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911.
In the series of 1-(2,4,6-trialkylphenyl-)3-methyl-1H-phospholes (1a–c) that are to a certain extent of aromaticity, only the isopropyl substituted one (1a) entered into reaction with dimeric (pentamethylcyclopentadienyl)rhodium dichloride to afford Rh(III) complex (2a) in a reversible manner. After a careful workup, (2a) could be prepared and characterized whose stereostructure was elucidated by B3LYP/3–21G*, B3LYP/6–31G* and LANL2DZ calculations. Complex (2a) as a preformed catalyst, as well as the Rh(acac)(CO)2 + 2(1a) in situ catalytic system were useful in the hydroformylation of styrene and gave the branched aldehyde in regioselectivities of 65–96%.  相似文献   
912.
Rational intervention in human affairs, if it is to constitute not only action but also research, so that future interventions may be made more effective, needs a well-defined methodological framework. Soft systems methodology (S.S.M.) provides one such framework. S.S.M. is doubly systemic: it is itself a learning system, and within that system it uses systems models, models of human activity systems. It accepts that such models are not models of parts of the real world, only models of ways of perceiving the real world, that is to say, models relevant to debate about ‘reality’ (one man's ‘terrorism’ is another's ‘freedom fighting’).S.S.M. is here illustrated by means of an account of a systems study of change in the information function of a sophisticated science-based company. The study is described from the point of view of a professional analyst who was helping a team of three managers carry out the study. The course of the study is described, and a separate commentary relates its activity to the seven stages of S.S.M. The study involved three cycles round stages 2–3–4–5 of S.S.M., the stages in which models of relevant human activity systems are built and compared with the real world in order to construct a rich debate about changes whose introduction in the problem situation world be both (systemically) desirable and (culturally) feasible.  相似文献   
913.
溶胶-凝胶法制备铁酸盐超微粒子催化剂   总被引:5,自引:0,他引:5  
采用溶胶-凝胶法制备了含Zn,Ni,Co的铁酸盐超微粒子催化剂,运用DTA-TG、IR、XRD以及BET比表面测试等手段对所制备的样品进行了表征。同时,考察了铁酸盐对二氧化碳选择性氧化乙苯制苯乙烯的催化性能。结果表明:制备的铁酸盐均为尖晶石型晶体,粒子的比表面积为31.9-36.3m^2/g,晶粒大小约为30-35nm,在由二氧化碳选择性氧化乙苯制苯乙烯的反应中表现出较好的催化活性。  相似文献   
914.
甲醇在超临界环已烷中形成簇团的Monte Carlo初探   总被引:1,自引:1,他引:1  
用Monte Carlo方法研究了甲醇-环己烷体系的微观结构随压力(密度)的变化情况,结果表明,在临界区域甲醇分子的聚集最为明显,形成的甲醇团簇尺寸最大,溶剂分子在甲醇周围的局部密度则在低于临界区或亚临界区较大。  相似文献   
915.
For the equilibrium immiscible Co-Ag system, a proven realistic ab initio derived n-body potential is applied to study the nonequilibrium solid phase formation at three chemical stoichiometries of Co/Ag = 1:3, 1:1, and 3:1. To predict the structural stability, the elastic constants and the phonon spectra are calculated at the chosen stoichiometries with a total of eight hypothetical crystalline structures. The calculated results suggest that four compounds, that is, D0(3) CoAg3, B1 CoAg, B2 CoAg, and D0(3) Co3Ag, are unstable, as they all feature negative elastic constants as well as imaginary phonons, and that another four compounds of both fcc-type L1(2) and hcp-type D0(19) structures at chemical stoichiometries of Co/Ag = 1:3 and 3:1, respectively, may elastically be favored and therefore obtainable under some specific conditions. It is also found that all the calculated elastic constants and phonon spectra are coincident within the framework of the elastic theory. Moreover, the calculated elastic constants are in good agreement with those acquired directly from ab initio calculations, lending support to the validity of the ab initio derived n-body Co-Ag potential as well as its resultant elastic constants and the phonon spectra. Interestingly, some of the predicted nonequilibrium solid phases, that is, two hcp-type compounds at chemical stoichiometries of Co/Ag = 1:3 and 3:1, respectively, are indeed obtained in ion beam mixing experiments and their lattice constants determined by diffraction analysis are in good agreement with those from calculations.  相似文献   
916.
近红外漫反射光谱法对固态样品的无损分析   总被引:1,自引:0,他引:1  
任玉林  邴春亭 《分析化学》1996,24(11):1291-1294
本文应用目标因子分析研究了固态样品的近红外漫反射光谱,用目标因子分析成功地确定了固态样品的物种数、物种种类和各物种的含量。  相似文献   
917.
镧与镍共沉积的研究   总被引:13,自引:0,他引:13  
由于含稀土的合金新材料具有多种特殊功能,因此,其制备技术已为人们所关注.制备含稀土合金的方法有高温烧结法、真空蒸发法、离子溅射法及电化学法等.其中电化学法设备简单,容易获得不同组份的表层材料,但是,由于稀土元素的电位很负,从电解质水溶液中沉积稀土及其合金是相当困难的,以往曾有采用熔融盐电解质或非水电解质制备稀土合金的一些报导[1,2],而从电解质水溶液中电沉积稀土合金的报导甚少.本研究采用适宜的络合剂,实现了从电解质水溶液中电沉积Ni-La合金,镀层中钠含量最高达22.58%(质量分数,下同).通过XPS及…  相似文献   
918.
用非水滴定法和Hammett系列指示剂测定了COS水解碱改性γ-Al_2O_3催化剂的表面碱强度分布.发现表面碱强度分布不均匀与表面能量分布不均匀相呼应.采用零点酸碱强度(H_(0,max))及碱中心区域分析法,Bronsted催化定律,进一步证实COS水解反应具有明显碱催化特征,较高活性催化剂的H_(0,max)一般为10左右,对COS水解反应起主要作用的碱性中心的碱强度(H_0)为4.8≤H_0≤9.8.对碱金属氧化物改性后的γ-Al_2O_3催化剂,Bronsted规律在每个碱强度分区域内是适用的.  相似文献   
919.
Micron-sized, monodisperse, non-spherical polymer particles with "rugby ball" and "red blood corpuscle"-like shapes were produced by seeded polymerization of the dispersion of (divinylbenzene/vinylbiphenyl/xylene)-swollen polystyrene particles prepared by utilizing the dynamic swelling method which the authors proposed in 1991. Their non-spherical shapes were based on buckling of the shell of the resultant hollow particles. In this article, the reversible shape transformation of the hollow composite polymer particle between spherical and such non-spherical shapes was studied in detail by controlling the shell strength. A part of the shell was buckled by external pressure which was caused by evaporation of xylene from the hollow when the shell had the tensile modulus below the critical value calculated from the pressure-buckling relationship of a spherical shell proposed by Uemura. The plasticization of the shell by a good solvent was one of key factors for the shape transformation.  相似文献   
920.
A novel cyclic ammonium salt, N,N-dimethylpyrrolidinium tetrafluoroborate (P11-BF4), was successfully synthesized for the first time. The smallest cyclic structure of P11-BF4 induced high solubility and conductivity in PC, which can easier enter the micropores of activated carbon and occupy more surface area during charge/discharge process.  相似文献   
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