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Association of DNA with nuclear matrix in in vitro assembled nuclei induced by rDNA from Tetrahymena shanghaiensis in Xenopus egg extracts

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Cell Research 1997年第1期7卷 107-117页

作者： CHEN YING BO ZHANG XIU FEN LI ZHONG HE ZHAI(Department of Cell Biology and Genetics, college of life sciences, peking university, beijing 100871) Department of Cell Biology and Genetics College of Life Sciences Peking University Beijing 100871On the occasion of Professor Lu Ji SHI's (L. C. Sze) eightieth birthday we present this paper and extend our sincere greetings to Professor SHI. As we mentioned in our paper in early 1950's it is Professor SHI who first studied the behavior of exogenous homologous desoxyribose nucleoprotein (chromatin) in amphibian eggs. His work later led to the study of nuclear assembly in cell-free system. No words can be said too much to describe Professor SHI's achievements in this field. Since the beginning of our research in this field in 1989 Professor SHI always shows high interests in our work exchanges ideas with us and encourages us. We want to express our deep indebtedness to Professor SHI for his many kindness.Received 31March1997 Revised 7May1997 Accepted 6June1997

The nuclei assembled from exogenous DNA or chromatin in egg extracts resemble their in vivo counterparts in many aspects. However, the distribution pattern of DNA in these nuclei remains unknown. We introduced rDNA from the macronuclei of Tetrabymena into Xenopus cellfree extracts to examine the association of specific DNA sequences with nuclear matrix (NM) in the nuclei assembled in vitro. Our previous works showed the 5'NTS (nontranscription sequences) of the rDNA specifically bind to the NM system in the macronuclei. We show now the rDNA could induce chromatin assembly and nuclear formation in Xenopus cell-free system. When we extracted the NM system and compared the binding affinity of different regions of rDNA with the NM system, we found that the 5'NTS still hold their binding affinity with insoluble structure of the assembled nuclei in the extracts of Xenopus eggs.

关键词： Nuclear assembly nuclear matrix Xenopus egg extracts Tetrahymena rDNA

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On the Linear Representations of Circle Expanding Maps

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Acta Mathematica Sinica,English Series 1994年第2期10卷 202-208页

作者： Cui Guizhen Department of Mathematics peking university beijing, 100871 china 1. Department of Mathematics Peking University 100871 Beijing China

In this paper, it is proved that the two real analytic expanding endomorphisms of the unit circle are equivalent if and only if they have equal eigenvalues along corresponding cycles. A sufficient and necessary condit... 详细信息

关键词： Expand maps Circles representations Real number If and only if Equivalent Unit circle Corresponding

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A counter example for nilpotent groups

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Science china Mathematics 2010年第11期53卷 3041-3048页

作者： LIU HeGuo1, ZHANG JiPing2 & LIAO Jun2 1Department of Mathematics, Hubei university, Wuhan 430062, china 2School of Mathematical sciences, peking university, beijing 100871, china 1. Department of Mathematics Hubei University Wuhan 430062 China2. School of Mathematical Sciences Peking University Beijing 100871 China

Let R be a ring with 1, I be a nilpotent subring of R (there exists a natural number n, such that In = 0), and I be generated by {xj |j ∈ J} as ring. Write U = 1 + I, and it is a nilpotent group with class ≤ n - 1. Let G be the subgroup of U which is generated by {1 + xj|j ∈ J}. The group constructed in this paper indicates that the nilpotency class of G can be less than that of U.

关键词： nilpotency class nilpotent group nilpotent ring Lie ring

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Estimates of solutions of initial-irregular oblique derivative problems for fully nonlinear parabolic equations

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Communications in Nonlinear Science and Numerical Simulation 2000年第4期5卷 174-178页

作者： Guochun WEN (Departmet of Mathematics, peking university, beijing 100871, china e-mail: wengc@***) (Received October 24, 2000) Departmet of Mathematics Peking University Beijing 100871 China

In this paper the initial-irregular oblique derivative problems for fully nonlinear parabolic equations of second order are proposed, and then some a priori estimates of solutions for the above problems are given.

关键词： initial-irregular oblique derivative problems fully nonlinear parabolic equatit

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The relative generalized Hamming weight and the semilinear equivalence of codes

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Science china(Information sciences) 2011年第4期54卷 787-794页

作者： LIU ZiHui 1 & WANG Jie 2 1 Department of Mathematics,beijing Institute of Technology,beijing 100081,china 2 School of Mathematical sciences,beijing university,beijing 100871,china 1. Department of Mathematics Beijing Institute of Technology Beijing 100081 China2. School of Mathematical Sciences Beijing University Beijing 100871 China

Certain equivalent conditions are given for the semilinear equivalence of linear codes by using the relative generalized Hamming weight and the value function.

关键词： value function semilinear equivalence support weight relative generalized Hamming weight

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Synthesis,Structure and Antitumor Activities of Tridccapeptide PSPP3 from Papaver Somniferum Pollen

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Chinese Chemical Letters 1999年第2期10卷 115-116页

作者： Jia Xi XU Sheng JIN(college of Chemistry and Molecular Engineering, peking university, beijing 100871) Coll. of Chem. and Molec. Eng. Peking University Beijing 100871 China

Five analogs and five segments of the Papavor Somniferum pollen tridecapeptidePSPP3 were designed and synthesized by using solid-phase peptide synthesis method. Theirinhibitive activities to human liver tumor cell Bel-7402 were assayed by MTT method and theirsecondary structures in solution were determined by CD spectra. The relationship of the structureand activity was discussed.

关键词： Pollen peptide anti-tumor activity structure and activity

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PROPERTIES OF POLYURETHANE ELASTOMERS BASED ON POLY (OXYETHYLENE-co-OXYTETRAMETHYLENE) DIOL

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Chinese Journal of Polymer Science 2001年第4期19卷 371-376页

作者： Chen-yu Su Guang-li Zhang Hong-zhi Zhang Department of Polymer Science and Engineering college of Chemistry and Molecular Engineering peking university beijing 100871, china peking Univ Dept Polymer Sci & Engn Coll Chem & Mol Engn Beijing 100871 Peoples R China

Polyurethane elastomers derived from 4,4 ' -methylene bis(phenyl isocyanate), butylene glycol and the low oxyethylene moiety content copolyether of tetrahydrofuran and ethylene oxide, obtained by copolymerization using heteropolyacid-ethylene oxide initiator system, were prepared. The polyurethanes exhibited an increased water absorption and much better low temperature resilience, which remained high even at a temperature of -3 degreesC, while that of polyurethane based upon poly(tetramethylene ether) glycol of the 'same molecular weight, i.e. being 2000, and molecular weight distribution, i.e, in the range of 1.4-1.5, starts to decrease dramatically at 5 degreesC.

关键词： polyurethane poly(oxyethylene-co-oxytetramethylene) diol low temperature resilience heteropolyacid-ethylene oxide initiator system

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The study of two-color excitation upconversion of Pr(0.5)Yb(3):ZBLAN

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Science china(Physics,Mechanics & Astronomy) 2006年第2期49卷 169-177页

作者： CHEN Xiaobo1 & SONG Zengfu2 1. Applied Optics beijing Area Major Laboratory, Analysis and testing center, beijing Normal university, beijing 100875, china 2. peking university, Physics School, beijing 100871, china Applied Optics beijing Area Major Laboratory Analysis testing center Beijing Normal University Beijing 100875 China Physics School Peking University Beijing 100871 China

The excited state absorption upconversion of Pr(0.5)Yb(3):ZBLAN glass material, under two-color excitation of the 960 nm semiconductor laser and the Xe lamp light simultaneously, is reported in this article. It was found that the upconversion emission spectra of 480.1, 519.0, 601.9 and 631.8 nm coincide with the common emission spectra. Meanwhile, the upconversion-excitation spectrum has three obvious peaks under two-color excitation, and they respectively correspond to the 856.0 nm upconversion ex-citation transition [1G4(Pr3+)→1I6(Pr3+) and 1G4(Pr3+)→3P1(Pr3+)], the 789.0 nm upconver-sion excitation transition 1G4(Pr3+)→3P2(Pr3+), and the 803.7 nm upconversion excitation transition 3H6(Pr3+)→1D2(Pr3+). The upconversion excitation transition 1G4(Pr3+)→1I6(Pr3+) is strong because its oscillator strength f = 23.040×10?6 is large, which results in a large peak appearing in the upconversion excitation spectrum. That is just the new interesting two-color excitation upconversion luminescence phenomenon of Pr(0.5)Yb(3):ZBLAN induced by one laser and one continuous normal light simultaneously.

关键词： upconversion volumetric three-dimensional display two-color excitation.

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The numerical method for three-dimensional impact with friction of multi-rigid-body system

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Science china(Physics,Mechanics & Astronomy) 2006年第1期49卷 102-118页

作者： ZHAO Zhen1,2, LIU Caishan2 & CHEN Bin2 1. beijing Institute of Graphic Communication, beijing 102600, china 2. Department of Mechanics & Engineering Science, peking university, beijing 100871, china beijing Institute of Graphic Communication Beijing 102600 China Department of Mechanics & Engineering Science Peking University Beijing 100871 China

The differential equations for planar impacts reduce to an algebraic form, and can be easily solved. For three dimensional impacts with friction, there is no closed-form solution, and numerical integration is required due to the swerve behavior of tangential impulse during collisions. The dynamic governing equations in the impact process are built up in impulse space based on the Lagrangian equation in this paper. The coefficient of restitution defined by Poisson is used as the condition of impact termination. A valid nu- merical method for solving three-dimensional frictional impact of multi-rigid body system is established. The singular cases of tangential movement in sticking point are especially noticed and analyzed. Several examples are present to reveal the different kinds of tan- gential movement modes varied with the normal impulse during collision.

关键词： multi-rigid body, impact, friction.

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Combinatorial rigidity of unicritical maps

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Science china Mathematics 2010年第3期53卷 831-848页

作者： PENG WenJuan 1, & TAN Lei 2 1 School of Mathematical sciences, peking university, beijing 100871, china 2 Departement de Mathematiques, Universited’Angers, Angers 49045, France 1. School of Mathematical sciences Peking University Beijing 100871 China2. Departement de Mathématiques Université d’Angers Angers 49045 France

In this paper, we combine the KSS nest constructed by Kozlovski, Shen and van Strien, and the analytic method proposed by Avila, Kahn, Lyubich and Shen to prove the combinatorial rigidity of unicritical maps.

关键词： combinatorial rigidity unicritical maps KSS nest

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