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701.
A highly efficient ultrasonic-assisted method was successfully applied to prepare the strong fluorescence Tb/acetyl acetone (acac)/poly (2-Acrylamidoglycolic acid monohydrate) (PAAM) composite nanoparticles. Based on the fluorescence quenching of Tb/acac/PAAM by Cr(VI), an assay for the selective determination of Cr(VI), without separation of Cr(III), was developed. It is characteristic of very few interferences, stable fluorescence signals (at least 2 h), simple instrument (common spectrofluorometer) and simple step. Under optimal experimental conditions, the fluorescence intensity of the system is linearly proportional to the concentration of Cr(VI) in concentration range of 5-800 ng mL−1 with a correlation coefficient of 0.9983. The limit of detection was found to be 0.5 ng mL−1.The proposed method has been applied to the selective quantification of Cr(VI) in synthetic samples with satisfactory results. 相似文献
702.
Simple arguments are used to construct a model to explain the extreme ultraviolet radiation conversion efficiency(EUV-CE) of a tin-based droplet target laser produced plasmas by calculating the laser absorption efficiency,radiation efficiency,and spectral efficiency.The dependence of drive laser pulse duration and laser intensity on EUV-CE is investigated.The results show that at some appropriate laser intensity,where the sum energy of the thermal conduction,out-off band radiation and plasma plume kinetic losses is at a minimum,the EUV-CE should reach a maximum.The EUV-CE predicted by the present simple model is also compared with the available experimental and simulation data and a fair agreement between them is found. 相似文献
703.
稻瘟病、玉米锈病和蚕豆锈病叶的傅里叶变换红外光谱研究 总被引:2,自引:0,他引:2
利用傅里叶变换红外光谱(FTIR)研究了水稻、玉米、蚕豆正常叶和稻瘟病叶、玉米和蚕豆锈病叶。结果显示,其红外光谱均主要由多糖、蛋白质的振动吸收谱带组成。光谱整体相似,差异主要表现为光谱峰位、峰形及吸收强度比。三种作物正常叶的二阶导数光谱在1 750~1 500 cm-1范围内的相关系数差异明显。水稻正常叶与稻瘟病叶的吸收强度比A1 056/A1 652;蚕豆正常叶与锈病叶的吸收强度比A1 652/A2 920;玉米正常叶和锈病叶(非病斑部位)吸收强度比A1 056/A2 920,玉米正常叶和玉米锈病叶(病斑处)吸收强度比A1 652/A2 920,均呈现出病变叶吸收强度比正常叶要小的趋势。表明他们之间的多糖和蛋白质的含量存在差异。 相似文献
704.
Madhan Vinu Souvik Pal Jia‐Dian Chen Yi‐Feng Lin Yu‐Lun Lai Cheng‐Shiuan Lee Chia‐Her Lin 《中国化学会会志》2019,66(9):1165-1171
An aluminum metal–organic framework (Al‐MOF), [Al(OH)(BPDC)] (DUT‐5; BPDC = Biphenyl‐4,4′‐dicarboxylate), was synthesized using solvothermal reactions. The high surface area and micropores (approximately 1.2 nm) of DUT‐5 were characterized using N2 gas sorption measurements. The thermal stability of DUT‐5 and its phase purity were also investigated. The different amounts of DUT‐5 (0.1, 0.15, and 0.2 wt%) were successfully incorporated into the chitosan (CS) polymer to prepare a mixed matrix membrane (MMM) for the pervaporation of water/ethanol at 25°C. In particular, when 0.15 wt% of DUT‐5 was loaded, the DUT‐5@CS MMMs displayed excellent permeability and selectivity in ethanol/water separation. The results indicated that compared with pristine chitosan membranes, the flux of DUT‐5@CS membranes with 0.15 wt% loading significantly increased from 315 to 378 (g/m2 h?1) and the separation factor from 347 to 3,429. These promising results of the microporous Al‐MOF doped into chitosan MMMs reveal its good application potential for the bio‐ethanol separation processes. 相似文献
705.
Wai‐Lun Chan Xiaodong Tang Fuhao Zhang Glenn Quek Guang‐Jian Mei Yixin Lu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(19):6326-6330
Construction of contiguous all‐carbon quaternary stereogenic centers is a long‐standing challenge in synthetic organic chemistry. In this report, a phosphine‐catalyzed enantioselective (3+2) annulation reaction between allenes and isoindigos, containing either two identical or different oxindole moieties, is introduced as a powerful strategy for the construction of spirocyclic bisindoline alkaloid core structures. The reported reactions feature high chemical yields, excellent enantioselectivities, and very good regioselectivities, and are highly useful for creating structurally challenging bisindoline natural products. 相似文献
706.
Zhi Xu Shi‐Jia Zhao Jia‐Lun Deng Qin Wang Zao‐Sheng Lv 《Journal of heterocyclic chemistry》2019,56(1):325-330
A new class of diethylene glycol tethered moxifloxacin–isatin hybrids 5a–l was designed, synthesized, and evaluated for their in vitro antimycobacterial activity against Mycobacterium tuberculosis (MTB) H37Rv and multidrug‐resistant tuberculosis (MDR‐TB) strains. Our results showed that all hybrids with higher lipophilicity than the parent moxifloxacin exhibited promising activity against the tested strains with minimum inhibitory concentration (MIC) in a range of 0.2–16 μg/mL. In particular, hybrid 5h (MIC: 0.20 and 0.5 μg/mL), which was found to be most active against MTB H37Rv and MDR‐TB, was twofold more potent than isoniazid (MIC: 0.39 μg/mL) against MTB H37Rv and ≥64‐fold more active than isoniazid and rifampicin (MIC: >128 and 32 μg/mL, respectively) against MDR‐TB. 相似文献
707.
Zhi Xu Shi‐Jia Zhao Zao‐Sheng Lv Feng Gao Yin‐Ling Wang Feng Zhang Liu‐Yang Bai Jia‐Lun Deng Qin Wang Yi‐Lei Fan 《Journal of heterocyclic chemistry》2019,56(3):1127-1132
We report herein the design and synthesis of a series of novel tetraethylene glycol‐tethered isatin–1,2,3‐triazole–coumarin hybrids and evaluate their in vitro antitumor activities against seven common human cancer cell lines including drug‐resistant cell line. Results revealed that all the synthesized hybrids showed weak to moderate activities against the tested seven cancer cell lines. The structure–activity relationship was also discussed, and the enriched structure–activity relationship may pave the way for further rationale design of this kind of hybrids. 相似文献
708.
A convenient and effective protocol for the synthesis of 3‐sulfonated quinolines via copper‐catalyzed electrophilic cyclization of N‐propargylamines has been developed, in which cheap and stable sodium sulfinates were utilized as green sulfonylation reagents. This cascade transformation involves radical addition, cyclization and dehydrogenative aromatization processes in a one‐pot reaction under mild conditions. 相似文献
709.
DUAN Chenglin SONG Jinling WANG Baoying LI Lun WANG Ruifen ZHANG Bangwen 《高等学校化学研究》2019,35(2):277-284
A series of BiOClxI1-x(x=0,0.1,0.3,0.5,0.7,0.9,1.0)photocatalysts was firstly prepared by means of a facile solvothermal route with the help of lactic acid.The measured results show that the morphologies of the as-prepared samples are similar sheets with different thickness and diameters.Thinner nanosheets assembled flower-like BiOCI0.5I0.5 solid solution exhibited the highest photocatalytic activity and stability among the prepared samples for the degradation of methylene blue(MB)and methyl orange(MO)under the illumination of visible light.The excellent photocatalytic properties of BiOCI0.5I0.5 could be attributed to the high specific surface area,the suita-ble band gap energy and the lower recombination rate of the electrons and holes.In addition,catalyst BiOCI0.5I0.5 was further used to degradate a more complicated mixed dye(MCH-RhB+MB)system under visible light,displaying an excellent photocatalytic activity.Finally,the photocatalytic mechanism of catalyst BiOCI0.5I0.5 to degradate colorful dyes was proposed.The trapping experiments of active species indicated that the holes are the main active species for the degradation of the mixed dyes. 相似文献
710.