蒙脱石修饰电极伏安法同时测定人血中的铅、镉

报道了一种快速同时测定人血中痕量铅、镉的电分析方法 ,在pH 4.0 0的磷酸盐缓冲溶液中 ,铅、镉在钠型蒙脱石修饰玻碳电极上通过离子交换有十分灵敏的阳极溶出峰 ,由此可同时测定痕量的铅、镉离子 ,且相互间的影响较小 .优化了各种试验条件 ,如支持电解质的选择、pH值的影响、修饰剂的用量、富集电位及时间、以及扫描速度 .利用该方法测定铅、镉时线性范围分别为 4× 10 -9到 8× 10 -6mol/L和 4× 10 -9到 2× 10 -6mol/L ,检出限分别是 5× 10 -10 mol/L和 8× 10 -9mol/L .该方法简便、快速 ,灵敏度高 .用此修饰电极测定了血样中的铅、镉离子 ,结果令人满意 .     

漆酚金属盐聚合物修饰电极伏安法测定水样中痕量铜的研究

用漆酚金属盐聚合物修饰碳糊电极能高灵敏度测定水样中痕量的Cu~(2+)。在pH6.0的HAc+NaAc缓冲溶液中,在电极表面Cu~(2+)通过化学和物理吸附而富集,在溶出过程中,于-0.04V(vs.SCE)处有一灵敏的氧化峰。该修饰电极测定Cu~(2+)的线性范围为4×10~(-9)～2.5×10~(-7) mol/L,富集20min后检测限为8×10~(-11)mol/L。用该修饰电极测定了环境水样中的铜离子,平均回收率为99.10％。     

吸附伏安法同时测定中草药中痕量的镍和钴

提出一种有效的测定痕量镍和钻的吸附伏安法。利用悬汞电极作为工作电极,在0.005mol/L NH_3～0.06 mol/L NH_4Cl—3.0×10~(-6)mol/L锌试剂的最佳底液中,测定镍和钴的线性范围分别为1×10~(-10)～8×10~(-8)mol/L和1×10~(-10)～1×10~(-7)mol/L,检测下限均为5×10~(-11)mol/L。在工作中探讨了镍、钻和锌试剂配合物的吸附伏安行为及其在电极表面上的电化学反应机理。研究证明,该方法灵敏、可靠、省时,特别适用于中草药中痕量镍和钴的定量分析。     

8—羟基喹啉修饰玻碳电极阳极溶出伏安法测定痕量镉

以8-羟基喹啉(Ox)作为修饰剂制备化学修饰电极,用于痕量镉的伏安法测定.研究了支持电解质种类及酸度、修饰膜厚度、富集电位、富集时间、扫描速度等因素对伏安曲线的影响,获得较为优化的测试条件.在0.1mol/LHAc-NaAc缓冲溶液(pH4.0)中,Cd(Ⅱ)的浓度在4.0×10-8mol/L～7.0×10-5mol/L范围内与其氧化峰电流呈良好线性关系(r=0.9933),检测限达2.0×10-8mol/L.该电极具有很好的重现性,在含2.0×10-6mol/LCd(Ⅱ)试液中连续测定10次,其RSD为7.8%.本法用于实际水样测定,获得满意的结果.     

铂微粒修饰固体石蜡碳糊电极对过氧化氢的电催化特征及分析应用

研究铂微粒修饰的固体石蜡碳糊电极(Pt-SCPE)对H2O2的电催化行为。在pH值4.6的柠檬酸盐-0.03 mol/L硝酸钾溶液中,用该电极H2O2在+0.18V(vs．SCE)可产生灵敏的还原电流,线性范围为1.0×10-1 mol/L～3.0×10-7 mol/L,检出限为7.5×10-8 mol/L。Pt-SCPE与液体石蜡碳糊电极比较,在峰电位、线性响应范围、检出限方面有更好的结果。用该电极测定样品中的过氧化氢,获得满意结果。     

多巴胺在聚L-天冬氨酸修饰电极上的催化氧化及测定

研究了聚L_天冬氨酸修饰电极的制备及其电化学性质。实验表明 ,该修饰电极对神经递质多巴胺的电化学氧化有显著的催化作用 ,使电极反应过程的可逆性变好 ,峰电流明显增大。采用差示脉冲伏安法对多巴胺进行定量分析 ,线性范围为 1 0× 10 - 7～ 1 0× 10 - 4 mol L ,检出限为 5 0× 10 - 8mol L。该聚合物修饰电极具有良好的选择性 ,能有效地排除抗坏血酸对测定的影响 ,用于合成样品分析 ,结果令人满意。     

氧氟沙星的极谱测定及电化学行为研究

在0.25mol/L KCl(pH=3.60)的底液中,采用线性扫描极谱法测定氧氟沙星,得到一良好的还原峰. 峰电位Ep=-1.40V(vs.SCE),峰电流Ip与氧氟沙星的浓度在2.0×10-7-8.0×10-6mol/l范围内成线性关系,相关系数r=0.9978,检出限为9.0×10-8mol/L.采用本法测定片剂的含量,回收率在98.13%- 100.68%,RSD为1.69 - 2.31%之间,方法简便,结果准确可靠.用多种电化学方法研究了氧氟沙星在汞电极上的电化学行为,结果表明氧氟沙星的电极过程具有吸附性、动力性和不可逆性.     

硫酸预活化测定痕量氟的离子选择性电极法

研究了一种在0.5 mol/L的硫酸介质中先活化氟离子选择性电极,然后再在含有硫酸总离子强度调节混合溶液(TISAM)介质中测定痕量氟的方法.该方法线性范围为1.00×10-2~1.00×10-7mol/L,检出限为1.9μg/L,应用到绿茶饮料、水、牛奶中痕量氟的测定,结果令人满意.     

表面活性剂存在下安非他酮电化学特性及其分析应用

研究了安非他酮的电化学特性.在pH=3.5,含0.010 mol/L NaCl的Britton-Robinson缓冲溶液中,安非他酮在汞电极上吸附并发生电化学反应,于-0.87 V处呈现灵敏的极谱波,当有0.002 0%OP存在时,峰电位移至-0.80 V,且峰电流增加数倍.利用此波可测定痕量安非他酮,线性范围为5.0×10-9~5.0×10-7mol/L,检测下限达1.0×10-9mol/L.循环伏安法和脉冲极谱实验结果表明,OP促进安非他酮在汞电极上吸附.     

聚组氨酸修饰电极测定多巴胺的研究

本文研究了多巴胺在聚组氨酸修饰电极上的循环伏安行为.在pH7.0的磷酸盐缓冲溶液中,用线形扫描伏安法测定多巴胺的线性范围为:6.0×10-8～1.0×10-5mol/L,1.5×10-5～1.0×10-3mol/L,检出限为4×10-8mol/L.用于药剂中多巴胺的测定,结果满意.     

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.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

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.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

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