检索结果-南通市图书馆

Decomposition mechanisms and non-isothermal kinetics of LiHC_2O_4.H_2O

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2012年第6期31卷 615-620页

作者： CHOU Kuo-Chih School of Materials science and engineering University of Science and Technology Beijing

The thermal decomposition process of LiHC2O4.H2O from 30 to 600 ℃ was investigated by the thermogravimetric and differential scanning calorimetry (TG-DSC). The phases decomposited at different temperature were characterized by X-ray diffraction (XRD), which indicated the decompositions at 150, 170, and 4.0℃, relating to LiHC2O4. Li2C2O4. Li2C2O4. and Li2CO3, respectively. Reaction mechanisms in the whole sintering process were determined, and the model fitting kinetic approaches were applied to data for non-isothermal thermal decomposition of LiHC2O4.H2O; finally, the kinetic parameters of each reaction were also calculated herein.

关键词： apparent activation energy non-isothermal reaction mechanism thermal decomposition

Relaying Selection with Network-coded Cooperative Protocols in Aeronautical Communications

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2010年第1期23卷 75-83页

作者： Du Bing,Zhang Jun School of Electronics and Information engineering,beijing university of Aeronautics and Astronautics,beijing 100191,{4. School of Electronics and Information engineering Beijing University of Aeronautics and Astronautics Beijing 100191 China

In this article, we exploit the idea of network-coded cooperative protocol in aeronautical communications which combines different source nodes＇ information at the relay and joint decoding at the destination. Recently, the network coding in cooperative communications has been categorized into two mainstreams, bit-level and signal-level combinations, which are both discussed in the article. And to be exclusively,multiple access relay channel（MARC） is adopted. The mutual information expressions of both above-cited network-coded protocols are deduced, which prove that without proper selected relays to perform network coding, the spatial diversity of the proposed protocol cannot be obtained. This then leads to search for the selection and grouping algorithms. An adjacency matrix is defined to describe the connectivity of the nodes in one radio contact disk, so that, the selection and grouping of algorithm is equivalent to constructing this adjacency matrix to minimize the system outage probability evaluated in term of the mutual information. Besides, a network-coded cooperative protocol requires the acyclic network, of which the construction is to avoid loop-4.in the matrix. The article ends with simulations to demonstrate the viability of the proposed algorithms.

关键词： communication network coding outage probability mutual information bit-level signal-level

Comparison study of two aldehyde group finishing agents in surface modification of up-conversion luminescence materials

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2008年第2期27卷 127-130页

作者： CUI Lili FAN Huili XIAO Junping XU Xiaowei Department of Chemistry University of Science and Technology Beijing Beijing 100083 China Department of Inorganic Nonmetallic Materials University of Science and Technology Beijing Beijing 100083 China

Surface modification of up-conversion luminescence materials （Na[Y0.57Yb0.39Er0.04.F4.modified by amino groups） by grafting and modifying with aldehyde groups was studied by means of Fourier transform infrared spectroscopy （FTIR）, scanning electron microscopy （SEM）, thermogravimetric analysis （TGA）, and emission spectrum （EM）. The surface modification effect was compared using two different finishhag agents, p-phthalaldehyde and glutaraldehyde. It was found that the surface of up-conversion luminescence materials could be modified by aldehyde groups of the two finishing agents, the systematic dispersibility and the thermostability of the up-conversion luminescence material modified by p-phthalaldehyde were better than those of the material modified by glutaraldehyde, and the luminous intensity of the material modified by p-phthalaldehyde was increased. The AI （the ratio of the suspended segmental quality in the specimen to the total mass of the specimen） of the material modified by p-phthalaldehyde was higher than that of the material modified by glutaraldehyde. It is obviously seen that the embellishment effect of p-phthalaldehyde as a finishing agent was better than that of glutaraldehyde. In addition, the reasons why p-phthalaldehyde is a good finishing agent are also explained.

关键词： luminescence materials up-conversion surface modification luminescence aldehyde groups

The crustal structure under Sanjiang and its dynamic implications:Revealed by seismic reflection/refraction profile between Zhefang and Binchuan,Yunnan

在线全文

学校读者我要写书评

暂无评论

science china Earth sciences 2005年第9期48卷 1329-1336页

作者： ZHANG Zhongjie1, BAI Zhiming1, WANG Chunyong2, TENG Jiwen1, Lü Qingtian3, LI Jiliang1, LIU Yifeng1 & LIU Zhenkuan4.1. Institute of Geology and Geophysics, Chinese Academy of sciences, beijing 100029, china 2. Institute of Geophysics, china Seismological Bureau, beijing 100085, china 3. Institute of Deposition Resource, Chinese Academy of Geosciences, beijing 100037, china 4. School of Exploration and Information, china university of Geosciences, beijing 100083. china Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China Institute of Geophysics China Seismological Bureau Beijing China Institute of Deposition Resource Chinese Academy of Geosciences Beijing China School of Exploration and Information China University of Geosciences Beijing China

The fault belts in Sanjiang mainly include Jinshajiang-Honghe fault, Lancangjiang fault and Nujiang fault (called Sanjiang faults) in western Yunnan Province, china. By interpreting the wide-angle seismic reflection/refraction profile between Zhefang and Binchuan, which crosses Tengchong and Baoshan blocks in Dianxi (western Yunnan) tectonic zone, we recon- struct the crustal structure with seismic traveltime tomography for crustal P-wave velocity and the seismic scattering image for crustal seismic reflection structure. In this paper, we firstly present the crustal structure images of P-wave velocity and seismic reflection under the wide-angle seismic profile. These results demonstrate that, the crustal velocity structure and seismic reflec- tion structure along the profile can be divided into 3 segments, and there is an obvious difference of crustal structure among the eastern, the western and the middle segment. Generally, crustal P-wave velocities in the Baoshan segment are 0.1―0.2 km/s slower and seismic reflection am- plitudes from Moho discontinuity are stronger than the other 2 segments. In the studied area, crustal thickness is about 4. km, and shows the thickening tendency from west to east along the profile. Additionally, it can be seen that there is one strong-amplitude seismic reflection event as bright points at the depths of 8―10 km, along the segment of 80―115 km of the profile (south- ward of Tengchong); and seismic reflection wave-field from Moho discontinuity varies obviously along the lateral direction. Finally, we make some discussions on the crustal thickening pattern in the Sanjiang fault belt, structural environment of earthquake development and the contact rela- tionship between the Tengchong block, Banshan block and Luxi trough.

关键词： Sanjiang area wide-angle seismic profile crustal structure.

Preparation and properties of a nano TiO_2/Fe_3O_4.composite superparamagnetic photocatalyst

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2009年第5期28卷 423-427页

作者： LI Yuxiang ZHANG Mei GUO Min WANG Xidong School of Metallurgical and Ecological engineering University of Science and Technology Beijing Beijing 100083 China College of engineering Peking University Beijing 100871 China

Nano TiO2/Fe3O4.composite particles with different molar ratios of TiO2 to Fe3O4.were prepared via sol-gel method. X-ray diffraction, transmission electron microscopy, and vibration sample magnetometry were used to characterize the TiO2/Fe3O4.particles. The photocatalytic activity of the particles was tested by degrading methyl blue solution under UV illumination （254.nm）. The results indicate that with the content of TiO2 increasing, the photocatalytic activity of the composite particles enhances, while the magnetism of the particles decreases. When the molar ratio of TiO2 to Fe3O4.is about 8, both the photocatalytic activity and magnetism of the TiO2/Fe3O4.particles are relatively high, and their photocatalytic activity remains well after repeated use.

关键词： photocatalysis superparamagnetism sol-gel method TiO2 Fe3O4

Thermochemical Evaluation of Combustion Synthesis of Al_2O_3/B_4. Composite

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 1998年第2期12卷 90-92页

作者： Yonghe Liu~(1,2)) Sheng Yin~(1)) Weijing Zhang~(1)) Hoyi Lai~(1)) 1) Materials science and engineering School, UST beijing, beijing {4. china 2) School of Materials science and engineering, Shandong university of Technology, Jinan 250014 Materials science and engineering School UST Beijing Beijing 100083 China School of Materials science and engineering Shandong University of Technology Jinan 250014 China

The equilibrium phase and adiabatic temperature for combustion synthesis of Al_2O_3/B_4. employing Al, B_2O_3 and C as starting materials is analyzed by both conventional and CALPHAD method. The adiabatic temperature calculed by CALPHAD method is significantly lower than that obtained by conventional method. The CALPHAD calculation also reveals that the equilibrium phases presented at the adiabatic temperature are different to the desired composites. The adiabatic temperature in this system can be lowered by introducing Al_2O_3 as diluents. The maximum amount of Al_2O_3 that can be added to the system while maintain a self-sustaining combusion mode is 1.3 mol.

关键词： thermochemical evaluation SHS Al_2O_3/B_4. composite

Synthesis and magnetic properties of CdS/α-Fe_2O_3 hierarchical nanostructures

在线全文

学校读者我要写书评

暂无评论

science china(Physics,Mechanics & Astronomy) 2009年第7期52卷 997-1002页

作者： CHEN YuJin1,2,3, SHI XiaoLing1, CAO MaoSheng1 & ZHU ChunLing4.1 School of Materials science and engineering, beijing Institute of Technology, beijing 100081, {4. 2 Micro-Nano Technologies Research Center, Hunan university, Changsha 4.0082, {4. 3 College of science, Harbin engineering university, Harbin 150001, {4. 4.College of Material science and Chemical engineering, Harbin engineering university, Harbin 150001, {4. School of Materials science and engineering Beijing Institute of Technology Beijing China Micro-Nano Technologies Research Center Hunan University Changsha China College of science Harbin Engineering University Harbin China College of Material science and Chemical engineering Harbin Engineering University Harbin China

CdS/α-Fe2O3 hierarchical nanostructures, where the CdS nanorods grow irregularly on the side surface of α-Fe2O3 nanorods, were synthesized via a three-step process. The diameters and lengths of CdS nanorods can be tuned by changing the ethylenediamine (EDA) and Cd ion concentrations. The magnetic investigations by superconducting quantum interference device indicate that the hierarchical nanostructures have an Morin transition at lower temperature (230 K) than that of the single bulk α-Fe2O3 materials (263 K). Importantly, the hierarchical nanostructures exhibit weakly ferromagnetic characteristics at 300 K. A sharp peak assigned to the surface trap induced emission are observed in room temperature PL spectra. Combining with the optoelectronic properties of CdS, the CdS/ α-Fe2O3 hierarchical nanostructures may be used as multi-functional materials for optoelectronic and magnetic devices.

关键词： α-Fe2O3 CdS hierarchical nanostructures magnetic properties

Exotic structure of the third excited state in^(21)Na

在线全文

学校读者我要写书评

暂无评论

Chinese science Bulletin 2005年第23期50卷 2677-2680页

作者： LI Xihan1,2,3, LIANG Yujie1,2,3, DENG Fuguo1,2,3, LIU Zuhua1,4.& ZHOU Hongyu1,2,3 1. Key Laboratory of Beam Technology and Material Modification of Minister of Education, beijing Normal university, beijing 100875, china 2. Institute of Low Energy Nuclear Physics, and Department of Material {4. and engineering, beijing Normal university, beijing 100875, china 3. beijing Radiation Center, beijing 100875, china 4. china Institute of Atomic Energy, beijing 1024.3, china Key Laboratory of Beam Technology and Material Modification of Minister of Education Beijing Normal University Beijing 100875 China Institute of Low Energy Nuclear Physics Department of Material Science and Engineering Beijing Normal University Beijing 100875 China beijing Radiation Center Beijing 100875 China china Institute of Atomic Energy Beijing 102413 China

The probability of the last proton being out of the binding potential, P and the root-mean-square (rms) ra- dius (1/2= of the third excited state in 21Na are calcu- lated by means of asymptotic normalization coefficient (ANC) method with the experimental date existing. The results are P=54.73% and 1/2=5.28 fm respectively. The P value and the contribution of the asymptotic part to the 1/2 are compared with those of several other low energy states in 21Na. It is found that the valence particle in the third excited state has an obvious larger P than those of other states. The density distribution of the valence proton in this state is also compared with the nucleons in the nuclear core 20Ne, and a far extended tail can be seen clearly. These results show that the third ex- cited state in 21Na is a proton halo state.

关键词：钠第三激发态外部结构有效半径密度分布渐近标准化系数

Cardioprotective effects of ghrelin and des-octanoyl ghrelin on myocardial injury induced by isoproterenol in rats

在线全文

学校读者我要写书评

暂无评论

Acta Pharmacologica Sinica 2006年第5期27卷 527-535页

作者： LLian LI~2 Li-ke ZHANG~5 Yong-zheng PANG~(2.4. Chun-shui PAN~(3.4. Yong-fen QI~(3.4. Li CHEN~4.Xian WANG~(3,4. Chao-shu TANG~(3,4. Jing ZHANG~(2,4.6) ~2Institute of Cardiovascular Research,Peking university First Hospital,beijing 100034.china:~3Department of Physiology and Pathophysiology,Peking university Health {4. Center,beijing 100083.china ~4.ey Laboratory of the Ministry of Education on Molecular Cardiology,beijing 100083.china:~5Department of Pathophysiology,Capital university of Medicine,beijing 100054.china Institute of Cardiovascular Research Peking University First Hospital Beijing China Department of Pathophysiology Capital University of Medicine Beijing China Key Laboratory of the Ministry of Education on Molecular Cardiology Beijing China Department of Physiology and Pathophysiology Peking University Health Science Center Beijing China

Aim:To determine the cardioprotective action of ghrelin and des-octanoyl ghrelinin rats with isoproterenol-induced myocardial ***:Rats were subcu-taneously injected with isoproterenol （ISO;20,10,and 5 mg/kg） on d 1,2 and 3,respectively,and then 3 mg/kg for the next 7d with or without ghrelin or des-octanoyl-ghrelin （100μg/kg,twice daily）.Plasma ghrelin and growth hormonelevels were assayed using radioimmunoassay *** hormone secreta-gogue receptor （GHSR） and ghrelin mRNA were determined using *** binding capacity and the affinity for [3H]ghrelin were determined by re-ceptor binding ***:Compared with controls,ISO-treated rats showedsevere myocardial injury,cardiomegaly,infarction-like necrosis and massive fi-brosis with increases in irradiated-ghrelin （ir-ghrelin） content in plasma by 67%and myocardia by 66% and in the mRNA level in the myocardia by 93% （P<0.01）.ISO-treated rats had 95% （P<0.01） higher GHSR mRNA levels in the *** maximal binding capacity of [3H]ghrelin for myocardial sarcolemma was higherin ISO-treated rats than in *** administration improved cardiac func-tion and ameliorated cardiomegaly and attenuated myocardial lipid peroxidationinjury and relieved cardiac fibrosis as compared with ISO treatment ***-istration of des-octanoyl ghrelin effectively antagonized ISO-induced myocardialinjury and improved all parameters ***,the therapeutic effect ofdes-octanoyl ghrelin was significantly weaker than that of *** plasmagrowth hormone level increased markedly,by 1.5-fold （P<0.01）,with ghrelinadministration as compared with that in controls,but was unaltered in the des-octanoyl ghrelin ***:Myocardial ghrelin and GHSR were up-regulated during ISO-induced myocardial *** protective effect of ghrelinagainst ISO-induced cardiac function injury and fibrosis was more potent thanthat of des-octanoyl ghrelin,which suggests that ghrelin could be an endog

关键词： ghrelin des-octanoyl ghrelin myocardium fibrosis isoproterenol