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81.
82.
Inorganic electrides are a novel kind of ionic compounds in which the anions are electrons confined in a complex array of cavities or channels and the cations are nanoscale arrays of alkali metal ions that provide charge balance. In electrides the donated electron behaves like a low-density correlated electron gas, whereby the dimensionality of the electron gas and its electronic and magnetic properties are determined by the topology of the cavities in the host matrix. Unlike traditional electrides, in which alkali cations are encapsulated within an organic cage, inorganic electrides are thermally stable. The current inorganic electrides based on alkali metal loaded zeolites can be designed as useful reduced-dimensionality materials. Inorganic electrides are powerful reducing agents, and they are able to reduce small aromatic molecules to the radical anions within the channels of the zeolite. 相似文献
83.
Liu JF Ye P Zhang B Bi G Sargent K Yu L Yohannes D Baldino CM 《The Journal of organic chemistry》2005,70(16):6339-6345
A microwave-promoted three-component one-pot reaction has been developed to provide access to the core pyrazino[2,1-b]quinazoline-3,6-dione (1) scaffold, which is common to several families of alkaloids with significant biological activities. By adapting this synthetic strategy through the use of selected Boc-amino acids and amino acid esters, we have accomplished highly efficient and concise total syntheses of glyantrypine (2), fumiquinazoline F (3), and fiscalin B (5), achieving overall yields of 55, 39, and 20%, respectively. 相似文献
84.
The chemical adsorption of H atoms on an (8,0) zigzag boron nitride nanotube is studied using the density functional theory with the supercell method. One to four H atoms per 32 B and 32 N are considered. The results show that H atoms prefer to adsorb on the top sites of adjacent B and N atoms to form an armchair chain along the tube axis. An even-odd oscillation behavior of the adsorption energy of H atoms on the tube is found, and the average adsorption energy of even H atoms is obviously bigger than that of odd H atoms. The results can be understood with the frontier orbital theory. Based on this adsorption behavior, several high-symmetric structures of H adsorbed boron nitride nanotubes with 50% and 100% coverages are studied. The pairs of lines' pattern with 50% coverage has the biggest average adsorption energy per H(2) among the chosen configurations, corresponding to approximately 4 wt % hydrogen storage. 相似文献
85.
以4-N,N-二乙基氨基水杨醛为原料,制备了2-(苯并噻唑-2-基)-5-(N,N-二乙基氨基)苯酚衍生物(探针L),并对其结构进行了表征。在DMSO/PBS(体积比3∶7,pH=7.4)溶液中,探针L具有高选择性并可荧光"关-开"识别H_2S,在365nm紫外灯照射下,由无荧光变成蓝色荧光。实验表明,探针L识别H_2S的检测限为2.05×10~(-6)mol/L,pH适用范围为6~9,可用于检测实际水样中的H_2S。 相似文献
86.
A simple and accurate RP-HPLC method using photodiode array detection (PAD) was developed for the simultaneous determination of four flavonoids, namely quercetin (QU),luteolin(LU),apigenin(AP) and isorhamnetin (IS) in pigeonpea leaves.Extract samples were separated on HIQ SIL C18V column using methanol-acetonitrile-water(31:10:59, v/v/v) as mobile phase.The flavonoids were detected at 254.5 nm for QU and IS, and at 345 nm for LU and AP.Contents were determined with satisfactory repeatability (R. S. D. < 2.2%) and recovery (97.27 – 99.98%). The developed method was found to be simple and efficient. 相似文献
87.
88.
钪—镧—对氟偶氮氯膦体系共显色效应的研究及应用 总被引:3,自引:0,他引:3
本文研究了钪-镧-对氟偶氮氯膦体系共显色效应的光度特性及测定钪的最佳条件,建立了光度法测定痕量钪的新方法。该法的表观摩尔吸光系数为8.57×10^4L·mol^-1·cm^-1,Sc(Ⅲ)浓度在0.0-5.0μg/25ml范围符合比尔定律。将本法用于镁基,铁基合成试样中痕量钪的测定,结果满意。 相似文献
89.
地质样品中金,银,铊等元素的连续原子吸收光谱法测定 总被引:4,自引:0,他引:4
本文提出了一个一次称样连续测定金、银、铊的简便、快速的新方法。该法是以泡塑吸附金、铊,使银等定量地保留在溶液中。泡塑上的铊用EDTA解脱后,再用硫脲溶液继续解脱金,然后,采用原子吸收光谱法连续测定金、银、铊。方法用于黄铁矿、方铅等单矿矿物及岩石、土壤样品中xng/g~xxxμg/g金、银、铊的测定,获得满意结果。 相似文献
90.