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991.
Aqueous-soluble monolayer-protected palladium nanoparticles were synthesized by hydrogen reduction of Pd(II) in a water solution. The particles were then further functionalized by incorporating multiple copies of mercapto derivatives of viologen into the particle protecting monolayers. The electrochemistry of the viologen moieties with the particles dissolved in solution or immobilized onto electrode surfaces was carefully studied using various electrochemical techniques. The particle molecular capacitance was evaluated by rotating-disk-electrode voltammetry and the electron-transfer rate constant of the particle-bound viologen moieties was estimated by impedance measurements. 相似文献
992.
DENG Sheng Lou CHEN Ru Yu * 《结构化学》2000,19(4)
1 INTRODUCTIONAsherbicides,thearyloxycarboxylicacidssuchas2,4-D(2,4-Dichlorophenoxyaceticacid)etc.havenotbeenusedwidelysince1970sbecauseoftheircausingenvi-ronmentalpollutionandinjuriestothecrops.Studiesonthenewtypeofherbicideshavebeendevelopinginrecentyears.Itwasreportedrecentlythatthederivativesofdiazaphospholidinoneorthecorrespondingthionespossessinterestingherbicidalactiv-ity[1~3].Itwasalsoknownthat1,4,2-diazaphospholidine-5-thione-2-oxideshasgoodselectiveherbicidalactivity[4,5],but… 相似文献
993.
磷原子团簇同分异构体的理论研究I:P5+、P5-和P5的预测 总被引:2,自引:0,他引:2
由激光产生的磷原子团簇正离子的质谱图中呈现很强的 P5 和 P5- 谱峰。使用分子图形学方法设计出 9种可能的同分异构体 ,对其中性及正负离子分子进行了分子力学、PM3半经验量子化学和 ADF密度泛函优化。在磷原子团簇模型中 ,磷原子采用 2、3或 4配位方式成键。从各异构体成键能量的比较可得知 ,最稳定的 P5 构型是四方锥的结构 ,最稳定的 P5-构型是平面五边形的结构 ,而最稳定的 P5构型是在最稳定的 P4的增加一个 2配位原子所生成的结构 相似文献
994.
The surface organization of enol units of polyacryloylacetone (PAA) and polyethylacrylacetate (PEAA) monolayers at the air–water interface is examined using surface pressure, surface potential and rheological measurements and theoretical calculations based on molecular models. The mechanism and kinetics of the photochemical enol–keto tautomerization of PAA and PEAA polymers organized in a monolayer of closely packed monomer units are studied by measuring the surface area increase at constant surface pressure. The results indicate an increase in the area per unit during the consecutive enol-to-keto photoconversion and the slow interfacial reorganization of these ¶forms to a more favourable state. 相似文献
995.
996.
997.
998.
Summary A new graphitized carbon black (Carbograph 5) with a specific surface area (560 m2 g−1) greater than those of commerically available graphitized carbons was studied by gas chromatography to determine the enthalpy,
entropy, and free energy of adsorption of a series of alkanes (C2−C6). The adsorption properties were also investigated by considering changes in the isosteric heats and entropies of adsorption
when a nonpolar stationary phase (squalane) was added to the adsorbent. The data obtained are discussed and compared with
literature values for other graphitized carbon blacks. 相似文献
999.
Summary Early diagnosis of fatty acid oxidation (FAO) disorders is important to reduce severe morbidity and mortality. Although analysis
of plasma free fatty acids (FFAs) is frequently performed using stable isotope-dilution gas chromatography-mass-spectrometry
(GC-MS), there are institutions where the required instrumentation is not available to support a rapid work-up of acutely
ill patients. For this reason, we have developed a novel cyanomethyl derivatization method for FFAs which is followed by GC
analysis of the resulting esters using nitrogen-phosphorus detector (NPD) for the rapid diagnosis of mitochondrial fatty acid
oxidation disorders.
FFAs were extracted from plasma and derivatized to the cyanomethyl ester by heating with bromoacetonitrile at 60°C for 30
min GC-NPD analysis was then performed.
The mean recoveries of C6:0-C18:0FFAs were between 87% abd 96%. The method detection limits (S/N=3) were 0.1–0.5 ng for C6:0-C14:0
FFAs, and 0.001–0.01 ng for C16:0-C18:0 FFAs.
We succesfully performed differential diagnosis of representative FAO disorders from the confimed patient's plasmas. This
simple method offers cost-effective and time-saving alternative to GC-MS for the biochemical diagnosis of selected FAO disorders. 相似文献
1000.
Entropy of a Black Hole with Distinct Surface Gravities 总被引:1,自引:0,他引:1
Zhong Chao Wu 《General Relativity and Gravitation》2000,32(9):1823-1833
In gravitational thermodynamics, the entropy of a black hole with distinct surface gravities can be evaluated in a microcanonical ensemble. At the WKB level, the entropy becomes the negative of the Euclidean action of the constrained instanton, which is the seed for the black hole creation in the no-boundary universe. Using the Gauss-Bonnet theorem, we prove the quite universal formula in Euclidean quantum gravity that the entropy of a nonrotating black hole is one quarter the sum of the products of the Euler characteristics and the areas of the horizons. For Lovelock gravity, the entropy and quantum creation of a black hole are also studied. 相似文献