检索结果-南通市图书馆

Collision dynamics of He@C_(60)+He@C_(60) at low energies

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7期51卷 765-772页

作者： ZHAO Qiang1,2. ZHANG FengShou1,2.3.& ZHOU HongYu1,2.1 {3. laboratory of Beam Technology and Material Modification of Ministry of Education, {2. of Low energy Nuclear {3., beijing Normal University, beijing 100875, China 2.beijing Radiation Center, beijing 100875, China 3.Center of Theoretical Nuclear {3., National laboratory of Heavy Ion Accelerator of Lanzhou, Lanzhou 73.000, China key laboratory of Beam Technology and Material Modification of Ministry of Education Institute of Low Energy Nuclear Physics Beijing Normal University Beijing China beijing Radiation Center Beijing China Center of Theoretical Nuclear physics National Laboratory of Heavy Ion Accelerator of Lanzhou Lanzhou China

A semi-empirical molecular dynamics model is developed. The central collisions of C60+C60 and He@C60+He@C60 at different incident energies are investigated based on this model. It is found that the dimer structures have been produced at proper incident energies and these fullerene dimers could be formed by a self-assembly of C60 fullerene and He@C60. The He atom has a significant effect at higher incident energy and this embedded He atom can enhance the stability of the dimer structure.

关键词： C60 He@C60 collision molecular dynamics

A puzzle of the radio-quiet quasar PG 1407+2.5:Are optical and X-ray emissions produced from a relativistic jet?

在线全文

学校读者我要写书评

暂无评论

Science China(physics,Mechanics & Astronomy) 2011年第1期54卷 183-186页

作者： CHEN Liang 1,2.3.& BAI JinMing 1,2.1 National Astronomical Observatories/Yunnan Observatory,Chinese academy of {3.,Kunming 650011,China {2. {3. for the Structure and Evolution of Celestial Objects,Chinese academy of {3.,Kunming 650011,China 3.Graduate University of Chinese academy of {3.,beijing 10004.,China National Astronomical Observatories/Yunnan Observatory Chinese Academy of Sciences Kunming China key laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming China Graduate University of Chinese academy of sciences Beijing China

PG 1407+2.5 is a radio quiet quasar that has a relativistic *** this report,we show some peculiar properties of its optical and X-ray emissions,which indicate possible non-thermal origins produced from the *** use a simple synchrotron + synchrotron self Compton (SSC) model to fit the emissions with different ratios of energy densities between the magnetic field and electrons (η≡U B/U e),which predicts a different γ-ray *** First LAT AGN Catalog (1LAC) did not include PG 1407+2.5,which indicates an upper limit of γ-ray *** upper limit constrains the ratio to be unreasonably large (η≥10 4-5).This inversely indicates that the optical and X-ray emissions may not be produced from the beaming *** discuss the physical implications of these results.

关键词： active galactic nuclei jet non-thermal emission PG 1407+2.5

fMRI time series analysis based on stationary wavelet and spectrum analysis

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2006年第11期16卷 1171-1176页

作者： ZHI Lianhe~ 1,2.3., ZHAO Xia~4, SHAN Baoci~1**, PENG Silong~5, YAN Qiang~1, YUAN Xiuli~1 and TANG Xiaowei~ 1,6 (1. key laboratory of Nuclear Analysis Techniques,{2., Chinese academy of {3., beijing 10004., China 2. Graduate School of Chinese academy of {3., beijing 10004., China 3. Department of physics, Zhoukou Normal University, Zhoukou 466100, China 4. Research Imaging Center, University of Texas Health Science Center, San Antonio, Texas 782.9, USA 5. National ASIC Design and Engineering Center, {13. of Automation, Chinese academy of {3., beijing 10004., China 6. Department of physics, Zhejiang University, Hangzhou 3.002., China) key laboratory of Nuclear Analysis Techniques Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China Graduate School of Chinese academy of sciences Beijing 100049 China Department of physics Zhoukou Normal University Zhoukou 466100 China Research Imaging Center University of Texas Health Science Center San Antonio TX 78229 United States National ASIC Design and Engineering Center Institute of Automation Chinese Academy of Sciences Beijing 100049 China Department of physics Zhejiang University Hangzhou 310027 China

The low signal to noise ratio (SNR) of functional MRI (fMRI) prefers more sensitive data analysis methods. Based on stationary wavelet transform and spectrum analysis, a new method with high detective sensitivity was developed for analyzing fMRI time series, which does not require any prior assumption of the characteristics of noises. In the proposed method, every component of fMRI time series in the different time-frequency scales of stationary wavelet transform was discerned by the spectrum analysis, then the components from noises were removed using the stationary wavelet transform, finally the components of real brain activation were detected by cross-correlation analysis. The results obtained from both simulated and in vivo visual experiments illustrated that the proposed method has much higher sensitivity than the traditional cross-correlation method.

关键词： fMRI stationary wavelet transform spectrum analysis data analysis.

An Explicit Function Expression for dc Bias and Temperature Dependence of Magnetoresistances in Magnetic Tunnel Junctions

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2002年第6期18卷 497-501页

作者： Xiufeng HANState key laboratory of Magnetism, {2. of {3. and Center of Condensed Matter {3., Chinese academy of sciences, beijing 100080, China Chinese Acad Sci Inst Phys State Key Lab Magnetism Beijing 100080 Peoples R China Chinese Acad Sci Ctr Condensed Matter Phys Beijing 100080 Peoples R China

An explicit function expression for the bias voltage or/and temperature dependences of tunnel magnetoresistance ratio and resistances were obtained with a unique set of intrinsic parameters. Two of these intrinsic parameters are the Curie temperature TC and the density of state (DOS) for itinerant majority and minority electrons ξ(ρM/ρm), which are the eigen parameters of ferromagnetic electrodes. Others are the spin-dependent matrix-element ratio (i.e., |Td|2.|TJ|2.) and the anisotropic-wavelength-cutoff energy ECγ of spin-wave spectrum in magnetic tunnel junction (MTJ), which are the structure parameters of an MTJ. These intrinsic parameters can be predetermined using the experimental measurement or, in principle, using the first-principle calculation method for an MTJ with the three {3. layers of FM/I/FM. Furthermore, a series of experimental data for an MTJ, for example, a spin-valve-type MTJ of Ta (5 nm)/Ni79Fe2.(2. nm)/lr2.Mn78(12.nm)/Co75Fe2.(4 nm)/AI(0.8 nm)-oxide/Co75Fe2.(4 nm)/Ni79Fe2.(2. nm)/Ta (5 nm) in this work, can be self-consistently evaluated and explained using such concise explicit function formulations.

关键词： Magnetic tunnel junction TMR Spin-electron transport Magnon excitation Spin-polarization Magnetotransport

Investigation into the rotational bands of ^(185)Pt with the particle-rotor model

在线全文

学校读者我要写书评

暂无评论

Science China(physics,Mechanics & Astronomy) 2011年第S1期54卷 114-118页

作者： LI GuangShun1,2. ZHOU XiaoHong1,2. ZHANG ShuangQuan3. ZHANG YuHu1 & MENG Jie3.1 institute of Modern {3., Chinese {2. of {3., Lanzhou 73.000, China 2.Graduate University of Chinese {2. of {3., beijing 10004., China 3.School of {3. and SK laboratory of Nuclear {3. & Technology, Peking University, {13. 100871, China institute of Modern physics Chinese Academy of Sciences Lanzhou China Graduate University of Chinese academy of sciences Beijing China School of physics and SK laboratory of Nuclear physics & Technology Peking University Beijing China

Theoretical calculations have been performed for the ν9/2.[62.](i13.2. and ν7/2.[503.(f7/2. bands of 185Pt in the framework of particle-rotor model. The band properties of signature splitting and configuration mixing have been analyzed. The level energy and signature splitting before the band crossing can be well interpreted by introducing triaxiality. The positive-parity yrast band is pro posed to be dominated by the ν9/2.[62.](i13.2. component, while the negative-parity band shows strong mixing of ν7/2.[503.(f7/2. and ν9/2.[505](h9/2. configurations.

关键词： high-spin states particle-rotor model signature splitting configuration mixing

Evolution of desertification in a two-dimensional energy balance model coupled with thermodynamics and dynamics

在线全文

学校读者我要写书评

暂无评论

Science China Earth sciences 2010年第11期53卷 1726-1733页

作者： CHAO JiPing1,2.& LI YaoKun3.4 1National Marine Environmental Forecasting Center, beijing 100081, China 2.irst {3. of Oceanography, State Oceanic Administration, Qingdao 2.6061, China 3.tate {2. laboratory of Numerical Modeling for Atmospheric {3. and Geophysical Fluid Dynamics, {3. of Atmospheric physics, Chinese academy of {3., beijing 10002., China 4Graduate University of Chinese academy of {3.,{12., China National Marine Environmental Forecasting Center Beijing China First institute of Oceanography State Oceanic Administration Qingdao China State key laboratory of Numerical Modeling for Atmospheric {2. and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China Graduate University of Chinese academy of sciences Beijing China

The relationship between desert evolution and change in albedo has been investigated quasi-analytically using a zonal mean two-dimensional energy balance model which considers the radiation transmission process due to thermodynamics and bound- ary layer movement caused by kinetics. A climate state including temperature, zonal wind, meridional wind and vertical wind can be simulated according to the current zonal distribution of albedo. Given desert distribution, characterized by the value and distribution of albedo, the response of climate on albedo has been studied to analyze the evolution of desert climate. One significant result is that the simple model can reproduce mean meridional circulation. Another result indicates that climate corresponds to two equilibria. This happens when the junction temperature between vegetation and desert is higher than a certain critical value. As for the first equilibrium, the desert belt is predicted to move southward in the northern hemisphere with the increasing values of albedo, which corresponds to the current trend of climate change. For the second equilibrium, vegetation will expand northward with increasing values of albedo, which would indicate a narrowing of the desert belt. In order to determine if the two equilibria exist, new physical models are needed.

关键词： two-dimensional energy balance model desertification two equilibria

Effects of nitrogen ion implantation on Ca^(2.) concentration and membrane potential of pollen cell

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2001年第20期46卷 1691-1693页

作者： HUANG Zhonglian, JING Yanping, ZHU Guoli, LU Ting, ZHOU Hongyu & REN Haiyun1. key laboratory of Cell Proliferation and Regulation Biology of the Ministry of Education, {2. Normal University, {2. 100875, China 2. key laboratory of Plant Physiology and Biochemistry of the Ministry of Agriculture, China Agriculture University, {2. 100094, China 3. Institution of Low energy Nuclear physics, {2. Normal University, {2. 100875, China key laboratory of Cell Proliferation Regulation Biology of Min. of Educ. Beijing Normal University Beijing 100875 China

The effects of low energy nitrogen ion implantation on Ca2. concentration and membrane potential of illy (Mum davidii Duch) pollen cell have been studied. The results showed that the Ca2. concentration was increased when pollen grain was implanted by nitrogen ion with energy 100 keV and dose 1013.ions/cm2. However, the increase of Ca2. concentration was partly inhibited by the addition of Ca2. channel inhibitor depending on dose. And nitrogen ion implantation caused depolarization of pollen cell membrane potential. In other words, membrane potential was increased, but the effect decreased by adding Ca2. channel inhibitor. However, it was still significantly {2.er than the membrane potential of control cells. It was indicated that the depolarization of cell membrane potential opened the calcium channel on the membrane that caused the increasing of intracel-lular calcium concentration. This might be an earlier step of the effect of low energy nitrogen ion implantation on pollen germination.

关键词： nitrogen ion implantation lily pollen calcium concentration membrane potential.

Progress in multi-waveband observations of supernova remnants

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2008年第9期18卷 1057-1062页

作者： Xuejuan Yang a,b, Fangjun Lua, Wenwu Tian c,d,* a particle astrophysics Center,{2., Chinese {3. of sciences, beijing 10004., China b Department of Astronomy, beijing Normal University, beijing 100875, China c National Astronomical Observatories, Chinese {3. of sciences, 2.A Datun Road, Chaoyang District, CAS, beijing 100012. China d Department of {13. & Astronomy, University of Calgary, Alberta, Canada T2. 1N4 particle astrophysics Center Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China Department of Astronomy Beijing Normal University Beijing 100875 China National Astronomical Observatories Chinese Academy of Sciences 20A Datun Road Chaoyang District CAS Beijing 100012 China Department of physics & Astronomy University of Calgary Alberta Canada T2N 1N4

The development of observational techniques has enriched our knowledge of supernova remnants. In this paper, we review the main progresses in the last decade, including new discoveries of supernova remnants and the associated (rare type of) pulsars, nucleosynthesis, the interaction between supernova remnants and molecular clouds, dust in the supernova remnants, shock physics, and cosmic ray accelerations.

关键词： Supernova remnant Observations

Transport　of　atmospheric　trace　elements　and　dust－soil　to　the　Western　Pacific　Ocean

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental sciences 1996年第4期8卷 460-465页

作者： Yang Shaojin Chen Bingru Yang Yinan(institute of high {2. {3.,Chinese academy of sciences,beijing 100080,China) institute of high {2. {3. Chinese Academy of Sciences Beijing 100080 China

Atmospheric aerosol and rainwater samples collected in the different Western Pacific area were analyzed by instrumental neutron activation and proton induced X-ray emission to (1) determine the atmospheric concentrations of trace elements over the Western Pacific and (2. to esti mate the atmospheric deposition of trace elements and dust-soil material to this region. high abundance of pollutant and crustal elements relative to oceanic sources was observed. Some characteristics of marine atmosphere relating to long-range transport of crustal and anthropogenic elements from continent to the remote ocean are discussed. The total dust-soil particle mass is estimated to be 0. 066-1.2.μg/m￣3.over the Western Pacific Ocean areas. Atmospheric inputs of dust-soil particles control the marine particle concentrations of crustal elements. In addition, the characteristics of marine rain water are discussed.

关键词： dust-soil marine rain-water atmospheric trace elements.