检索结果-南通市图书馆

A new method for deriving analytical solutions of partial differential equations-Algebraically explicit analytical solutions of two-buoyancy natural convection in porous media

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2008年第11期51卷 1733-1744页

作者： CAI RuiXian liu QiBin Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China

Analytical solutions of governing equations of various phenomena have their irre-placeable theoretical meanings. In addition, they can also be the benchmark solu-tions to verify the outcomes and codes of numerical solutions, and even to develop various numerical methods such as their differencing schemes and grid generation skills as well. A hybrid method of separating variables for simultaneous partial differential equation sets is presented. It is proposed that different methods of separating variables for different independent variables in the simultaneous equa-tion set may be used to improve the solution derivation procedure, for example, using the ordinary separating method for some variables and using extraordinary methods of separating variables, such as the separating variables with addition promoted by the first author, for some other variables. In order to prove the ability of the above-mentioned hybrid method, a lot of analytical exact solutions of two-buoyancy convection in porous media are successfully derived with such a method. The physical features of these solutions are given.

关键词： analytical solution hybrid method of separating variables two-buoyancy natural convection porous me-dium

Density-functional-theory formulation of classical and quantum Hooke's law

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2014年第4期57卷 692-698页

作者： HU Hao liu Feng Department of Materials Science and Engineering University of Utah

A fundamental property of solid materials is their stress state. Stress state of a solid or thin film material has profound effects on its thermodynamic stability and physical and chemical properties. The classical mechanical stress （σ^M） originates from lat- tice strain （e）, following Hooke＇s law： σ^M=Cε, where C is elastic constant matrix. Recently, a new concept of quantum electronic stress （o-QE） is introduced to elucidate the extrinsic electronic effects on the stress state of solids and thin films, which follows a quantum analog of classical Hooke＇s law： ~QE=E（An）, where E is the deformation potential of electronic states and An is the variation of electron density. Here, we present mathematical derivation of both the classical and quantum Hooke＇s law from density functional theory. We further discuss the physical origin of quantum electronic stress, arising purely from electronic excitation and perturbation in the absence of lattice strain （g=0）, and its relation to the degeneracy pressure of electrons in solid and their interaction with the lattice.

关键词： stress in the solid quantum electronic stress quantum Hooke's law density functional theory

The growth of B cell receptor microcluster is a universal response of B cells encountering antigens with different motion features

在线全文

学校读者我要写书评

暂无评论

Protein & Cell 2012年第7期3卷 545-558页

作者： Zhengpeng Wan Wanli liu School of Life Sciences Tsinghua UniversityBeijing 100084China

B lymphocyte cell senses and acquires foreign anti-gens through clonal distributed B cell receptors(BCRs)expressed on the surface of plasma *** presentation formats of antigens are quite *** on their Brownian diffusion mobility,there are three forms:free mobile soluble antigens,lateral mobile membrane bound antigens,and fixed immobile ***,using high resolution high speed live cell imaging approaches,we provide evidence that BCR microclusters are formed on the surface of B cells shortly after B cell’s encountering of antigens with each format of motion *** high speed live cell imaging,we determine that these BCR microclusters show dynamic growth feature and by doing so function as the basic platforms for B cells to acquire the *** propose that the formation and dynamic growth of BCR microcluster is a universal mechanism for B cell to response to antigens with diverse motion features.

关键词： BCR microcluster TIRFM live cell imaging fixed immobile antigen lateral mobile antigen free mobile antigen

Features of major greenhouse gases in loess,Shanxi Province,China

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2001年第17期46卷 1469-1472页

作者： Qiang liu Jiaqi liu Shuzhen Sui Chinese Acad Sci Inst Geol & Geophys Beijing 100029 Peoples R China

According to the investigations of five loess sections in Shanri Province, China, it was found that the concentrations of the major greenhouse gases CO2, CH4 and N2O in loess-paleosol sequences are generally high, even sometimes may be several times or scores of tunes higher than their atmospheric concentrations respectively. Although the CO2 concentration in the same loess section shows poor regularity among different layers, it increases slowly from north to south in space. The CH4 concentration in the layers under Malan Loess is much higher than that in the atmosphere, although it is not high in Malan Loess. Most of the δ13C values of CO2 in loess are -11.14‰-15.48‰, (relative to PDB standard). Analysis of carbon isotopic compositions of CO2 indicates that the main source of CO2 in loess section is decomposition of ’stable’ organic matters by microbes. The δ13Cg of CO2 is a little heavier than organic source for exchanging carbon isotope with carbonate in loess. The abundant carbonate in loess

关键词： loess-paleosol sequence major greenhouse gases concentration δ13Cg value deuterogenic carbonate carbon reservoir.

Enhancing sensitivity of microbial fuel cell sensors for low concentration biodegradable organic matter detection:Regulation of substrate concentration,anode area and external resistance

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2021年第3期33卷 227-235页

作者： Yangyang Gao Sha Wang Fengjun Yin Pin Hu Xingzu Wang Yuan liu Hong liu Key Laboratory of Reservoir Aquatic Environment Chinese Academy of SciencesChongqing 400714China Chongqing Institute of Green and Intelligent Technology Chinese Academy of SciencesChongqing 400714China University of Chinese Academy of Sciences Beijing100049China

The relatively low sensitivity is an important reason for restricting the microbial fuel cell(MFC)sensors'application in low concentration biodegradable organic matter(BOM)*** startup parameters,including substrate concentration,anode area and external resistance,were regulated to enhance the sensitivity of MFC *** results demonstrated that both the substrate concentration and anode area were positively correlated with the sensitivity of MFC sensors,and an external resistance of 210Ωwas found to be optimal in terms of sensitivity of MFC *** MFC sensors had lower detection limit(1 mg/L)and higher sensitivity(Slope value of the linear regression curve was 1.02),which effectively overcome the limitation of low concentration BOM *** essential reason is that optimized MFC sensors had higher coulombic efficiency,which was beneficial to improve the sensitivity of MFC *** main impact of the substrate concentration and anode area was to regulate the proportion between electrogens and nonelectrogens,biomass and living cells of the anode *** external resistance mainly affected the morphology structure and the proportion of living cells of the *** study demonstrated an effective way to improve the sensitivity of MFC sensors for low concentration BOM detection.

关键词： Microbial fuel cell sensor High sensitivity Biodegradable organic matter Substrate concentration Anode area External resistance

Recent Progress of Magnetically Actuated DNA Micro/Nanorobots

在线全文

学校读者我要写书评

暂无评论

Cyborg and Bionic Systems 2022年第1期2022卷 43-54页

作者： Fengyu liu Xiaoming liu Qiang Huang Tatsuo Arai Key Labraoryof Bmetic Robts and Sym Minsry of EduationState KeyLaboratoryofInteligent Controlandcisnof Complex SystemBejing Advanced Innovation Center for Intlligent Robots and Systems and School of Mechatron ical Engineering Bejing Institute of TechnologyBeijing 100081China Center for Neuroscience and Biomedical Enginring The University of Eletro-CommunicationsTokyo 182-8585 Japan

In the past few decades,the field of DNA origami based micro/nanotechnology has developed dramatically and spawned attention increasingly,as its high integrality,rigid structure,and excellent resistance ability to enzyme *** two-dimensional and three-dimensional DNA nanostructures coordinated with optical,chemical,or magnetic triggers have been designed and assembled,extensively used as versatile templates for molecular robots,nanosensors,and intracellular drug *** magnetic field has been widely regarded as an ideal driving and operating system for micro/nanomaterials,as it does not require high intensity lasers like light control,nor does it need to change the chemical composition similar to chemical ***,we review the recent achievements in the induction and actuation of DNA origami-based nanodevices that respond to magnetic *** magnetic actuation-based DNA nanodevices were regularly combined with magnetic beads or gold nanopartides and applied to generate single stranded scaffolds,assemble various DNA nanostructures,and purify specific DNA ***,they also produced artificial magnetism or moved regularly driven by *** fields to explain deeper scientific issues.

关键词： resistance magnetic versatile

Transition metal-catalyzed decarboxylative cross-coupling reactions

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Chemistry 2011年第11期54卷 1670-1687页

作者： SHANG Rui liu Lei Key Laboratory of Bioorganic Phosphorus Chemistry ＆ Chemical Biology （Ministry of Education） Department of Chemistry Tsinghua University Beijing 100084 China State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic Chemistry Chinese Academy of Sciences Shanghai 200032 China

Transition metal-catalyzed decarboxylative cross-coupling reactions have recently emerged as a new and important category of organic transformations that find versatile applications in the construction of carbon-carbon and carbon-heteroatom bonds. The use of relatively cheap and stable carboxylic acids to replace organometallic reagents enables the decarboxylative cross-coupling reactions to proceed with good selectivities and functional group tolerance. In the present review we summarize the various types of decarboxylative cross-coupling reactions catalyzed by different transition metal complexes. The scope and applications of these reactions are described. The challenges and opportunities in the field are discussed.

关键词： decarboxylation cross-coupling reaction transition metal catalysis organic synthesis

Mid-Cretaceous Hainan back-arc basin:record of the sustained extension of South China margin

在线全文

学校读者我要写书评

暂无评论

Journal of Palaeogeography 2022年第4期11卷 584-600页

作者： Yan Chen Jun Meng Hao liu Tao liu Ze-Ying Zhao State Key Laboratory of Biogeology and Environmental Geology School of Earth Sciences and ResourcesChina University of Geosciences(Beijing)Beijing100083China School of Ocean Sciences China University of Geosciences(Beijing)Beijing100083China

The continued subduction of the Pacific oceanic lithosphere during the Jurassic-Cretaceous time formed a large magmatic province as“Basin and Range”at the South China ***,the timing and mechanisms of such a huge rifting and magmatism belt are still *** we present new petrological,sedimentological and geochemical analyses for the Cretaceous Lumuwan Formation and coeval intruded mafic dykes under the robust age constrain in Hainan *** results show that the midCretaceous Lumuwan Formation was a typical lacustrine stratigraphic sandwich that accumulated in an intracontinental back-arc extensional *** Hainan mafic dykes(~108-93 Ma)were probably sourced from asthenospheric and lithospheric mantle which were metasomatized by subducted oceanic sediments in a backarc extension of the continental *** timing of the NW-SE-directed back-arc extension in the Hainan Basin has been constrained as 108-93 Ma and played a significant role in the formation of Basin and Range-type tectonics and landscape evolution in the South China.

关键词： Mid-cretaceous Lumuwan Formation Mafic dykes Back-arc extension South China

3D printing of high-performance micro-supercapacitors with patterned exfoliated graphene/carbon nanotube/silver nanowire electrodes

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2021年第5期64卷 1065-1073页

作者： liu Lang LU JunYong LONG XinLin ZHOU Ren liu YingQuan WU YiTing YAN KangWei National Key Laboratory of Science and Technology on Vessel Integrated Power System Naval University of EngineeringWuhan 430033China

Micro-supercapacitors(MSCs)show great potential as on-chip energy storage devices for portable *** major flaw of thin-film MSCs is their low energy *** improve the energy density,thicker electrodes are ***,the fabrication of MSCs with thick electrodes remains a *** this work,a novel 3D printing method is employed to fabricate high-performance MSCs with interdigitated exfoliated graphene(EG)/carbon nanotube(CNT)/silver nanowire(Ag NW)*** nanowelding of Ag NW junction plays a critical role in the realization of 3D *** enhance the electrochemical performances of EG,phosphorus atoms are incorporated into the carbon framework with 1.7 at%.The areal capacitance of the 3D printed MSC is 21.6 mF cm^(-2)at a scan rate of 0.01 V s^(-1).The areal energy density of the MSC ranges from 0.5 to 2μWh cm^(-2)with a maximum power density of 2.5 mW cm^(-2).

关键词： micro-supercapacitor 3D printing silver nanowire exfoliated graphene micro-plasma-jet