期刊文献+
共找到43篇文章
< 1 2 3 >
每页显示 20 50 100
Inheritance and Sustainable Development of Concession Gardens of Tianjin City,China
1
作者 MENG Jin CHEN Liang 《Journal of Landscape Research》 2012年第11期34-36,共3页
Through reviewing development history of concession gardens in Tianjin City,features,advantages and problems of these gardens were analyzed.It was stressed that cultural context should be inherited,and features of the... Through reviewing development history of concession gardens in Tianjin City,features,advantages and problems of these gardens were analyzed.It was stressed that cultural context should be inherited,and features of the city highlighted.The gardens should be protected from the perspective of development,combined with urban green space system,integrated with cultural life of local citizens,and coordinated with contemporary architectural style of the city.In addition,plant landscapes should be enriched,and infrastructure of the gardens supplemented to properly handle the relationship between urban construction and protection of historical image,and provide reference for inheriting cultural context of the city in the urban development. 展开更多
关键词 TIANJIN City CONCESSION GARDEN INHERITANCE SUSTAINABLE development
下载PDF
Numerical Simulation on Hydraulic Performances of Quarter Circular Breakwater 被引量:10
2
作者 蒋学炼 谷汉斌 李炎保 《China Ocean Engineering》 SCIE EI 2008年第4期585-594,共10页
Quarter circular breakwater (QCB) is a new-type breakwater developed from senti-circular breakwater (SCB). The superstructure of QCB is composed of a quarter circular front wall, a horizontal base slab and a verti... Quarter circular breakwater (QCB) is a new-type breakwater developed from senti-circular breakwater (SCB). The superstructure of QCB is composed of a quarter circular front wall, a horizontal base slab and a vertical rear wall. The width of QCB' s base slab is about half that of SCB, which makes QCB suitable to be used on relatively finn soil foundation. The numerical wave flume based on the Reynolds averaged Navier-Stokes equations for impressible viscosity fluid is adopted in this paper to simulate the hydraulic performances of QCB. Since the geometry of both breakwaters is similar and SCB has been studied in depth, the hydraulic performances of QCB are given in comparison with those of SCB. 展开更多
关键词 quarter circular breakwater Reynolds averaged Navier-Stokes equations semi-circular breakwater wave forces wave reflection numerical wave flume
下载PDF
Experimental Researches on Reflective and Transmitting Performances of Quarter Circular Breakwater Under Regular and Irregular Waves 被引量:9
3
作者 史艳娇 吴米玲 +1 位作者 蒋学炼 李炎保 《China Ocean Engineering》 SCIE EI 2011年第3期469-478,共10页
A series of regular and irregular wave experiments are conducted to study the reflective and transmitting performances of quarter circular breakwater (QCB) in comparison with those of semi-circular breakwater (SCB... A series of regular and irregular wave experiments are conducted to study the reflective and transmitting performances of quarter circular breakwater (QCB) in comparison with those of semi-circular breakwater (SCB). Based on regular wave tests, the reflection and transmission characteristics of QCB are analyzed and a few influencing factors are investigated. Then, the wave energy dissipation as wave passing over the breakwater is discussed based on the hydraulic coefficients of QCB and SCB. In irregular wave experiments, the reflection coefficients of QCB and their spectrums are studied. Finally, the comparisons between the experimental results and numerical simulations for QCB under regular and irregular wave conditions are presented. 展开更多
关键词 quarter circular breakwater regular wave irregular wave reflection transmission
下载PDF
Glass-ceramics made from arc-melting slag of waste incineration fly ash 被引量:5
4
作者 刘汉桥 魏国侠 +1 位作者 梁茵 董飞英 《Journal of Central South University》 SCIE EI CAS 2011年第6期1945-1952,共8页
Grate fly ash and fluidized bed fly ash mixed with glass cullet additive respectively were melted in the electronic arc-furnace. The product, arc-melting slag, was further treated by crushing, pressing and heat treatm... Grate fly ash and fluidized bed fly ash mixed with glass cullet additive respectively were melted in the electronic arc-furnace. The product, arc-melting slag, was further treated by crushing, pressing and heat treatment in order to make the glass-ceramics. The crystallization behaviors of the produced glass-ceramics were examined by differential thermal analysis (DTA), X-ray diffractometry (XRD) and scanning electron microscopy (SEM). Results show that main crystalline phase of the glass-ceramics fi'om grate fly ash is wollastonite (CaSiO3) with small amount of diopside (Ca(Mg,Al)(Si,Al)206), and that from fluidized bed fly ash is diopside (Ca(Mg,Al)(Si,Al)206). It is found that the glass-ceramics sintered at 850 ℃and 1 000℃ from grate fly ash and fluidized bed fly ash respectively have the optimal physical, mechanical and chemical characteristics. Glass-ceramics samples, produced from incinerator fly ash with desirable properties and the low leaching concentration of heavy metals, can be the substitute of nature materials such as marble, granite and porcelain tiles. 展开更多
关键词 waste incineration fly ash ARC-MELTING GLASS-CERAMICS crystallization behavior
下载PDF
Human-induced landslide on a high cut slope: a case of repeated failures due to multi-excavation 被引量:6
5
作者 Fanyu Zhang Gao Liu +3 位作者 Wenwu Chen Shouyun Liang Ransheng Chen Wenfeng Han 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE 2012年第4期367-374,共8页
The paper attempts to represent a case of repeated failures on a high cut slope due to multi-excavation. The characteristics of each failure induced by excavation are analyzed through geological investigation, and the... The paper attempts to represent a case of repeated failures on a high cut slope due to multi-excavation. The characteristics of each failure induced by excavation are analyzed through geological investigation, and then a geological model at different failure stages is proposed. The geological analysis shows that the excavation-induced repeated failures are related to the exposure of the weak bedding plane and the toe unloading of the cut slope, Numerical modeling is conducted based on a sequential method, taking into account the main failure stages of cut slope. The simulation results fairly coincide with the practical phenomena observed in field. It is shown that the decrease in normal stress of displaced mass on cut slope will induce the increase in shear stress in bedding planes and that at the toe of the cut slope. The released stress leads to repeated gravitational instabilities of cut slope due to the decrease in normal stress and the increase in shear stress along the bedding planes of mudstone. 展开更多
关键词 LANDSLIDE repeated failures multi-excavation instability of cut slope human activity
下载PDF
Effect of Water Washing Pre-treatment on the Properties of Glass-ceramics from Incinerator Fly Ash Using Electronic Arc Furnace 被引量:5
6
作者 刘汉桥 WEI Guoxia ZHANG Rui 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2013年第1期62-68,共7页
Production of glass-ceramics by sintering the molten slag obtained from electric arc furnace treatment of fly ash was investigated. The effect of washing pretreatment prior to melting the fly ash on the microstructure... Production of glass-ceramics by sintering the molten slag obtained from electric arc furnace treatment of fly ash was investigated. The effect of washing pretreatment prior to melting the fly ash on the microstructure and properties of the glass-ceramics was examined. The results show that washing pretreatment of fly ash can decrease alkali metal chloride and increase network former in fly ash, which results in the increase of peak crystallization temperature of parent glass and strengthening of properties of bending strength and chemical stability of the glass-ceramics. The optimal heat treatment temperature for parent glass of washed fly ash is 1 173 K, at which the crystalline phase of glass-ceramics is composed of gelignite (Ca2A12SiO7) and akermanite (Ca2MgSi207). Glass-ceramics produced at optimal heat treatment temperature are excellent in term of the physical and chemical properties and leaching characteristics, indicating attractive potential as substitute of nature materials. 展开更多
关键词 waste incineration fly ash ARC-MELTING GLASS-CERAMICS water washing
下载PDF
Existence of Solutions to Multi-point BVP with p-Laplacian at Resonance 被引量:2
7
作者 LI Li-fang GE Wei-gao 《Chinese Quarterly Journal of Mathematics》 CSCD 2010年第3期379-384,共6页
This paper is concerned with the existence of solutions for the following multipoint boundary value problem at resonance{(Φp (x'))' + f(t,x)=0,0 < t < 1,x' (0)=x'(ξ) x(1)=m-3 ∑i=1 βi x(η i),... This paper is concerned with the existence of solutions for the following multipoint boundary value problem at resonance{(Φp (x'))' + f(t,x)=0,0 < t < 1,x' (0)=x'(ξ) x(1)=m-3 ∑i=1 βi x(η i),where βi∈ R,m-3 ∑i=1 β i=1,0 < η 1 < η 2 < ··· < ηm-3 < 1,m-3 ∑i=1 βiηi=1,0 < ξ < 1.An existence theorem is obtained by using the extension of Mawhin's continuation theorem.Since almost all the multi-point boundary value problem at resonance in previous papers are for the linear operator without p-Laplacian by the use of Mawhin's continuation theorem,our method is new. 展开更多
关键词 multi-point boundary value problem the extension of Mawhin’s continuation theorem RESONANCE p-Laplacian operator
下载PDF
Cake models applied to evaluate the fouling mechanism in separation of anionic polyacrylamide using modified PVDF ultrafiltration membranes 被引量:1
8
作者 衣雪松 时文歆 +3 位作者 于水利 孙楠 王硕 孙力平 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2012年第1期125-128,共4页
In the present study,nano-sized TiO2 /Al2O3 modified PVDF membranes (MM) were fabricated and utilized for anionic polyacrylamide ( APAM) separation. The results showed that,compared with PVDF membrane (OM) ,the contac... In the present study,nano-sized TiO2 /Al2O3 modified PVDF membranes (MM) were fabricated and utilized for anionic polyacrylamide ( APAM) separation. The results showed that,compared with PVDF membrane (OM) ,the contact angle of MM decreases from 83. 64° to 67. 42°,which indicates the increase of the hydrophilicity of MM. The relative flux (RF) decline curve of this ultrafiltration of APAM in water with time shows an obvious two stage properties. The cake filtration models were used to predict the performance of different time over the complete range of filtration times. All the four cake models could simulate this UF process to a certain extent,and the suitability of the two kinds of membranes was: cake filtration > intermediate pore blocking > standard pore blocking > complete pore blocking models. However,they became more and more unsuited to this process with time extending. Surface and cross-sectional morphology of membrane was investigated by SEM to make an advanced certificate of this UF mechanism. 展开更多
关键词 CAKE MODELS APAM NANO-PARTICLES Al2O3 /TiO2 PVDF ultrafiltration membranes FOULING MECHANISM
下载PDF
Changes of local agricultural landscape patterns induced by land consolidation in hilly and mountainous Southwestern China 被引量:1
9
作者 张贞 魏朝富 《Journal of Chongqing University》 CAS 2009年第3期151-164,共14页
Land consolidation (LC), as a type of human disturbance, improves land production efficiency and changes landscape distribution through land parcel reallocation. The objective of this study was to comparatively analyz... Land consolidation (LC), as a type of human disturbance, improves land production efficiency and changes landscape distribution through land parcel reallocation. The objective of this study was to comparatively analyze the changes of landscape patches before and after a land consolidation project (LCP) and the effects of land levelling, irrigation and drainage work and road engineering on the landscape structure. FRAGSTAT3.3 and buffer zone analysis were used to investigate those changes. The results suggest that the heterogeneity of landscape depressed, and tended to simplification after LC. Dry land was the most highly variable land use pattern, and the change of forestland was least due to its locations at a gradient larger than 25°. LC resulted in a more rational use of land, and could be an important step in promoting rural development in depressed and fragmented agricultural areas through unused land exploitation, small-patch combination, irrigation and water conservancy, and road construction. Land levelling leveled off the gradient field surface and decreased the slope. The fragmentized patches were much more incorporated with increasing slope. On the other hand, the ridge of a field became longer so that the length of field surface and area of patch were increased. Land levelling regulated, simplified and combined patches, so that the complexity degree was reduced. It is found that the buffer distance of 35 m was a turning point of human disturbance by irrigation and drainage systems, and patches presented flaky distribution when the buffer distance was smaller than 35 m. Meanwhile, the distance range between 25 m to 50 m was an impressible area for road engineering, which was sensitive to human actions, and the changes of all landscape metrics were larger than those in other buffer zones. In general, LC not only reallocated fragmented parcels, but also improved agricultural conditions. 展开更多
关键词 land consolidation land use local agricultural landscape pattern landscape patch hilly and mountainous in Southwestern China
下载PDF
Research on Partial Coefficients for Design of Quarter-circular Caisson Breakwater 被引量:4
10
作者 Luwen Qie Xiang Zhang +1 位作者 Xuelian Jiang Yinan Qin 《Journal of Marine Science and Application》 2013年第1期65-71,共7页
The quarter-circular caisson breakwater (QCB) is a new type of breakwater, and it can be applied in deepwater. The stability of QCB under wave force action can be enhanced, and the rubble mound engineering can be le... The quarter-circular caisson breakwater (QCB) is a new type of breakwater, and it can be applied in deepwater. The stability of QCB under wave force action can be enhanced, and the rubble mound engineering can be less than that of semi-circular breakwaters in deepwater. In order to study the wave force distribution acting on the QCB, to find wave force formula for this type of breakwater, firstly in this paper, the distribution characteristics of the horizontal force, the downward vertical force and the uplift force on the breakwater were gotten based on physical model wave flume experiments and on the analysis of the wave pressure experimental data. Based on a series of physical model tests acted by irregular waves, a kind of calculation method, which was modified by Goda formula, was proposed to carry out the wave force on the QCB. Secondly, the reliability method with correlated variables was adopted to analyze the QCB, considering the high correlation between wave forces or moments. Utilizing the observed wave data in engineering field, the reliability index and failure probability of QCB were obtained. Finally, a factor Q=0.9 is given to modify the zero pressure height above SWL of QCB, and wave force partial coefficient 1.34 to the design expressions of QCB for anti-sliding, as well as 1.67 for anti-overturning, were presented. 展开更多
关键词 quarter-circular caisson breakwater (QCB) wave force modified Goda formula reliability index partial coefficient
下载PDF
Development Paths of Low-carbon Landscape Design 被引量:1
11
作者 MENG Jin CHEN Liang 《Journal of Landscape Research》 2013年第Z1期17-18,共2页
Through interpreting significance of low-carbon landscape, and analyzing common problems in landscape design industry, paths of low-carbon landscape design were explored from the following perspectives: establishing l... Through interpreting significance of low-carbon landscape, and analyzing common problems in landscape design industry, paths of low-carbon landscape design were explored from the following perspectives: establishing low-carbon index system for the landscape construction of eco-city; constructing scientific and reasonable spatial layout; using landscapes to interpret low-carbon concepts; enhancing the carbon sink function of urban green spaces; choosing reasonable landscape materials; reducing landscape maintenance cost. The study aims at applying low-carbon concepts in all design projects to achieve sustainable development of urban landscapes. 展开更多
关键词 Low-carbon landscapes DEVELOPMENT PATH THINKING
下载PDF
Mechanism of Visible Photoactivity of F-Doped TiO2 被引量:2
12
作者 郭美丽 张晓东 +1 位作者 梁春恬 贾国治 《Chinese Physics Letters》 SCIE CAS CSCD 2010年第5期204-207,共4页
We calculate the electronic structure and optical properties of F-doped anatase TiO2. The results indicate that the band gap ofF-doped TiO2 increases slightly compared with the pure TiO2. However, it is interesting th... We calculate the electronic structure and optical properties of F-doped anatase TiO2. The results indicate that the band gap ofF-doped TiO2 increases slightly compared with the pure TiO2. However, it is interesting that the visible absorption of F-doped TiO2 located between 600 and 700 nm is observed, and it enhances gradually with the increasing F concentration. Furthermore, according to the results of densities of states and imaginary part of dielectric function ε2(ω), we propose that the transition between Ti 3d and Ti 3d states may be responsible for the visible absorption, but not the band gap narrowing. 展开更多
下载PDF
Effects of Potential and Temperature on the Electrodeposited Porous Zinc Oxide Films
13
作者 李军伟 刘志锋 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2011年第1期47-51,共5页
Porous ZnO films were prepared by electrodeposition method in zinc nitrate aqueous solution using ITO glass covered with polystyrene sphere (PS) colloidal crystal arrays as substrates. The preparation procedure incl... Porous ZnO films were prepared by electrodeposition method in zinc nitrate aqueous solution using ITO glass covered with polystyrene sphere (PS) colloidal crystal arrays as substrates. The preparation procedure includes two parts: deposition of ZnO in the interstices of the colloidal crystals and subsequent removal of the PS templates. The influences of deposition potential and temperature on the ZnO films were investigated. The ordered, uniform porous ZnO films with optical transmittance of approximately 63.6% at 600 nm could be obtained when the deposition potential and temperature were –1.1 V and 70 ℃, respectively. The optical band gap energy increased along with the absolute deposition potential and temperature, ranging from 3.33 to 3.43 eV and from 3.35 to 3.42 eV, respectively. 展开更多
关键词 porous ZnO film ELECTRODEPOSITION TEMPLATE band gap energy
下载PDF
OH^- absorption bands of LiNbO_3 with varying composition
14
作者 陈洪建 师丽红 +3 位作者 阎文博 陈贵锋 沈俊 李养贤 《Chinese Physics B》 SCIE EI CAS CSCD 2009年第6期2372-2376,共5页
This paper reports that OH^- absorption bands of lithium niobate crystal have been measured at room temperature, and the band shape depending on the crystal composition has been observed. The OH^- absorption bands are... This paper reports that OH^- absorption bands of lithium niobate crystal have been measured at room temperature, and the band shape depending on the crystal composition has been observed. The OH^- absorption bands are fitted with three Lorentzian peaks by varying position, halfwidth, and height. Nearly constant peak positions (3468, 3481 and 3490 cm^-1) are obtained for all samples. It shows that the height and area of the decomposed peaks vary with the Li composition in a complex way. However, the combinations of these fitting parameters show a linear dependence on the composition up to nearly 50 mol%, which is very useful for the composition determination in a wide range. The linear relationships between the parameter combinations and Li composition are also presented quantitatively. In addition, the explanations were given for the excellent composition linearity of parameter combinations. 展开更多
关键词 optical materials Fourier transform infrared heat treatment ADSORPTION
下载PDF
Photocatalytic Degradation of Diethyl Phthalate with Surfactant Addition
15
作者 张天永 扈娟 +2 位作者 张友兰 李彬 费学宁 《Transactions of Tianjin University》 EI CAS 2006年第4期258-263,共6页
This paper studies the adsorption of diethyl phthalate (DEP,an environmental hormone) on the surface of nanoscale TiO2, effects of pH value of solutions, initial concentrations of DEP and additive surfactant on phot... This paper studies the adsorption of diethyl phthalate (DEP,an environmental hormone) on the surface of nanoscale TiO2, effects of pH value of solutions, initial concentrations of DEP and additive surfactant on photocatalytic degradation and dynamics of DEP. Under ultra violet illumination, the interaction between DEP and surfactants including DBS (sodium dodecylbenzenesulfonate), CTAB (cetyltrimethylammonium bromide), and OP-10 (nonylphenol polyoxyethylene ether) was exploited from the perspective of degradation speed calculated by the data of high pressure liquid chromatography (HPLC) and UV-Vis spectra, respectively. Photocatalytic degradation of DEP followed pseudo first-order reaction kinetics. DEP as substrate degraded fast when its initial concentration was 130 mg/L. TiO2 had certain adsorption ability of DEP. TiO2 could adsorb the most DEP at the approximately neutral pH of 6.91. Degradation of DEP was not affected obviously by additives OP-10 and DBS. Degradation rate of DEP was not enhanced greatly in the presence of surfactants, but degradation of DBS was sped up. Degradation rate of DEP was depressed in the presence of additive CTAB. The more CTAB was added, the less DEP was degraded. Degradation rate of CTAB became slow with the increase of initial CTAB concentration. The possible adsorption models among TiO2, DEP and surfactants were given. 展开更多
关键词 diethyl phthalate SURFACTANT ADSORPTION dynamics PHOTOCATALYSIS DEGRADATION
下载PDF
Thermodynamics of martensite transformation hysteresis in Ni-Ti shape memory alloys
16
作者 贾堤 韩明 +2 位作者 刘文西 王德法 董治中 《中国有色金属学会会刊:英文版》 CSCD 2000年第3期411-413,共3页
A thermodynamic calculation method on the temperature hysteresis of thermoelastic martensite transformation in Ni Ti shape memory alloys was developed. The thermodynamic analysis indicates that the irreversible consum... A thermodynamic calculation method on the temperature hysteresis of thermoelastic martensite transformation in Ni Ti shape memory alloys was developed. The thermodynamic analysis indicates that the irreversible consumed energy and the elastic energy are the important factors influencing transformation hysteresis. It is revealed that the wide inherent transformation hysteresis can be attributed to the higher irreversible consumed energy of martensite transformation in Ni Ti Nb based alloys than those of Ni Ti binary alloys. 展开更多
关键词 THERMODYNAMICS THERMOELASTIC MARTENSITE TEMPERATURE HYSTERESIS Ni Ti ALLOYS
下载PDF
Crystal Structure and Photochromism in Paint and Solutions of 2,2-Dithiophene-naphthopyran
17
作者 谈廷风 柏立岗 +1 位作者 庞美丽 吴边鹏 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2009年第1期41-44,共4页
The title compound 2,2-dithiophene-naphthopyran (C21H14OS2, Mr = 346.44) was synthesized and characterized by IR,^1lH NMR, elemental analysis and single-crystal X-ray diffraction. It belongs to the monoclinic system... The title compound 2,2-dithiophene-naphthopyran (C21H14OS2, Mr = 346.44) was synthesized and characterized by IR,^1lH NMR, elemental analysis and single-crystal X-ray diffraction. It belongs to the monoclinic system, space group P21/n, with a = 8.2349(14), b = 6.1964(11), c = 32.458(5)A, β= 95.051(3)°, V= 1649.8(5)A^3, Z = 4, Dc = 1.395 g/cm^3,μ = 0.327 cm^-1, F(000) = 720, the final R = 0.0559 and wR = 0.1442 for 3370 observed reflections (I 〉 2σ(I)). X-ray analysis revealed that the interatomic distance of C(13)-O(1) is 1.456(3)A, longer than that of normal C-O bond (1.41 - 1.43 A) in a six-membered heterocycle. The UV-vis spectra of the title compound showed that it exhibits excellent photochromic property in polyester coating and solutions. 展开更多
关键词 2 2-dithiophene-naphthopyran crystal structure PHOTOCHROMISM PAINT
下载PDF
Three-dimensional interfacial wave theory of dendritic growth: (Ⅰ). multiple variables expansion solutions
18
作者 陈永强 唐熊忻 徐鉴君 《Chinese Physics B》 SCIE EI CAS CSCD 2009年第2期671-685,共15页
Dendritic pattern formation at the interface between liquid and solid is a commonly observed phenomenon in crystal growth and solidification process. The theoretical investigation of dendritic growth is one of the mos... Dendritic pattern formation at the interface between liquid and solid is a commonly observed phenomenon in crystal growth and solidification process. The theoretical investigation of dendritic growth is one of the most profound and highly challenging subjects in the broad areas of interfacial pattern formation, condensed matter physics and materials science, preoccupying many researchers from various areas. Some longstanding key issues on this subject finally gained a breakthrough in the late of last century, via the 'Interracial Wave (IFW) Theory' on the ground of systematical global stability analysis of the basic state of dendritic growth. The original form of the IFW theory mainly focus on the investigation of various axi-symmetric unsteady perturbed modes solutions around the axi-symmetrie basic state of system of dendritic growth. In reality, the system may allow various non-axi-symmetric, unsteady perturbed states. Whether or not the system of dendritic growth allows some growing non-axi-symmetric modes? Will the stationary dendritic pattern be destroyed by some of such non-axi- symmetric modes? Or, in one word, what is the stability property of the system, once the non-axi-symmetric modes can be evoked? The answers for these questions are important for the solid foundation of IFW theory. The present work attempts to settle down these issues and develop a three-dimensional (3D) interfacial wave theory of dendritic growth. Our investigations verify that dendritic growth indeed allows a discrete set of non-axi-symmetric unstable global wave modes, which gives rise to a set of multiple arms spiral waves propagating along the Ivantsov's paraboloid. 展开更多
关键词 Dendritic growth pattern formation interfacial waves selection criterion
下载PDF
Three-dimensional interfacial wave theory of dendritic growth: (Ⅱ). non-axi-symmetric global wave modes and selection criterion of pattern formation
19
作者 陈永强 唐熊忻 徐鉴君 《Chinese Physics B》 SCIE EI CAS CSCD 2009年第2期686-698,共13页
This paper is ttie continuation of part (Ⅰ), which completes the derivations of the 3D global wave modes solutions, yields the stability criterion and, on the basis of the results obtained, demonstrates the selecti... This paper is ttie continuation of part (Ⅰ), which completes the derivations of the 3D global wave modes solutions, yields the stability criterion and, on the basis of the results obtained, demonstrates the selection criterion of pattern formation. 展开更多
关键词 dendritic growth pattern formation interracial waves selection criterion
下载PDF
Ring-opened Crystal Structure and Photochromism of 2,2-Bis(4-tertiary butyl phenyl)-3H-naphtho[2,1-b]pyran
20
作者 谈廷风 庞美丽 吴边鹏 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2009年第2期187-190,共4页
The title compound, 2,2-bis(4-tertial butyl phenyl) naphthopyran, has been prepared and characterized by means of IR, ^1H NMR and elemental analysis, and its crystal structure was determined with X-ray diffraction i... The title compound, 2,2-bis(4-tertial butyl phenyl) naphthopyran, has been prepared and characterized by means of IR, ^1H NMR and elemental analysis, and its crystal structure was determined with X-ray diffraction in the ring-opened form after hydrolyzation. It belongs to monoclinic, space group P21/c, with a = 14.358(3), b = 7.6725(15), c = 24.470(5) А, β= 97.147(4)°, C_33H_36O2, Mr=464.62, V= 2674.8(9)А^3, Z = 4, Dc = 1.154 g/cm^3,μ= 0.070 mm^-1, F(000) = 1000, the final R = 0.0514 and wR = 0.1272 for 5444 observed reflections (I 〉 2σ(I)). X-ray analysis revealed that the C(13)-O(1) bond of the title compound cracks after UV irradiation, the six-membered heterocycles are destroyed, and zwitterionic intermediates come into being. The molecular structure in the ring-opened form is obtained after hydrolyzation. It is infrequent that the single-crystal structure is determined in a ring-opened form. A two-dimensional framework is formed by O-H…O and CAr-H…O hydrogen bonds. The UV-vis spectra show that the title compound exhibits excellent photochromic properties in solutions and polymers. 展开更多
关键词 NAPHTHOPYRAN ring-opened form crystal structure PHOTOCHROMISM
下载PDF
上一页 1 2 3 下一页 到第
使用帮助 返回顶部