检索结果-南通市图书馆

Photoluminescence Properties of Porous Silicon Based on FZ(H) Si Wafer

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2001年第1期20卷 38-42,57页

作者： Yuejiao He, Huaixiang Li, Chenghua Guo, Guirong Liu, Yansheng Chen, Shuzhen Duan (Institute of Semiconductors, Shandong Normal university, Jinan 250014. china Metallurgy {3., university of Science and Technology {4., beijing 100083. china) Shandong Normal Univ Inst Semicond Jinan 250014 Peoples R China Univ Sci & Technol beijing Met Sch Beijing 100083 Peoples R China

The photoluminescence (PL) properties of porous silicon (PS) have been studied based on n-type single-crystal (111) silicon wafers (80-90 Omega .cm in the resistivity). The porous silicon layers (PSL) were created by anodizing the wafers with a denuded zone of 20-4. mum formed by neutron transmutation doping (NTD) and thermal treatment at 94. degreesC for 4.h and then 700 degreesC for 2 h, two-step heating of the floating-zone silicon (FZ Si) grown in a hydrogen (H,) ambience. By surface modification with stannic chloride or amine immersion and rapid thermal oxidation (RTO), the PL peak position from the PS can be qualitatively controlled factitiously. The as-prepared PS shows an orange-yellow luminescence, while the modified samples emit red, green and blue luminescence. Mechanisms for the different colors of the PL are discussed. Fourier transform infrared (FTIR) is carried out to analyze the differences in the structural configuration of the PS samples.

关键词： porous silicon photoluminescence surface modification rapid thermal oxidation

CJZ3.a Iomerizine derivative,modulates P-glycoprotein function in rat brain microvessel endothelial cells

在线全文

学校读者我要写书评

暂无评论

Acta Pharmacologica Sinica 2006年第4期27卷 414-418页

作者： Bian-sheng JI~2 Ling HE~3.Xiao-qu LI~4.Guo-qing LIU~(3.5) ~2Institute of Pharmacy,Henan university,Kaifeng 4.5001.{3. ~3.epartment of Pharmacology,{3. Pharmaccutical university.Nanjing 210009,{3.:~4.5} of Life Sciences,beijing Normal university,beijing 100875,{3. Institute of Pharmacy Henan University Kaifeng China Department of Pharmacology China Pharmaceutical University Nanjing China school of Life Sciences Beijing Normal University Beijing China

Aim:To investigate the modulatory effect of CJZ3.a lomerizine derivative,onP-glycoprotein(P-gp)function in rat brain microvessel endothelial cells(RBMEC).Methods:RBMEC were isolated and cultured in Dulbecco's modified Eagle's me-dium/F12(1:1)medium,and the amount of intracellular rhodamine 123.Rh 123.wasdetermined using a fluorescence spectrophotometer to evaluate the modulatoryeffect of CJZ3.on P-gp ***:The accumulation of Rh 123.was poten-tiated in a concentration-dependent manner after incubation with CJZ3.for RBMEC,but not for human umbilical vein endothelial cells(HUVEC).CJZ3.caused theaccumulation of intracellular Rh123.in a time-dependent manner and significantlydecreased the effiux of Rh 123.from the *** inhibitory effect of CJZ3.on P-gpfunction was reversible and remained for 120 min after CJZ3.2.5 μmol/L)wasremoved from the ***:CJZ3.has a potent in vitro effect on theinhibition of P-gp function.

关键词： CJZ3 P-glycoprotein blood-brain barrier

Refinement of packet size in low carbon bainitic steel by special thermo-mechanical control process

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of university of Science and Technology beijing 2004年第3期11卷 221-224页

作者： Chengjia Shang Xuemin Wang Shanwu Yang Xinlai He Materials Science and Engineering school, university of Science and Technology beijing,{3. Mat. Sci. and Eng. Sch. Univ. of Sci. and Technol. Beijing Beijing 100083 China

The packet size of bainitic steel can be refined by a specialrelaxation-precipitation-control phase transformation (RFC) technology. When processed by RPCprocess, the low carbon bainitic steel composes of two kinds of main intermediate transformationphases. One is ultra-fine lath-like bainitic ferrite and the lath is less than 1μm in width andabout 6 μm in length; the alignment of laths forms a refined packet, and the size of packets isabout 5-7 μm in length and about 3.4.m in width. The other is acicular structure. The morphologyand distribution of these acicular structures are influenced by relaxation process, the thin andshort acicular structures cut the prior austenite grain and refine the bainitic packet size. For theoptimum relaxation time, the packet size can be refined to the finest. The mechanical propertiesare influenced by relaxation time and the 800 MPa grade low carbon bainitic steel with excellenttoughness can be obtained by RPC process.

关键词： packet size refinement bainitic steel RPC process

Sticking-up Behaviors and Surface Friction of IF Electrogalvanized Sheet Steel in Forming

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 1999年第1期13卷 61-63,68页

作者： Jiming Hu Jixun Wu Yanping Lu Yanrong Zhu (Material Science and Engineering school, university of Science and Technology beijing,{3.) Univ of Science and Technology Beijing Beijing China

X-ray diffraction (XRD), ball-disc friction and wearing machine and draw-bead test were introduced to investigat the strcusture and workability of IF sheet steel electrogalvanized deposits prepared from sulphate solution system. It was shown that the picking-up of the zinc coating on die strengthened with the increasing of friction factor which was originally affected by the coating's structure. Duing forming, (00X) planes (X= 2, 4. preferential orientation of zinc deposits increased, which resulted in enhanc ing the coating's friction behaviors. Therefore, the forming mechanism of electrogalvedzed deposit was demonstrated that both friction and the stricking -up behaviors of the coating are intensified simultaneously and affect each other.

关键词： electrogalvanized deposit forming friction factor

Origin of the Red Earth sequence on the northeastern Tibetan Plateau and its implications for regional aridity since the middle Miocene

在线全文

学校读者我要写书评

暂无评论

Science china Earth Sciences 2006年第5期49卷 505-517页

作者： WANG Xianyan1,7, LU Huayu1,2, JI Junfeg3. WANG Xiaoyong1,7, ZHAO Jingbo4. HUANG Baochun5 & LI Zhen6 1. SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710075, china 2. Department of Urban and Resources Sciences, Nanjing university, Nanjing 210093. china 3. Department of Earth Sciences, Nanjing university, Nanjing 210093. china 4. Department of geography, Shaanxi Normal university, Xi’an 710062, china 5. Institute of geology and geophysics, Chinese Academy of Sciences, beijing 100029, china 6 Department of geography, Qinghai Normal university, Xining 810008, china 7. Graduate school of the Chinese Academy of Sciences, beijing 10003., china 1. SKLLQG Institute of Earth Environment Chinese Academy of Sciences Xi’an 710075 China 7. Graduate school of the Chinese Academy of Sciences Beijing 100039 China 2. Department of Urban and Resources Sciences Nanjing University Nanjing 210093 China 3. Department of Earth Sciences Nanjing University Nanjing 210093 China 4. Department of geography Shaanxi Normal University Xi’an 710062 China 5. Institute of geology and geophysics Chinese Academy of Sciences Beijing 100029 China 6. Department of geography Qinghai Normal University Xining 810008 China

The Red Earth deposit around Xining, northeastern Tibetan Plateau, has beenstudied in terms of soil micro-structure, grain-size distribution, major- and trace-elementchemistry and magne-tostratigraphy. Field investigations indicate that the Red Earth sequenceconsists of 25 visually definable yellow-brown and weakly-developed soils interbedded with reddishstrongly-developed soils, and has a similar structure to the aeolian Red Clay deposit on the ChineseLoess Plateau. Grain-size analysis shows that the Red Earth deposit is very fine-grained with anegligible sand fraction ( > 63.μm). Thin-section observations under light microscopy show that thedeposit has a clayey texture and the coarse fraction ( > 10 μm) mainly consists of quartz,feldspar and micas. Pyroxene and hornblende were also observed. This mineralogical composition ofthe coarse fraction is similar to that of the Quaternary loess. In addition, all of the mineralgrains are semi angular semi-angular and are generally finer than 63.μm. There is a good agreementbetween the major and minor trace element chemistry of loess-soil units and the Red Earth *** REE distributions of the loess-soil and the Red Earth deposit are similar in shape, withenriched LREE and fairly flat HREE profiles and a clear negative Eu anomaly. The geochemicalcharacteristics of the Red Earth deposit are also identical to those of upper continental crust,thus indicating a wind-blown origin. Magnetostratigraphic investigation shows that onset of the RedEarth deposition predates 11.4.Ma BP (13.6 Ma at a nearby site). The distribution of the reportedMiocene aeolian loess at Qin''an of the Loess Plateau is still unknown. Our results indicate thatthis aeolian deposit had extended to the northeastern Tibetan Plateau by at least the middleMiocene. The similarity of the element geochemistry between the Red Earth deposit and the overlyingloess shows that they may have similar sources and dynamic transport system, and may indicate thatthe

关键词： Red Earth deposit, Northeastern Tibetan Plateau, aeolian deposit, aridity of Asia, the middle Miocene.

Multi-dimensional project management models for mega-construction companies and their applications

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2011年第S1期54卷 118-124页

作者： LIN ZhengHang 1,2,QIANG MaoShan 1,2,TANG WenZhe 1,2,FAN QiXiang 3.&LIU Qiang 4.1 Institute of Project Management and Construction Technology,Tsinghua university,beijing 100084.china 2 State Key Laboratory of Hydraulic and Engineering,Tsinghua university,beijing 100084.china 3.china Three Gorges Corporation,Yichang 4.3.02,china 4.{13. of Software,Tsinghua university,beijing 100084.china 1. Institute of Project Management and Construction Technology Tsinghua University Beijing 100084 China2. State Key Laboratory of Hydraulic and Engineering Tsinghua University Beijing 100084 China3. China Three Gorges Corporation Yichang 443002 China4. School of Software Tsinghua University Beijing 100084 China

china is undertaking an increasing number of mega-infrastructure projects along with its rapid economic *** participants in these projects,understand how to adapt the proper and efficient management strategies is *** this paper,we propose three distinct models for companies under various background and management requirements,based on sophisticated data analysis and model ***,we successfully committed these models with hydropower development projects and achieved a great progress in enhancing management efficiency.

关键词： project management models mega-construction companies applications hydropower development companies

Perceptual video hashing robust against geometric distortions

在线全文

学校读者我要写书评

暂无评论

Science china(information Sciences) 2012年第7期55卷 1520-1527页

作者： XIANG ShiJun 1,4.,YANG JianQuan 2 & HUANG JiWu 3.1 school of information Science and Technology,Jinan {3.,Guangzhou 51063.,china 2 Shenzhen Institutes of Advanced Technology,Chinese Academy of Sciences,Shenzhen 518055,china 3.school of information Science and Technology,Sun Yat-sen {3.,Guangzhou 510275,china 4.State Key Laboratory of information Security,Institute of Software,Chinese Academy of Sciences,beijing 10004.,china 1. school of information Science and Technology Jinan University Guangzhou 510632 China4. State Key Laboratory of Information Security Institute of Software Chinese Academy of Sciences Beijing 100049 China2. Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences Shenzhen 518055 China3. School of Information Science and Technology Sun Yat-sen University Guangzhou 510275 China

In this paper,we propose a robust perceptual hashing algorithm by using video luminance histogram in *** underlying robustness principles are based on three main aspects:1) Since the histogram is independent of position of a pixel,the algorithm is resistant to geometric deformations; 2) the hash is extracted from the spatial Gaussian-filtering low-frequency component for those common video processing operations such as noise corruption,low-pass filtering,lossy compression,etc.; 3. a temporal Gaussian-filtering operation is designed so that the hash is resistant to temporal desynchronization operations,such as frame rate change and *** a result,the hash function is robust to common geometric distortions and video processing *** results show that the proposed hashing strategy can provide satisfactory robustness and uniqueness.

关键词： video hashing geometric distortion histogram Gaussian filtering

An analysis of seismic attenuation in random porous media

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2010年第4期53卷 628-637页

作者： LIU Jiong1, BA Jing2, MA JianWei1 & YANG HuiZhu1 1 Institute of Seismic exploration, school of Aerospace, Tsinghua university, {3. 100084. {4. 2 Research Institute of Petroleum exploration & Development, Petro{4., beijing 100083. china 1. Institute of Seismic exploration School of Aerospace Tsinghua University Beijing 100084 China2. Research Institute of Petroleum Exploration & Development PetroChina Beijing 100083 China

The attenuation of seismic wave in rocks has been one of the interesting research topics, but till now no poroelasticity models can thoroughly explain the strong attenuation of wave in rocks. In this paper, a random porous medium model is designed to study the law of wave propagation in complex rocks based on the theory of Biot poroelasticity and the general theory of stochastic process. This model sets the density of grain, porosity, permeability and modulus of frame as random parameters in space, and only one fluid infiltrates in rocks for the sake of better simulation effect in line with real rocks in earth strata. Numerical simulations are implemented. Two different inverse quality factors of fast P-wave are obtained by different methods to assess attenuation through records of virtual detectors in wave field (One is amplitude decay method in time domain and the other is spectral ratio method in frequency domain). Comparing the attenuation results of random porous medium with those of homogeneous porous medium, we conclude that the attenuation of seismic wave of homogeneous porous medium is far weaker than that of random porous medium. In random porous media, the higher heterogeneous level is, the stronger the attenuation becomes, and when heterogeneity σ = 0.15 in simulation, the attenuation result is consistent with that by actual observation. Since the central frequency (50 Hz) of source in numerical simulation is in earthquake band, the numerical results prove that heterogeneous porous structure is one of the important factors causing strong attenuation in real stratum at intermediate and low frequency.

关键词： the theory of stochastic process the theory of Biot poroelasticity the attenuation of seismic wave inverse quality factor

Conformal isoparametric hypersurfaces with two distinct conformal principal curvatures in conformal space

在线全文

学校读者我要写书评

暂无评论

Science china Mathematics 2010年第4期53卷 953-965页

作者： NIE ChangXiong 1,2,LI TongZhu 3.HE YiJun 4.& WU ChuanXi 5 1 Faculty of Mathematics and Computer Sciences,Hubei university,Wuhan 4.0062,{3. 2 school of Mathematical Sciences,Peking university,{4. 100871,{3. 3.Faculty of Sciences,{4. Institute of Technology,{4. 100081,{3. 4.school of Mathematical Sciences,Shanxi university,Taiyuan 03.006,{3. 5 Institute of Mathematics,Hubei university,Wuhan 4.0062,{3. 1. Faculty of Mathematics and Computer Sciences Hubei University Wuhan 430062 China2. School of Mathematical Sciences Peking University Beijing 100871 China3. Faculty of Sciences Beijing Institute of Technology Beijing 100081 China4. School of Mathematical Sciences Shanxi University Taiyuan 030006 China5. Institute of Mathematics Hubei University Wuhan 430062 China

The conformal geometry of regular hypersurfaces in the conformal space is *** classify all the conformal isoparametric hypersurfaces with two distinct conformal principal curvatures in the conformal space up to confor... 详细信息

关键词： Lorentz conformal geometry conformal invariants conformal isoparametric hypersurfaces