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排序方式: 共有1502条查询结果,搜索用时 15 毫秒
1.
Direct determination of brucine by square wave voltammetry on 4-amino-2-mercaptopyrimidine self-assembled monolayer gold electrode 总被引:1,自引:0,他引:1
4-Amino-2-mercaptopyrimidine self-assembled monolayer (AMP SAMs/Au) was prepared on a gold electrode. The AMP SAMs/Au was characterized by using attenuated total reflection-fourier transform infrared (ATR-FTIR) and A.C. Impedance. The electrochemical behavior of brucine on AMP SAMs/Au was studied by cyclic voltammetry (CV) and square wave adsorptive stripping voltammetry (SWASV). The modified electrode showed an excellent electrocatalytic activity for the redox of brucine. The catalytic current increased linearly with the concentration of brucine in the range of 4.0 x 10(-7) to 2.0 x 10(-4) mol l(-1) by square wave voltammetry response. The detection limit was 6.0 x 10(-8) mol l(-1). 相似文献
2.
Y. Z. Song J. M. Xie Y. Song Y. Ye 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2007,81(10):1669-1676
The geometric parameters, vibrational frequencies, and thermochemical values of p-quinonimine (p-AQ) and p-aminophenol (p-AP) were computed ab initio (IIF) and by the density functional theory (DFT) method with the 6-31G(d, p) basis set. Cyclic voltammetry with a golden electrode of p-AP solutions in phosphate buffers at pH 7.30 showed that the standard electrode potential of half reaction for p-QI and p-AP was 0.728 V. The standard electrode potentials of half reactions for p-QI and p-AP were calculated using the free energies and solvation energies of p-QI, p-AP, p-benzoquinone (p-BQ), and hydroquinone (p-HQ). The results showed that the standard electrode potential of half reaction for p-QI and p-AP was 0.743 V at the B3LYP/6-31G(d, p) level and 0.755 V at the HF/6-31G(d, p) level. The standard electrode potentials computed at the B3LYP/6-31G(d, p) and HF/6-31G(d, p) levels were close to their experimental values.
The article is published in the original. 相似文献
3.
4.
The potential energy functions of 200 diatomic systems, with dissociation energies De ranging from few eV to hundreds of mueV, are well described by a new three-parameter potential energy function. Identification of the evaluated values of a dimensionless quantity, xin=L2/Ln [Ln=(n!De/fn)1/n, a scaled length parameter, and fn, the nth force constant evaluated at the equilibrium internuclear distance Re], is proposed as a reliable criterion to search for the universal scaling features of potentials and spectroscopic constants for bound diatomic systems. Our study suggests a useful approach to predicting future molecular spectroscopic constants. 相似文献
5.
Ultralight flexible polymers enable promising application in many fields but are often hindered by low reusability with fatigue failure, weak mechanical stability and low temperature resistance. Here, superelastic polyimide nanofiber aerogels (PNFAs) with high hydrophobicity have been prepared by utilizing the polyamic acid (PAA) nanofibers to construct a continuous and isotropic fibrous architecture. “Fiber-bonding” effect is designed to endow the PNFAs with the structure-derived superelasticity. The results demonstrate that the PNFAs possess ultralight densities (9.7–19.1 mg cm−3), excellent absorption capacity (58 times for n-hexane), broad working-temperature range, high resilience after 1000 fatigue cycles at 60% strain, and outstanding thermal insulation performance. Analysis of 50 absorption-harvesting cycle tests reveals that these highly hydrophobic PNFAs possess an ultrahigh reusability. The compressed PNFAs return to their original shape after they are distilled to recover the absorbed pollutants. These PNFAs with high absorption capacity and robust mechanical stability are promising to be applied in a variety of industrial and environmental applications. 相似文献
6.
《中国化学快报》2020,31(12):3015-3026
Multifunctional bismuth sulfide (Bi2S3) nanomaterials exhibit significant potential as nanomedicines for the diagnosis and treatment of cancer. These nanomaterials act as excellent photothermal agents and radiation sensitizers for the treatment of tumors, and they can also act as contrast agents for computed tomography (CT) imaging, photoacoustic imaging (PA), and other forms of imaging to provide real-time tumor monitoring and testing guidance. Compared with other nanomaterials, Bi2S3 nanomaterials can readily adapt to different applications by virtue of the fact that they can be easily functionalized. However, these nanomaterials have some limitations that cannot be ignored and need to be addressed, such as poor biocompatibility, toxicity, and low chemical stability. It is widely believed that appropriate functionalization of Bi2S3 nanomaterials could remedy such defects and significantly improve performance. This review summarizes the ways in which Bi2S3 nanomaterials can be functionalized and discusses their applications in cancer theranostics over the last few years, focusing particularly on imaging and therapy. We also discuss issues relating to how Bi2S3 nanomaterials can be analyzed, including how we might be able to use these systems to inhibit and treat tumors and how current limitations might be overcome to improve treatment efficacy. Finally, we hope to provide inspiration and guidance as to how we might create a more optimized multifunctional nano-system for the diagnosis and treatment of tumors. 相似文献
7.
Cui-Fen Lu Shou-Bo Zhang Yan Li Gui-Chun Yang Zu-Xing Chen 《Tetrahedron: Asymmetry》2009,20(19):2267-2269
The stereoselective synthesis of (R)-10-methyltridecan-2-one, the sex pheromone of the southern corn rootworm, was carried out in 20.7% overall yield based on (4S)-benzylthiazolidinethione (five steps). In the crucial step, the stereogenic center was generated by an asymmetric Michael addition using enantiomerically pure (4S)-benzylthiazolidinethione as a chiral auxiliary. 相似文献
8.
The microphase adsorption-spectral correction (MPASC) technique was described and applied to the study of the interactions of fluorinated surfactants such as potassium perfluorooctanesulfonate (PFOS) and potassium perfluorobutanesulfonate (PFBS) with human serum albumin (HSA). Sodium octanesulfonate (SOS) was also studied as non-fluorinated surfactant. The aggregation of PFOS, PFBS and SOS obeys the Langmuir monolayer adsorption. The results show that the adsorption ratios of surfactants to HSA are PFOS:HSA = 120:1, PFBS:HSA = 205:1 and SOS:HSA = 18:1. The adsorption constants are KPFOS-HSA = 5.01 × 103, KPFBS-HSA = 9.79 × 102 and KSOS-HSA = 4.03 × 103. The detection limits are 2.7 mg/L for BSA using PFOS, 3.1 mg/L using PFBS and 3.1 mg/L using SOS. It was found that fluorinated surfactant exhibited stronger interaction with protein than hydrogenated one, and fluorinated surfactant with long hydrophobic chain exhibited stronger interaction with protein than that with short hydrophobic chain. 相似文献
9.
SHEN Yi ZHU Hua HUANG Rong ZHAO Li & YAN ShaNing Faculty of Material Science Chemical Engineering China University of Geosciences Wuhan China Faculty of Materials Science Engineering Hubei University Wuhan 《中国科学B辑(英文版)》2009,(5)
Tungsten trioxide powder with the novel morphology was prepared via the hydrothermal method with oxalic acid as the organic inducer, the structure and shape of which were detected by X-ray diffraction (XRD), scanning electron microscopy (SEM) and BET. Furthermore, photochromic properties of the as-prepared powder samples were tested by an ultraviolet-visible spectrophotometer combined with a color difference meter. The corresponding results indicated that the induced product was still hexagonal WO3, made up... 相似文献
10.
We report graphene nanosheets as a durable alternative support material for Pt nanoparticle catalysts for oxygen reduction
in proton exchange membrane (PEM) fuel cells and compared them to XC-72. The materials were characterized by X-ray diffraction
and transmission electron microscopy. Electrochemical surface oxidation of XC-72 and graphene, and of Pt/XC-72 and Pt/graphene
has been compared following treatments for up to 120 h. The electrochemical performance of the specimens was evaluated by
cyclic voltammetry and linear sweep voltammetry at different surface oxidation time intervals. Electrochemical measurements
indicate that the graphene exihibits greatly enhanced electrochemical durability. It is suggested that graphene nanosheet
is a promising, low-cost, and durable electrocatalyst support for oxygen reduction in the PEM fuel cell. 相似文献