检索结果-南通市图书馆

Chinese Journal of Chemical Engineering 2020年第5期28卷 1424-1435页

作者： Jing Zhao Yifu Zhang Lei Xu Fuping Tian Tao Hu Changgong Meng School of Chemical Engineering Dalian University of TechnologyDalian 116024China

The key to improve the performance of heteroatom catalysts is to ensure the orderliness of catalysts and the good dispersion of *** alkalinity plays the indispensable role in synthetic process of V-MCM-41 *** excessive alkalinity of synthetic system will make the MCM-41 difficult to crystallize,even to *** is easy to accumulate for heteroatomic species in the system of low ***,the highly ordered VMCM-41 with high vanadic content in framework is synthesized in the condition of excessive NH3·H2 O in this paper.A series of characterization results prove the good dispersion of vanadium species,and most of vanadium gets into the framework of MCM-41 with the states of tetravalence and ***,the modified MCM-41 by other transition metals is successful synthesized by the method of V-MCM-41 in this *** VMCM-41 shows well catalytic activity for the selective oxidation of benzyl alcohol,which up to 74.83%for the conversion of benzyl alcohol and 96.20%for selectivity of benzaldehyde when initial V/Si=*** paper provides the possibility for industrial application of V-MCM-41 in the oxidation of benzyl alcohol for ***,the work provides a significant idea for the synthesis of modified MCM-41 by well-dispersed transition metals.

关键词： V-MCM-41 Well-dispersed vanadium Framework weak base Benzyl alcohol Selective oxidation

Vibration diagnostics of weak base embankments

在线全文

学校读者我要写书评

暂无评论

Research in Cold and Arid Regions 2013年第5期5卷 530-533页

作者： Evgenij Ashpiz Vladimir Kapustin Svetlana Klepikova Maxim Shirobokov Moscow State University of Railway Transportation Research and Survey Institute Geotech

In this paper the theoretical background was analyzed for vibration diagnostics method and experience in its application for weak base embankments. General schemes of survey and recommendations on hardware systems and... 详细信息

关键词： vibration diagnostics embankments weak base

Adsorption and desorption properties for rhenium using a kind of weak-base anion resin

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2018年第8期37卷 707-715页

作者： Hong-Zhao Liu Bo Zhang Xiao-Jing Jing Wei Wang Li-Jun Wang Rare Metal and Metallurgy Materials Research Institute General Research Institute for Nonferrous Metals Beijing 100088 China Zhengzhou Institute of Multipurpose Utilization oI Mineral Resources Zhengzhou 450006 China Key Laboratory of Evaluation and Multipurpose Utilization of Polymetallic Ore of Ministry of Land and Resources Zhengzhou 450006 China

In this paper, a weak-base resin was adopted to recycle rhenium because of its excellent adsorption and desorption properties for rhenium, while the kinetics and thermodynamics properties of adsorbing rhenium from the rhenium stock solution were systematically investigated. The kinetics investigations confirm that the adsorption process of Re belongs to kinetic control by particle diffusion process and the corresponding reaction rate constant is 2.68 × 10-s s^-1. Then, the Langmuir and Freundlich models were used to describe the adsorption equilibrium behaviors of Re and the thermodynamics parameters are obtained. The results show that the Langmuir model is the best-fitted model, and the Gibbs free energy change of Re adsorption onto ZS 15 weak-base resin is AGO = - 10.59 ＋ 12.66T. To verify the weak-base resins for extracting rhenium in industrial application, the column experiments were operated in the spray solution generating by roasting the molybdenum concentrates. The results indicate that the weak-base resins possess excellent adsorptive selectivity for rhenium, and the ammonia solution with low concentration could sufficiently desorb rhe- nium from the resins.

关键词： Rhenium weak base Thermodynamics Kinetics

A Novel Method for the Synthesis of Mesoporous Molecular Sieve MCM-41

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2005年第6期16卷 843-845页

作者： XiuMeiTAI HongXiaWANG XiuQiSHI ChinaResearchInstituteofDailyChemicalIndustry Taiyuan030001

Using glycerol, glycol and water as solvent, cetyltrimethylammonium bromide (CTAB) as template, tetraethyl orthosilicate (TEOS) as silica source, ethylenediamine (EDA) as base source, mesoporous molecular sieve MCM-41 has been synthesized at room temperature, characterized by X-ray power diffraction and N2 adsorption. Compared with the samples synthesized by glycol and water, the samples synthesized by glycerol have larger pore diameter and high surface areas. Thus glycerol is an efficient solvent for preparing larger pore mesoporous MCM-41.

关键词： MCM-41 synthesis glycerol glycol weak base room temperature.

Spaces with σ-locally Countable weak bases

在线全文

学校读者我要写书评

暂无评论

Chinese Quarterly Journal of Mathematics 2001年第2期16卷 37-41页

作者：夏省祥菏泽教育学院数学系山东菏泽274016

In this paper, by msss_mappings, the relations between metric spaces and spaces with σ _locally countable cs_networks or spaces with σ _locally countable weak bases are established. These are some answers to A... 详细信息

关键词： msss_mapping sequence_covering mapping cs_network weak base

K-Spaces Property of Product Spaces

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 1997年第4期13卷 537-544页

作者： Liu Chuan Lin Shou Department of Mathematics, Guangxi University, Nanning 530004, China Department of Mathematics, Ningde Teachers College, Fujian 352100, China Department of Mathematics Guangxi University Department of Mathematics Ningde Teachers College

Let K be a class of spaces which are eigher a pseudo-open s-image of a metric space or a k-space having a compact-countable closed k-network. Let K′ be a class of spaces which are either a Fréchet space with a point-countable k-network or a point-G_δ k-space having a compact-countable k-network. In this paper, we obtain some sufficient and necessary conditions that the products of finitely or countably many spaces in the class K or K′ are a k-space. The main results are that Theorem A If X, Y ∈ K. Then X x Y is a k-space if and only if (X, Y) has the Tanaka’s condition. Theorem B The following are equivalent: (a) BF(w2) is false. (b) For each X, Y ∈ K′, X x Y is a k-space if and only if (X, Y) has the Tanaka’s condition.

关键词： K--space K--network weak base Product space BF(ω2) Tanaka’s condition

cs＊-regular Families and Metrization Theorems

在线全文

学校读者我要写书评

暂无评论

Chinese Quarterly Journal of Mathematics 2009年第4期24卷 609-613页

作者： LI Ke-dian XU Hua-wei Department of Mathematics and Information Science Zhangzhou Normal University Zhangzhou363000 China Department of Mathematics Shangqiu Teacher＇s College Shangqiu 476000 China

In this paper, we proved that a sequential space has a cs＊-regular cs＊-network （or a cs＊-regular weak base） is metrizable, which generalized related results in [6], [12] and [14].

关键词： cs*-regular families network weak base metrizable spaces