检索结果-南通市图书馆

A measurement error model for microarray data analysis

在线全文

学校读者我要写书评

暂无评论

Progress in Natural science:materials International 2005年第7期15卷 614-620页

作者： ZHOU Yiming and CHENG Jing ( department of Biological sciences and Biotechnology, tsinghua university, beijing 100084, china State key laboratory of Biomembrane and Membrane Biotechnology, tsinghua university, beijing 100084, china National engineering Research Center for beijing Biochip Technology, 18 Life science Parkway, beijing 102206, china) department of Biological sciences and Biotechnology Tsinghua University Beijing 100084 China State key laboratory of Biomembrane and Membrane Biotechnology Tsinghua University Beijing 100084 China National engineering Research Center for beijing Biochip Technology 18 Life Science Parkway Beijing 102206 China

Microarray technology has been widely used to analyze the gene expression levels by detecting fluorescence intensity in a high throughput fashion. However, since the measurement error produced from various sources in microarray experiments is heterogeneous and too large to be ignored, we propose here a measurement error model for microarray data processing, by which the standard deviation of the measurement error is demonstrated to be linearly increased with fluorescence intensity. A robust algorithm, which estimates the parameters of the measurement error model from a single microarray without replicated spots, is provided. The model and algorithm for estimating of the parameters from a given data set are tested on both the real data set and the simulated data set, and the result has been proven satisfactory. And, combining the measurement error model with traditional Z-test method, a full statistical model has been developed It can significantly improve the statistical inference for identifying differentially expressed genes.

关键词： microarray measurement error model parameter estimation differentially expressed genes.

Thermodynamic properties and phase stability of nanocrystalline metals

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2006年第5期25卷 582-586页

作者： SONG Xiaoyan LI Lingmei ZHANG Jiuxing College of materials science and engineering Key Lab of Advanced Functional Materials Miniswy of Education Beijing University of TechnologyBeijing 100022 China

The fundamental thermodynamic functions of enthalpy, entropy, and Gibbs free energy, as functions of the excess free volume at interfaces, temperature, and grain size, have been derived for single-phase metal nanocrystals. The model was applied to predict the thermal features of nano-grain boundaries and the characteristics of phase transformation in nanocrystalline metals, such as the transformation temperature and the critical grain size for phase transformation at a given temperature. The model predictions have been verified by experimental studies on the β-Co ←→α-Co phase transformation in nanocrystalline Co prepared by ball milling.

关键词： thermodynamics phase transformation metal nanocrystals nano-scale effect

Effects of Nucleating Additives on Crystallization and Properties of CaO-B_2O_3-SiO_2 Glass-ceramics

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan university of Technology(materials science) 2009年第6期24卷 997-1000页

作者：王中俭 key laboratory for Ultrafine materials of ministry of education Shanghai Key Laboratory of Advanced Polymeric MaterialsSchool of Materials Science and EngineeringEast China University of Science and Technology

ZrO2, TiO2 and P2O5 were doped in CaO-B2O3-SiO2 glass-ceramics as nucleating additives. Effects of different nucleating additives on the phase separation and crystalline behaviors were investigated by using gradient temperature furnace, DTA and XRD. Then, sintering process of the glass-ceramics was investigated by testing sintering shrinkage, dielectric constant and loss. The experimental results shows that the glass-ceramics doped with nucleating additives represents higher crystallization, with ZrO2 as an exceptional effective dopant to promote the precipitation of wollastonite crystal. Finally, ZrO2 containing glass-ceramics was chosen to study the influence of sintering temperature and soaking time with the help of X-ray diffraction analysis and density measurement. The glass-ceramics can be well consolidated at 850 ℃ for 10 min, with low dielectric constant （5.87） and loss （3.21×10^-4）, which is desirable for LTCC application.

关键词： CaO-B2O3-SiO2 glass-ceramics nucleating additives crystallization sinterability

Review of metal matrix composites with high thermal conductivity for thermal management applications

在线全文

学校读者我要写书评

暂无评论

Progress in Natural science:materials International 2011年第3期21卷 189-197页

作者： Xuan-hui QU,Lin ZHANG,Mao WU,Shu-bin REN State key laboratory for advanced Metals and materials, beijing key laboratory for Powder Metallurgy and Particulate materials, university of science and Technology beijing,beijing 100083,china State key laboratory for advanced Metals and materials Beijing Key Laboratory for Powder Metallurgy and Particulate Materials University of Science and Technology Beijing Beijing 100083 China

Metal matrix composites with high thermal conductivity and tailorable coefficient of thermal expansion are found widespread applications in electronic package and thermal *** latest advances in manufacturing process,thermal properties and brazing technology of SiC/metal,carbon/metal and diamond/metal composites were *** factors controlling the thermo-physical properties were discussed in *** problems involved in the fabrication and the brazing of these composites were elucidated and the main focus was put on the discussion of the methods to overcome these *** review shows that the combination of pressureless infiltration and powder injection molding offers the benefits to produce near-net shape composites. Improving wettability and optimizing interfacial structure are prerequisites for successful fabrication and further enhancement of thermal properties.A new Ag-Cu-Sn brazing alloy with low melting point is found to be effective to braze Al-matrix composites.

关键词： metal matrix composites electronic packaging thermal conductivity coefficient of thermal expansion brazing

LATTICE BGK MODEL SIMULATION OF ASYMMETRIC FLOW INSIDE A CONTINUOUS SLAB CASTING MOLD

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 Hydrodynamics 2006年第4期18卷 431-435页

作者： ZHANG Xiao-jun SHEN Hou-fa key laboratory for advanced Manufacturing by materials Processing Technology Department of Mechanical Engineering Tsinghua University Beijing 100084 China

The incompressible lattice Bhatnager-Gross-Krook （BGK） model of computational fluid dynamics, from which the unsteady incompressible Navier-Stokes equations can be exactly derived with the limit of small Mach number, was established in continuous casting mold. An asymmetric flow pattern in the two-dimensional central plane of continuous slab casting mold was simulated, and the flow pattern is not stationary but changes over frequently if the Reynolds number is larger than 3000 or so. The results are found to be in excellent agreement with previous experimental results.

关键词： lattice Bhatnager-Gross-Krook (BGK) method incompressible Navier-Stokes equation continuous slab casting mold

Giant Magnetostrictions of Tb-Dy-Fe Polycrystals with < 110 > Axial Alignment

在线全文

学校读者我要写书评

暂无评论

Journal of materials science & Technology 2000年第2期16卷 175-176页

作者： Shouzeng ZHOU, Xuexu GAO, Maocai ZHANG, Qing ZHAO and Zhenhlla SHI (State key laboratory for advanced Metals and materials, university of science and Technology beijing, beijing 100083, china) State key laboratory for advanced Metals and materials University of Science and Technology Beijing Beijing 100083 China

Preparing method and processing of Tb-Dy-Fe alloy samples with [110] axial orientation as well as their magnetostrictive properties have been studied. It has been found that the magnetostrictive strains of polycrystal samples with [110] axial orientation can reach (1550-1900) ×10~-6 in a low magnetic field less than 80 kA/m, which are equal to or somewhat better than that of the polycrystal samples with [112] axial orientation.

关键词： 110 Giant Magnetostrictions of Tb-Dy-Fe Polycrystals with Axial Alignment Fe Dy

A Binder of Phosphogypsum-Ground Granulated Blast Furnace Slag-Ordinary Portland Cement

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan university of Technology(materials science) 2011年第3期26卷 548-551页

作者：黄赟 key laboratory of Silicate materials science and engineering Ministry of EducationWuhan University of Technology

A new hydraulic cementitious binder was developed by mainly utilizing industrial byproducts phosphogypsum（PG）and ground granulated blast furnace slag（GGBFS）with small addition of ordinary portland cement（OPC）.The hydration process and microstructure were studied by X-ray diffraction（XRD） and scanning electronic microscopy（SEM）.OPC hydrated first at early age to form primarily C-S-H gel,ettringite and calcium hydroxide（CH）.GGBFS activated by CH and sulfate ions hydrated continuously at later age,producing more and more hydration products,C-S-H gel and *** the paste developed a denser microstructure and its strength *** 28 d compressive strength of the mixture of 50%PG,46% GGBFS and 4%OPC exceeded 45 *** setting time was faster and 3 d and 7 d strength were higher when the proportion of OPC *** the 28 d strength decreased when OPC exceeded 4%due to large amount of ettringite formed at late hydration age which damaged the microstructure.

关键词： phosphogypsum ground granulated blast furnace slag hydraulic cementitious binder

State of the art:Mechanical behavior of soil-structure interface

在线全文

学校读者我要写书评

暂无评论

Progress in Natural science:materials International 2009年第10期19卷 1187-1196页

作者： Ga Zhang,Jianmin Zhang State key laboratory of Hydroscience and engineering,tsinghua university,beijing 100084,china State key laboratory of Hydroscience and engineering Tsinghua University Beijing 100084 China

The monotonic and cyclic behavior of a soil-structure interface has a significant effect on the mechanical response of a soil-structure interaction ***,the behavior of the interface should be investigated with focusing on the individual characters different from other geomaterials.A brief introduction and critical review are presented on the state of the art of monotonic and cyclic behavior of soil- structure interface,including the test device and measurement techniques,fundamental rules and deformation mechanism,constitutive models and their applications in the numerical *** tendencies of the investigation on the interface are also predicted in this paper.

关键词： Interface Soil Mechanical behavior Test Constitutive model Numerical analysis

Strength of Limestone-based Non-calcined Cement and its Properties

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 Wuhan university of Technology(materials science) 2009年第3期24卷 471-475页

作者：林宗寿 key laboratory of Silicate materials science and engineering (ministry of education) Wuhan University of Technology

A new type of cement was prepared with ground limestone powder, blastfumace slag, steel slag and gypsum without calcination. The fraction of ground limestone powder in the cement was as high as 40 wt%-60 wt% without Portland clinker. All of its physical properties can meet the requirements of masonry cement standards. The impact of limestone content on physical properties of the cement and determined its impact on law was investigated. The steel slag can excit the aquation activity of this cement effectively, and the influence of its quantity on the strength of the materials was studied, which shows that the optimum quantity of mixing is 10%. By way of changing the different content of the lime stone by quartzy sample, the law of the compression strength and the PH value was determined, confirming that the lime stone can promote the early aquation of the slag and improve the early strength. The main hydration product of this cement is calcium aluminate hydrate, ettringite and calcium silicate hydrate, as indicated by XRD and SEM analysis.

关键词： ground limestone powder non-calcined clinker-free cement steel slag