检索结果-南通市图书馆

Endpoint Estimates of Generalized Homogeneous Littlewood–Paley g-functions over Non-Homogeneous Metric Measure Spaces

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2016年第9期32卷 1035-1074页

作者： Xing fu ji Man ZHAO School of Mathematical Sciences Beijing Normal University Laboratory of Mathematics and Complex Systems Ministry of Education Beijing 100875 P. R. China

Let （x, d,u） be a metric measure the upper doubling conditions. Under the weak space satisfying both the geometrically doubling and reverse doubling condition, the authors prove that the generalized homogeneous Littlewood-Paley g-function gr （r ∈ [2, ∞）） is bounded from Hardy space H1（u） into L1（u）. Moreover, the authors show that, if f ∈ RBMO（u）, then [gr（f）]r is either infinite everywhere or finite almost everywhere, and in the latter case, [gr（f）]r belongs to RBLO（u） with the norm no more than ｜｜f｜｜ RBMO（u） multiplied by a positive constant which is independent of f. As a corollary, the authors obtain the boundedness of gr from RBMO（u） into RBLO（u）. The vector valued Calderon-Zygmund theory over （X, d, u） is also established with details in this paper.

关键词： Non-homogeneous metric measure space generalized homogeneous Littlewood-Paley g-function Hardy space RBMO(u) RBLO(u) vector valued Calderon Zygmund theory

Heteroscedastic regression analysis method for mixed data

在线全文

学校读者我要写书评

暂无评论

航空动力学报 2011年第4期26卷 721-726页

作者： fu Hui-min YUE Xiao-rui Research Center of Small Sample Technology Beijing University of Aeronautics and Astronautics Beijing 100191 China

The heteroscedastic regression model was established and the heteroscedastic regression analysis method was presented for mixed data composed of complete data,type-Ⅰ censored data and type-Ⅱ censored data from the location-scale *** best unbiased estimations of regression coefficients,as well as the confidence limits of the location parameter and scale parameter were ***,the point estimations and confidence limits of percentiles were ***,the traditional multiple regression analysis method which is only suitable to the complete data from normal distribution can be extended to the cases of heteroscedastic mixed data and the location-scale *** the presented method has a broad range of promising applications.

关键词： heteroscedastic regression analysis censored data performance test life prediction reliability analysis

Organosilicon polymer-derived ceramics: An overview

在线全文

学校读者我要写书评

暂无评论

Journal of Advanced Ceramics 2019年第4期8卷 457-478页

作者： Shengyang fu min ZHU Yufang ZHU School of Materials Science and Engineering University of Shanghai for Science and Technology

Polymer-derived ceramics(PDCs) strategy shows a great deal of advantages for the fabrication of advanced ceramics. Organosilicon polymers facilitate the shaping process and different silicon-based ceramics with controllable components can be fabricated by modifying organosilicon polymers or adding fillers. It is worth noting that silicate ceramics can also be fabricated from organosilicon polymers by the introduction of active fillers, which could react with the produced silica during pyrolysis. The organosilicon polymer-derived ceramics show many unique properties, which have attracted many attentions in various fields. This review summarizes the typical organosilicon polymers and the processing of organosilicon polymers to fabricate silicon-based ceramics, especially highlights the three-dimensional(3 D) printing technique for shaping the organosilicon polymerderived ceramics, which makes the possibility to fabricate silicon-based ceramics with complex structure. More importantly, the recent studies on fabricating typical non-oxide and silicate ceramics derived from organosilicon polymers and their biomedical applications are highlighted.

关键词： polymer-derived ceramics(PDCs) organosilicon polymers 3D printing silicon-based ceramics

Identification of the bound residue composition derived from ^(14)C-labeled chlorsulfuron in soil by using LC-MS and isotope tracing method

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2004年第1期16卷 73-78页

作者： YEQing-fu WUjian-min SUNjin-he InstituteofNuclear-AgriculturalScience ZhejiangUniversityHangzhou310029China

A new method for extracting the bound residue(BR) derived from 14 C-labeled chlorsulfuron in soils was developed, and the technique of combining LC-MS with isotope tracing method was subsequently applied to identify the composition of the 14 C-BR in a loamy Fluvent derived from marine deposit. The results showed that the 14 C-[2-amino-4-methoxyl-6-methyl-1,3,5]-triazine, 14 C-[2-amino-4-hydroxyl-6-methyl-1,3,5]-triazine and 14 C-chlorsulfuron parent compound constituted the main composition of the 14 C-BR derived from 14 C-labeled chlorsulfuron in the soil. The radioactive ratio of three compounds accounted for 39.8%, 35.4% and 17.9% of total recovered radioactivity, respectively. However, a small amount(3.6% of total recovered radioactivity) of the complex of 14 C-[2-amino-4-hydroxyl-6-methyl-1,3,5]-triazine might have existed in the 14 C-BR in association with an unknown soil substrate. 2-chlorobenzenesulfonamide was also detected to be one of the components of the BR. The results could well explain the mechanism of phytotoxicity caused by the BR derived from chlorsulfuron in soil. In addition, the mechanism of BR formation in soil was also discussed in details.

关键词： bound residue chlorsulfuron composition identification soil

Preparation of Ferrioxalate Submicrorods/Graphene Composites and Their Photocatalytic Properties

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2014年第2期30卷 117-122页

作者： min fu Yun Zhao Qingze jiao School of Chemical Engineering and the Environment Beijing Institute of Technology

Ferrioxalate submicrorods/graphene composites were synthesized through a simple solvothermal process in a mixture of ethylene glycol and water. The in situ growth of ferrioxalate submicrorods and the reduction of graphene oxide （GO） were completed in a one-step reaction. Fourier transform infrared and Raman spectroscopy confirmed the reduction of GO. Uniform rod-like ferrioxalates with diameter of about 600 nm and length of several micrometers were well distributed on the graphene sheets. As-obtained composites exhibited better photocatalytic properties than pure ferrioxalate submicrorods. The influence of different contents of GO on photocatalytic performance was also investigated. A possible photocatalytic mechanism of ferrioxalate submicrorods/graphene composites was proposed.

关键词： Ferrioxalate submicrorods Graphene Photocatalysis

Bioavailability of bound residue derived from ^(14)C-labeled chlorsulfuron in soil and its mechanism of phytotoxicity

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2004年第2期16卷 262-267页

作者： YEQing-fu WUjian-min SUNjin-he InstituteofNuclearAgriculturalSciences ZhejiangUniversityHangzhou310029China. DepartmentofChemistry ZhejiangUniversityHangzhou310029China

The bioavailability of bound residue(BR) derived from 14 C-labeled chlorsulfuron in soil and effect of the main components of the BR on growth of rape(brassica napus) and rice(Oryza sativa L.) were investigated. The results showed that the BR with the concentration of 0 28 and 0 56 nmol/g air-dried soil, which was calculated by special radioactivity of 14 C-labeled chlorsulfuron parent compound, resulted in significant depression effect on growth of rape seedling. It was assured that the main components(2-amino-4-methoxyl-6-methyl-1,3,5-triazine, 2-amino-4-hydroxyl-6-methyl-1,3,5-triazine, and 2-chloro-benzenesul-f onamide) of the BR did not inhibit the growth of rape and rice. LC-MS analysis demonstrated that the parent compound previously bound to the soil matrix could be again released and transformed into methanol-extractable residue during the course of rape growth. It was concluded that the molecular leading to the phytotoxicity to rape and rice in the BR is still the parent compound.

关键词： chlorsulfuron bound residue bioavailability phytotoxicity mechanism

A Middle Pleistocene Glaciation Record from Lacustrine Sediments in the Western Tibetan Plateau and Discussion on Climate Change

在线全文

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 2023年第2期97卷 623-635页

作者： ZHAO Zhenming ji Wenhua fu Chaofeng Xi'an Center China Geological SurveyXi'an 710054China Key Laboratory of Western mineral Resources and Geological Engineering Ministry of Education of China and Chang'an UniversityXi'an 710054China State Key Laboratory of Loess and Quaternary Geology Institute of Earth and EnvironmentCASXi'an 710075China

The Tibetan Plateau is an important area for studying global climate change,but the answers to many scientific problems remain ***,we present new information from the lacustrine sedimentary record in the western Tibetan Plateau,related to the third most-recent *** sediment data,including sporopollen,particle size,total organic carbon,mass susceptibility,CaCO_(3),CaSO_(4),BaSO_(4)contents and chronological data,were reconstructed and revealed that climate and environmental conditions obviously and distinctly changed between 600 and 700 thousand years *** comparison,the data obtained from the Guliya ice core in this area also corresponds to the global glacial climatic characteristics recorded in basin sediments in the eastern and southeastern regions of the plateau and to the information obtained from ice cores in the Antarctic and Arctic *** this study,we conclude that the main reason for the glaciations and new tectonic movement must be a geomagnetic polarity reversal 774 thousand years ago(from Matuyama to Brunhes).Indeed,the results of this study suggest that the described reversal event might have influenced the current global climate pattern and will continue to impact climatic changes in the future.

关键词： glacial record global climate change geomagnetic polarity reversal middle Pleistocene western Tibetan Plateau

Nitrogen release and re-adsorption dynamics on crop straw residue during straw decomposition in an Alfisol

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2021年第1期20卷 248-259页

作者： LI ji-fu ZHONG Fang-fang Engineering Research Center of Ecology and Agricultural Use of Wetland Ministry of Education/College of AgricultureYangtze UniversityJingzhou 434025P.R.China

Returning crop straw to the field not only improves the nitrogen(N) supplying capacity and N retention of soil but also decreases the amount of rural organic waste and prevents air pollution. Therefore, understanding the mechanisms of the N release and re-adsorption dynamics on crop straw residue during straw decomposition in agricultural soil is important, and this understanding can help us strengthen N fertilizer management during the crop growth period. An on-farm incubation experiment was conducted in the jianghan Plain in Central China under flooded conditions using the nylon mesh bag method. Results showed that the decomposition rate of crop straw was much faster at the beginning of the incubation stage, whereas it was steady during the later stage with no observed differences among the three types of crop straw. After 120 d of incubation, the cumulative decomposition proportion of rice straw, wheat straw and rape straw was 72.9, 56.2, and 66.9%, respectively. The proportion of N that released from the three crop straws was 52.0, 54.4 and 54.9%, respectively. The zeta potentials and Brunauer, Emmett and Teller(BET) surface area of the rice, wheat and rape straw residues increased gradually as the decomposition period progressed. The water adsorption capacity of the rice straw was significantly affected during the decomposition period. The saturated water adsorption capacity of rice straw was the highest at 30 d of decomposition(4.17 g g^–1) and then decreased slightly. The saturated water adsorption of wheat and rape straws reached the lowest value at 30 d and then gradually increased and became stable. All the results demonstrated that crop straw and straw residue can re-adsorb NH4^+ ions from the surrounding solution. The re-adsorption was affected by the decomposition period and concentration of exogenous NH4^+ and was independent of the crop species via the combined efforts of physical and chemical adsorption, ion exchange and water retention on residue su

关键词： adsorption decomposition nitrogen(N) Alfisol straw substrate

Fission law of solitary waves propagating over sharply variable topography

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2020年第4期32卷 727-734页

作者： Da-lin Tan ji-fu Zhou Xu Wang Key Laboratory for Mechanics in Fluid Solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Sciences University of Chinese Academy of SciencesBeijing 100049China

The fission of solitary waves propagating over variable topography is *** previous theories,to predict the number and the amplitudes of disintegrated solitons in the wave packet generated from a solitary wave,the parameters of the water environment and the incident solitary wave are ***,it is difficult to measure these parameters in the ocean because of their temporal and spatial *** this paper,a fission law,in the form of the expressions of the number and the amplitudes of the disintegrated solitons,is derived from the partial information available on the wave *** analysis shows that the law is suitable fbr describing the fission of both surface and internal solitary waves and is also applicable to the cases of wave damping and wave *** between the model output and the results from laboratory experiments,numerical simulations and field observations available in the literature demonstrate that the fission law can efficiently estimate the number and the amplitudes of solitons in the wave packet generated by a solitary wave.

关键词： Fission law solitary wave packet wave breaking