检索结果-南通市图书馆

SYNTHESIS AND CHARACTERIZATION OF FLUORINATED POLYAMIDES DERIVED FROM unsymmetrical DIAMINES CONTAINING THE PHTHALAZINONE MOIETY

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2007年第3期25卷 311-317页

作者：程琳 Department of Materials Science & Engineering Huaqiao UniversityQuanzhou 362021China

A novel unsymmetrical fluorinated diamine monomer with kink non-coplanar heterocyclic structures, 1,2-dihydro- 2-（4-amino-2-trifluoromethyophenyo）-4-[4-（4-amino-2-trifluoromethyophenoxy）phenyo]（2H）phthaoazin-1-oneo was prepared through the nucleophilic substitution reaction of 1-trifluromethyl-2-chloro-5-nitrobenzene with 1,2-dihydro-4-（4- hydroxyphenyl）（2H）phthalazin-l-one in the presence of potassium carbonate, followed by catalytic reduction with hydrazine and Pd-C. A series of new fluorinated polyarnides were synthesized by the phosphorylation polyamidation of the fluorinated diamine with various dicarboxylic acids. The prepared polymers were obtained in quantitative yields with moderately and high inherent viscosities （0.47-0.87 dL/g）. They were all amorphous and readily soluble in various polar aprotic solvents such as N-methyl-2-pyrrolidone （NMP）, N,N-dimethylformamide （DMF）, N,N-dimethylacctamide （DMAc）, pyridine （Py） and m-cresol at room temperature. These fluorinated polyamides have excellent thermal properties. The glass transition temperatures were all above 300℃. The 5% and 10% weight loss temperatures were in the range of 437-466℃ and 482-525℃ in nitrogen atmosphere, respectively.

关键词： Fluorinated polyamides Phthalazinone unsymmetrical Kink non-coplanar Solubility

Stress dilatancy analysis of shallow tunnels subjected to unsymmetrical pressure

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2008年第S2期15卷 28-33页

作者：杨小礼王金明 School of Civil and Architectural Engineering Central South University

Numerical simulation using finite differential code was conducted for the single line railway and four-lane road shallow tunnels subjected to unsymmetrical pressure. The mechanical behavior of weak rock mass was studied considering the influences of stress dilatancy on the failure mechanisms, and the results of numerical simulation were compared with the analytical solutions in specifications. The results show that the dilatancy angle has great influences on the surrounding rock displacement and the shape of failure face for the shallow tunnels. When the dilatancy angle equals zero, the failure face of the surrounding rock forms and extends to the ground surface. With the dilatancy angle increasing, the loose region decreases gradually, and failure surface discontinues. When the dilatancy angle equals the friction angle, the loose region is only distributed in a small range around the crown and sidewalls. On the side of smaller buried depth, the difference of break angle between numerical simulation and the code is less than 10% for single line railway tunnels with the dilatancy angle of zero. However, for the four-lane road tunnels, the difference reaches 20.8%. On the side of larger buried depth, the break angles are smaller than those by the code, the difference reaches 16.8% for single line railway tunnels, and 13.8% for four-lane road tunnels. With the dilatancy angle increasing, especially the dilatancy angle approximating to internal friction angle, it is on safe side to calculate the break angle using the analytical solution method of specifications. Therefore, the influence of stress dilatancy should be considered while determining the failure mechanisms of shallow tunnels subjected to unsymmetrical pressure in weak rocks.

关键词： stress dilatancy shallow tunnel failure mechanism unsymmetrical pressure

Synthesis, mechanism and NMR spectra of lanthanide complexes with a novel unsymmetrical Schiff base

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 1999年第2期42卷 164-169页

作者：姚克敏周文鲁桂沈联芳 Department of Chemistry Zhejiang University Hangzhou China State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics &amp Mathematics Chinese Academy of Sciences Wuhan China

Owing to its two unsymmetrical-NH2 groups sited on different terminals, 2, 6-diaminocaproic acid (lysine) was used as a reactant for synthesizing a novel unsymmetrical Schiff base with salicylaldehyde on one side and ovanillin on the other for the first time. It is a new way to synthesize such a special unsymmetrical Schiff base. It is named “hetero bis-Schiff base” for distinguishing it from others. The synthesis method, formation mechanism as well as twelve new lanthaniHe complexes with the above ligand are reported and discussed herein. They were characterized by elementary analysis, molar conductivity, IR-spectra and especially by1H and13C NMR spectra. The results obtained may provide a new promising method for synthesizing similar unsymmetrical Schiff bases and their complexes.

关键词： unsymmetrical Schiff base novel lanthanide complexes synthesis method NMR.

Regression Optimal Functional Control for a Kind of unsymmetrical System

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics 2020年第5期11卷 363-376页

作者： Xixi Yue Baili Su College of Engineering Qufu Normal University Rizhao China

Because of the widespread existence of unsymmetrical system in the production process, its research is getting more and more attention. In this paper, a regression optimal functional control method is proposed for a class of unsymmetrical system. For the positive-negative model of the unsymmetrical system, a regression optimal functional controller is designed, which can make the system stable. The proposed algorithm has less computation and good control effect. Finally, three simulation examples are given to verify the effectiveness of the proposed algorithm.

关键词： unsymmetrical System Positive-Negative Model Basis Functions Regression Optimal Functional Control

Analysis and Design for unsymmetrical Block Encryption Algorithm

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of China Textile University(English Edition) 1999年第2期16卷 50-52页

作者：王以刚孔令飞

This article explains the imbalance in DES and introduces the operators in IDEA. At last it puts forward a Unsym-metrical Block Encryption Algorithm which is achieved by adding some operators to DES.

关键词： black cipher cipher algorithm DES IDEA unsymmetrical block encryption

Displacement Solution of Circular Plates With unsymmetrical Large Deflection

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 1994年第1期 90-107页

作者：王新志王林祥洪小波王尚勇 Basic Courses Teaching Department Gansu University of Technology Lanzhou 730050 PRC

The displacement equations of circular plates with unsymmetrical large deflection are derived, and the common displacement boundary conditions are presented. By using the function transformation, the nonlinear displacement equations are changed into a system of nonlinear equations which can be easily linearized, and the approximate boundary value problems are obtained by linearizing the system of nonlinear equations. For the two coupled sets of the displacement equations in the radial and the tangential directions, an equivalent system of equations is derived and the exact solutions are obtained. Finally, a calculating example is given and the characteristic curves are plotted.

关键词： unsymmetrical displacement equation large deflection nonlinear equation.

Regio-and Stereoselective Functionalization of unsymmetrical Internal Alkynes

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Regio-and Stereoselective Functionalization of Unsymmetrical...

Analysis of the heat transfer in unsymmetrically heated triangular microchannels in slip flow regime

中国化学会第十四届全国有机合成化学学术研讨会

作者： Shengtao Ding College of Chemical Engineering Beijing University of Chemical Technology

In organic chemistry, transformation of the C-C triple bond of alkynes usually is one of the most straightforward and atom-economical strategies to the synthesis of a vast variety of chemicals. During the past several decades, alkyne chemistry has experienced an explosive growth. One important factor is the developments of new synthetic methods based on transition metal catalysis. However, there are still lots of challenges in related fields, such as regio-and stereoselectivity-control in functionalizations of unsymmetrical internal alkynes. The existence of heteroatoms in organic molecules, such as nitrogen, oxygen, silicon and sulphur, usually has some influences on their physical and chemical properties. Based on this and through rational designs, a series of functionalizations of internal alkynes with excellent regio-and/or stereoselectivity were achieved. Theoretical and experimental studies elucidate the important roles of heteroatoms in the process of selectivity control.

关键词： unsymmetrical Transition metal Regioselective addition Stereoselective addition

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2004年第4期47卷 436-446页

作者： ZHU Xun LIAO Qiang XIN Mingdao Institute of Engineering Thermophysics Chongqing University Chongqing 400044 China Institute of Engineering Thermophysics Chongqing University Chongqing 400044 China Institute of Engineering Thermophysics Chongqing University Chongqing 400044 China

A theoretical analysis of heat transfer characteristics is presented for the fully developed laminar flow of the incompressible gas in the triangular microchannels heated unsymmetrically with constant axial heat flux. Through solving the energy equation with temperature jump boundary conditions in slip flow regime by virtue of a computation- oriented method of the orthonormal function analysis, the dimensionless temperature profiles and the average Nusselt number for various thermal boundary conditions are obtained. The effects of Knudsen number, aspect ratio, and thermal boundary conditions on the heat transfer are discussed. The calculated results show that the orthonormal function method can be used to study the heat transfer characteristics of the unsymmetrically heated triangular microchannels. The average Nusselt number in triangular microchannels is lower for slip flow than for no-slip flow, and decreases with increasing Knudsen number. The aspect ratios and thermal boundary conditions of triangular microchannels have significant influences on the change of average Nusselt numbers with the increase in the Knudsen number. For the equilateral triangular microchannels, the decrease of the Nusselt number ratio due to temperature jump is smaller at large Knudsen number and larger at small Knudsen number on the boundary condition of bottom wall heated alone as compared with the one on the boundary condition of two heated hypotenuse walls. The correlations of the average Nusselt number with the Knudsen number for equilateral triangular microchannels are obtained.

关键词： slip flow regime, triangular microchannel, unsymmetrical thermal boundary, heat transfer.

Selective C-C bonds formation,N-alkylation and benzo[d]imidazoles synthesis by a recyclable zinc composite

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2022年第1期33卷 266-270页

作者： Guanxin Zhu Zheng-Chao Duan Haiyan Zhu Dongdong Ye Dawei Wang The Key Laboratory of Synthetic and Biological Colloids Ministry of EducationSchool of Chemical and Material EngineeringJiangnan UniversityWuxi 214122China State Key Laboratory of Pulp and Paper Engineering South China University of TechnologyGuangzhou 510640China School of Chemical and Environmental Engineering Hubei Minzu UniversityEnshi 445000China

Earth abundant metals are much less expensive,promising,valuable metals and could be served as catalysts for the borrowing hydrogen reaction,dehydrogenation and heterocycles synthesis,instead of noble *** uniformly dispersed zinc composites were designed,synthesized and carefully characterized by means of XPS,EDS,TEM and *** resulting zinc composite showed good catalytic activity for the N-alkylation of amines with amines,ketones with alcohols in water under base-free conditions,while unsaturated carbonyl compounds could also be synthesized by tuning the reaction ***,it was the first time to realize the synthesis of 2-aryl-1H-benzo[d]imidazole derivatives by using this zinc composite under green ***,this zinc catalyst could be easily recovered and reused for at least five times.

关键词： unsymmetrical Zinc Borrowing hydrogen Recyclability Selective