检索结果-南通市图书馆

RE-PONDERING BASIC CHARACTERISTICS OF CHINA

在线全文

学校读者我要写书评

暂无评论

Bulletin of the Chinese Academy of Sciences 1997年第2期11卷 105-113页

作者： He Zuoxiu(institute of theoretical {2., CAS, beijing)

Through the re-understanding of the basic characteristics of China being "vast in territory, rich in resources and large in population", this article puts forward its comments on the formulation of a basic state policy of China, which is based on the understanding of the contradiction between man and nature and suitable to the condition of the country and on a strategy for China’s long-term development, and makes significant suggestions such as saving resources, strictly protecting the environment, controlling the growth of population, advocating science, proposing rational and appropriate consumption, and exploiting and remaking nature.

关键词： BASIC

b→ssin a Vector Quark Model

在线全文

学校读者我要写书评

暂无评论

Communications in theoretical physics 2005年第11期44卷 887-890页

作者： CAI Hai-Ying ZHANG Da-Xin institute of theoretical {2.,School of {2.,Peking University,beijing 100871,China

The rare decay b→ss(?) is studied in a vector quark model by adding the contributions from exoticvector-like *** find that the contribution from box diagrams amounts to 10-9in the branching ratio,while theZ-mediated ... 详细信息

关键词： rare decay vector-like quarks

Non-spectator Contributions to Lifetime of Ab

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Communications in theoretical physics 2004年第11期 723-734页

作者： CHANG Chao-Hsi~(1,2.) GUO Peng~3 LI Xué-Qian~(1,3) WANG Guo-Li~3 ~1institute of theoretical {2.,Academia Sinica,P.O.Box 2.35,beijing 100080,China ~2.CAST (World Laboratory),P.O.Box 8730,beijing 100080,China ~3Department of {2.,Nankai University,Tianjin 300071,China institute of theoretical {2.，Academia Sinica，P.O. Box 2.35，beijing 100080，China CCAST (World Laboratory)，P.O. Box 8730，beijing 100080，China Department of physics，Nankai University，Tianjin 300071，China institute of theoretical {2.，Academia Sinica，P.O. Box 2.35，beijing 100080，China Department of physics，Nankai University，Tianjin 300071，China

In this work,we study the contributions of non-spectator effects to the lifetimes of A;and *** on the well-established theoretical framework about the effective weak Lagrangian,we derive theformulation of the non-spectator effects at the quark ***,for A;we have considered two pictures:thethree-valence-quark picture and the quark-diquark *** the two pictures,the interference contributions to thetotal width are different,in this work,we investigate the interference effects in *** a preliminary estimate onthe lifetimes,we evaluate the hadronic matrix elements appearing in the final formulas of the lifetimes by means of asimple phenomenological model for both *** results show that the contributions of the non-spectator effectscan reduce the ratio of lifetime of A;to that of B-mesons by 5～7%.It is noted that in the quark-diquark picturethe ratio can be further reduced if excited states of the diquark system are taken into *** conclude that themeasured ratio τ（A;）/τ（B;）0.79 [The Data Group,***.D66 （2.02. 010001] can be partly understood bythe non-spectator effects,although the problem on the discrepancy between theoretical prediction and experimentalmeasurement is not fully solved.

关键词： lifetime non-spectator (?)_b

Dynamical Structure of A≤4 Hypernuclei and Charge Symmetry Breaking

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese journal of nuclear physics 1994年第2期16卷 139-145页

作者： Luo Bin Kong Fanxin Liu Xianhui(Center of theoretical physics CCA ST( World Lab.),{2. 100080)(institute of High Energy physics,Academia Sinica,{2. 100039) Guangxi Teacher’s University,Guilin,541001. 中科院高能物理所北京 100039 中科院高能物理所北京

-The dynamical structure of A≤4 Λ-hypernuclei is studied by using thefew-body theoretical *** AN interaction is taken to be the meson exchange po-tential with the single k,ω,η exchange diagrams and the box diagrams of π and πρ ex-change containing the intermediate state particles Σ,Δ.The Λ binding energy differenceof the mirror hypernuclei _Λ~4He and _Λ~4H is *** is shown that the root meansquare distances between the particles in the light hypernuclei are almost the same andthere does not exist any nuclear *** relative motion between particles stay mainlyin 1S state.

关键词： Hypernuclei Few body Meson exchange

VERTICAL HEREDITY VS. HORIZONTAL GENE TRANSFER: A CHALLENGE TO BACTERIAL CLASSIFICATION

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2003年第3期16卷 307-314页

作者： HAO Bailin(institute of theoretical {2., Academy of Chinese Sciences, beijing 100080, China Senior International Fellow of the Santa Fe institute T-Life Research Center, Fudan University,Shanghai 2.0433, China)QI Ji(institute of theoretical {2., beijing 100080, China) institute of theoretical {2. Academy of Chinese Sciences 北京 100080 institute of theoretical {2. Chinese Academy of Sciences 北京 100080

The diversity and classification of microbes has been a long-standing *** phylogeny of the prokaryotes based on comparison of the 16S rRNA sequences of the small ribosomal subunit has led to a reasonable tree of life in the late 1970s. How-ever, the availability of more and more complete bacterial genomes has brought about complications instead of refinement of the tree. In particular, it turns out that different choice of genes may tell different history. This might be caused by possible horizontal gene transfer (HGT) among species. There is an urgent need to develop phylogenetic methods that make use of whole genome data. We describe a new approach in molecular phylogeny,namely, tree construction based on K-tuple frequency analysis of the genomic *** aside the technicalities, we emphasize the transition from randomness to determin-ism when the string length K increases and try to comment on the challenge mentioned in the title.

关键词： prokaryote phylogeny horizontal gene transfer fitness compositionaldistance

Anomaly of the Anomalous Delays of the Crossing Frequencies in Odd Proton Nuclei

在线全文

学校读者我要写书评

暂无评论

Chinese journal of nuclear physics 1994年第3期 211-216页

作者： Chen Yong-shou~(1,2. Lou Wen-dong~(1)((1)institute of Atomic Energy,P.O.Box 2.5(18),beijing 102.13)((1)institute of theoretical physics,Academia Sinica,beijing 100080)

The anomaly,or the “V” shape feature,of the anomalous delays of the cros-sing frequencies of 1/2.541]bands observed in Ta isotopes was reproduced very well bythe present calculation based on the mean field theory and was interpreted as the inter-play of the deformation driving effect of the 1/2.541]proton orbit and the pairingmean fields for the first time.

关键词： Band crossing Odd proton nuclei Deformation drive

p and pp Elastic Scattering at High Energies

在线全文

学校读者我要写书评

暂无评论

Communications in theoretical physics 2007年第9期 541-544页

作者： ZHOU Li-Juan~1 MA Wei-Xing~(1,2.1 Collaboration Group of Hadron physics and Non-perturbative QCD Study,Guangxi University of Technology,Liuzhou 545006,China2.institute of High Energy physics,the Chinese Academy of Sciences,beijing 100049,China Collaboration Group of Hadron physics and Non-perturbative QCD Study，Guangxi University of Technology，Liuzhou 545006，China Collaboration Group of Hadron physics and Non-perturbative QCD Study，Guangxi University of Technology，Liuzhou 545006，China institute of High Energy physics the Chinese Academy of SciencesBeijing 100049China

Based on the eikonalized Glauber representation of hadron-hadron scattering,we study the diffractiveprocesses of p and pp elastic scattering at high *** our theoretical calculations and fits to the correspondingexperimental data at high energies and all available momentum transfer,we find that the Pomeron exchange contributionsplay a significant role in description of differential cross section dσ/dt in the whole experimentM *** Pomeronexchange contributions are related to multi-gluon exchanges in QCD,which are color singlet bound state of Reggeizedgluons,such as tensor glueball and ***,we may claim that the p and pp diffractive processes at highenergies s and moderate momentum transfer t would be a good tool to verify the existence of the color singlet multigluonbound states and to test QCD since QCD theory does predict the existence of these ***,we believe thatthe experimental measurement should be done for these diffractive processes.

关键词： pp and p scattering eikonalized Glauber model Reggeon and Pomeron exchanges

GENERAL INTERPOLATION FORMULAS FOR SPACES OF DISCRETE FUNCTIONS WITH NONUNIFORM MESHES

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 Computational Mathematics 1995年第1期13卷 70-93页

作者： Zhou Yu-lin(institute of Applied physics and Computational Mathematics, {2., China ) 北京应用物理和计算数学所北京

The unequal meshsteps are unavoidable in general for scientific and engineering computations especially in large Scale computations. The analysis of difference schemes with nonuniform meshes is very rare even by use of fully heuristic methods. For the purpose of the systematic and theoretical study of the finite difference method with nonuniform meshes for the problems of partial differential equations, the general interpolation formulas for the spaces of discrete functions of one index with unequal meshsteps are established in the present work. These formulas give the connected relationships among the norms of various types, such as' the sum of powers of discrete values, the discrete maximum modulo, the discrete Holder and Lipschitz coefficients.

关键词： Discrete functions Interpolation Mathematical constants Partial differential equations Difference quotients Real lines Finite difference methods Mathematical theorems Ratios Engineering

Digitalization decoupling method and its application to the phased array in MRI

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2003年第9期 45-51页

作者： SONG Xiaoyu, WANG Weidong, ZHANG Bida, LEI Ming and BAO Shanglian (1. institute of Heavy Ion physics, the {2. Key Laboratory of Medical physics & Engineering, Peking University, {2. 100871, China 2. The General Hospital of PLA, {2. 100853, China 3. institute of 503, Spaceflight Scientific Group Company, {2. 100086, China) institute of Heavy Ion physics，the {2. Key Laboratory of Medical physics & Engineering，Peking University，{2. 100871，China institute of Heavy Ion physics，the {2. Key Laboratory of Medical physics & Engineering，Peking University，{2. 100871，China The General Hospital of PLA，beijing 100853，China institute of 503，Spaceflight Scientific Group Company，beijing 100086，China

A general network decoupling method for phased array radio frequency coil used in magnetic resonance imaging is devel-oped. A more flexible digital approach further simplifies the method, which has an even higher signal-to-noise ratio. The performance ofthe digitalized decoupling method was confirmed by the calculated result by using a high frequency structure simulation software with themethod of finite element for a tree-port phased array RF coil. The consistence was well established between the theoretical and simulatedresults.

关键词： MRI phased array coil decoupling digitalization.