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Extremal Quasiconformal Mappings Compatible with Fuchsian Groups

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Acta Mathematica Sinica,English Series 1996年第3期12卷 285-291页

作者： Shen Yuliang, department of Mathematics peking university beijing, 100871 chinaPresent address: department of Mathematics Suzhou university Suzhou, 215006 china department of Mathematics Peking University Beijing China

For every torsion free Fuchsian group F with Poincaré’s -operator norm ║г║=1, it is proved that there exists an extremal Beltrami differential of F which is also extremal under its own boundary correspondence. It is also proved that the imbedding of the Teichmüller space T(Γ) into the universal Teichmüller space T is not a global isometry unless Γ is an elementary group.

关键词： Extremal quasiconformal mapping Extremal Beltrami differential Fuchsian group Poincaré operater

Mossbauer　Spectra　of　Valleriite　from　china

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北京大学学报(自然科学版) 1997年第2期 40-45页

作者： QIN Shan CAO Zhengmin CHEN Yanjing (department of Geology, peking university, beijing, 100871, china)

在墨铜矿的结构中，Ｆｅ离子可占据硫化物层中四面体和氢氧化物层的八面体两种配位位置。穆斯堡尔谱结果表明：高自旋的Ｆｅ２＋占据四次配位位置，同质异能位移为０．４２～０．４８ｍｍｓ－１、四极分裂为０．８１～１．２８ｍｍｓ－... 详细信息

在墨铜矿的结构中，Ｆｅ离子可占据硫化物层中四面体和氢氧化物层的八面体两种配位位置。穆斯堡尔谱结果表明：高自旋的Ｆｅ２＋占据四次配位位置，同质异能位移为０．４２～０．４８ｍｍｓ－１、四极分裂为０．８１～１．２８ｍｍｓ－１；低自旋的Ｆｅ３＋占据六次配位位置，同质异能位移为０．３２～０．３６

关键词：墨铜矿穆斯堡尔谱配位

Microstructural and deformational studies on mylonite in the detachment faults of Yalashangbo dome, North Himalayan domes zone

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Progress in Natural Science:Materials International 2005年第11期15卷 1005-1013页

作者： ZHANG Bo, ZHANG Jinjiang, GUO Lei and WANG Weiliang (department of Geology, School of Earth and Space Sciences, peking university, beijing 100871, china) department of Geology School of Earth and Space Sciences Peking University Beijing 100871 China

The Yalashangbo dome, located at the eastern end of North Himalayan domes zone, has a geometry and structure similar to those of a metamorphic core complex. Ductile shear zones formed the detachment system around the dome and these zones are composed of garnet-bearing phyllonite, mylonitic schist, mylonitic gneiss and mylonitic granite. Ductile shear fabrics developed well in my-lonitic rocks, and penetrative lineation and foliation were formed by stretched quartz and feldspar and preferred orientation of mica. Polar Mohr diagram method is used to calculate the kinematic vorticity numbers of the shear zones in the detachment system. Results indicate that the shear zone is a thinned shear zone (thinning of 23 % ) in an extensional setting which underwent a general shear dominated by simple shear. Comparison of the vorticity numbers between the northern and southern flanks of the Yalashangbo dome shows that the dome is an asymmetric system formed by a north-northwest-directed detaching unanimously. Statistical fractal analysis shows that the shapes of dynamically recrystallized quartz grains in the mylonites have characteristics of self-similarity, with fractal numbers ranging from 1.05 to 1.18. From these fractal numbers, the strain rate of the rock was deduced from 10-9.2S-1 to 10-7.3S-1, the differential paleao-stress was 13.7-25.6 MPa during the deformation happened at a temperature over 500 ℃. The ductile shear zones in the detachment system around Yalashangbo dome were formed under a high green-schist grade condition or happened simultaneously with the intrusion of granite.

关键词： Yalashangbo dome ductile shear zone kinematic vorticity fractal analysis deformation temperature strain rate.

A study on the possible impacts of climate warming on rice production in china

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Journal of Geographical Sciences 1999年第2期9卷 147-154页

作者： ZHANG Yu WANG Fu-tang (department of geophysics, peking university, beijing 100871, china, Chinese Academy of Meteorological Sciences, beijing 100081, china)

Based on climate change scenarios projected from GCMs (GFDL, UKMO and MPI), this study evaluates possible impacts of climate warming on rice production in china using numerical simulation experiments. A stochastic weather generator is used to make the projected climatic change scenarios suitable to the input of crop model, ORYZA1. The results show that the duration of rice growing season will be lengthened by 6-11 days and the accumulated temperature will increase by 200℃.d-330℃.d when CO2 concentration in the atmosphere doubles. The probability of cool injury in reproductive and grain filling period will decrease while that of heat stress will increase. Rice yield will decrease if cultivars and fanning practices are unchanged. If the dates of rice development stages can be maintained unchanged through cultivar adjustment although rice yield in most parts of the areas will decrease, the decrements will be much less than that when cultivars and farming practices are unchanged.

关键词： climate warming impacts rice model GCMs stochastic weather generator

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

INVESTIGATION　ON　THE　WATER－SOLUBLE　YTTERBIUM　PORPHYRIN　PART　***，COMPOSITION　AND　STRUCTURE

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Chinese Chemical Letters 1995年第2期6卷 147-148页

作者： QianKun ZHUANO Xiao Xia GAO(department of Chemistry, peking university, beijing, 100871) beijing Univ Dept Chem Beijing 100871 Peoples R China

Water-soluble ytterbium complex of tetra-p-sulfonatophenylporphyrin (H2TPPS)with the formulation Yb·TPPS·OH·2 im·3H2O (im=imidazole), stable in pH5 solution, has been synthesized and characterized by clemental analysis, IR and electronic absorption spectroscopy,Its structure is also proposed. The ytterbium atom exbibits a coordination number of seven with the ytterbium atom out of the prophyrin plane.

关键词： J

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

Inclusive　Minimal　Surfacein　G2，n1

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北京大学学报(自然科学版) 1996年第3期 3-7页

作者： MO Miaohuan (department of Mathematics, peking university, beijing, 100871)

刻划了从Ｒｉｅｍａｎｎ面到复Ｇｒａｓｓｍａｎｎ流形的具有拓扑度＞２ｎ（ｇ－１）或′阶有限的一切可兼极小浸入。

关键词：可兼极小浸入 Riemann面复Grassmann流形

A new enzymatic method for determination of E. coli

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Chinese Chemical Letters 1999年第10期10卷 849-850页

作者： Yun Xiang CI Tian Le LI(department of Chemistry, peking university. beijing 100871) beijing Univ Dept Chem Beijing 100871 Peoples R China

beta-Galactosidase, a kind of endoenzyme in E. coli cells. can be released by the pore-forming action of colicin El. and E. coli can be detected rapidly by enzymatic method.

关键词： E-coli colicin E1 enzymatic method