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51.
52.
采用共沉淀法,用不同金属盐为Cu源和Zn源合成了一系列CuZnAl水滑石,以此为前体经600℃焙烧后制得相应催化剂.用硝酸盐和醋酸盐合成的水滑石结晶度高,其衍生催化剂比表面积大、Cu的分散性好且易于还原;而用硫酸盐和盐酸盐合成的水滑石结晶度差,其衍生催化剂比表面积小、Cu的分散性差且不易还原.反应评价结果显示,用硝酸盐和醋酸盐制得的催化剂活性高、反应稳定性好;而用硫酸盐和盐酸盐制得的催化剂由于低的Cu表面积以及S和Cl的毒化作用而几乎无催化活性.在醋酸盐制备的催化剂上,产物干气中CO的浓度明显较低,在250℃和WHSV=3.28 h-1的条件下约为0.03%~0.04%,仅为硝酸盐所制催化剂上CO浓度的1/5;在210℃和WHSV=0.5 h-1的条件下,该催化剂上甲醇几乎完全转化,同时CO浓度降至约0.005%.N2O滴定、CO2程序升温脱附和程序升温还原结果显示,用醋酸盐和硝酸盐制备的催化剂具有极相近的Cu表面积和表面碱性,但前者CuO的还原峰温较后者低近70℃,归因于ZnO与CuO间的强相互作用,这是催化剂具有良好选择性的可能原因. 相似文献
53.
A concise method to synthesize benzo[c]phenanthridine alkaloid, nornitidine, was developed utilizing nickel- or palladium-catalyzed iminoannulation of an internal alkyne. The advantages of this strategy included readily available starting materials, inexpensive reagents, short reaction steps, and good yields. 相似文献
54.
Yang Xie-long Sun Xiao-duo Zhou Nai-fu 《Applied Physics A: Materials Science & Processing》1987,42(1):65-67
The presence of m=0 lines of the Mössbauer spectra of small Fe3O4 particles coated with an organic surfactant in an applied field of 7 T at 5 K shows a non-collinear magnetic structure in the surface layer of these particles. From the temperature dependence of the hyperfine field, the anisotropy constantK was calculated.Projects supported by the Science Fund of the Chinese Academy of SciencesNow working at the Shanghai Institute of Education 相似文献
55.
Li-Juan Jia Yuan-Yuan Wang Hui Chen Yong-Kui Shan Li-Yi Dai 《Reaction Kinetics and Catalysis Letters》2005,86(2):267-273
Summary The alkylation of benzene with 1-hexene has been investigated in different triethylamine hydrochloride-ferric chloride (Et3NHCl-FeCl3) and triethylamine hydrochloride-aluminium chloride (Et3NHCl-AlCl3) ionic liquids. Both high catalyst activity and monoalkylation selectivity were observed for these two type of ionic liquids.
Systems prepared by modification with HCl in Et3NHCl-FeCl3ionic liquids prove to be very suitable solvents and catalysts for the reaction. When employing Et3NHCl-AlCl3ionic liquids as catalysts, the reaction takes place in biphasic mode with facile catalyst separation and catalyst recycling. 相似文献
56.
The excessive production and deposition of amyloid-β (Aβ) is one of the most important etiologies of Alzheimer''s disease (AD). The interaction between Aβ and metal ions produces aberrant reactive oxygen species (ROS), which induce oxidative stress and accelerate the progression of AD. To reduce Aβ plaques and ROS to maintain their homeostasis is an emerging and ingenious strategy for effective treatment of AD. Herein, we report the rational design of multifunctional micelles (MPGLT) based on a polymer-grafted peptide to simultaneously clear Aβ and ROS for AD therapy. The MPGLT integrating three functional peptides as a ROS scavenger (tk-GSH), β-sheet breaker (LP) and an autophagy activator (TK) respectively, could capture and degrade Aβ. Meanwhile, the tk-GSH on the surface of MPGLT effectively scavenges the intracellular ROS. Consequently, MPGLT reduced the cytotoxicity of Aβ and ROS. In vivo animal studies using an AD mouse model further showed that MPGLT could transport across the blood–brain barrier for decreasing the Aβ plaque and eliminating ROS in vivo. This peptide micelle-based synergistic strategy may provide novel insight for AD therapy.Multifunctional micelles based on a peptide–polymer for simultaneously targeting Aβ degradation and ROS scavenging for AD therapy. 相似文献
57.
Kun Zhao Shuqi Zhuang Zhu Chang Haiyan Songm Liming Dai Pingang He Yuzhi Fang 《Electroanalysis》2007,19(10):1069-1074
A sensitive amperometric glucose biosensor based on platinum nanoparticles (PtNPs) combined aligned carbon nanotubes (ACNTs) electrode was investigated. PtNPs which can enhance the electrocatalytic activity of the electrode for electrooxidating hydrogen peroxide by enzymatic reaction were electrocrystallized on 4‐aminobenzene monolayer‐grafted ACNTs electrode by potential‐step method. These PtNPs combined ACNTs' (PtNPs/ACNTs) surfaces were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The highly dispersed PtNPs on ACNTs can be obtained. The enzyme electrode exhibits excellent response performance to glucose with linear range from 1×10?5–7×10?3 mol L?1 and fast response time within 5 s. Furthermore, this glucose biosensor also has good reproducibility. It is demonstrated that the PtNPs/ACNTs electrode with high electrocatalytic activity is a suitable basic electrode for preparing enzyme electrodes. 相似文献
58.
Different from Rh(II) catalysts, X-H (X = O, S, N) insertion of methyl styryldiazoacetate catalyzed by Lewis acids including Cu(I), Cu(II) and Ag(I) complexes occurred at γ-position preferably. Only (E)-isomer was observed in the reactions. This method provides an alternative for the synthesis of γ-hydroxyl or γ-amino acid derivatives. 相似文献
59.
Ion-exchanger phase Spectrophotometry withp-nitrochlorophosphonazo (CPApN) has been developed for the determination of scandium. The linear range is 1–8 g of scandium in 50 ml of solution, using 0.8 g of resin, with an apparent molar absorptivity of 2.76 × 105 1 mol–1 cm–1. Aluminum and rare earth elements in reasonable amounts do not interfere. The method has been applied successfully to the determination of scandium in alloys, with relative standard deviations of 2–4%. 相似文献
60.
《中国化学快报》2020,31(5):1317-1321
Dipyrrolyldiketone difluoroboron complexes (BONEPYs) were synthesized by condensation of the corresponding pyrroles and malonyl chloride followed by treatment with BF3·OEt2. The aryl-substituted pyrrole is introduced to form a cyclic system in order to investigate anion binding studies. In BONEPYs 1–3 the o-H of the aryl group forms hydrogen bonding with F− to give a more table complex. In contrast, the intramolecular hydrogen-bonded BONEPY endo-4 is more stable than its exo isomer. While adding F−, the hydrogen bonds must be broken first to give 4·(3)F−. Owing to the electron-rich group (-OMe), the o-H of the phenyl group can hardly interact with F− via hydrogen bonding to give the less stable complex 4·(5)F−. The energy differences between the different conformations were calculated using DFT methods, which is consistent to the experimental observations. 相似文献