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N-heterocyclic Carbenes Catalyzed Phospho-Aldol Reaction of Aldehydes

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Chinese Journal of Chemistry 2013年第12期31卷 1573-1576页

作者： Lin he zhihua Cai Xiaowei Ma Guangfen Du Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan and School of Chemistry and Chemical Engineering Shihezi University Xinjiang 832000 China

An efficient phospho-aldol reaction of aldehydes catalyzed by N-heterocyclic carbenes （NHCs） has been developed. With 10 mol% stable NHC 1,3-bis（2,6-diisopropylphenyl）imidazol-2-ylidene, various aldehydes reacted with dialkylphosphites smoothly to provide a-hydroxy phosphonates in 59%--99% yield. In this process, NHC was assumed to function as a carbon-centered bronsted base.

关键词： N-heterocyclic carbenes phosphite aldehyde phospho-aldol reaction a-hydroxy phosphonate

Increased glacier melt enhances future extreme floods in the southern Tibetan Plateau

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Advances in Climate Change Research 2024年第3期15卷 431-441页

作者： he SUN Tan-Dong YAO Feng-Ge SU Tinghai Ou zhihua he Guoqiang TANG Deliang CheN State Key Laboratory of Tibetan Plateau Earth System Environment and Resources(TPESER)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China Regional Climate Group Department of Earth SciencesUniversity of GothenburgGothenburg 40530Sweden Centre for Hydrology University of SaskatchewanSaskatoon S7N 1K2Canada Climate and Global Dynamics National Center for Atmospheric ResearchBoulder CO 80307USA

Mountainous areas are of special hydrological concern because topography and atmospheric conditions can result in large and sudden floods,posing serious risks to water-related safety in neighbouring *** Yarlung Zangbo(YZ)River basin is the largest river basin on the Tibetan Plateau(TP),but how floods will discharge in this basin and how the role of glacier melt in floods will change throughout the 21st-century under shared socioeconomic pathways scenarios(SSP2-4.5 and SSP5-8.5)remain ***,we comprehensively address this scientific question based on a well-validated large-scale glacier-hydrology *** results indicate that extreme floods was projected to increase in the YZ basin,and was mainly reflected in increased duration(4–10 d per decade)and intensity(153–985 m^(3)s^(−1)per decade).Glacier runoff was projected to increase(2–30 mm per decade)throughout the 21st-century,but there was also a noticeable decrease or deceleration in glacier runoff growth in the late first half of the century under the SSP2-4.5,and in the latter half of the century under the *** melt was projected to enhance the duration(12%–23%)and intensity(15%–21%)of extreme floods under both SSPs,which would aggravate the impact of future floods on the socioeconomics of the YZ *** effect was gradually overwhelmed by precipitation-induced floods from glacier areas to YZ *** study takes the YZ basin as a projection framework example to help enrich the understanding of future flood hazards in basins affected by rainfall-or meltwater across the TP,and to help policy-makers and water managers develop future plans.

关键词： floods glacier Tibetan

Topological analysis of methane lean premixed flame in turbulent jet flow by direct numerical simulation

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Chinese Science Bulletin 2010年第13期55卷 1231-1239页

作者： LV Yu WANG zhihua PEI he ZHOU JunHu CEN KeFa State Key Laboratory of Clean Energy Utilization Institute for Thermal Power Engineering of Zhejiang University Hangzhou 310027 China

Direct numerical simulation is employed to investigate the premixed jet flame of methane in lean, combined with a detailed chemical kinetics including 17 species and 58 elemental steps and distinct Lewis numbers. Cold methane-air mixture at 0.55 equivalence ratio is injected into the coflow area with 9500 Reynolds number. The coflow ambient gas is set to be the burnt gas of the methane-air mixture in main jet and temperature is assigned to be the corresponding adiabatic flame temperature 1515 K. The whole simulation process is run based on paralleled calculation method, and chemical sources are acquired by dynamically calling CheMKIN library function. The flame structure at 6.98 ms is shown to demonstrate the obvious dependence of flame structure and reaction rate on vortices motion. Then by tracing the interaction between different flame elements and vortices, the mechanism behind this dependence is found. The concepts including surface density function, mean curvature and stretch rate are used to describe the geometrical structure of vortex-affected flame. Those are all calculated according to simulation result and statistically associated with heat release rate that indicates reaction intensity. The statistical results show that surface density function and reaction rate own direct positive correlation; largely wrinkled flames with greater curvatures magnitude tend to become thick and weaken surface density function and reaction rate, appearing local extinction phenomena; large tangential stretch rates exerted on flame usually produce a local thinning effect in normal making reaction rate intensified. The DNS presented will supply beneficial references to better understanding of flame-vortex interaction and development of more accurate general model for turbulent premixed combustion.

关键词：直接数值模拟湍流射流拓扑分析预混火焰甲烷

Fabrication of ZnO films by radio frequency magnetron sputtering and annealing

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Rare Metals 2005年第3期24卷 267-271页

作者： GAO Haiyong ZHUANG Huizhao XUE Chengshan WANG Shuyun DONG zhihua he Jianting Institute of Semiconductor Shandong Normal University Jinan 250014 China

ZnO thin films were deposited on Si（111） substrates through a radio frequency （rf） magnetron sputtering system. Then the samples were annealed at different temperatures in air ambience and ammonia ambience respectively. The structure and composition of the ZnO films were studied by X-ray diffraction （XRD） and X-ray photoelectron spectroscopy （XPS）. The morphology of the samples was studied by scanning electron microscopy （SEM）. Measured results show that ZnO films with hexagonal wurtzite structure were grown on Si（111） substrates when annealed in the two ambiences. The volatilization process of ZnO in the ammonia ambience at high temperature was discussed and the mechanism of the reaction was analyzed.

关键词： ZnO films radio frequency magnetron sputtering annealing ammonia ambience buffer layers

Hot Corrosion Behavior of a High Velocity Arc-Sprayed Fe-Cr-B-C Coating

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稀有金属材料与工程 2012年第S1期41卷 456-459页

作者： Guo Wenmin Wu Yuping Li Gaiye Wang Qian he zhihua Hong Sheng Hohai Univ Coll Mech & Mat Nanjing 210098 Jiangsu Peoples R China

A Fe-Cr-B-C coating was prepared by electric arc spraying process to prevent the boiler tubes from hot corrosion at elevated temperatures.A hot corrosion resistance test was conducted in a mixed molten salt of Na2SO4 and K2SO4(7:3)at 700 ℃for a total period of 156 *** microstructure and phases of the coatings before and after exposed to the hot corrosion were investigated by scanning election microscopy(SEM),optical microscopy(OM)and X-ray diffraction(XRD).The hardness and porosity were *** hot corrosion behavior of the coatings was examined by the measurement of corrosion mass gain and the observation of corrosion *** results show that some splats of particles are formed on flat substrate surfaces and the coatings have a dense typical layer structure of electric arc thermally spraying *** amorphous phase exist in the *** coatings have an excellent resistance to hot *** formation of oxides of chromium on the exposed surface may be contributing better resistance to hot *** corrosion of the coatings follows the oxidation and sulfidation mechanism.

关键词： arc spraying coating hot corrosion

Silt Erosion Characteristics of a Cr_3C_2-NiCr Coating Fabricated by High Velocity Oxy-Fuel (HVOF) Thermal Spray

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稀有金属材料与工程 2012年第S1期41卷 453-455页

作者： Wang Qian,Wu Yuping,Li Gaiye,Guo Wenmin,he zhihua,Hong Sheng Hohai University,Nanjing 210098,China Hohai Univ Coll Mech & Mat Nanjing 210098 Jiangsu Peoples R China

A Cr3C2-NiCr coating was prepared by high velocity oxy-fuel(HVOF)thermal spray on 1Cr18Ni9Ti stainless *** and microstructures of the coating were investigated by X-ray diffraction(XRD),optical microscopy(OM)and scanning election microscopy(SEM),*** cavitation erosion resistance and silt erosion resistance of the coating were evaluated using a GB/T6383-2009 standard method in two experimental conditions(fresh water and water contained fine silt),compared with the coatings hydro machine material 1Cr18Ni9Ti stainless *** coating shows a layered structure and has a significantly higher microhardness(11.97 GPa)than that of the 1Cr18Ni9Ti stainless steel(2.1 GPa),which results in less mass losses both in cavitation erosion and silt erosion *** HVOF coating has a predominant performance in the cavitation erosion and silt erosion *** higher microhardness of the coating is the main cause which results in a less mass losses in the erosion *** the mass loss usually happens at the edges of the pores.

关键词： Cr3C2-NiCr coating cavitation erosion silt erosion

Synthesis of GaN nanorods on Si substrates with assistance of the vola-tilization of ZnO middle layers

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Rare Metals 2005年第2期24卷 110-114页

作者： ZHUANGHuizhao GAOHaiyong XUEChengshan WANGShuyun DONGzhihua heJianting CollegeofPhysicsandElectronics ShandongNormalUniversityJinan250014China

GaN nanorods have successfully been synthesized on Si(111) substrates via ammoniating ZnO/Ga2O3 films at 950 degrees C. Ga2O3 thin films and ZnO middle layers were deposited in turn on Si(111) substrates by r.f. magnetron sputtering system. ZnO volatilized at 950 degrees C in the ammonia ambience and Ga2O3 reacted to NH3 to fabricate GaN nanorods in the later ammoniating process. The volatilization of ZnO layers played an important role in the fabrication. The structure and composition of the GaN nanorods were studied by X-ray diffraction (XRD) and Fourier transform infrared spectrophotometer (FTIR). The morphology of GaN nanorods was investigated using scanning electron microscopy (SEM) and transmission electronic microscope (TEM). The analyses of measured results revealed that GaN nanorods with hexagonal wurtzite structure were prepared by this method.

关键词： semiconductor materials GaN nanorods r.f. magnetron sputtering ZnO/Ga2O3 films

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论简化平面镜(英文)

哈尔滨工业大学学报 1989年第6期21卷 109-113页

作者：何志华哈尔滨工业大学仪器系

0 IntroductionBy means of quaternion,we can easily describe the imaging regularities forplane mirrors systems in parallel ray *** convergent ray paths,however,thebiquaternion has to be used because the posistion of the image has to be *** one plane mirror's operator N in biquaternion can be written asWhere (?) is the unit normal vector of the plane mirror and l is the perpendicular dis-tance from the origin to the plane mirror,ωis Clifford *** and ω~2=*** this shows that the image can be obtained by rotating the inver-sion-object through 180°around (?) and then removing it a distance of 21 along (?).If some plane mirrors systems' operators can be written in the form of Eq.(1),then these systems may be simplified into one plane mirror,which is called simpli-fied plane mirror.

关键词：平面镜光学仪器

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商业企业如何做好在途商品安全输送

中国市场 2008年第10期 86-87页

作者：何志华唐山职业技术学院

如今随着电子商务的发展,企业的配送服务成为商家竞争的利器。无论是以自营为主的商品配送、以第三方物流配送为主、还是以用自营物流的配送网络为主而第三方物流配送为辅或反之,商业企业最终只有一个目的,就是保障配送商品的安全,以方... 详细信息

如今随着电子商务的发展,企业的配送服务成为商家竞争的利器。无论是以自营为主的商品配送、以第三方物流配送为主、还是以用自营物流的配送网络为主而第三方物流配送为辅或反之,商业企业最终只有一个目的,就是保障配送商品的安全,以方便服务的客户,增强企业的竞争力。

关键词：商品流通物流配送信息化配送