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排序方式: 共有1639条查询结果,搜索用时 137 毫秒
81.
Quasi-one-dimensional(Q1D) Cr-based pnictide K2Cr3As3 exhibits superconductivity probably with spin-triplet pairing. It is of fundamental importance to explore the parent compound from which superconductivity emerges. Here we report the synthesis,crystal structure, physical properties, and density functional theory(DFT) calculations of(nearly) fully hydrogenized K2Cr3As3 H.It is found that the intercalation of hydrogen in K2<...  相似文献   
82.
Colloidal synthesis of metal nanoclusters will inevitably lead to the blockage of catalytically active sites by organic ligands. Here, taking [Au25(PET)18]-(PET = 2-phenylethanethiol) nanocluster as a model catalyst, this work reports a feasible procedure to achieve the controllably partial removal of thiolate ligands from unsupported [Au25(PET)18]-nanoclusters with the preservation of the core structure. This procedure shortens the processi...  相似文献   
83.
Ru with Pt-like hydrogen bond strength,knockdown cost(~1/3 of Pt),and eximious stability is a competitive replacement for Pt-based catalysts towards the hydrogen evolution reaction(HER) in water splitting.The design of Ru-based catalysts via interface construction,crystal phase control,and specific light element doping to realize the impressive promotion of limited activity and stability remains challenging.Herein,we report the fabrication of Pd@RuP core-shell nanorods(NRs) via an epitaxial grow...  相似文献   
84.
Lithium-sulfur batteries are severely restricted by low electronic conductivity of sulfur and Li2S, shuttle effect, and slow conversion reaction of lithium polysulfides(LiPSs). Herein, we report a facile and highyield strategy for synthesizing dual-core single-atom catalyst(ZnCoN4O2/CN) with atomically dispersed nitrogen/oxygen-coordinated Zn-Co sites on carbon nanosheets. Based on density functional theory(DFT)calculations and LiPSs conversion catalytic ability, ZnCoN...  相似文献   
85.
Fe-Mn based layer oxides cathode materials have attracted widespread attention as a potential candidate for sodium-ion batteries(SIBs) owing to the earth abundance, cost-effectiveness and acceptable specific capacity. However, the irreversible phase transition often brings rapid capacity decay, which seriously hinders the practical application in large-scale energy storage. Herein, we design a nickel-doped Na0.70Fe0.10Cu0.20Ni0.05Mn0.65O  相似文献   
86.
Atpresent,thecommonlyusedmethodforanalyzingherbalmedicinesishighperformanceliquidchromatography(HPLC).However,theuseofHPLCisrestrictedformanyreasons.Themostseriousproblemisthatthechromatographiccolumniseasilycontaminated.ComparedwithHPLC,capillaryelectrophoresis(CE)ischaracterizedwithhighefficiency,rapidity,lowcostandmultiplemodestobechosen.Inaddition,thecapillarycanbeeasilyregenerated.SoCEisidealforanalyzing"dirty"samples,suchasChineseherbalmedicines.Infact,studiesintheareaarebecoming…  相似文献   
87.
IntroductionFive- coordinated complexes with d9- configuredcations have received much attention stereochemi-cally,spectrochemically and biologically,and havebeen comprehensively discussed[1] . Usually thereare two stable configurations for the copper( )complexes with five equal coordinating atoms:anapically elongated square pyramid( SP) and a com-pressed trigonal bipyramid( TBP) ,with an obviousenergetic preference for the latter coordination.When the ligands are rigid and provide angular d…  相似文献   
88.
Soap-free poly(methyl methacrylate-ethyl acrylate-methacrylic acid) latex particles with narrow size distribution were synthesized by seeded emulsion polymerization, and the porous particles were created by a stepwise alkali/acid treatment method. Effects of acid treatment conditions on the particle morphology were investigated. Results show that one to three pores were formed inside most of particles after post-treatment. At pH 7.0, when the treatment temperature was lower than 70℃, the size of particles and the volume of pores remained almost unchanged, and these two values increased significantly when the temperature was higher than 70℃. Both the particle size and the pore volume decreased with the increase of initial pH value and treatment time in the acid treatment. As the pH was below 4.0 and the treatment time was longer than 180 min, the particles shrunk in size.  相似文献   
89.
The present study examines the effect of polyphenols extract of adlay (Coix lachryma-jobi L. var. ma-yuen Stapf) (APE) on high cholesterol diet fed rats (HCD). APE was orally administrated by gavage at doses of 10, 40 and 200 mg total phenolics/kg body weight of rats once a day for 28 days. At the end of four weeks, serum triglyceride (TG), total cholesterol (TC), low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C), and markers of oxidative stress viz., malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) in the serum and liver of HCD and normal rats were assessed and compared. The results showed that administration of APE was significantly effective in decreasing the serum levels of TC, LDL-C and MDA, increasing the serum level of HDL-C and antioxidant capacity. In addition, oral gavage of APE could also increase the antioxidant capacity, CAT and GSH-Px activities in liver. These results suggested that APE exerted a high hypocholesterolemic and antioxidant activities, which might be characterized by a protective effect on cardiovascular health in vivo.  相似文献   
90.
Guo D  Yi X  Qu L 《色谱》2011,29(10):967-973
建立了液相色谱-串联质谱分析多种肉及肉制品中利谷隆及其代谢产物3,4-二氯苯胺残留的方法。样品用丙酮-乙腈(5:95, v/v)提取,冷冻去脂,经弗罗里硅土固相萃取柱净化后进行液相色谱-串联质谱检测,采用内标法定量。利谷隆及3,4-二氯苯胺在1~500 μg/L范围内呈良好的线性关系,相关系数(r)均大于0.998,方法的定量限(信噪比(S/N)>10)为10 μg/kg,检出限(S/N>3)为5 μg/kg。在各种肉及肉制品基质中添加低、中、高3种不同水平的利谷隆及3,4-二氯苯胺,其回收率范围分别为88.3%~101.2%和91.6%~101.6%,相对标准偏差(RSD)分别为4.8%~13.7%和4.7%~11.8%。结果表明所建立的方法可以满足肉及肉制品中利谷隆和3,4-二氯苯胺残留量的检测需要。  相似文献   
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