     

污水中微量氨氮的光度测定方法

用苯酚作为显色剂、次氯酸钠作为氧化剂,亚硝基铁氰化钠作为催化剂,使NH3定量生成靛酚,用以测定污水中的微量氨.最大吸收波长λmax=625 nm,最大摩尔吸光系数εmax=1806 L*mol/cm.水样经过碱性预蒸馏,馏出液中加入二乙胺四乙酸(EDTA)后,用酚钠使溶液呈碱性,在催化剂作用下,用次氯酸钠氧化显色30 min后,可直接测定浓度为0.08～20 mg/L的氨(以氮计)样品.测定结果与钠氏试剂光度法基本吻合,该方法可消除石油类等19种物质的干扰.     

亚硝酰铁氰化钠法测定复杂样品中半胱氨酸含量的方法研究

本文首次建立了亚硝酰铁氰化钠法测定半胱氨酸的方法 ,该法灵敏度高 ,选择性好 ,干扰少 ,线性范围为 1 - 90μg/m L ,检出极线为 0 .78μg/m L ,回归方程为 y=0 .0 1 76x 0 .2 1 1 4,相关系数 r=0 .9991 ,尤其适用于复杂样品中半胱氨酸含量的测定 .     

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