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In this paper, 4-dimethylamino 2,5-dihydroxy chalcone (DMADHC), which exhibits excited state intramolecular charge transfer (ICT) characteristics, was synthesized and characterized. A sensitive optochemical sensor for Fe3+ ion was developed using DMADHC as fluorescence receptor. The fluorescence of DMADHC was gradually quenched with the addition of Fe3+ ion, which attributed to the formation of 1:1 complex between DMADHC and Fe3+ ion. The sensor exhibited excellent selectivity for Fe3+ ion over a large number of cation ions such as alkali, alkaline earth and transitional metal ions with a linear range of 3.984×10−7-1.135×10−5 and a limit of detection of 8.223×10−8 mol/L. On this basis, the sensor was preliminary applied to the determination of the content of iron ions in multi-vitamin tablet with satisfied results and the recoveries were in the 95-100% interval, and precision (n=5) was better than 5%. 相似文献
113.
Electronic chirality near the Dirac point is a key property of graphene systems, which is revealed by the spectral intensity patterns as measured by angle-resolved photoemission spectroscopy under various polarization conditions. Specifically, the strongly modulated circular patterns for monolayer (bilayer) graphene rotate by ±90° (±45°) in changing from linearly to circularly polarized light; these angles are directly related to the phases of the wave functions and thus visually confirm the Berry's phase of π (2π) around the Dirac point. The details are verified by calculations. 相似文献
114.
A joint clustering and classification approach is proposed.This approach exploits unlabeled data for efficient clustering,which is applied in the classification with support vector machine(SVM) in the case of small-size training samples.The proposed method requires no prior information on data labels,and yields better cluster structures.Through cluster assumption and the notions of support vectors,the most confident k cluster centers and data points near the cluster boundaries are labeled and used to train a reliable SVM classifier.Our method gains better estimation of data distributions and mitigates the unrepresentative problem of small-size training samples.The data set collected from Landsat Thematic Mapper(Landsat TM-5) validates the effectiveness of the proposed approach. 相似文献
115.
选取具不同生长应力水平的人工林尾巨桉(Eucalyptus uroph ylla×E.grandis)正常木为研究对象,借助场发射环境扫描电子显微镜系统,结合以溴元素做标记的X射线能谱分析技术,分析了尾巨桉细胞壁微区木质素沉积与生长应力的关系.研究结果表明,木纤维细胞壁各微区间木质素含量的大小关系与生长应力高低无关,其... 相似文献
116.
也谈中学生自学能力的培养 总被引:1,自引:0,他引:1
利用自编学案诱导学生分步自学,培养学生的自学习惯;加强学生阅读能力的培养,结合物理学科知识的联系,让学生比较、归纳,促使学生掌握自学方法;强化信息题的训练,培养信息处理能力,实现自学能力的有效提升. 相似文献
117.
XIONG Zi-jun DU Peng LI Bian XU Li-li ZHEN Xue-chu FU Wei .Key Laboratory of Smart Drug Delivery Ministry of Education & PLA 《高等学校化学研究》2011,(4):655-660
The serotonin 2A(5-HT2A) receptor has been implicated in several neurological conditions and potent 5-HT2A antagonists have therapeutic effects in the treatment of schizo phrenia and depression.In this study,a potent novel 5-HT2A inhibitor 05245768 with a Ki value of (593.89±34.10) nmol/L was discovered by integrating a set of computational approaches and experiments(protein structure prediction,pharmacophore-based virtual screening,automated molecular docking and pharmacological bioassay).The 5-HT2A recept... 相似文献
118.
Fei Gao Bian‐Hong Meng Yi‐Bin Wei 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(7):m360-m362
The crystal structure of the title compound, [Mg(H2O)6]0.5[Mg2(C16H14ClN2O9)(H2O)4]·10H2O, shows that this binuclear complex consists of two Mg centres in distorted octahedral geometry, joined by an oxo bridge which is a derivative of the deprotoned hydroxy group of the phenolate in the ligand molecule. In the anion, the coordination sphere of each MgII ion is completed by two carboxylates, a tertiary N atom and two water molecules. The inner coordination spheres for the MgII ions are very similar, both in ligand sets and in geometry. Each unit of the binuclear complex has one negative charge neutralized by a neighbouring hydrated cation, [Mg(H2O)6]2+, in which the Mg atom lies on an inversion centre. In each cell, there are 34 water molecules and most of them participate in the formation of hydrogen bonds, which contribute greatly to the stability of the whole structure. 相似文献
119.
Jin-Fang Nie Hai-Long Wu A-Lin Xia Shao-Hua Zhu Ying-Chao Bian Shu-Fang Li Ru-Qin Yu 《Analytical sciences》2007,23(12):1377-1382
This paper proposes a new and effective approach for the quantitative analysis of sulpiride, a significant antipsychotic drug, in human urine samples by the incorporation of excitation-emission matrix (EEM) fluorescence and second-order calibration methodologies based on the alternating fitting residue (AFR) and self-weighted alternating trilinear decomposition (SWATLD) algorithms. With the application of a second-order advantage, the proposed strategy could be utilized for a direct concentration determination of sulpiride with a simple pretreatment step, even in the presence of serious natural fluorescent interferences. The average recoveries of sulpiride in complex urine samples by using AFR and SWATLD with an estimated component number of three were 101.2 +/- 2.1 and 94.4 +/- 0.7%, respectively. Moreover, the accuracy of the two algorithms was also evaluated through elliptical joint confidence region (EJCR) tests as well as the figures of merit, such as sensitivity (SEN), selectivity (SEL) and limit of detection (LOD). The experimental results demonstrated that both algorithms, as promising quantitative alternatives, have been satisfactorily applied to the determination of sulpiride in human urine, but the performance of AFR was slightly better than that of SWATLD. 相似文献
120.