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961.
M. C. Mahedero A. Muñoz De La Peña A. Bautista J.J. Aaron 《Journal of inclusion phenomena and macrocyclic chemistry》2002,42(1-2):61-70
The effect of -cyclodextrin (-CD) and hydroxypropyl--cyclodextrin (HP--CD) upon the photochemically-induced fluorescence (PIF) properties of four phenylurea herbicides, including linuron, diuron, isoproturon and neburon has been studied. Photochemical conversion of these nonfluorescent herbicides into strongly fluorescent photoproducts was shown to occur in -CD and HP--CD aqueous media. The influence of pH, UV irradiation time and photoproduct stability on the fluorescence intensity was also investigated. In addition, the stoichiometry and formation constants of the complexes formed between herbicides and -cyclodextrin (-CD) or 2-hydroxypropyl--cyclodextrin (HP--CD) were determined. The formation constant values, ranging from 184 ± 40 to 1498 ± 245 M-1, were calculated by applying the iterative nonlinear regression (NLR) approach to the PIF data. Linear calibrations graphs were established in the interval 1–12 g/mL, for diuron, linuron and neburon. The IUPAC limits of detection ranged between 580 and 700 ng/mL, according to the compound. Application to the analysis of phenylurea herbicides in spiked river water was also described. 相似文献
962.
963.
Akira Ando 《Journal of fluorine chemistry》2005,126(5):765-770
Treatment of 2-chloro-3,3-difluoroprop-2-en-1-ol derivatives (2) with methanesulfonyl chloride in the presence of a base did not give the expected esters but 2-chloro-1,1-difluoroprop-2-enyl methanesulfonates (4) through a novel [3,3] sigmatropic rearrangement. Reaction of 4 with diethylzinc in the presence of tetrakis(triphenylphosphine) palladium gave 1-alkyl- or 1-aryl-2-chloro-3-fluoropenta-1,3-dienes in moderate to good yields through a CC bond formation followed by dehydrofluorination. 相似文献
964.
研究了半导体隔片光电化学电池(SC-SEP)中光池溶液的pH、暗池溶液的氧化还原电对以及两池中的暗电极对电池的开路电压、光生电压、短路光电流和光伏安特性的影响。对它们的影响机制进行了初步分析。通过合理选择电池体系,SC-SEP的性能可比单隔室的光电化学电池(PEC)优越。 相似文献
965.
966.
Jie Bai Shenglin Liu Sujuan Xie Longya Xu Liwu Lin 《Reaction Kinetics and Catalysis Letters》2004,82(2):279-286
A comparison of methane dehydroaromatization (MDA) on 6Mo/MCM-22 and 6Mo/ZSM-5 was carried out using a gas mixture of 90%CH4, 2%CO2 and 8%Ar as the feed. The results indicate that the stability of 6Mo/MCM-22 is better than that of 6Mo/ZSM-5. A detailed
study reveals that the ability for coke accommodation and the retention of the shape selectivity for aromatics formation is
responsible for the stability of a MDA catalyst.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
967.
采用带八级杆碰撞/反应池(ORS)的电感耦合等离子体质谱法(ICP-MS),直接测定丙烯腈或乙腈产品中的Fe、Cu,标准加入法定量.结果表明,方法的线性范围宽,线性相关系数均大于0.999.2种元素的相对标准偏差均低于5%,加标回收率在90%~110%.该方法简便、快速、准确. 相似文献
968.
The dehydrogenation reaction of ethane over Cr/CeO2 catalysts in presence of CO2 was studied with fixed-bed micro-reactor. The Cr/CeO2 catalysts of different Cr loading have been synthesized using impregnation techniques. The Cr/CeO2 system has already been found to be active and selective in the reaction at around 740 ℃. The function of carbon dioxide is to remove coke and hydrogen to accelerate dehydrogenation of ethane. The results of catalysts characterizations indicated that Cr3+ and Cr6+ occurred on the surface of the catalysts. The 1.2 mmol Cr/100m2 CeO2 catalyst sample with a monolayer dispersion of Cr on CeO2 support showed a stronger surface acidity and a maximum yield of ethylene of about 35.5% at 36.6% conversion of ethane. 相似文献
969.
ChangLuSHAO HongYuGUAN ShangBinWEN BinCHEN XingHuaYANG JianGONG YiChunLIU 《中国化学快报》2004,15(4):492-494
Thin PVA/cobalt acetate composite fibers were prepared by using sol-gel processing and electrospinning technique.After calcination of the above precursor fibers,Co3O4 nanofibers with a diameter of 50-150 nm could be successfully obtained.The fibers were characterized by SEM,FT-IR,WAXD,respectively. 相似文献
970.
建立了QuEChERS-气相色谱-串联质谱法测定枸杞中农药残留的分析方法。样品经乙腈提取,采用乙二胺-N-丙基硅烷(PSA)、C18和石墨化炭黑(GCB)3种吸附剂净化,在多反应监测模式(MRM)下进行检测,基质外标法定量。结果显示,检测项目在5~500 μg/L范围内呈良好线性(R2>0.99),在3个添加水平下测得回收率为71.5%~109.7%,相对标准偏差(RSD)为1.94%~9.87%(n=6)。该方法灵敏度高、净化效果好,可同时快速检测有机磷类、有机氯类农药。 相似文献