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991.
We describe the static charge susceptibility and correlation function of the charge density in the twodimensional t-J-V model based on the method of equations of motion for the relaxation functions of the Hubbard operators. We obtain the dependence of the susceptibility and correlation function on the hole concentration and temperature. Charge density waves can develop if the intersite Coulomb interaction is sufficiently strong. 相似文献
992.
AbstractThe continuing studies on the fruits of Stauntonia brachyanthera led to the isolations of 6 normal and nor-oleanane triterpenoids, including two new compounds, brachyantheoraside B10 (1) and brachyantheraside C1 (2). Compounds 1–3 showed inhibitory activity on lipopolysaccharide (LPS)-induced nitric oxide production in RAW 264.7 macrophages with the IC50 values of 27.04, 26.22, and 21.41?μM, respectively, which were all stronger than that of indomethacin. The study not only revealed a new type of nor-oleanane triterpenoids, but also confirmed the anti-inflammation abilities of three type nor-oleanane triterpenoids as the inhibitors of NO production. 相似文献
993.
Huiye Zhong Wei-Shang Lo Tiantian Man Benjamin P. Williams Dan Li Dr. Sheng-Yu Chen Prof. Dr. Hao Pei Prof. Dr. Li Li Prof. Dr. Chia-Kuang Tsung 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(57):12931-12935
DNAzymes are a promising class of bioinspired catalyst; however, their structural instability limits their potential. Herein, a method to stabilize DNAzymes by encapsulating them in a metal–organic framework (MOF) host is reported. This biomimetic mineralization process makes DNAzymes active under a wider range of conditions. The concept is demonstrated by encapsulating hemin-G-quadruplex (Hemin-G4) into zeolitic imidazolate framework-90 (ZIF-90), which indeed increases the DNAzyme's structural stability. The stabilized DNAzymes show activities in the presence of Exonuclease I, organic solvents, or high temperature. Owing to its elevated stability and heterogeneous nature, it is possible to perform catalysis under continuous-flow conditions, and the DNAzyme can be reactivated in situ by introducing K+. Moreover, it is found that the encapsulated DNAzyme maintains its high enantiomer selectivity, demonstrated by the sulfoxidation of thioanisole to (S)-methyl phenyl sulfoxide. This concept of stabilizing DNAzymes expands their potential application in chemical industry. 相似文献
994.
Naphthalimide and BINOL framework based fluorescent probe NP-B was rationally designed and synthesized. NP-B exhibited ‘turn-on’ fluorescence for Cr3+ and high selectivity over other metal ions. 1:1 binding mode between NP-B and Cr3+ was proposed and the mode was verified through MALDI-TOF mass spectrum. The detection limit was calculated to be 0.20 μM, which indicated the good sensitivity for Cr3+. 相似文献
995.
Simultaneous determination of five triterpene acids in rat plasma by liquid chromatography–mass spectrometry and its application in pharmacokinetic study after oral administration of Folium Eriobotryae effective fraction
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Xue‐Ping Cai Dan‐Dan He Jun‐Lei Hua Jian‐Ming Ju Han Lv Li Ma Wei‐Lin Li 《Biomedical chromatography : BMC》2015,29(12):1791-1797
Folium Eriobotryae effective fraction (FEA), the extract of Folium Eriobotryae, had been used as anti‐hyperglycemia and anti‐hyperlipemia medicine in China. A previous study indicated that euscaphic acid, maslinic acid, corosolic acid, oleanolic acid and ursolic acid, the five structurally similar triterpene acids (containing two groups of structural isomers), are the major components of FEA. In the present study, we developed a specific and reliable LC‐MS method for simultaneous determination of the five triterpene acids in rat plasma, and further investigated their pharmacokinetic properties after oral administration of FEA. Following a simple sample preparation, chromatographic separation was achieved on a C18 column with a mobile phase composed of methanol–0.1% ammonium acetate (80:20, v/v). Quantification was achieved by monitoring the selected ions at m/z 487.6 for euscaphic acid, m/z 471.5 for maslinic acid and corosolic acid, m/z 455.5 for oleanolic acid and ursolic acid and m/z 469.5 for internal standard. The method was validated to be specific, accurate and precise over the concentration ranges of 10–3000 ng/mL with limits of detections of 5 ng/mL for the five triterpene acids. Finally, the method was successfully applied to the pharmacokinetic study of the five structurally similar triterpene acids in rats after oral administration of FEA. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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通过恒电位电沉积法在离子液体N,N-二乙基-N-甲基-N-(2-甲氧基乙基)铵四氟硼酸铵([DEME][BF4])中,在玻碳电极上制备了铂纳米颗粒。首先探究了不同沉积电势和不同沉积时间对铂纳米粒子微观形貌的影响,由SEM和TEM图发现在-2.5 V下沉积480 s制备的铂纳米粒子的平均粒径约为2.38 nm。使用高分辨率透射电子显微镜(HRTEM)和电子衍射(SAED)对其晶体结构进行表征,证明了铂纳米粒子为面心立方(fcc)晶体结构。在硫酸中测试铂纳米粒子的催化性能,发现其暴露出明显的(110)和(100)晶面。进一步对铂的电沉积行为进行研究发现,Pt(Ⅳ)的两步还原是由扩散过程和电化学过程共同控制。 相似文献
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