检索结果-南通市图书馆

Synthesis, catalytic and biological activity of novel dinuclear copper complex with Schiff base

在线全文

学校读者我要写书评

暂无评论

Science China chemistry 2006年第3期49卷 225-229页

作者： WEI Danyi1,2. LI Ning1, LU Gui1 & YAO Kemin1 1. Department of chemistry, Zhejiang university, Hangzhou 31002., China 2. {2. of Inorganic chemistry, Ningbo university, Ningbo 3152.1, China 1. Department of chemistry Zhejiang University Hangzhou 310027 China 2. institute of Inorganic chemistry Ningbo University Ningbo 315211 China

A novel dinuclear copper complex with tetraglycol aldehyde-phenylalanineSchiff base has been synthesized. It was characterized and formulated as [Cu_2.(NO_3)]NO_3 byelemental analysis, magnetic susceptibility, TG-DTA, IR, EPR and ~1H NMR spectra. The obtainedcomplex can be used as a good catalyst for the polymerization of methyl methacrylate (MMA). Theoptimum polymerization conditions are: MMA/catalyst = 500 (molar ratio); [catalyst] =7.5x10^(-3)mol·L^(-1); dioxane as solvent; 80℃; 6 h. Polymethyl methacrylate (PMMA) with 80%conversion, 7.2.10^5 viscosity-average molecular weight and 60.5% syndiotacticity was obtained. Thiscomplex has also been shown to play an important role in scavenging O_2.-.

关键词： novel copper complex, Schiff base, catalytic activity, scavenging effect of O-·2.

Structures and stability of isomers of[Si,N,N,P]system

在线全文

学校读者我要写书评

暂无评论

Science China chemistry 2004年第2期47卷 98-105页

作者： KAN Wei1, YU Haitao1, LI Mingxia1, FU Honggang1,2.& SUN Jiazhong1,2.1. College of chemistry and Chemical Engineering, Heilongjiang university, Harbin 150080, China 2. State Key Laboratory of Theoretical and Computational chemistry, institute of Theoretical chemistry, Jilin university, Changchun 13002., China 1. College of chemistry and Chemical Engineering Heilongjiang University 150080 Harbin China 2. State Key Laboratory of Theoretical and Computational chemistry Institute of Theoretical Chemistry Jilin University 130023 Changchun China

Some stationary points on the potential energy surface of [Si, N, N, P] system were located at the B3LYP/6-311G(d) and QCISD(t)/6-311+G(2.f)(single-point) levels of theory, while the isomerization, structures, and stability of these obtained isomers were suggested. The computed results indicate that only four-membered ring isomer SiNPN(E1, 2.'), which possesses butterfly-like structure and Si-P cross bonding, is kinetically stable in all optimized isomers. Other isomers may be considered as kinetically unstable towards isomerization or dissociation because of the corresponding smaller reaction barriers. Furthermore, the present paper also proposes electronic and geometric structures, vibrational frequencies and the corresponding vibrational modes, dipole moments, and rotational constants of isomer E1. To make use of the computed results, we can clearly know that the reaction pathway via an intermediate E3 (SiNPN) is the most favorable channel producing isomer E1 from fragments SiN(2.) and PN (1Σ), which have been well characterized in space, and thus, isomer E1 can be considered as a candidate for interstellar observation. The reaction enthalpy of SiN(2.) + PN(1Σ)→ E1 and the standard enthalpy of formation of isomer E1 are 2.5.2. and 457.99 kJ/mol, respectively, at 2.8.15 K. Keywords potential energy surface - [Si,N,N,P] system - isomerization - kinetic stability

关键词： potential energy surface, [Si,N,N,P] system, isomerization, kinetic stability.

Mineralogy and crystal structure determination of Mg-fillowite

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2005年第5期48卷 635-646页

作者： MA Zhesheng 1 , SHI Nicheng 1 & YE Danian 2.1. China university of Geosciences, Beijing 100083, China 2. institute of Geology, Chinese Academy of Sciences, Beijing 10002., China 1. China university of Geosciences 100083 Beijing China 2. institute of Geology Chinese Academy of Sciences 100029 Beijing China

Accurate crystal structure determination of complex phosphate Mg-fillowite ? Na2.a(Mn4Mg2.e)7[PO4]6 has been finished. Mg-fillowite occurs in muscovite-pegmatite in the Altay area, xinjiang, China. It is of the trigonal lattice, with space group R-3, unit cell a=1.5143(3) nm, c=4.3191(2. nm, V=8.5736 nm3, Z = 18. The R-factor of the determination accuracy is R (I > 2. ( I )) = 0.0776. The cationic polyhedra consist of two kinds of structural units: compound col- umn and screw column. In three-dimensional space, they are linked with each other through corner sharing or edge sharing to build the entire structure. There are 45 atoms in an asymmetric unit and 72. atoms in a unit cell. In terms of types and connection manners of the coordination polyhedra, the degree of complicity is rarely seen in all mineral crystal structures. Study of such a structure is significant for the classification of phosphate and the building rule of coordination polyhedra in a complex crystal structure.

关键词： Mg-fillowite, complex phosphate, crystal structure, coordination polyhedron.

K-uniformly rotund spaces and k-uniformly smooth spaces

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1998年第2期43卷 92-95页

作者： Suyalatu 1 and WU Congxin 2.1. Department of Mathematics,Inner Mongolia Normal university, Huhhot 01002., China 2. Department of Mathematics, Harbin institute of Technology, Harbin 150006, China Department of Mathematics Inner Mongolia Normal University Huhhot China Department of Mathematics Harbin Institute of Technology Harbin China

The conception of k_uniform smoothness (KUS) is introduced. It is the extension of the conception of uniform smoothness. It is proved that the k_uniform smoothness and Sullivan’s K_uniform rotundity (KUR) are the daul notions. X+* is a KUR space if and only if X is a KUS space, X+* is a KUS space if and only if X is a KUR space. If X is a KUS space, then X is a (K+1)US space. It is also proved that the KUS space includes the Nan’s k_strongly smooth space.

关键词： K_uniform smoothness K_uniform convexity.

Transitional function of DG to CA3 in the hippocampus

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2007年第12期17卷 1436-1444页

作者： Yan Chuankui1 and Liu Shenquan2.1. Department of Mathematics, Hangzhou Normal university, Hangzhou 310036, China 2. Department of applied Mathematics, School of Mathematical Sciences, South China university of Technology, Guangzhou 510640, China) Department of Mathematics Hangzhou Normal University Hangzhou 310036 China Department of applied Mathematics School of Mathematical Sciences South China University of Technology Guangzhou 510640 China

Using single cell channel model, the transmission features of CA3-DG network in the hippocampus are investigated. The influence of the stimulation on discharge pattern of pyramidal neurons is analyzed, which shows that it starts with period spiking discharges, followed by period-doubling bifurcation to chaos, and period 3 discharge evolving into chaos, and ultimately a period of bursting discharges. By the synaptic model, the CA3-DG network model is constructed, which analyzes the summation of postsynaptic currents in the network, the influence of postsynaptic current on discharge rhythm as well as the mechanism of bursting discharges. The strong capacity of spatiotemporal encoding in the network indicates the features of CA3 network during the information transmission process in the hippocampus. The modeling result with time delay of the synaptic transmission is in accordance with the experimental phenomena of action potential in the hippocampus.

关键词： hippocampus CA3-DG period-doubling bifurcation chaos.

In situ reproductive organs of Early Cretaceous ferns from Northeast China

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1997年第23期42卷 1977-1980,2026页

作者： DENG Shenghui and CHEN Fen1. Research institute of Petroleum and Development, Beijing 100083 2. China university of Geosciences, Beijing 100083, China Research institute of Petroleum and Development Beijing China university of Geosciences Beijing China

FILICOPSIDA is a predominant group of the Early Cretaceous floras of Northeast China, whichapproximates 100 species and accounts for more than one third of the floras. The majority ofthis group are of great importance and significance in stratigraphy. The previous studies ofthese ferns are mainly morphological, with only a few concerning the in situ spores andsporangia. In recent years. the authors have carried out a research project on the in situreproductive organs of the Early Cretaceous ferns from/ basins of Inner Mongolia, Liaoning,Jilin and Heilongjiang of Northeast China. The study focuses on 35 species of 17 genera be-longing to 10 families. The present note briefly introduces the results of this study by listingsome representative species.

关键词： Northeast China Early Cretaceous Filicopsida in situ reproductive organs.

Comparative study of the effect of Cu_2. and MoO_3 on flame retardance and smoke emission of PVC by Cone and TGA

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1998年第13期43卷 1090-1094页

作者： LI Bin\+1 and WANG Jianqi\+2.1. Department of chemistry, Northeast Forestry university, Harbin 150040, China 2. National Laboratory of Flame Retardant Materials, Beijing {2. of Technology, Beijing, 100081, China Department of chemistry Northeast Forestry University Harbin China National Laboratory of Flame Retardant Materials Beijing Institute of Technology Beijing China

Cuprous and molybdic oxides exhibit extremely effectiveness in smoke suppression for PVC. However, few are the data reported concerning flame retardance and smoke emission of PVC taken from Cone calorimetry relative to the conventional thermal analysis technique. Abundant data from Cone calorimetry have been acquired. Data analysis was achieved through the study of MLR, HRR, SEA tested at irradiance of 2. kWm -2.. The understandable flame retardance of PVC/Cu\-2. and PVC/MoO\-3 relative to pure PVC has been rationalized by their lowered heat release rates and enhanced char residues. The difference in smoke reduction between these two oxides consists in the time scale. As clearly seen under air atmosphere both oxides exert themselves to the afterglow which has been recognized as a dangerous source, in particular in the full_scale fire situation.

关键词： cone calorimetry poly(vinyl chloride) flame retardation smoke emission cuprous oxide molybdic oxide.

Properties and applications of cold supersonic gas jet

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2006年第6期49卷 709-715页

作者： ZHANG Shaofeng1,2.MA Xinwen1,2.LIU Huiping2.LI Bin1,2.& ZHU Xiaolong1,2.1. institute of Modern Physics,Chinese Academy of Sciences,Lanzhou 730000,China 2. Graduate university of Chinese Academy of Sciences,Beijing 100049,China 1. institute of Modern Physics Chinese Academy of Sciences Lanzhou 730000 China 2. Graduate university of Chinese Academy of Sciences Beijing 100049 China

By analyzing the formation mechanism of a supersonic gas jet,a set of equations which describe the atomic beam properties were established. The influence of initial temperature,initial pressure,background gas pressure and pumping speed was discussed in detail. A simulation program was developed based on the equations,and the results under different initial conditions were obtained. The results are in good agreement with the experimental data,and suggest that,in order to get much smaller transverse momentum in collision experiments,it is necessary to lower the initial temperature and the initial pressure of the supersonic gas jet,together with increasing the pumping speed. These results are very instructive for construction of a new generation of cold supersonic gas jets.

关键词： cold supersonic gas jet,zone of silence,nozzle,skimmer.

Large-scale boron nanowire nanojunctions and their highly-oriented arrays

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2004年第5期47卷 621-632页

作者： CAO Limin1,2. ZHANG Ze2.& WANG Wenkui1,2.1. Key Laboratory of Metastable Materials Science and Technology, Yanshan university, Qinhuangdao 066004, China 2. institute of Physics, Chinese Academy of Sciences, Beijing 100080, China 1. Key Laboratory of Metastable Materials Science and Technology Yanshan University 066004 Qinhuangdao China 2. institute of Physics Chinese Academy of Sciences 100080 Beijing China

Highly oriented multiple boron nanowire nanojunctions with unilateral feather- like morphology were first successfully prepared using a radio-frequency magnetron sputtering method. The branched boron nano-feathers always nucleate and grow on the same sidewall of the stems, and align in parallel to form multiple T- and/or Y-type nanojunctions. The diameters of the branches and the stems are in the range of 2.—40 and 60—80 nm, respectively. The thinner branches and thicker stems of the boron nanowires self-assembled into large-scale, highly ordered arrays on various substrates. During the formation and self-assembly of the arrays, no template or catalyst was needed. We believe that the approach presented here can be used to fabricate heterostructures with bottom-up assembly of a wide variety of one-dimensional nanostructures via the rational design of targets and the proper control of the experimental conditions.

关键词： boron nanowires, nanojunctions, self-assembly, magnetron sputtering.