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等分化时代商票业务风险管理探究 被引量:1
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作者 王绪刚 《西部金融》 2023年第9期89-97,共9页
票据经历了纸票时代、电票时代,现在已经来到等分化时代,并具有可拆分、公开化、电子化、标准化等特征,叠加三年疫情、票据新规发布、商票信息披露等新政发布,各类商票业务风险同时显现,风险管理难度空前加大。文章首先概述商票市场产... 票据经历了纸票时代、电票时代,现在已经来到等分化时代,并具有可拆分、公开化、电子化、标准化等特征,叠加三年疫情、票据新规发布、商票信息披露等新政发布,各类商票业务风险同时显现,风险管理难度空前加大。文章首先概述商票市场产品模式和运营情况,然后通过案例探究背后风险成因,最后从监管机构、出票与背书企业、融资金融机构角度,提出应对操作风险、法律合规风险、市场风险和信用风险的具体举措,以期对商票市场风险管理提供借鉴意义。 展开更多
关键词 等分化 商业承兑汇票 风险管理
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供应链票据发展现状、问题及对策 被引量:3
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作者 付英俊 《吉林金融研究》 2023年第4期26-29,共4页
当前,供应链票据在促进产业链供应链稳定、支持中小企业融资等方面发挥着重要作用。供应链票据推出两年多时间里,发展速度不断加快,但在实践中也暴露出一些制约发展的问题。本文阐述了供应链票据业务发展现状,分析了供应链票据在发展中... 当前,供应链票据在促进产业链供应链稳定、支持中小企业融资等方面发挥着重要作用。供应链票据推出两年多时间里,发展速度不断加快,但在实践中也暴露出一些制约发展的问题。本文阐述了供应链票据业务发展现状,分析了供应链票据在发展中面临的困难与挑战,并提出了相应的对策建议,以期进一步推动供应链票据高质量发展。 展开更多
关键词 供应链票据 标准化票据 双循环 等分化
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Non-isothermal oxidation and ignition prediction of Ti-Cr alloys 被引量:6
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作者 弭光宝 黄秀松 +3 位作者 李培杰 曹京霞 黄旭 曹春晓 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2012年第10期2409-2415,共7页
The non-isothermal oxidation behavior and oxide scale microstructure of Ti-Cr alloy (0≤w(Cr)≤25%) were studied from room temperature to 1723 K by thermogravimetric analysis (TGA), X-ray diffraction (XRD) and... The non-isothermal oxidation behavior and oxide scale microstructure of Ti-Cr alloy (0≤w(Cr)≤25%) were studied from room temperature to 1723 K by thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The influencing mechanism of chromium on the oxidation resistance of Ti-Cr alloys was discussed. The results show that the oxidation resistance of the alloys decreases with Cr below a critical chromium content wC and increases above wC; above 1000 K, the oxidation kinetics obeys parabolic rule and titanium dominates the oxidation process; after oxidation, the oxygen-diffusing layer is present in the alloy matrix, the oxide scale is mainly composed of rutile whose internal layer is rich in chromium, and chromium oxides separated out from TiO2 near the alloy-oxide interface improve the oxidation resistance. Ignition of metals and alloys is a fast non-isothermal oxidation process and the oxidation mechanism of Ti-Cr alloys during ignition is predicted. 展开更多
关键词 Ti-Cr alloy non-isothermal oxidation thermogravimetric analysis (TGA) oxide scale microstructure IGNITION
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Effects of hierarchical structure on the performance of tin oxide-supported platinum catalyst for room-temperature formaldehyde oxidation 被引量:6
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作者 段媛媛 宋少青 +2 位作者 程蓓 余家国 姜传佳 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2017年第2期199-206,共8页
Flower-like tin oxide-supported platinum(Pt/SnOx) with a hierarchical structure was synthesized by a hydrothermal method and characterized by XRD,SEM,TEM,high resolution TEM,XPS and nitrogen adsorption.The flower-li... Flower-like tin oxide-supported platinum(Pt/SnOx) with a hierarchical structure was synthesized by a hydrothermal method and characterized by XRD,SEM,TEM,high resolution TEM,XPS and nitrogen adsorption.The flower-like Pt/SnOx microspheres of 1 μm in diameter were composed of staggered petal-like nanosheets with a thickness of 20 nm.Pt nanoparticles(NPs) of 2-3 nm were well dispersed on the SnOx nanosheets.The catalyst was tested in the catalytic oxidation of gaseous formaldehyde(HCHO) at room temperature,and exhibited enhanced activity compared to Pt NPs supported on commercial SnO and ground SnOx.HCHO removal of 87%was achieved over the hierarchical Pt/SnOx after 1 h of reaction,which was 1.5 times that over the ground SnOx-supported Pt(Pt/g-SnOx),and the high activity was maintained after six recycles,showing the high stability of this catalyst.HCHO decomposition kinetics was modeled as a second order reaction.The reaction rate constant for Pt/SnOx was 5.6 times higher than Pt/g-SnOx.The hierarchical pore structure was beneficial for the diffusion and adsorption of HCHO molecules,and the highly dispersed Pt NPs on the SnOx nanosheets were the active sites for the oxidative decomposition of HCHO into CO2 and H2O.This study provided a promising approach for designing efficient catalysts for indoor HCHO removal at ambient temperature. 展开更多
关键词 Formaldehyde catalytic oxidation Room temperature Tin oxide PLATINUM Hierarchical structure FLOWER-LIKE
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Hierarchical Ni-Al hydrotalcite supported Pt catalyst for efficient catalytic oxidation of formaldehyde at room temperature 被引量:13
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作者 Zhaoxiong Yan Zhihua Xu +2 位作者 Lin Yue Ling Shi Linyong Huang 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2018年第12期1919-1928,共10页
Catalytic oxidation at room temperature is recognized as the most promising method for formaldehyde(HCHO)removal.Pt‐based catalysts are the optimal catalyst for HCHO decomposition at room temperature.Herein,flower‐l... Catalytic oxidation at room temperature is recognized as the most promising method for formaldehyde(HCHO)removal.Pt‐based catalysts are the optimal catalyst for HCHO decomposition at room temperature.Herein,flower‐like hierarchical Pt/NiAl‐LDHs catalysts with different[Ni2+]/[Al3+]molar ratios were synthesized via hydrothermal method followed by NaBH4 reduction of Pt precursor at room temperature.The flower‐like hierarchical Pt/NiAl‐LDHs were composed of interlaced nanoplates and metallic Pt nanoparticles(NPs)approximately 3–4 nm in diameter were loaded on the surface of the Pt/NiAl‐LDHs with high dispersion.The as‐prepared Pt/NiAl21 nanocomposite was highly efficient in catalyzing oxidation of HCHO into CO2 at room temperature.The high activity of the hierarchical Pt/NiAl21 nanocomposite was maintained after seven recycle tests,suggesting the high stability of the catalyst.Based on in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)studies,a reaction mechanism was put forward about HCHO decomposition at room temperature.This work provides new insights into designing and fabricating high‐performance catalysts for efficient indoor air purification. 展开更多
关键词 HYDROTALCITE NiAl‐layered double hydroxides Hierarchical structure Catalytic oxidation Formaldehyde removal
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Preparation of Mo(Si,Al)_2 feedstock used for air plasma spraying
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作者 侯晖东 宁先进 +3 位作者 王全胜 高斌 柳彦博 刘颖 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2016年第11期2939-2946,共8页
In order to prepare high quality Mo(Si,Al)2 feedstock characterized with C40 phase, higher Al doping amount andexcellent flowability, Mo(Si1-x,Alx)2 with different Al contents (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) were... In order to prepare high quality Mo(Si,Al)2 feedstock characterized with C40 phase, higher Al doping amount andexcellent flowability, Mo(Si1-x,Alx)2 with different Al contents (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) were synthesized by self-propagatinghigh-temperature synthesis first and Mo(Si0.6,Al0.4)2 was confirmed as the suitable material through X-ray diffraction analysis. Aseries of tests with different parameters of induction plasma spheroidization were applied to improving the flowability of feedstock.Mo(Si,Al)2 feedstock with excellent flowability (26.2 s/50 g) was prepared through adding hydrogen into sheath gas and decreasingthe powder feeding rate. The composition segregation occurred in the spheroidized powder after Al consumption and oxidation. Theinhomogeneous structure of the same particle was caused by the asymmetric heating and cooling when particle passed through theplasma jet. 展开更多
关键词 Mo(Si Al)2 C40 phase self-propagating high-temperature synthesis induction plasma spheroidization compositionsegregation
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Genetic Variation and Differentiation of Larix decidua Populations in Swiss Alps
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作者 赵桂仿 Fran0is FELBER Philippe KPFER 《Acta Botanica Sinica》 CSCD 2001年第7期731-735,共5页
Genetic diversity within and among six subpopulations of Larix decidua Mill. from two altitudinal transects of Swiss Alps was investigated using 6 enzyme systems coding for 8 loci. Globally, the mean proportion of pol... Genetic diversity within and among six subpopulations of Larix decidua Mill. from two altitudinal transects of Swiss Alps was investigated using 6 enzyme systems coding for 8 loci. Globally, the mean proportion of polymorphic loci was 22.9%, the average number of alleles per locus was 1.3, and the mean expected heterozygosity was 0.095. Only 5.8% of the genetic variation resided among populations. The mean genetic distance was 0.006. Several significant differences of gene frequencies were found between different age classes. Positive values of the species mean fixation index observed in this study suggested a considerable deficit of heterozygotes in the populations of L. decidua of Swiss Alps. At one of the sites (Arpette), the highest subpopulation in elevation gave the lowest level of genetic diversity (as evidenced by the lowest proportion of polymorphic loci and the lowest mean expected heterozygosity) and the largest value of genetic distance when compared to other subpopulations. The genetic differences between the highest subpopulation and the other ones suggest that the founder effect may be an important factor influencing genetic differentiation of L. decidua populations at Arpette transect. 展开更多
关键词 Larix decidua Swiss Alps allozyme variation genetic differentiation age classes
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Synthesis of Ni-CeO_2 catalyst for the partial oxidation of methane using RF thermal plasma 被引量:5
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作者 M.Y.Lee J.S.Nam J.H.Seo 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2016年第5期743-749,共7页
Ni‐CeO2 catalysts with a nickel content of 50 mol% were prepared using RF thermal plasma, and their catalytic activities for methane partial oxidation were characterized. For the synthesis of Ni‐CeO2 catalysts, a pr... Ni‐CeO2 catalysts with a nickel content of 50 mol% were prepared using RF thermal plasma, and their catalytic activities for methane partial oxidation were characterized. For the synthesis of Ni‐CeO2 catalysts, a precursor containing Ni(~5‐μm diameter) and CeO2(~200‐nm diameter)powders were heated simultaneously using an RF plasma at a power level of ~52 kVA and a powder feeding rate of ~120 g/h. From the X‐ray diffraction data and transmission electron microscopy images, the precursor formed into high crystalline CeO2 supports with nanosized Ni particles( 50‐nm diameter) on their surfaces. The catalytic performance was evaluated under atmospheric pressure at 500 °C and a CH4:O2 molar ratio of 2:1 with Ar diluent. Although the Ni content was high(~50 mol%), the experimental results reveal a methane conversion rate of 70%, selectivities of CO and H2 greater than 90% and slight carbon coking during an on‐stream test at 550 °C for 24 h.However, at 750 °C, the on‐stream test revealed the formation of filament‐like carbons with an increased methane conversion rate over 90%. 展开更多
关键词 RF thermal plasma METHANE Partial oxidation Nickel catalyst CERIA Carbon deposition
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Kinetics and Mechanism of Decomposition of Nano-sized Calcium Carbonate under Non-isothermal Condition 被引量:7
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作者 刘润静 陈建峰 +2 位作者 郭奋 吉米 沈志刚 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2003年第3期302-306,共5页
Experiments on thermal decomposition of nano-sized calcium carbonate were carried out in a thermo-gravimetric analyzer under non-isothermal condition of different heating rates (5 to 20K·min-1). The Coats and Red... Experiments on thermal decomposition of nano-sized calcium carbonate were carried out in a thermo-gravimetric analyzer under non-isothermal condition of different heating rates (5 to 20K·min-1). The Coats and Redfern's equation was used to determine the apparent activation energy and the pre-exponential factors. The mechanism of thermal decomposition was evaluated using the master plots, Coats and Redfern's equation and the kinetic compensation law. It was found that the thermal decomposition property of nano-sized calcium carbonate was different from that of bulk calcite. Nano-sized calcium carbonate began to decompose at 640℃, which was 180℃lower than the reported value for calcite. The experimental results of kinetics were compatible with the mechanism of one-dimensional phase boundary movement. The apparent activation energy of nano-sized calcium carbonate was estimated to be 151kJ·mol-1 while the literature value for normal calcite was approximately 200kJ·mol-1. The order of magnitude of pre-exponential factors was estimated to be 10~9 s-1. 展开更多
关键词 nano-sized calcium carbonate non-isothermal decomposition kinetic mechanism
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Photocatalytic Activity of Hierarchical Flower-Like TiO_(2) Superstructures with Dominant {001} Facets 被引量:27
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作者 XIANG Quanjun YU Jiaguo 《催化学报》 SCIE EI CAS CSCD 北大核心 2011年第4期525-531,共7页
The fabrication of well defined hierarchical structures of anatase TiO_(2) with a high percentage of reactive facets is of great importance and challenging.Hierarchically flower-like TiO_(2) superstructures(HFTS)self-... The fabrication of well defined hierarchical structures of anatase TiO_(2) with a high percentage of reactive facets is of great importance and challenging.Hierarchically flower-like TiO_(2) superstructures(HFTS)self-assembled from anatase TiO_(2) nanosheets with exposed{001}facets(up to 87%)were synthesized by a simple alcohothermal strategy in a HF-H_(2)O-C_(2)H_(5)OH mixed solution using titanate nanotubes as precursor.The samples were characterized by X-ray diffraction,scanning electron microscopy,transmission electron microscopy,and N2 adsorption-desorption isotherms.The photocatalytic activity was evaluated by the photocatalytic oxidation decomposition of acetone in air and methyl orange in aqueous solution under UV illumination.The photocatalytic activity of HFTS was much higher than that of commercial Degussa P25 and tabular-shaped anatase TiO_(2) obtained using pure water as the synthesis medium.The enhancement in photocatalytic activity was related to several factors,including the hierarchically porous structure,exposed{001}facets,and increased light harvesting ability.The HFTS was also of interest for use in solar cells,photocatalytic H_(2) production,optoelectronic devices,sensors,and catalysis. 展开更多
关键词 titanium dioxide {001}facet hierarchical flower-like titanium dioxide superstructure photocatalytic activity acetone methyl orange
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Study on Synthesis and Catalytic Performance of Hierarchical Zeolite
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作者 Zhang Lingling Li Fengyan +1 位作者 ZhaoTianbo Sun Guida 《China Petroleum Processing & Petrochemical Technology》 SCIE CAS 2007年第3期57-60,共4页
A kind of hierarchical zeolite catalyst was synthesized by hydrothermal method. X-ray diffraction (XRD) and nitrogen adsorption-desorption method were used to study the phase and aperture structure o( the prepared ... A kind of hierarchical zeolite catalyst was synthesized by hydrothermal method. X-ray diffraction (XRD) and nitrogen adsorption-desorption method were used to study the phase and aperture structure o( the prepared catalyst. Infrared (IR) spectra of pyridine adsorbed on the sample showed that the hierarchical zeolite really had much more Bronsted and Lewis acidic sites than the HZSM-5 zeolite. The catalytic cracking of large hydrocarbon molecules showed that the hierarchical zeolite had a higher catalytic activity than the HZSM-5 zeolite. 展开更多
关键词 hierarchical zeolite catalytic cracking of large hydrocarbon molecules SELECTIVITY HZSM-5zeolite
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Studies of Differentially-Expressed Genes in Human Endometrial Cancer of Various Differentiated Grades
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作者 Bin Cai David Hogg +6 位作者 Guangzhong Lu Ling Liu Xiaowei Xi Wei Xu Huifang Lu Yongbin Yang Xiaoping Wan 《Chinese Journal of Clinical Oncology》 CSCD 2007年第2期77-82,共6页
OBJECTIVE To study the gene expression profiles of human endometrial cancers at various differentia0ted grade levels and to identify the genes related to differentiation of the endometrial cancers. METHODS cDNA microa... OBJECTIVE To study the gene expression profiles of human endometrial cancers at various differentia0ted grade levels and to identify the genes related to differentiation of the endometrial cancers. METHODS cDNA microarray technology was used to analyze the differentially-expressed genes among different differentiated grades of 32 cases of endometrial cancer. Hierarchical cluster analysis (HCA) for the gene expression profiles of the cases was employed. RESULTS The tissue samples were grouped based on the various differentiated tumor grades with 33 differentiation-related genes identified out (P〈0.001). Based on the results from the HCA, the conformity rate was 91% among the 33 differentially-expressed genes, and the analysis of pathological classification.CONCLUSION Genes related to the differentiation of endometrial cancer can be identified by using gene chips to analyze the expression profiles of endometrial cancers at various differentiated grades; HCA of the gene expression profiles can be helpful for distinguishing high-risk endometrial cancers before surgery. 展开更多
关键词 cDNA microarray endometrial tumor gene expression profile hierarchical cluster analysis.
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A Controlled Composition Kinetic Study Dissolution of Barium Fluoride
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作者 S.M.Hamza 《人工晶体学报》 EI CAS CSCD 1990年第2期140-145,共6页
A constant-composition technique has been used to study thekinetic of dissolution of barium fluoride in which the activities of the latticeions were maintained constant during the experiments. The method enableskineti... A constant-composition technique has been used to study thekinetic of dissolution of barium fluoride in which the activities of the latticeions were maintained constant during the experiments. The method enableskinetic data to be obtained at very low undersaturation. A striking change inthe mechanism of dissolution is observed as the driving force is changed. Athigher driving forces (relative undersaturation 0.15--0.20) the process appearsto follow normal diffusion-controlled dissolution, while at very low undersatu-ration (0.04--0.12) a surface controlled reaction predominates. The tworegions of undersaturation a show marked difference in reactions. 展开更多
关键词 barium fluoride constant-composition technique KINETIC
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Genetic diversity and differentiation of masu salmon(Oncorhynchus masou masou) between and within cultured populations inferred from microsatellite DNA analysis 被引量:2
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作者 Zhiying JI Yuyong ZHANG +1 位作者 Shuqiang CHEN Lianyu SHI 《Zoological Research》 CAS CSCD 北大核心 2012年第4期I0005-I0011,共7页
Masu salmon,Oncorhynchus masou masou,is one of the most valuable fishery species that has been introduced to China,though to date no studies on the genetic diversity and genetic relationship among hatchery populations... Masu salmon,Oncorhynchus masou masou,is one of the most valuable fishery species that has been introduced to China,though to date no studies on the genetic diversity and genetic relationship among hatchery populations has been performed with molecular markers.We undertook such a study and sampled 120 individuals from three hatchery stocks and analyzed 20 microsatellite loci.All loci were polymorphic and a total of 91 alleles were detected.A relatively low level of genetic diversity was revealed with effective number of allele of 3.1094,3.3299 and 3.1894 and expected heterozygosity of 0.6600,0.6648 and 0.6638 in the three stocks,respectively.Deviations from Hardy-Weinberg equilibrium were found due to heterozygote deficit.Accordingly,evidence of genetic bottlenecks were found in the three stocks.An individual assignment test demonstrated that 85% of individuals were correctly assigned into their original stocks.Pairwise Fst revealed that significant differentiation occurred between these three stocks.The results of the study indicated that disequilibrium of genetic structure and differentiation has occurred in all three stocks.This information collectively provides a basis for measures to avoid of loss of genetic diversity and introgression in Chinese aquaculture. 展开更多
关键词 Oncorhynchus masou masou MICROSATELLITE Genetic diversity Genetic differentiation
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Decorating non-noble metal plasmonic Al on a TiO2/Cu2O photoanode to boost performance in photoelectrochemical water splitting 被引量:4
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作者 Shaoce Zhang Zhifeng Liu +2 位作者 Weiguo Yan Zhengang Guo Mengnan Ruan 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2020年第12期1884-1893,共10页
Designing low-cost and high-performance photoelectrodes with improved light harvesting and charge separation rates is significant in photoelectrochemical water splitting.Here,a novel TiO2/Cu2O/Al/Al2O3 photoelectrode ... Designing low-cost and high-performance photoelectrodes with improved light harvesting and charge separation rates is significant in photoelectrochemical water splitting.Here,a novel TiO2/Cu2O/Al/Al2O3 photoelectrode is manufactured by depositing plasmonic nanoparticles of the non-noble metal Al on the surface of a TiO2/Cu2O core/shell heterojunction for the first time.The Al nanoparticles,which exhibit a surface plasmon resonance(SPR)effect and are substantially less expensive than noble metals such as Au and Ag,generate hot electron-hole pairs and amplify the electromagnetic field at the interface under illumination.The as-prepared TiO2/Cu2O/Al/Al2O3 photoelectrodes have an extended absorption range and enhanced carrier separation and transfer.Their photocurrent density of 4.52 mA·cm^-2 at 1.23 V vs.RHE represents an 1.84-fold improvement over that of TiO2/Cu2O.Specifically,the ultrathin Al2O3 passivation layer spontaneously generated on the surface of Al in air could act as a protective layer to significantly increase its stability.In this work,the synergistic effect of the heterojunctions and the SPR effect of the non-noble metal Al significantly improve the photoelectrode performance,providing a novel concept for the design of electrodes with good properties and high practicability. 展开更多
关键词 TIO2 PHOTOANODE Non-noble metal Al Surface plasmon resonance Photoelectrochemical water splitting
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Glow Discharge Plasma-Assisted Preparation of Nickel-Based Catalyst for Carbon Dioxide Reforming of Methane
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作者 Fang Guo Wei Chu +1 位作者 Jun-qiang Xu Lin Zhong 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 北大核心 2008年第5期481-486,共6页
A plasma-assisted method was employed to prepare Ni/γ-All2O3 catalyst for carbon dioxide reforming of methane reaction. The novel catalyst possessed higher activity and better coke-suppression performance than those ... A plasma-assisted method was employed to prepare Ni/γ-All2O3 catalyst for carbon dioxide reforming of methane reaction. The novel catalyst possessed higher activity and better coke-suppression performance than those of the conventional calcination catalyst. To achieve the same CH4 conversion, the conventional catalyst needed higher reaction temperature, about 50 ℃ higher than that of the N2 plasma-treated catalyst. After the evaluation test, the deactivation rate of the novel catalyst was 1.7%, compared with 15.2% for the conventional catalyst. Different from the characterization results of the calcined catalyst, a smaller average pore diameter and a higher specific surface area were obtained for the plasma-treated catalyst. The variations of the reduction peak temperatures and areas indicated that the catalyst reducibility was promoted by plasma assistance. The dispersion of nickel was also remarkably improved, which was helpful for controlling the ensemble size of metal atoms on the catalyst surface. The modification effect of plasma- assisted preparation on the surface property of alumina supported catalyst was speculated to account for the concentration increase of absorbed CO2. An enhancement of CO2 adsorption was propitious to the inhibition of carbon formation. The coke amount deposited on plasma treated catalyst was much smaller than that on the conventional catalyst. 展开更多
关键词 Nickel-based catalyst PLASMA CO2 reforming of CH4 COKE Adsorption of CO2
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A Simple Method to Extract Tropical Monsoon Forests Using NDVI Based on MODIS Data:A Case Study in South Asia and Peninsula Southeast Asia 被引量:3
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作者 LIN Sen LIU Ronggao 《Chinese Geographical Science》 SCIE CSCD 2016年第1期22-34,共13页
Distribution of monsoon forests is important for the research of carbon and water cycles in the tropical regions. In this paper, a simple approach is proposed to map monsoon forests using the Normalized Difference Veg... Distribution of monsoon forests is important for the research of carbon and water cycles in the tropical regions. In this paper, a simple approach is proposed to map monsoon forests using the Normalized Difference Vegetation lndex (NDVI) derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) data. Owing to the high contrast of greenness between wet season and dry season, the monsoon forest can be easily discriminated from other forests by combining the maximum and minimum annual NDVI. The MODIS-based monsoon forest maps (MODMF) from 2000 to 2009 are derived and evaluated using the ground-truth dataset. The MODMF achieves an average producer accuracy of 80.0% and the Kappa statistic of 0.719. The variability of MODMF among different years is compared with that calculated from MODIS land cover products (MCD 12Q 1). The results show that the coefficient of variation of total monsoon forest area in MODMF is 7.3%, which is far lower than that in MCD12Q1 with 24.3%. Moreover, the pixels in MODMv which can be identified for 7 to 9 times between 200l and 2009 account for 53.1%, while only 7.9% ofMCD12QI pixels have this frequency. Additionally, the monsoon forest areas estimated in MODMF, Global Land Cover 2000 (GLC2000), MCDI2Q1 and University of Maryland (UMD) products are compared with the statistical dataset at national level, which reveals that MODMv has the highest R^2 of 0.95 and the lowest RMSE of 14 014 km^2. This algorithm is simple but reliable for mapping the monsoon forests without complex classification techniques. 展开更多
关键词 monsoon forest Moderate Resolution Imaging Spectroradiometer (MODIS) Normalized Difference Vegetation Index(NDVI) amplitude THRESHOLD classification
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The Effect of the Under-dense Magnetized Plasma on Electron Density Distribution and Field Profile
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作者 Vali Markani Nader Azizi 《Journal of Energy and Power Engineering》 2012年第2期216-219,共4页
Propagation of a high frequency electromagnetic wave in under-dence plasma in presence of an external magnetic field is investigated. When a constant magnetic field perpendicular to the motion of electrons is applied,... Propagation of a high frequency electromagnetic wave in under-dence plasma in presence of an external magnetic field is investigated. When a constant magnetic field perpendicular to the motion of electrons is applied, then the electrons rotate around the magnetic field lines and generate electromagnetic part in the wake with a nonzero group velocity. Using of the Maxwell equations and nonlinear differential equation for the electric field a direct one dimensional (ID) procedure for calculating wake equations are developed and the electric and magnetic field profile in the plasma are investigated. 展开更多
关键词 Electron density PLASMA MAGNETIZED Maxwell equations.
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Taxonomy of the lesser jerboa Jaculus jaculus (Dipodidae,Rodentia) based on allozymic and morphological variation
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作者 Abderraouf BEN FALEH Abdelwaheb BEN OTHMEN Khaled SAID 《Current Zoology》 SCIE CAS CSCD 北大核心 2010年第4期421-431,共11页
The lesser Egyptian jerboa Jaculus jaculus, is a member of the subfamily Dipodinae, known to have a number of subspecies. Previous studies of J. jaculus from North Africa found various morphological forms of unknown t... The lesser Egyptian jerboa Jaculus jaculus, is a member of the subfamily Dipodinae, known to have a number of subspecies. Previous studies of J. jaculus from North Africa found various morphological forms of unknown taxonomic status, which are frequently grouped into two taxa: J. jaculus and J. deserti. We assessed the taxonomic status of this taxon in Tunisia using allozymic (phylogenetic analysis of 23 genetic loci encoding 16 enzymatic proteins) and morphological (multivariate analysis of 13 craniodental characters) analyses of 136 J. jaculus specimens collected from seven localities within its distribution range. Allozymic analysis clearly indicated the existence of two distinct groups of J. jaculus, with a mean genetic distance (D) value of 0.99 and FΩ=0.52. Individuals within the two groups did not show any obvious geographical structuration, even within the Matmata locality which represents the meeting point for the two groups where they were found in sympatry. Additionally, morphometric analysis of 13 craniodental characters was clearly separated the two groups. These results were obtained over a very restricted area of the total distribution of J. jaculus and strongly suggest the occurrence of two separate and often sympatric species within the currently accepted J.jaculus in Tunisia: J.jaculus and J. deserti 展开更多
关键词 DIPODIDAE Jaculus jaculus TAXONOMY ALLOZYME Morphomotric analysis Tunisia
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Mapping Soil Salinity Using a Similarity-based Prediction Approach:A Case Study in Huanghe River Delta,China 被引量:4
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作者 YANG Lin HUANG Chong +2 位作者 LIU Gaohuan LIU Jing ZHU A-Xing 《Chinese Geographical Science》 SCIE CSCD 2015年第3期283-294,共12页
Spatial distribution of soil salinity can be estimated based on its environmental factors because soil salinity is strongly affected and indicated by environmental factors. Different with other properties such as soil... Spatial distribution of soil salinity can be estimated based on its environmental factors because soil salinity is strongly affected and indicated by environmental factors. Different with other properties such as soil texture, soil salinity varies with short-term time. Thus, how to choose powerful environmental predictors is especially important for soil salinity. This paper presents a similarity-based prediction approach to map soil salinity and detects powerful environmental predictors for the Huanghe(Yellow) River Delta area in China. The similarity-based approach predicts the soil salinities of unsampled locations based on the environmental similarity between unsampled and sampled locations. A dataset of 92 points with salt data at depth of 30–40 cm was divided into two subsets for prediction and validation. Topographical parameters, soil textures, distances to irrigation channels and to the coastline, land surface temperature from Moderate Resolution Imaging Spectroradiometer(MODIS), Normalized Difference Vegetation Indices(NDVIs) and land surface reflectance data from Landsat Thematic Mapper(TM) imagery were generated. The similarity-based prediction approach was applied on several combinations of different environmental factors. Based on three evaluation indices including the correlation coefficient(CC) between observed and predicted values, the mean absolute error and the root mean squared error we found that elevation, distance to irrigation channels, soil texture, night land surface temperature, NDVI, and land surface reflectance Band 5 are the optimal combination for mapping soil salinity at the 30–40 cm depth in the study area(with a CC value of 0.69 and a root mean squared error value of 0.38). Our results indicated that the similarity-based prediction approach could be a vital alternative to other methods for mapping soil salinity, especially for area with limited observation data and could be used to monitor soil salinity distributions in the future. 展开更多
关键词 soil salinization similarity-based prediction approach digital soil mapping Huanghe (Yellow) River Delta environmental factor
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