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31.
Activated carbon production from almond shells using phosphoric acid activation agent was achieved by applying both conventional heating and microwave heating in succession. The morphology and surface properties of activated carbon were studied using thermogravimetric and differential gravimetric analysis, Fourier-transform infrared spectroscopy, scanning electron microscopy, and Brunauer–Emmett–Teller analysis. A surface area of 1128 m2/g was achieved by optimizing the microwave power (500?W), microwave application time (15?minutes), conventional heating time (45?minutes), conventional heating temperature (500?°C), and the phosphoric acid:sample ratio (0.7:1). An adsorption capacity of methylene blue of 148?mg/g and an iodine value of 791?mg/g was obtained for the prepared activated carbon.  相似文献   
32.
A first example of an Et2Zn mediated silylation of 1-aklynes is reported. A series of functional groups are tolerated in this reaction. Mechanistic studies support Zn alkynilides as intermediates in the reaction. This reaction protocol provides a practical method for the preparation of alkynylsilanes and expands the application of organometallic zinc in organic synthesis.  相似文献   
33.
文[1]提出了两个DEA的逆问题,并用搜索法来解.而本文根据所证的定理,对每个问题一般只要解二、三个线性规划问题就能得到答案.  相似文献   
34.
All 3-dimensional convex polytopes are known to be rigid. Still their Minkowski differences (virtual polytopes) can be flexible with any finite freedom degree. We derive some sufficient rigidity conditions for virtual polytopes and present some examples of flexible ones. For example, Bricard's first and second flexible octahedra can be supplied by the structure of a virtual polytope.  相似文献   
35.
New tetradentatebis-benzimidazole ligands have been synthesized and utilized to prepare copper (II) complexes. Some of these copper (II) complexes have been characterized structurally. The copper (II) in these complexes is found to possess varying geometries. A distorted octahedral geometry is found with a highly unsymmetrical bidentate nitrate group. An unusual polymeric one-dimensional structure is observed where copper (II) is in a distorted square pyramidal geometry with a monodentate nitrate ion, having long Cu-O bond, while a distorted triagonal bipyramidal geometry is found with two carbonyl O atoms and a Cl atom in the equatorial plane, and two benzimidazole imine N atoms occupy the axial position. These compounds are found to activate the cumylperoxyl group, and this has been utilized in the facile oxidation of aromatic alcohols to aldehydes, where they act as catalysts with large turnovers. The yields of the respective products vary from 32 to 65%. The role of molecular oxygen has been studied and an attempt has been made to identify the “active copper species”. Activation of molecular oxygen has also been observed and has been used for oxidative dealkylation of a hindered phenol, producing di-butyl quinones with yields of 20–25% and 10–12 fold catalytic turnover. Dihydroxybenzenes and substituted catechols are also readily oxidized to the corresponding quinones, in oxygen-saturated solvents. Yields of 84% have been observed with 34-fold catalyst turnover, with di-t-butylcatechol. The activity of these copper (II) —bis-benzmidazolediamide compounds is reminiscent of the functioning of copper centres in galactose oxidase, tyrosinase and catechol oxidase.  相似文献   
36.
By making creep and recoverable creep measurements of a nearly monodisperse low molecular weight poly(methyl phenyl siloxane) sample, we have found on decreasing temperature towardsT g that there is continuously a change in the viscoelastic spectrum concomitant with a decrease of the steadystate recoverable compliance. This behavior is exactly the same as previously observed in low molecular weight poly(styrene), proving that this spectacular anomaly in the viscoelasticity of low molecular weight polymers is general and deserves an explanation. Photon correlation spectroscopic measurements performed on the same sample have extended the observation of the viscoelastic response to shorter times and the result corroborates the trend of variation established by the creep data.Dedicated to Prof.Dr. E. W. Fischer on his 65th Birthday. Prof.Dr. Fischer is known for his valuable contribution to fosterine, international collaboration of research in polymer science. This work is an example of his contribution because it would not be possible without him bringing us together. One of us (KLN) would like to take this opportunity to thank Prof. Dr. Fischer for his unwaiving support of the 1st (Crete) and the 2nd (Alicante) International Discussion Meeting on Relaxations in Complex Systems  相似文献   
37.
38.
用等厚干涉测定液体折射率   总被引:7,自引:0,他引:7  
介绍一种采用等厚干涉原理测定液体折射率的简单可靠的方法。  相似文献   
39.
Summary. The analytic treatment of problems related to the asymptotic behaviour of random dynamical systems generated by stochastic differential equations suffers from the presence of non-adapted random invariant measures. Semimartingale theory becomes accessible if the underlying Wiener filtration is enlarged by the information carried by the orthogonal projectors on the Oseledets spaces of the (linearized) system. We study the corresponding problem of preservation of the semimartingale property and the validity of a priori inequalities between the norms of stochastic integrals in the enlarged filtration and norms of their quadratic variations in case the random element F enlarging the filtration is real valued and possesses an absolutely continuous law. Applying the tools of Malliavin’s calculus, we give smoothness conditions on F under which the semimartingale property is preserved and a priori martingale inequalities are valid. Received: 12 April 1995 / In revised form: 7 March 1996  相似文献   
40.
HIRFL–CSR加速器中束流与真空中剩余气体的碰撞损失   总被引:1,自引:1,他引:0  
研究了重离子加速器中束流与真空中剩余气体的碰撞损失过程和碰撞截面,在依据大量实验数据的基础上,提出了一组计算离子一原子的电荷交换截面的经验公式.以兰州重离子加速器HDRFL及冷却储存环CSR为例,给出了依据碰撞截面的公式计算束流在加速器真空中的传输效率的方法,并计算了在不同真空度下HIRFL的ECR源轴向注入束运线、注入器SFC、前束运线、主加速器SSC和后束运线等不同加速阶段及CSR的传输效率,并提出合理的真空度要求.HIRFL的真空分布测量和束流的损失测量证明了该计算方法的可靠性.  相似文献   
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