共查询到20条相似文献,搜索用时 722 毫秒
1.
IC5000型离子色谱仪在水环境监测中的应用 总被引:1,自引:0,他引:1
利用IC5000型离子色谱仪建立了水环境中F^-、Cl^-、NO3^--N和SO4^2-的定量分析方法,相对标准偏差为0.54%-3.63%,回收率为97.2%-104.1%。对该仪器使用中常见的问题及解决方法作了论述。 相似文献
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西江干流梧州--肇庆段水化学特征研究 总被引:1,自引:0,他引:1
河流水化学特征可以从一定程度上反映出人类活动对水环境的影响。对西江干流梧州———肇庆段水化学参数分析表明,该段水体中阴离子以HCO3-占优势,阳离子以Ca2+为主,其矿化度为256~414 mg/L。岩石风化作用成为控制河流离子化学组成主导因素,工农业污染物输入在一定程度上改变了天然河流的离子化学组成,使NO3-、 SO2-4等呈现富集趋势。 相似文献
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叙述了近岸海域水环境采样前的准备及采样计划的编制、监测站住布设、样品采集贮存与运输、实验室分析、数据处理和传输等水环境监测的全过程,提出近岸海域监测的质量保证体系。 相似文献
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用物理化学原理从分子水平研究有机污染物在水环境介质中的分布。建立了模拟水环境介质一维模型,推导出计算分布值的数学表达式. 相似文献
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对淮河流域水环境监测中心新购置的ISC–2100型离子色谱仪进行了工作性能检验。保留时间重现性为0.664%~1.501%(n=10),4种阴离子(F–,Cl–,SO42–,NO3––N)标准曲线的线性相关系数大于0.999。对硝酸盐氮标准物质进行测定,测定结果的相对标准偏差为0.23%(n=8),加标回收率为91.8%~95.9%。实验结果表明,该离子色谱仪仪器性能稳定,各项检验结果满足实际监测工作的要求。 相似文献
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离子色谱法测定糙米中微量总溴的研究 总被引:8,自引:0,他引:8
本文研究了在有乙醇存在的碱性介质中,含溴熏蒸剂中的溴被转化为无机溴,随后用带电导检测器的离子色谱进行分离测定的方法。在Dionex AS4A分离柱上,用1.0mmol/L NaHCO3/2.0mmol/L Na2CO3作为流动相进行洗脱,被测组份得到了满意的仞了。方法简便、快速。对样品中溴离子的检测限为1.25mg/kg,相对标准偏差与回收率分别为5.73%和94.9%。首次用于实际糙米样品中微量 相似文献
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为了进一步提高金属离子探针的选择性和灵敏性,以3,5-二氨基苯甲酸和2,4-二羟基苯甲醛为原料,设计合成了一种比率型金属离子探针L(3,5-二(2,4-二羟基)苯基亚氨基)苯甲酸)。通过核磁、质谱和红外等方法对探针L的结构进行了表征,并利用荧光光谱、紫外光谱对探针L的光学性能进行了研究,结果表明:L对Al3+具有良好的选择性和灵敏性,受其它金属离子的干扰较小,并且反应前后伴有明显的颜色变化(黄色到无色)。通过计算,缔合常数为Kb = 1.35×104,L对Al3+的检出限低至8.6×10-8 mol/L,低于饮用水和食品中铝含量的国家标准,该离子探针有望应用于食品和水环境中Al3+的检测。 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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Uroš Grošelj Mojca Žorž Amalija Golobič Branko Stanovnik Jurij Svete 《Tetrahedron》2013,69(52):11092-11108
A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives. 相似文献
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The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp3)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp2)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp2)?H and aliphatic 1,5- and 1,6-C(sp3)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp3)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp2)?H insertion. 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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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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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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N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%). 相似文献
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Shashikant U. Dighe Surya K. Samanta Shivalinga Kolle Sanjay Batra 《Tetrahedron》2017,73(17):2455-2467
An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y1 and Y2. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones. 相似文献