共查询到20条相似文献,搜索用时 31 毫秒
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本文通过大量实验,研究了一种新的锇的最佳支持电解质体系为:1.3×10~(-3)mol/LCH_4N_2S-6.3×10~(-2)mol/L ClCH_2COOH-0.1mol/L NaAc(pH=4.39)。在该体系中,以硫脲作吸附剂,并在直流极谱仪上于+0.55V(vs.SCE)发现一锐敏的锇峰。如在该体系中含有AS_2O_3(0.25μg/ml)时,测定锇的线性范围从0.037~0.224μg/ml扩展到0.037~0.37μg/ml,这很适宜于用As_2O_3吸附蒸馏试样。方法的灵敏度达37ng/ml。本法已成功地用于精矿测定,结果与原含量相符。 相似文献
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鲁米诺-锰(Ⅱ)-高碘酸钾化学发光体系测定痕量锰的研究 总被引:8,自引:0,他引:8
本文提出1种以三乙醇胺作活化剂,基于鲁米诺-锰(Ⅱ)-高碘酸钾化学发光体系高灵敏度、高选择性测定痕量锰的分析方法。检测限达8×10~(-6)μg/mLMn(Ⅱ)。Mn(Ⅱ)浓度在10~(-5)~0.1μg/mL范围内呈良好的线性关系。测定1.0×10~(-3)μg/mL Mn(Ⅱ)的相对标准偏差小于±3%。应用于井水及人发样品中锰的测定,结果令人满意。 相似文献
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用冠醚和硫氰酸钾萃取光度法测定钢铁中微量铌 总被引:2,自引:0,他引:2
报道了用双(苯并-18-冠-6)和硫氰酸钾试剂萃取光度测定钢铁中的微量铌,方法的选择性好,灵敏度高,ε_(400nm)=3.85×10~4L·mol~(-1)·cm~(-1),铌在1~20μg/25ml范围内有较好的线性关系,线性回归方程A=0.936C(mg·ml~(-1))-1.425×10~(-3)。 相似文献
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微量铼在2.2MH_2SO_4-1.5×10~(-3)M甲醛-1.6×10~(-3)MCuSO_4-5μg/10ml碲溶液中在单扫描示波导数极谱上可产生灵敏的催化氢波。铼的浓度在0.001~0.015μg/ml范围内与峰电流有正比关系,文中讨论了催化电流的性质。拟定了矿石中痕量铼的测定方法。 相似文献
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均相伏安免疫法检测白喉类毒素和白喉抗毒素 总被引:3,自引:0,他引:3
白喉类毒素在pH9.4的0.1MNH_4Cl-NH_3·H_2O底液中改性,产生还原峰和氧化峰,峰电位分别为-1.52V和-1.46V(vs.SCE)。用单扫示波极谱法得到还原(或氧化)峰的峰电流与白喉类毒素浓度在2.5—180μg/ml范围内均呈良好线性关系。用微分脉冲极谱法可检测浓度低至0.3μg/ml的白喉类毒素。由特异性免疫结合反应,微分脉冲极谱法测得白喉类毒素的峰电流降低值与白喉抗毒素浓度在2.5×10~(-6)—5×10~(-5)IU/ml范围内呈正比关系,可测定白喉抗毒素浓度。方法简便、快速、灵敏度较高,可均相测定。用氧化峰电流测定百日咳菌苗-白喉-破伤风类毒素混合剂中白喉类毒素的含量,结果满意。 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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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
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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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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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A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL. 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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A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions. 相似文献