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991.
The structure modification and its mechanism have been studied when perlite products changed from water-affinity state to anti-water state. The structure of fused perlite and its surface physicochemical properties have also been studied. The modification of perlite products has provided the products with anti-water property, which not only enhanced the quality of thermal insulating function, reduced the lost of heat energy, but also made the products water-proof. These modified perlite products are used as ideal thermal insulating layers for the thermodynamic equipment and heat transporting conducts.  相似文献   
992.
把目标管理引入到学科建设管理中,提出学科建设目标管理的概念,对学科建设目标管理的目标设置、组织保障、应遵循的原则等作了探索性研究,以期提高学科建设的效率,缩短建设一流学科的时间  相似文献   
993.
国外精确制导技术的现状及发展   总被引:7,自引:2,他引:5  
李文 《红外技术》1999,21(1):10-12,17
对国外精确制导武器系统的现状和发展进行了介绍,并对发展我国制导武器技术提出建议;加强基础研究和预研,加强系统总体,多模传感器,信号实时处理等方面的研究。  相似文献   
994.
The corrosion behaviour of-SiC in V2O5 melt has been investigated at elevated temperatures. The corrosion products on the surface of the specimen are removed using HF. The morphologies are also examined. From the observations of bubble formation in the scale and the temperature dependence of the corrosion rate, a kinetic mechanism is proposed. Based on the consistency of the plotted data with the proposed equation and high values of surface reaction rate constant, a diffusion controlling process has been developed.  相似文献   
995.
氧化亚铜微米晶的水热合成与生长机理   总被引:1,自引:0,他引:1  
氧化亚铜是一种重要的P型半导体材料,目前因其独特的可见光催化性能在科研领域引起了广泛的重视。以CuSO4·5H2O为铜源,以α—D-葡萄糖为还原剂,并利用水热还原反应合成出了不同形貌的Cu2O微米晶。利用X射线粉末衍射分析(XRD)、透射电子显微镜(TEM)对合成的样品进行了形貌与结构的表征与分析。结果表明所合成的晶粒尺寸均匀且分散性好。讨论了不同条件下的晶粒生长机理,运用扩散机制与聚集机制解释了不同形貌的成因。  相似文献   
996.
The solubility of lithium in aluminum and the chemical diffusion coefficient in this solid solution have been investigated as a function of temperature between 400 and 600°C using the electrochemical cell: (-)A1, “LiAl”/LiCl-KCl(eut.)/Al(Li)(+) The solubility limit of lithium in aluminum was found to decrease from 13.8 at. pct at 595°C to 8.0 at. pct at 395°C, in good agreement with data previously reported by other investigators using different techniques. The chemical diffusion coefficient has been measured by two different electrochemical transient techniques. The data can be represented by the relation: 1 $$\tilde D = 0.155\exp (--\Delta H/RT)cm^2 /s$$ where ΔH is 119.2 kJ/mol. This electrochemical technique has also been used to obtain values of the composition dependence of the Gibbs free energy of mixing and the enhancement factor d lnaLi/dlnXLi which relates the chemical diffusion coefficient and the self diffusion coefficients within the Li-Al solid solution.  相似文献   
997.
The electrochemical properties of alpha-MoO3 nanorods, which were synthesized via a solution-based method and following calcination, have been reported as a cathode material for rechargeable lithium batteries. Detailed lithium-insertion process of the material has been conducted by means of cyclic voltammetry, galvanostatic method, and impedance technique, and superior features associated with the nanostructures have been observed. The alpha-MoO3 nanorods exhibited an initial discharge capacity of 271.8 mAh/g under a current density of 0.1 mA/cm2 in the range 1.0 approximately 3.0 V, which nearly approached the theoretical capacity 280 mAh/g. Comparison of the structural and electrochemical characteristics with those of bulk alpha-MoO3 suggests the enhanced electrochemical performance might be related to the rodlike structure and increased edge and corner effects.  相似文献   
998.
Gene expression profiles that are anchored to phenotypic endpoints may lead to the identification of signatures that predict mutagenicity or carcinogenicity. The study presented here describes the analysis of DNA adducts in the human TK6 lymphoblastoid cell line after exposure to N-hydroxy-4-aminobiphenyl, a mutagenic metabolite of 4-aminobiphenyl. A validated nano-LC microelectrospray mass spectrometry assay is reported for the detection and quantification of N-(deoxyguanosin-8-yl)-4-aminobiphenyl (dG-C8-ABP), the principal DNA adduct of 4-aminobiphenyl. Limits of quantification, based on a signal-to-noise ratio of 10:1, are determined to correspond to approximately 27 fg of dG-C8-ABP injected on-column. The assay has been used to measure the steady-state levels of the adduct in the human TK6 lymphoblastoid cell line as a function of dose (0.5, 1.0, and 10.0 microM) and time (2, 6, and 27 h) after exposure to N-hydroxy-4-aminobiphenyl. The levels of dG-C8-ABP adducts in the cells, ranging from 18 to 500 adducts in 10(9) nucleotides, were then correlated to cell toxicity, induced mutation at the TK (thymidine kinase) and HPRT loci, and gene expression profiling through microarray analysis. Cell cultures were evaluated for toxicity by growth curve extrapolation, mutation assays were performed on the HPRT and TK loci, and gene expression profiles were generated by analyses using microarray technology. In the mutation assay analysis, as the toxicant concentration increased, there was an increase in mutation fraction, indicating a direct correlation to metabolite dosing level and mutations occurring at these two loci. Statistical analysis of the gene expression data determined that a total of 2250 genes exhibited statistically significant changes in expression after treatment with N-OH-AABP (P < 0.05). Among the genes identified, 2245 were up-regulated, whereas 5 genes that had functions in cell survival and cell growth and, hence, could be indicators of toxicity, were down-regulated relative to controls. The results demonstrate the value of anchoring gene expression patterns to phenotypic markers, such as DNA adduct levels, toxicity, and mutagenicity.  相似文献   
999.
Sensor delay and observation uncertainty often occur in modern computer-based systems, e.g., when the measurement is transmitted to a remote controller through a network medium. In this paper, we revisit the Kalman filter design problem for a stochastic dynamic system with random one-step sensor delay, and derive the optimal unbiased state estimation algorithm. Both full- and reduced-order filters are studied, and the results compare favorably with those of the existing algorithms in examples via simulation.  相似文献   
1000.
Al2O3 and Y2O3 have been respectively chosen for additional dopants to investigate the influence on the ferromagnetism of Co doped CeO2 bulk. Results indicate that ferromagnetism (FM) of Co doped CeO2 decrease with additional Al3+. Accordingly, certain amount of Y3+ can readily be incorporated into the lattice of CeO2 with the decrease of its grain size as well as some pores formation, leading to an enhancement of FM with a positive correlation between magnetization and Y3+ doping content. This experimental result is helpful both in understanding FM origination in diluted magnetic oxide (DMO) as well as to improve the moments of DMO applicable in spintronic devices.  相似文献   
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