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1.
试样用硫酸、硫酸钾溶解,借碳在高温将五价锑还原成三价锑,同时五价砷也被全部还原成三价砷。在酸性溶液中三价锑能被硫酸铈氧化成五价锑,而大量的三价砷则保持原价态,过量的硫酸铈可以使甲基橙褪色用以确定终点,滴定完锑的溶液再加几滴甲基橙指示剂可后用溴酸钾滴定砷,溴酸钾即将溴离子氧化成游离溴,游离溴能破坏甲基橙而引起终点明显变化。  相似文献   

2.
催化动力学光度法测定抗坏血酸的反应动力学   总被引:1,自引:0,他引:1  
研究了溴酸钾氧化甲基橙体系催化动力学测定抗坏血酸(维生素C)的反应动力学规律,实验表明:反应对甲基橙为一级反应,对维生素C也是一级反应,并求得了相应的表观活化能.  相似文献   

3.
在盐酸与硫酸混合酸介质中,铟 (Ⅲ )对溴酸钾氧化甲基橙褪色的反应具有强烈的催化作用,而甲基橙在电极上还原产生灵敏的极谱吸附波,据此作为监测催化反应过程中甲基橙浓度的变化,建立了催化动力学极谱法测定痕量铟的新方法。该方法的线性范围为 20- 400ng/ ml,检出限为 3.75ng/ ml。方法用于金属锌中铟的测定,结果令人满意。  相似文献   

4.
双波长双指示剂催化动力学光度法测定痕量亚硝酸根   总被引:1,自引:0,他引:1  
在磷酸介质中,利用亚硝酸根催化溴酸钾氧化亮绿和甲基橙褪色的指示反应,建立催化光度法测定痕量亚硝酸根的新方法.该反应的最大吸收峰在500 nm和640 nm处,线性范围1-11μg/25 mL,其检出限为2.82 × 10-10g/L,相对标准偏差0.05%.本方法灵敏度高,体系稳定,具有较好的选择性,用于自来水中痕量亚硝酸根的测定,结果较为满意.  相似文献   

5.
催化动力学极谱法测定痕量亚硝酸根   总被引:2,自引:0,他引:2  
在硫酸介质中,痕量亚硝酸根对溴酸钾氧化甲基橙的反应有极强的催化作用,而甲基橙在电极上产生曼敏的极谱吸附波.以极谱法测定催化反应过程中甲基橙浓度的变化,建立了催化动力学极谱法测定痕量亚硝酸根的方法.在选定最佳实验条件下,方法的线性范围是0,0052-0.5336mg/L  相似文献   

6.
砷形态分析方法   总被引:3,自引:0,他引:3  
建立了水环境中的4种砷形态亚砷酸(As(Ⅲ))、砷酸(AS(V))、一甲基砷酸(MMA)、二甲基砷酸(DMA)的形态分析方法.在pH 6.0磷酸盐作流动相、梯度洗脱条件下,4种砷形态在IC-Anion-PW阴离子交换色谱上获得了分离.以20g/L的KzS2 08溶液作氧化荆,紫外催化氧化消解,可使有机砷完全转化为无机态的As(V).并在10%的盐酸栽流、20g/LKBH4+5g/LKOH溶液为还原剂的条件下,实现了氢化发生原子荧光检测.将所建立的方法用于地下水样品的测定,4种形态砷系物在O~20mg/L的质量浓度范围内都表现出良好的线性关系.各检出限均保持在约0.1/g/L水平,回收率控制在95%~110%以内,相对标准偏差≤3%.  相似文献   

7.
珠江广州河段底泥中砷的形态分析   总被引:1,自引:0,他引:1  
对底泥中4种结合态的几种形态砷(As(Ⅲ)、As(Ⅴ)、甲基胂酸盐和二甲基胂酸盐)的测定表明,底泥中砷的污染严重,平均为41.7ppm.酸溶解态、碱溶解态和残渣态含砷量分别占72.4%、8.8%和18.9%,水溶态含砷量为全砷量的千分之几(ppb级).各结合态中都以无机砷为主,As(Ⅲ)占多数,占总砷量1/2以上;有机砷占总砷量1/2左右,以二甲基胂酸盐为主.  相似文献   

8.
以含H2SO4、As、Sb、Bi的酸性溶液为研究体系,采用化学分析及电化学测试研究了电解液中砷的氧化还原规律及价态转化途径。试验结果表明:溶解在铜电解液中的空气在一定温度下将As3+氧化,而且Sb可显著促进As3+的氧化。通过向电解液中通入适量的SO2可实现电解液中砷的价态调控,促进砷锑铋的共沉淀反应。采用SO2还原电解液中的As5+,使砷物质的量比(n(As3+)/n(As5+))维持在1∶1附近,Sb、Bi在一定条件下脱除率分别高达60.0%和46.0%。电化学测试表明:加入As3+后,阴极过程在-0.1~-0.2 V出现还原峰,随着As3+加入量增大,峰电位负移。加入As5+后,阳极和阴极过程分别在-0.01 V和-0.18 V附近出现氧化峰和还原峰,随着As5+浓度的增加,氧化峰电流逐渐增大;还原峰电位负移,峰电流先增大后减小。  相似文献   

9.
在硫酸介质中,阿莫西林可以催化溴酸钾氧化甲基橙使其褪色,且褪色程度(△A)与阿莫西林浓度在一定范围内符合朗伯-比尔定律,据此建立了催化光度法测定阿莫西林的新方法。在最优试验条件下,阿莫西林含量在0.70~9.0μg/mL范围内与吸光度呈良好的线性关系,检出限0.33μg/mL,回收率在96%~104%之间。可用于胶囊中阿莫西林含量的测定,结果满意。  相似文献   

10.
超声降解水溶性偶氮染料甲基橙的实验研究   总被引:1,自引:0,他引:1  
文章以水溶性偶氮染料甲基橙为对象,进行了超声降解实验研究.实验结果表明,甲基橙初始体积质量、溶液体系pH值及超声时间对甲基橙降解效果均有影响,并通过实验证明,甲基橙的超声降解途径为自由基氧化,且甲基橙分子结构中-N=N-显色基团断裂程度较苯环的断裂程度明显.  相似文献   

11.
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.  相似文献   

12.
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.  相似文献   

13.
何延凌 《科技信息》2008,(4):258-258
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.  相似文献   

14.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

15.
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。  相似文献   

16.
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.  相似文献   

17.
本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。  相似文献   

18.
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.  相似文献   

19.
20.
The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to  相似文献   

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