维普中文期刊产品整合服务
132篇 您的检索式:作者名="and Theoret"
    题名 作者 年代 出处 被引量
1Comparison of dark energy models:A perspective from the latest observational data显示文摘We compare some popular dark energy models under the assumption of a flat universe by using the latest observational data including the type Ia supernovae Constitution compilation,the baryon acoustic oscillation measurement from the Sloan Digital Sky Survey,the cosmic microwave background measurement given by the seven-year Wilkinson Microwave Anisotropy Probe observations and the determination of H0 from the Hubble Space Telescope.Model comparison statistics such as the Bayesian and Akaike information criteria are applied to assess the worth of the models.These statistics favor models that give a good fit with fewer parameters.Based on this analysis,we find that the simplest cosmological constant model that has only one free parameter is still preferred by the current data.For other dynamical dark energy models,we find that some of them,such as the αdark energy,constant w,generalized Chaplygin gas,Chevalliear-Polarski-Linder parametrization,and holographic dark energy models,can provide good fits to the current data,and three of them,namely,the Ricci dark energy,agegraphic dark energy,and Dvali-Gabadadze-Porrati models,are clearly disfavored by the data.LI Miao1,2,LI XiaoDong2,3 & ZHANG Xin1,4 1Kavli Institute for Theoretical Physics China,Chinese Academy of Sciences,Beijing 100190,China 2Key Laboratory of Frontiers in Theoretical Physics,Institute of Theoretical Physics,Chinese Academy of Sciences,Beijing 100190,China 3Interdisciplinary Center for Theoretical Study,University of Science and Technology of China,Hefei 230026,China 4Department of Physics,College of Sciences,Northeastern University,Shenyang 110004,China 2010Science China(Physics,Mechanics & Astronomy)2010,53,9:7
2Hamiltonian Formalism of de-Sitter Invariant Special Relativity显示文摘The Lagrangian of Einstein's special relativity with universal parameter c(SR_c)is invariant under Poincarétransformation,which preserves Lorentz metric η_μν.The SR_c has been extended to be one which is invariant underde Sitter transformation that preserves so-called Beltrami metric B_(μv).There are two universal parameters,c and R,inthis Special Relativity(denoted as SR_(cR)).The Lagrangian-Hamiltonian formulism of SR_(cR) is formulated in this paper.The canonic energy,canonic momenta,and 10 Noether charges corresponding to the space-time's,de Sitter symmetryare derived.The canonical quantization of the mechanics for SR_(CR)-free particle is performed.The physics related to itis discussed.YAN Mu-Lin XIAO Neng-Chao HUANG Wei Interdisciplinary Center for Theoretical Study,University of Science and Technology of China,Hefei 230026,ChinaLI Si Department of Mathematics,University of Science and Technology of China,Hefei 230026,China 2007Communications in Theoretical Physics2007,,7:7
3Two mode photon bunching effect as witness of quantum criticality in circuit QED显示文摘We suggest a scheme to probe critical phenomena at a quantum phase transition (QPT) using the quantum correlation of two photonic modes simultaneously coupled to a critical system. As an experimentally accessible physical implementation,a circuit QED system is formed by a capacitively coupled Josephson junction qubit array interacting with one superconducting transmission line resonator (TLR). It realizes an Ising chain in the transverse field (ICTF) which interacts with the two magnetic modes propagating in the TLR. We demonstrate that in the vicinity of criticality the originally independent fields tend to display photon bunching effects due to their interaction with the ICTF. Thus,the occurrence of the QPT is reflected by the quantum characteristics of the photonic fields.AI Qing1,WANG YingDan2,LONG GuiLu1,3 & SUN ChangPu4 1 Department of Physics,Tsinghua University,Beijing 100084,China 2 Department of Physics,University of Basel,Klingelbergstrasse 82,4056 Basel,Switzerland 3 Tsinghua National Laboratory for Information Science and Technology,Beijing 100084,China 4 Institute of Theoretical Physics,Chinese Academy of Sciences,Beijing 100080,China 2009Science China(Physics,Mechanics & Astronomy)2009,52,12:6
4Normal scalar curvature and a pinching theorem in S^m×R and H^m×R显示文摘We obtain an inequality in Sm×R and Hm×R which is similar to DDVV conjecture.As an application,we show that a minimal submanifold in H m×R with nonnegative scalar curvature must be a surface of the type γ×R,where γ is a geodesic in H m.In addition,we get a pinching theorem in Sm×R.CHEN Qun 1,2 & CUI Qing 3,1,1 School of Mathematics and Statistics,Wuhan University,Wuhan 430079,China 2 International Center for Theoretical Physics,Trieste 34100,Italy 3 School of Mathematics,Southwest Jiaotong University,Chengdu 610031,China 2011Science China Mathematics2011,54,9:6
5Studies of low-lying states of even-even Xe isotopes within the nucleon pair approximation显示文摘We study the relevance of nucleon pairs with higher spins, in addition to spin-zero and spin-two pairs (i.e., S D pairs), in low-lying states of even-even Xe nuclei. By including those higher-spin pairs in our configuration, we recalculate energy level schemes, elec trical quadrupole moments, magnetic moments and electric quadrupole transition rates, for low-lying states of even-even 128-142Xe nuclei. The agreement between our calculated results and the experimental data is substantially improved in comparison with previous studies.ZHANG LiHua1, JIANG Hui1,2 & ZHAO YuMin1,3,4 1Institute of Nuclear, Particle, Astrophysics and Cosmology, Department of Physics, Shanghai Jiao Tong University, Shanghai 200240, China 2School of Arts and Sciences, Shanghai Maritime University, Shanghai 200135, China 3Center of Theoretical Nuclear Physics, National Laboratory of Heavy Ion Accelerator, Lanzhou 730000, China 4CCAST, World Laboratory, P.O. Box 8730, Beijing 100080, China 2011Science China(Physics,Mechanics & Astronomy)2011,54,S1:5
6Jackknife and Bootstrap Tests of the Composition Vector Trees显示文摘Composition vector trees (CVTrees) are inferred from whole-genome data by an alignment-free and parameter-free method. The agreement of these trees with the corresponding taxonomy provides an objective justification of the inferred phylogeny. In this work, we show the stability and self-consistency of CVTrees by performing bootstrap and jackknife re-sampling tests adapted to this alignment-free approach. Our ultimate goal is to advocate the viewpoint that time-consuming statistical re-sampling tests can be avoided at all in using this alignment-free approach. Agreement with taxonomy should be taken as a major criterion to estimate prokaryotic phylogenetic trees.Guanghong Zuo1,2, Zhao Xu1,3, Hongjie Yu1,4, and Bailin Hao1,5,6 1T-Life Research Center & Department of Physics, Fudan University, Shanghai 200433, China 2Shanghai Institute of Applied Physics, Chinese Acadamy of Sciences, Shanghai 201800, China 3Applied Biosystems, Inc., Beijing 100027, China 4Fudan-VARI Center for Genetic Epidemiology, Fudan University, Shanghai 200433, China 5Institute of Theoretical Physics, Chinese Acadamy of Sciences, Beijing 100190, China 6Santa Fe Institute, Santa Fe, NM 87505, USA. 2010Genomics, Proteomics & Bioinformatics2010,8,4:5
7Three-Dimensional Simulation of Nonstationary Flow Phenomena in 'Last Stage-Exhaust Hood'Compartment显示文摘Three-dimensional nonstationary model of aerodynamical interaction of turbine stage and exhaust hood is realized, based on nonstationary 3D codes for calculation of inviscid transonic flow through stage[3] and exhaust hood[4] which consist of diffuser and space under casing. The codes are built with the use of the explicit Godunov’s 2nd order difference scheme. Some results of flow simulation through the compartments 'stage-exhaust hood,' 'stage-exhaust axial-radial diffuser' for wide range of volumetric flow rates are represented.V.G. Solodov (Heat of Department of Theoretical Mechanics and Hydraulics, Docent, Kharkov State Automobile & Highway Technical University, 310078, Kharkov, Ukraine) V.I. Gnesin (Head of Department of Aerodynamics of Power Machines, Professor, Institute fo 1997Journal of Thermal Science1997,6,4:4
8Sufficient Conditions of Robust Schur Stability for Uncertain 2-D PolynomialsXIAO Yang\+1\ \ DU Xi\|yu\+1\ \ Rolf Unbehauen\+2 1.Institute of Information Science, Northern Jiaotong University Beijing 100044, P.R.China 2. Institute of General and Theoretic Electronic\|Technique University of Erlangen\|Nürnberg Cauerstr.7, 910 1999Systems Science and Systems Engineering1999,9,3:4
9Simple Formula of β^+-Decay Half-Lives of Nuclei Far From β-Stable Line显示文摘We generalize the formula of β^+-decay half-lives [Phys.Rev.C 78 (2006) 014305] to include all availabledata of nuclei far from the β-stable line. Good agreement with experimental data is obtained by taking into accountthe even-odd (e-o) effect.It is shown that the e-o effect on β^+-deeay half-life is apparent for the allowed β^+-transition,whereas it is not apparent for the first and second forbidden transitions.This demonstrates that the allowed β^+-transitionis more sensitive to the nuclear even-odd effect than the forbidden β^+-transition.The underlying physics is discussed.This formula can be used to predict the β^+-decay half-lives of the nuclei far from β-stability.It is useful to experimentalphysicists for analyzing the data of β^+-decay.ZHANG Xiao-Ping~1 REN Zhong-Zhou~(1,2)and ZHI Qi-Jun~1~1 Department of Physics,Nanjing University,Nanjing 210008,China~2 Center of Theoretical Nuclear Physics,National Laboratory of Heavy-Ion Accelerator,Lanzhou 730000,China 2007Communications in Theoretical Physics2007,,12:4
10Theoretical studies on Ru(fppz)_2(CO)L (L=N-heterocyclic ligand):Electronic structure,absorption,phosphorescence,and solvatochromism显示文摘A series of ruthenium(II) complexes Ru(fppz)2(CO)L [fppz = 3-trifluoromethyl-5(2-pyridyl)pyrazole; L = pyridine (1), 4-dimethylaminopyridine (2), 4-cyanopyridine (3)] were designed and investigated theo-retically to explore their electronic structures, absorption, and emissions as well as the solvatochrom-ism. The singlet ground state and triplet excited state geometries were fully optimized at the B3LYP/LANL2DZ and CIS/LANL2DZ level, respectively. The HOMO of 1-3 is composed of dyz(Ru) atom and π(fppz). The LUMO of 1 and 2 is dominantly contributed by π*(fppz) orbital, but that of 3 is con-tributed by π*(L). Absorption and phosphorescence in vacuo, C6H12, and CH3CN media were calculated using the TD-DFT level of theory with the PCM model based on the optimized ground and excited state geometries, respectively. The lowest-lying absorption of 1 and 2 at 387 and 391 nm is attributed to {[dyz(Ru) + π(fppz)] → [π*(fppz)]} transition, but that of 3 at 479 nm is assigned to {[dyz(Ru) + π(fppz)] → [π*(L)]} transition. The phosphorescence of 1 and 2 at 436 and 438 nm originates from 3{[dyz(Ru) + π(fppz)] [π*(fppz)]} excited state, while that of 3 at 606 nm is from 3{[dyz(Ru) + π(fppz)] [π*(L)]} excited state. The calculation results showed that the absorption and emission transition character can be changed from MLCT/ILCT to MLCT/LLCT transition by altering the substituent on the L ligand. The phosphorescence of 1 and 2 does not have solvatochromism, but that of 3 at 606 nm (vacuo), 584 nm (C6H12), and 541 nm (CH3CN) is strongly dependent on the solvent polarity, so introducing elec-tron-withdrawing group on ligand L will induce remarkable solvatochromism.LIU Tao1, ZHOU Xin1, BAI FuQuan1, ZHANG JianPo1, XIA BaoHui1,2, PAN QingJiang3 & ZHANG HongXing1 1 State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, China 2 College of Chemistry, Jilin University, Changchun 130023, China 3 Laboratory of Physical Chemistry, School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080, China 2008Science China Chemistry2008,51,12:4
11Prokaryote phylogeny meets taxonomy: An exhaustive comparison of composition vector trees with systematic bacteriology显示文摘We perform an exhaustive, taxon by taxon, comparison of the branchings in the composition vector trees (CVTrees) inferred from 432 prokaryotic genomes available on 31 December 2006, with the bacte-riologists' taxonomy-primarily the latest online Outline of the Bergey's Manual of Systematic Bacteri-ology. The CVTree phylogeny agrees very well with the Bergey's taxonomy in majority of fine branchings and overall structures. At the same time most of the differences between the trees and the Manual have been known to biologists to some extent and may hint at taxonomic revisions. Instead of demonstrating the overwhelming agreement this paper puts emphasis on the biological implications of the differences.GAO Lei1,2, QI Ji1**, SUN JianDong2,3 & HAO BaiLin1,2,4 1 Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100080, China 2 T-Life Research Center, Fudan University, Shanghai 200433, China 3 Beijing Genomics Institute, Chinese Academy of Sciences, Beijing 101300, China 4 Santa Fe Institute, Santa Fe, NM87501, USA Center for Comparative Genomics and Bioinformatics, Penn State University, 310 Wartik Building, University Park, PA16802, USA 2007Science China(Life Sciences)2007,50,5:4
12Synthesis of superheavy nuclei with ^(238)U target显示文摘The production of superheavy nuclei with Z=108-116 via hot fusion reactions of the neutron-rich projectiles with 238U target is systematically studied.The results show that the production cross sections of superheavy nuclei do not decrease monotonously as the atomic number Z increasing.The cross sections of the superheavy nuclei at Z = 112 and 115 are enhanced as compared with the whole Z-trend in synthesis of the superheavy nuclei,which clearly illustrates that the reactions with large negative Q-value and shell correction are more favorable to synthesize superheavy nuclei.LIU ZuHua1,3 & BAO JingDong2,4 1 Key Laboratory of Beam Technology and Material Modification of Ministry of Education,Beijing Normal University,Beijing 100875,China 2 Department of Physics,Beijing Normal University,Beijing 100875,China 3 China Institute of Atomic Energy,Beijing 102413,China 4 Center of Theoretical Nuclear Physics,National Laboratory of Heavy Ion Accelerator of Lanzhou,Lanzhou 730000,China 2009Science China(Physics,Mechanics & Astronomy)2009,52,10:3
13A class of mechanically decidable problems beyond Tarski's model显示文摘By means of dimension-decreasing method and cell-decomposition,a practical algorithm is proposed to decide the positivity of a certain class of symmetric polynomials,the numbers of whose elements are variable.This is a class of mechanically decidable problems beyond Tarski model.To implement the algorithm,a program nprove written in maple is developed which can decide the positivity of these polynomials rapidly.Lu YANG~(1,2) Yong FENG~(1+) Yong YAO~1 1 Laboratory for Automated Reasoning and Programming,Chengdu Institute of Computer Applications,Chinese Academy of Sciences,Chengdu 610041,China 2 Institute of Theoretical Computing,East China Normal University,Shanghai 200062,China 2007Science China Mathematics2007,50,11:3
14Calculation of the molecular exchanging energy of binary surfactants system on the surface monolayer of aqueous solution显示文摘By using the binary anionic/cationic surfactants system CH3(CH2)nOSO_3/CH3(CH2)nN+(CH3)3 as an ex-ample, the molecular exchanging energy (ε) of adsorption on the surface monolayer of aqueous solu-tion has been studied. ε can be obtained with two methods. One is from the relationship between ε and the molecule interaction parameter (β). This relationship is founded by considering that the adsorption of mixed surfactants on the surface monolayer of solution satisfies the dimensional crystal model condition under which β can be obtained by testing the surface tension of solution. The other is directly from the molecular structure of surfactants with the Lennard-Jones formula. The results for the studied system show that these two methods coincide well.WANG ZhengWu1 & YI XiZhang2 1 Department of Food Sciences & Technology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China 2 Institute of Theoretical Chemistry, Shandong University, Jinan 250100, China 2007Science China Chemistry2007,50,4:2
15Some Remarks on the Symmetry of Self-Conjugate Minimal Surfaces in R^3Chen Weihuan M.S.Rahman Chen Weihuan International Centre for Theoretical Physics Trieste,Italy and Department of Mathematics Peking University Beijing,100871 ChinaRahman,M.S.International Centre for Theoretical Physics Trieste,Italy and Department of Maihematics Jahangirnagar University Dhaha,1342 Bangladesh 1996Acta Mathematica Sinica,English Series1996,12,2:2
16Collision dynamics of He@C_(60)+He@C_(60) at low energies显示文摘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.ZHAO Qiang1,2, ZHANG FengShou1,2,3 & ZHOU HongYu1,2 1 Key Laboratory of Beam Technology and Material Modification of Ministry of Education, Institute of Low Energy Nuclear Physics, Beijing Normal University, Beijing 100875, China 2 Beijing Radiation Center, Beijing 100875, China 3 Center of Theoretical Nuclear Physics, National Laboratory of Heavy Ion Accelerator of Lanzhou, Lanzhou 730000, China 2008Science China(Physics,Mechanics & Astronomy)2008,51,7:2
17Shape phase transitions in nuclei:Effective order parameters and trajectories显示文摘We analyze systematically the effective order parameters in nuclear shape phase transition both in experiments and in the interacting boson model. We find that energy ratios and B(E2) ratios can distinguish the first from the second-order phase transition in theory above a certain boson number N (about 50), but in experiments, only those quantities, such as E(L1+)/E(02+) and B(E2; (L+2)1 → L1)/B(E2; 21 → 01), etc., of which the monotonous transitional behavior in the second-order phase transition is broken in the first order phase transition independent of N, are qualified as the effective order parameters. By implementing the originally proposed effective order parameters and the new ones, we find that the isotones with neutron number Nn = 62 are a trajectory of the second order phase transition. In addition, we predict that the transitional behavior of isomer shifts of Xe, Ba isotopes and Nn = 62 isotones is approximately monotonous due to the finiteness of nuclear system.ZHANG Yu1,2, HOU ZhanFeng2 & LIU YuXin2,3 1Department of Physics, Liaoning Normal University, Dalian 116029, China 2Department of Physics and the State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871, China 3Center of Theoretical Nuclear Physics, National Laboratory of Heavy Ion Accelerator, Lanzhou 720000, China 2011Science China(Physics,Mechanics & Astronomy)2011,54,S1:2
18The dynamical properties of Rydberg hydrogen atom near a metal surface显示文摘The dynamical properties of Rydberg hydrogen atom near a metal surface are presented by using the methods of phase space analysis and closed orbit theory. Transforming the coordinates of the Hamiltonian, we find that the phase space of the system is divided into vibrational and rotational region. Both the Poincaré surface of section and the closed orbit theory verify the same conclusion clearly. In this paper we choose the atomic principal quantum number as n = 20. The dynamical character of the exited hydrogen atom depends sensitively on the atom-surface distance d. When d is sufficiently large, the atom-surface potential can be expressed by the traditional van der Waals force and the system is integrable. When d becomes smaller, there exists a critical value dc. For d > dc, the system is near-integrable and the motion is regular. While chaotic motion appears for d < dc, and the system tends to be non-integrable. The trajectories become unstable and the electron might be captured onto the metal surface.GE Meihua1, ZHANG Yanhui1, WANG Dehua2, DU Mengli3 & LIN Shenglu1 1. College of Physics and Electronics, Shandong Normal University, Jinan 250014, China 2. Department of Mathematics and Physics, Shandong Institute of Architecture and Engineering, Jinan 250014, China 3. Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100080, China 2005Science China(Physics,Mechanics & Astronomy)2005,48,6:2
19Transition metal coordination polymers with polycarboxylic acid as bridging ligands:Synthesis and structure characterization of[Fe(μ_(4)-bta)_(0.5)(phen)(OH)]_(n)显示文摘A new 2D (two-dimensional) coordination polymer, [Fe(μ4-bta)0.5(phen)(OH)]n (1), has been hydrothermally synthesized with FeCl3·6H2O, Na4bta (H4bta = 1,2,4,5-benzentetra- carboxylic acid), 1,10-phen (1,10-phenanthroline) and H2O as raw materials. The crystals of the compound belong to monoclinic P21/n space group, a = 1.0129(2) nm, b = 0.9265(2) nm, c = 1.5696(3) nm,β = 91.37(3) o, V = 1.4721(5) nm3, Z = 3, final R1 = 0.0292, Wr2 = 0.0798 for 2572 [I > 2σ (I )] observed reflections. The result of structure determination shows that in the compound each bta ligand is connected with four FeIII, forming a new μ4-coordination mode. Four deprotonated carboxylic groups of bta link to FeIII ions alternatively through monodentate and bidentate coordination fashion, constructing 2D layer network. The measurement of variable temperature magnetic susceptibility indicates that there exist antiferromagnetic interactions between FeIII ions in the compound. The TGA spectrum displays relatively fine thermal stability of the compound. In addition, IR and UV-Vis spectra of compound 1 have also been measured.XU Jiqing, CHU Deqing, YU Jiehui, WANG Tiegang & TANG AoqingCollege of Chemistry and State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin University, Changchun 130023, China Institute of Theoretical Chemistry, Jilin University, Changchun 130023, China 2004Science China Chemistry2004,47,1:2
20Shell effect and capture cross sections in the synthesis of superheavy nuclei显示文摘The shell effect is included in the improved isospin dependent quantum molecular dynamics model in which the shell correction energy of the system is calculated by using the deformed two-center shell model.A switch function is introduced to connect the shell correction energy of the projectile and the target with that of the compound nucleus during the dynamical fusion process.It is found that the calculated capture cross sections reproduce the experimental data quantitatively at the energy near the Coulomb barrier.The capture cross sections for reaction 8305 Br + 28028 Pb → 121878X are also calculated and discussed.DU SaiSai1,2,BIAN BaoAn1,2,3,LIU Min1,2,4,FENG ZhaoQing5,6 & ZHANG FengShou1,2,6 1 Key Laboratory of Beam Technology and Material Modification of Ministry of Education,College of Nuclear Science and Technology,Beijing Normal University,Beijing 100875,China 2 Beijing Radiation Center,Beijing 100875,China 3 School of Science,Jiangnan University,Wuxi 214122,China 4 College of Physics and Technology,Guangxi Normal University,Guilin 541004,China 5 Institute of Modern Physics,Chinese Academy of Sciences,Lanzhou 730000,China 6 Center of Theoretical Nuclear Physics,National Laboratory of Heavy Ion Accelerator of Lanzhou,Lanzhou 730000,China 2009Science China(Physics,Mechanics & Astronomy)2009,52,10:2
返回顶部 每页显示:
共7页 首页 上一页 第1页 下一页 末页 /7 跳转

网站首页 | 关于我们 | 联系我们 | 产品服务 | 客服中心 | 广告服务 | 版权声明 | 网站联盟 | 友情链接 | 售卡网点

版权所有© 渝B2-20050021-1 渝公网安备 50019002500403号 违法和不良信息举报中心

互联网出版许可证 新出网证(渝)字10号 全国400电话 - 免长途话费