共查询到20条相似文献,搜索用时 78 毫秒
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张根平 《理化检验(化学分册)》2007,43(6):510-510
钢铁中硅含量的测定有二氧化硅重量法[1],硅钼蓝光度法[2]。重量法操作繁琐耗时长,而光度法简便快速,故日常钢铁分析中多采用光度法。但高铬钢和高铬铸铁的试样溶解问题一直是困扰光度法得以很好应用的难题。行业中采用盐酸-过氧化氢快速法(亦称爆炸法)检测高铬钢中硅的含量,有效解决了高铬钢的溶样问题,但该法不适用于高铬铸铁中硅的测定;对溶样温度、煮沸时间均须严格控制。本法在盐酸-过氧化氢快速法的基础上,进一步改进溶样方法,解决了高铬钢及高铬铸铁的溶样问题,选择合适发色酸度,使检测过程快速准确。1试验部分1.1主要仪器与试剂TU1… 相似文献
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在測定硅鉄中硅的各种方法中,以重量法的准确度最高,但是所需要的时间很长,所消耗的劳动力又多,因此不能滿足工业分析的需要。用准确度很高的方法来测定(?)铁中的硅,除了分析标准试样之外,一般是不需要的。硅铁中一般含硅30—80%,在日常分析工作中,能把误差保持在±1%之内,已经完全能够滿足炼鋼方面的要求。为了快速测定硅铁中硅,常用的快速法有比重法、比色法和氢氟酸重量法。其中比重法最快,但是准确度最差,又需要大量试样。比色法和氫氟酸重量法虽然比重量法快得多,但是也需要1/2—1小时才能完成。硅铁中除了硅和铁之外还有一些錳,其他金属和非金属一般只有微量。下面所提出的测定硅铁中硅的 相似文献
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铝合金中高硅 (Si≥ 0 .4 % )的测定 ,国标采用重量法[1] ,但因流程较长且较繁琐 ,故日常快速分析仍常用比色法。目前应用较多的有 β型硅钼黄吸光光度法[2 ,3] ,其中文献 [2 ]方法稳定性较差 ,而文献 [3]需用恒温装置 ,不利于一般实验室操作。本法基于α型硅钼黄比 β型硅钼黄更稳定 ,且灵敏度更低 ,利于高含量硅的比色测定。同时 ,铝合金中其它干扰杂质如磷、砷等含量低 ,也便于应用α型硅钼黄比色测定高硅。结果证明本法较 β型硅钼黄吸光光度法稳定性和准确性都有较大提高 ,可用于铝合金中高硅的日常快速分析。1 试验部分1.1 仪器与… 相似文献
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金属材料分析方法的选择和施行第三讲钢铁中钼的测定(续) 总被引:2,自引:0,他引:2
吴诚 《理化检验(化学分册)》2002,38(6):311-313
2 钼的测定方法的选择及施行2 .1 测定方法的概况为适应钼含量跨度很宽的各类钢铁及合金中测定钼的要求 ,需要有在分析灵敏度、准确度和速度上各具特色的多种方法。就现行的标准方法和常用方法看 ,应用较普遍的以光度法和重量法为主。重量法中有α 安息香酮肟法、8 羟基喹啉法等 ,光度法中硫氰酸盐法几乎是一枝独秀。可用于测定钼的新光度显色剂 ,近年有很快的发展 ,其中不乏分析性能优良者 ,但由于需要经过一定的考核 ,至今在标准方法中被采用者几乎没有 ,而在日常分析中的推广应用也很少。目前 ,测定高含量钼大都采用重量法 ,分析组成复… 相似文献
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《理化检验(化学分册)》2016,(2)
正钼铁是钼与铁的合金,主要用途是炼钢时作为钼的加入剂。但钼铁中含有一定量的磷、铜、硅等杂质元素,它们对钢材的性能有一定的影响,技术条件中对其含量均有限制。目前,实验室采用8-羟基喹啉重量法测定钼[1],重量法测定硅[2],分光光度法测定磷[3],分光光度法或原子吸收光谱法测定铜[4],操作步骤繁琐,所用试剂较多,检验周期长,且不同元素必须采用不同的测定方法,很难满足生产时快速分析的需要。 相似文献
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光度法联测锰铁中的硅磷 总被引:2,自引:0,他引:2
梁家斌 《理化检验(化学分册)》1998,34(1):34-35
锰铁中的硅、磷测定,一般采用沉淀重量法,或氟硅酸钾容量法测定硅,磷钒钼黄光度法测定磷。在参阅文献[1~5]的基础上,通过试验,提出采用硫硝混合酸溶解样品,硅钼蓝光度法测定硅,铋磷钼蓝(三元络合物)光度法测定磷。数据处理采用同牌号锰铁标准样品,测定吸光度(A)值,绘制硅和磷的检量线(线性回归方程)。硅0.20~2.0μg·ml~(-1),磷0.050~0.50μg·ml~(-1)范围内符合比耳定律。本法测定结果快速、准确,适宜日常检验(例行)分析。 相似文献
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氯氧镁水泥水化相定量测定的重叠峰—K值法 总被引:1,自引:0,他引:1
用X射线衍射定量分析的重叠峰-K值法,测定了氯氧镁水泥水化相含量,回收实验的相对误差小于8%,水化相含量与氯氧镁水泥的抗压强度密切相关。 相似文献
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建立了硅钼蓝分光光度法测定卡托普利的方法,详细探讨了硅钼蓝光度法测定卡托普利的各种影响因素。结果表明,卡托普利分子中的巯基(-SH)可以定量地将硅钼黄还原为硅钼蓝,通过测定硅钼蓝的吸光度从而间接地测定卡托普利的含量。显色体系最大吸收波长为690 nm,卡托普利质量浓度在4.240~55.12μg·mL-1范围内与A呈良好的线性关系,线性回归方程为A=0.0044+10.259ρ(mg·mL-1),线性相关系数r=0.9998。方法用于测定实际药品中卡托普利的含量,结果与药典法相符。 相似文献
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利用手持技术改进测定乙醇分子结构实验 总被引:1,自引:0,他引:1
利用压强传感器代替排水集气法,改进测定乙醇分子结构实验的仪器装置,并探索最佳反应条件。另外,设计两个空白实验,结合压强变化曲线对实验误差进行相关讨论。 相似文献
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Mustafa R. Ibrahim Zacharia A. Fataftah Paul von Ragu Schleyer Peter D. Stout 《Journal of computational chemistry》1987,8(8):1131-1138
Sets of hydrogen molecule equivalents have been developed which permit the calculation of hydrogenation of different types of carbon-carbon bonds from ab initio total energies (3-21G and 6-31G* basis sets, and, to a more limited extent, for MP2/6-31G* data) of reactants and products. The calculated enthalpies of hydrogenation are in good agreement with experiment for unstrained molecules, with average errors on the order of 2 kcal/mol. The 6-31G* equivalents allow the enthalpies for strained molecules to be calculated accurately, but the 3-21G equivalents do not. The equivalents for both basis sets have been tested by calculating the enthalpies of hydrogenation of carbon-carbon bonds in nitrogen- and oxygen-containing organic molecules, free radicals, and classical carbocations. The results are in good agreement with experiment in most cases. 相似文献
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由于石化行业的生产需要,其材质的使用具有多样性和广泛性,经常会出现顾客委托的测试样品的一个或几个元素跨越光谱仪现有测试程序测量范围的情况。本法通过对光谱仪测试原理的认识,根据光谱仪的测试能力及标样的采集,实现了一个或几个元素测量范围的扩展,并对其测量的影响因素进行了研究。 相似文献
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V. I. Bol'shakova L. I. Demenkova É. N. Shmidt V. A. Pentegova 《Chemistry of Natural Compounds》1989,24(6):691-694
The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodynkh Soedinenii, No. 6, pp. 812–816, November–December, 1988. 相似文献
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V. I. Bol'shakova L. I. Demenkova É. N. Shmidt V. A. Pentegova 《Chemistry of Natural Compounds》1988,24(6):691-694
The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae. 相似文献
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Influence of viscosity of medium on processes of oxygen quenching of excited states of mesoporphyrin
E. I. Kapinus V. A. Ganzha B. M. Dzhagarov E. I. Sagun V. B. Pavlenko 《Theoretical and Experimental Chemistry》1989,25(2):146-151
The oxygen quenching rate constants for singlet and triplet excited states of the dimethyl ester of mesoporphyrin IX increase with decreasing viscosity of the medium and reach a maximum at a viscosity of approximately 0.4 mPa·sec, after which the rate constants begin to decrease. The drop in rate constant with increasing fluidity of the medium may be related to a nonequilibrium character of the elementary act in the interaction of the reactants in the solvent cage. In viscous media such as isopropyl alcohol, isobutyl alcohol, and isoamyl alcohol, the reaction radius is greater than the sum of the radii of the reacting particles. The long-range character of these processes is due to the relatively weak dependence of the quenching probability on distance.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 2, pp. 161–167, March–April, 1989. 相似文献