共查询到20条相似文献,搜索用时 78 毫秒
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《分析化学》2007,35(5):968-968
化学测量是科技创新、国民经济发展、国际贸易的重要技术支撑。准确可靠的分析测量结果与环境保护、公共安全、科技发展、人民健康、国家声誉等密切相关。《实验室溶液制备手册》是各行业化学和分析实验室必备的工具书。该手册包含四部分内容:(1)溶液配制的基础知识、量器具校准、溶液和化学试剂、计量单位、有效数字及不确定度评定等;(2)无机分析、有机分析及容量分析的标准溶液的配制,共计1525种;(3)非标准溶液的制备,包括常用酸碱溶液、盐溶液、有机溶液、生化分析用溶液、缓冲溶液及指示剂溶液等;(4)附录,列出了溶液配制必要的常备及辅助信息或知识、化学试剂标准目录、国家一级和二级溶液标准物质目录及相关的技术规范、分子吸收分光光度法通则和化学试剂电位滴定发通则等。 相似文献
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甲酸还原银氨溶液的实验,已有几篇文章论及。现将笔者多次试验的结果介绍如下。 1.试剂 5%AgNO3溶液稀氨水(1:4) 甲酸浓溶液(~80%) 2.配制银氨溶液取约5ml5%AgNO3溶液于一支洁净试管里,滴加稀氨水(1:4),边加边振摇,至黑色沉淀恰好溶解为止,溶液的pH值近于11。 相似文献
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胶体性质实验中的硅酸溶胶必须是;澄清、透明的液体,受热或注入盐酸时均应生成凝胶;若与氢氧化铁溶胶混合,立即凝聚。我的简易配制方法是:61%硅酸钠溶液(约0.54mol/L)与10.5%盐酸(约3mol/L)技体积比4:1混合制得硅酸溶胶。1.配制治波门)新制已1%硅酸钠溶液。将N:。a*。·9*。o和水按质量比1:6混合,微微加热、搅拌,使其完全溶解。(2)105%盐酸:将37%盐酸和水饺体积比1:3混合即得。2·制备硅镁溶胶选用口径小而相同的两支胶头滴管。向洁净试管中滴加30滴61%硅酸钠溶液,再改滴7~8滴10.5%盐酸,同时振摇试… 相似文献
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由于Fe2+极易被空气中的氧气氧化,故通常情况下配制的Fe2+溶液和在敞开环境中进行的性质实验都无法达到预期效果。经探究,优化了F2+溶液的制备方法并对其性质实验进行改进,收到了良好的效果。实验充分体现了简约性、微型化的设计理念,实现了废物的再利用。 相似文献
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实验步骤称取FeSO4•7H2O晶体约5克(应是淡绿色),用蒸馏水配制为5%左右的硫酸亚铁溶液。放入一、二枚光亮铁钉,并滴入几滴稀H2SO4溶液。塞紧瓶盖,备用。 相似文献
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准确测定钨矿和钨酸盐晶体等高钨基体样品中稀土元素的含量有助于开展矿床地球化学特征研究及钨酸盐激光晶体材料的制备和性质研究。在高钨基体样品电感耦合等离子体质谱法(ICP-MS)分析时,为了考察高钨及高含量阳离子等基体组成对分析结果的影响,实验针对Na2WO4、CaWO4、NaY(WO4)2、MnWO4和(Fe,Mn)WO4等高钨基体样品,采用硝酸和氢氟酸高压密闭消解,加入稀土元素并用2% HNO3溶液稀释定容配制成稀土元素浓度为1 ng·g-1的基体匹配标准溶液;同时,直接用2% HNO3溶液配制稀土元素浓度相同的非基体匹配标准溶液以对比系统考察两种基体溶液中稀土元素的相对灵敏度系数(RSC)差异。结果显示,基体匹配溶液与2% HNO3溶液中稀土元素的RSC相对偏差基本小于15%,表明基体效应的影响可以忽略不计。进而,为了准确测定常见高钨基体样品中稀土元素的含量,实验建立了基于ICP-MS的高钨基体样品中稀土元素准确定量分析方法,该方法线性关系好(R2 ? 0.9997),检出限低(0.5 ~ 27.9 pg·g-1),准确度理想(相对误差-6.25 ~ 10.74%)。采用该方法测定了钨酸钙单晶实际样品中稀土元素的含量并将其与基体匹配法的测定结果进行比对,结果显示两者相对偏差为0.80 ~ 12.75%,说明本文所建立的分析方法可靠,能用于定量测定高钨基体样品中稀土元素的含量。 相似文献
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用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%. 相似文献
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Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction
Laurent Gavara Thomas Boisse Jean-Pierre Hénichart Adam Daïch Philippe Gautret 《Tetrahedron》2010,66(38):7544-5571
In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments. 相似文献
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The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula. 相似文献
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Rebecca J. Burton Mandy L. CrowtherNeal J. Fazakerley Shaun M. FilleryBarry M. Hayter Jason G. KettleCaroline A. McMillan Paula PerkinsPeter Robins Peter M. SmithEmma J. Williams Gail L. Wrigley 《Tetrahedron letters》2013
The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines. 相似文献
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KMnO4-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields. 相似文献
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N. A. Nedolya 《Chemistry of Heterocyclic Compounds》2008,44(10):1165-1219
The review contains a concise historical account and information on the most significant researches undertaken by the staff
at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry
of Heterocyclic Compounds.
Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee.
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008. 相似文献
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Regiospecific and direct imidation of the methyl C(sp3)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products. 相似文献
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《Tetrahedron》2014,70(21):3377-3384
The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative. 相似文献
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Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields. 相似文献