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991.
International Journal of Information Security - 5G-based mobile ad hoc networks with cloud are a new paradigm that combines several real-world applications. Routing and security are current issues...  相似文献   
992.
Multimedia Tools and Applications - The active modality of handwriting is broadly related to signature verification in the context of biometric user authentication systems. Signature verification...  相似文献   
993.
This paper is devoted to the problem of global stabili sation for a class of switched high-order stochastic nonlinear systems under arbitrary switchings. By extending the adding -a -power -integrator technique and choosing an appropriate common Lyapunov function, a common state-feedback controller is explicitly constructed to render the closed-loop system globally asymptotically stable in probability. The effectiveness of the proposed approach is demonstrated by a simulation example.  相似文献   
994.
提出了石油精炼过程中产生的加氢脱硫镍-钼-铝系废催化剂的湿法全回收新工艺路线和工艺条件。研究了分离废催化剂中的钒、钼、镍、铝等有价金属的原理及技术特点。实验结果:n(碳酸钠)/(钼+钒):1.5,加入适量的添加剂,粉碎至≤180μm,700℃焙烧2h,用热水浸取,Mo和V的浸出率可达90%以上。  相似文献   
995.
The volatile components of Origanum dayi Post were analyzed in 10 wild populations grown in a limited area. ANOVA tests showed no significant differences among the compositions of plants that grew in different locations, which suggests that differences in composition are of genetic origin and do not spring from environmental variation. However, the use of new statistical methods (such as use of the correlation coefficient, r, as a parametric value) revealed that, despite their reduced range of variation, most of the 22 soil properties (SPs) measured correlated with the composition of the volatile components. This analysis also indicated that the main volatile components were modified in parallel in response to SP variations. It is concluded that variations in soil properties affected the composition of volatile components in O. dayi, and that the main influencing factors were soil microelement contents and texture. This study highlights the need for highly sensitive statistical tools to determine the actual influence of environmental factors in natural environments, especially when their range of variation is small.  相似文献   
996.
T-ZnO晶须增强环氧树脂复合材料的抗静电性   总被引:8,自引:0,他引:8  
陈尔凡  周本廉 《塑料工业》2003,31(10):40-42
研究了T—ZnO晶须增强环氧树脂复合材料的抗静电性。结果表明:具有半导体性的T—ZnO晶须在复合材料中,相互搭接形成导电通路,以价带传导方式传导电荷,而起抗静电作用,使环氧树脂材料的体积电阻率降低了8个数量级,用比表面因子修正了网络形成临界体积分数模型。T—ZnO晶须的网络形成临界体积分数(0.057)是球形粒子的网络形成临界体积分数(0.38)的1/10。  相似文献   
997.
At very low Reynolds numbers, we calculate the drag force exerted on a circular cylinder in cross flow fixed midway between two parallel plane walls which are fixed while the fluid experiences a Poiseuille profile at upstream and downstream. The drag wall correction factor is numerically investigated from a very weak interaction to the lubrication regime. The Navier-Stokes and continuity equations are expressed in the stream function and vorticity formulation and are rewritten in an orthogonal system of curvilinear co-ordinates. These equations are solved with using a finite differences method. The generation of the grid was carried out by the singularities method. We calculated the separate contributions of the pressure and viscous forces numerically. At very weak interactions, our numerical results are in good agreement with those obtained analytically by Harrison (Trans. Camb. Phil. Soc. 23 (1924) 71) and Faxèn (Proc. Roy. Swed. Acad. Eng. Sci. 187 (1946) 1). In the lubrication regime these numerical calculations are in very good agreement with those we carried out by asymptotic expansion. So that, the accuracy of the numerical code is tested. This analysis allowed us to show how that the pressure term prevails over the viscosity term in the lubrication regime. At very weak interaction, these forces have the same value.  相似文献   
998.
Bright and red‐emissive organic nanoparticles (NPs) are demonstrated as promising for in vivo fluorescence imaging. However, most red organic dyes show greatly weakened or quenched emission in the aggregated state. In this work, a robust red fluorophore (t‐BPITBT‐TPE) with strong aggregate‐state photoluminescence and good biocompatibility is presented. The NPs comprised of t‐BPITBT‐TPE aggregates encapsulated within 1,2‐distearoyl‐sn‐glycero‐3‐phosphoethanolamine‐N‐[methoxy(polyethylene glycol) (DSPE‐mPEG) micelles exhibit a photoluminescence peak at 660 nm with a high fluorescence quantum yield of 32% in aqueous media. The NPs can be facilely charged by using the same polymeric matrix with different terminal groups, e.g., methoxy (DSPE‐mPEG), amine (DSPE‐PEG‐NH2), or carboxymethyl (DSPE‐PEG‐COOH) groups. The biocompatibility, toxicity, circulation, and biodistribution of the NPs are assessed using the zebrafish model through whole embryo soaking and intravenous delivery. Furthermore, HeLa and MCF‐7 cells tagged with t‐BPITBT‐TPE in DSPE‐PEG‐NH2‐TAT polymer NPs are xenografted into zebrafish larvae to successfully track the cancer cell proliferation and metastasis, demonstrating that these new NPs are efficient cancer cell trackers. In addition, the NPs also show good in vivo imaging ability toward 4T1 tumors in xenografted BALB/c mice.  相似文献   
999.
Chlorination of organophosphorus pesticides in natural waters   总被引:3,自引:0,他引:3  
Unknown second-order rate constants for the reactions of three organophosphorus pesticides (chlorpyrifos, chlorfenvinfos and diazinon) with chlorine were determined in the present study, and the influence of pH and temperature was established. It was found that an increase in the pH provides a negative effect on the pesticides degradation rates. Apparent second-order rate constants at 20 degrees C and pH 7 were determined to be 110.9, 0.004 and 191.6 M(-1) s(-1) for chlorpyrifos, chlorfenvinfos and diazinon, respectively. A higher reactivity of chlorine with the phosphorothioate group (chlorpyrifos and diazinon) than with the phosphate moiety (chlorfenvinfos) could explain these results. Intrinsic rate constant for the elementary reactions of chlorine species with chlorpyrifos and diazinon were also calculated, leading to the conclusion that the reaction between hypochlorous acid and the pesticide is predominant at neutral pH. The elimination of these pesticides in surface waters was also investigated. A chlorine dose of 2.5 mg L(-1) was enough to oxidize chlorpyrifos and diazinon almost completely, with a formation of trihalomethanes below the EU standard for drinking water. However, the removal of chlorfenvinfos was not appreciable. Therefore, chlorination is a feasible option for the removal of organophosphorus pesticides with phosphorothioate group during oxidation and disinfection processes, but not for the elimination of pesticides with phosphate moiety.  相似文献   
1000.
A mono-functional silane reagent, 3-mercaptopropyltrimethoxysilane (MPS) was used to modify the surface of silicon wafers. The structure of the SAMs formed with the MPS was investigated by contact angle measurements, ellipsometry, AFM, and X-ray photoelectron spectroscopy (XPS). The deposition of a metallic gold layer via ultra-high vacuum (UHV) evaporation reveals good adhesion properties on Au/MPS/SiO2/Si structure. The “chemisorption” between the SAM and the gold evaporated layer is confirmed by adhesion tests and optimum curing treatment is found 1 h at 100 °C). This very simple methodology, avoiding the usage of Cr and other metals as undercoating layers and could be proposed further for (bio)sensors applications.  相似文献   
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