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991.
992.
Sho Inagaki Akari Sato Haruka Sato Satoru Tamura Tomikazu Kawano 《Tetrahedron letters》2017,58(52):4872-4875
A simple and efficient synthesis of 4,5-dihydro-4-oxo-3-furancarboxylates using an acylative intramolecular cyclization of sulfonium salts is described. The reaction involved the efficient formation of a mixed anhydride between a linear carboxylic acid and trifluoroacetic anhydride in the presence of N-methylimidazole, followed by the sequential conversion into a highly reactive acylammonium species in situ. This procedure is easily handled, uses readily available inexpensive reagents, and provides a variety of 2-substituted 4,5-dihydro-4-oxo-3-furancarboxylates. 相似文献
993.
层次分析法在步枪作战效能评估中的应用 总被引:1,自引:0,他引:1
应用层次分析法对两代(共10种)突击步枪和自动步枪作战效能的评估和排序进行了讨论,并对其作战效能和技术水平进行了判断.所得结论对了解我军装备的先进程度,适应新时期军事科学和战备具有特别重要的意义. 相似文献
994.
Klaudia Stando Patrycja Kasprzyk Ewa Felis Sylwia Bajkacz 《Molecules (Basel, Switzerland)》2021,26(24)
Metronidazole (MET) is a commonly detected contaminant in the environment. The compound is classified as poorly biodegradable and highly soluble in water. Heterogeneous photocatalysis is the most promoted water purification method due to the possibility of using sunlight and small amounts of a catalyst needed for the process. The aim of this study was to select conditions for photocatalytic removal of metronidazole from aquatic samples. The effect of catalyst type, mass, and irradiance intensity on the efficiency of metronidazole removal was determined. For this purpose, TiO2, ZnO, ZrO2, WO3, PbS, and their mixtures in a mass ratio of 1:1 were used. In this study, the transformation products formed were identified, and the mineralization degree of compound was determined. The efficiency of metronidazole removal depending on the type of catalyst was in the range of 50–95%. The highest MET conversion (95%) combined with a high degree of mineralization (70.3%) was obtained by using a mixture of 12.5 g TiO2–P25 + PbS (1:1; v/v) and running the process for 60 min at an irradiance of 1000 W m−2. Four MET degradation products were identified by untargeted analysis, formed by the rearrangement of the metronidazole and the C-C bond breaking. 相似文献
995.
具有荧光发射能力有机化合物的光物理和光化学问题研究 总被引:5,自引:0,他引:5
有机化合物的结构、构象和环境效应对发光化合物的荧光发射具有重要的影响.本文从化合物激发态的衰变过程出发,侧重于过程的光化学与光物理问题对发光行为和机制进行讨论.如:化合物分子结构的受阻和桥键化对发光的影响;光激发下的光诱导电子和电荷转移及其相互转化;化合物扭曲的分子内电荷转移(TICT);溶剂分子和发光化合物分子间不同的相互作用及对发光的影响;在发光过程中存在着最佳的发光构象等.对于这些问题的研究和掌握,将有利于设计和合成具有高荧光量子产率的发光化合物,更好地解释在研究中出现的种种现象和在实际工作中应用它们.文章还引用了大量发光化合物作为实例,对工作中所得的结果进行了详细讨论. 相似文献
996.
YAN Zi-Feng 《天然气化学杂志》1996,5(1):51-58
IntroductionInformationonrelativereactiviticsofsuffocccarbonfromthcdecompositionofmethaneontransitionmetalcataIystspla}.simportantruleinourunderstandingthenatllreofeffcctiveutiliZaionofmethane.Asignificantamountofdataonthissubjecthavealread}'bccnaccumulatcd.Itx"asdiscovercdthatrcactiviticsofthesuffocecarbonstrongl}'dependonthcstructuralparameters-suchasthctyPcofsuffocecarbon.thestrengthofsurfacecarbon-metalinteractionsandthetendencyoftransformationamongthemll'2].0fspecialsarcthatthenatureofth… 相似文献
997.
建立了一种新的基于过程分析技术(PAT)和质量源于设计(QbD)设计空间的中药制药过程终点分析与控制方法.以近红外(NIR)光谱技术为PAT工具, 采集正常操作条件下制药过程的多批次NIR光谱; 采用主成分分析结合移动块相对标准偏差(PCA-MBRSD)法, 确定每一批次过程的理想终点样本(DEPs), 由多批DEPs的光谱信息构成过程终点设计空间; 在过程终点设计空间确定的范围内, 建立多变量统计过程控制(MSPC)模型, 利用多变量Hotelling T2和SPE控制图对过程终点进行判断.应用上述方法, 进行了金银花醇沉加醇过程终点检测研究, 结果表明该方法灵敏、准确, 适宜于中药制药过程终点检测. 相似文献
998.
Ashkan Reisi-Dehkordi 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(8):642-647
Nowadays, quantification of the effects of basic parameters such as precursor, temperature oxidation, residence time, low temperature carbonization (LTC) and high temperature carbonization (HTC) on production process polyacrylonitrile based carbon fibers is not completely understood. In this way, there is not a completely theoretical model that accomplishes to quantitatively describe production process carbon fibers very accurately which needs to be used by engineers in design, simulation and operation of that process. This paper presents the development of a back propagation neural network model for the prediction of carbon fibers produced from PAN fibers. The model is based on experimental data. The precursors, temperature oxidation, residence time, LTC and HTC have been considered as the input parameters and the strength as output parameter to develop the model. The developed model is then compared with experimental results and it is found that the results obtained from the neural network model are accurate in predicting the strength of carbon fibers. 相似文献
999.
Yoshiro Masuyama Kazuki YoshikawaNoriyuki Suzuki Kenji HaraAtsushi Fukuoka 《Tetrahedron letters》2011,52(51):6916-6918
Copper(II)-exchanged hydroxyapatite, prepared by ion-exchanging of Ca(II) in calcium hydroxyapatite [Ca10(PO4)6(OH)2] with Cu(NO3)2 at 70 °C in water, functions as a reusable heterogeneous catalyst with neither reducing agents nor bases for azide-alkyne [3+2] cycloaddition at 50 °C in water under air. 相似文献
1000.