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The Middle Devonian Bimodal Association of Volcanic Rocks in the Northern Area of East Junggar, Xinjiang

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Acta Geologica Sinica(English Edition) 1992年第2期66卷 141-153页

作者： Han Baofu department of Geology, peking university, beijing department of Geology Peking University Beijing

The Middle Devonian volcanic rocks in the northern area of East Junggar, located between the Ertix andUlungur rivers of northern Xinjiang, may be divided into basic and acid ones. It is evident that a compositionalgap exists between the two groups so that the volcanic rocks are not in line with a calc-alkaline series becausethe intermediate rocks are absent in the area. The fact shows that the volcanic rocks are a typical bimodal asso-ciation. The formation of the bimodal association of volcanic rocks in the area was closely related to continen-tal rifting or continental extension in the Middle Devonian. In such a tectonic setting, magmas were first pro-duced by partial melting of the mantle. Where crustal thinning was greater, the magmas ascended and eruptedon the surface directly so that the basic volcanic rocks formed, but olivine and/or partial pyroxenefractionation occurred in the magmas during their ascent through the thinning crust. On the other hand, wherecrustal thinning was less, ascending mantle-derived magmas reached the lower crust and accumulated there, re-sulting in partial melting of the lower crust and thus giving rise to the contaminated magma which was consoli-dated as acid volcanic rocks on the surface.

关键词： rock REE area The Middle Devonian Bimodal Association of Volcanic Rocks in the Northern Area of East Junggar Xinjiang

Flooding 1990s along the Yangtze River, has it concern of global warming?

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Journal of Geographical Sciences 2001年第1期11卷 43-52页

作者： GONG Dao-yi1, ZHU Jin-hong2, WANG Shao-wu2 (1. Key Laboratory of Environmental Change and Natural Disaster, Institute of Resources Science, beijing Normal university, beijing 100875, china 2. department of geophysics, peking university, beijing 100871, Key Laboratory of Environmental Change and Natural Disaster Institute of Resources Science Beijing Normal University Beijing China department of geophysics Peking University Beijing China

There were a series of severe floods along the middle to lower reaches of the Yangtze River (Changjiang River) in china during the 1990s. The extensive summer (June, July and August) precipitation is mostly responsible for the flooding. The summer rainfall in the 1980s and the 1990s is much higher than that in the previous 3 decades. The means for 1990–1999 is +87.62 mm above normal, marked the 1990s the wettest decade since the 1950s. Six stations with a time span of 1880–1999 are selected to establish century-long rainfall series. This series also shows that the 1990s is the wettest decade during the last 120 years. In the wettest 12 years, four occurred in the 1990s (1991, 1996, 1998 and 1999). Both global and china’s temperature show there is a relative lower air temperature during the 1960–1970s, and a rapid warming in the 1980–1990s. Comparisons of rainfall between 1960–1979 and 1980–1999 show there are dramatic changes. In the cold period 1960–1979, the summer rainfall along the Yangtze River is 3.8 % to 4.7 % below the normal, during the warm period 1980–1999, over 8.4 % to 18.2 % of summer rainfall occurs. Over the whole eastern china, the summer rainfall shows opposite spatial patterns from the 1960–1970s to 1980–1990s. The consistent trend toward more rainfall with global warming is also presented by the greenhouse scenario modeling. A millennial Drought/flood Index for the middle to lower reaches of the Yangtze River showed that although the surplus summer rainfall in the 1990s is the severest during the past 150 years, it is not outstanding in the context of past millennium. Power spectra of the Drought/flood Index show significant interdecadal periods at 33.3 and 11.8 years. Thus, both the natural interdecadal variations and the global warming may play important roles in the frequent floods witnessed during the last two decades.

关键词： summer rainfall Yangtze River global warming interdecadal variation

Study of Photostimulable Luminescence Materials Sr_9Ca(PO_4)_6Cl_2:Eu

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Rare Metals 1989年第4期9卷 49-53页

作者： Song Qingfang china Criminal Police Institute,Shenyang 110035Wang Yanji Zhao Wei Su Mianzeng department of Chemistry,peking university,beijing 100871 china Criminal Police Institute 辽宁沈阳北京大学北京

The polycrystalline Sr_9Ca(PO_4)_6Cl_2:Eu has been synthesized by solid state *** reaction condition,the appropriate raw materials and their quantity used,which may affect the photostimulable luminescence (PSL),have been systematically inves- *** properties of this PSL phosphor as a material for storing and reproducing the X-ray image in computer-aided radiography have been reported briefly.

关键词： Eu PO4 Study of Photostimulable Luminescence Materials Sr9Ca Sr Cl

AlkB recognition of a bulky DNA base adduct stabilized by chemical cross-linking

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Science china Chemistry 2010年第1期53卷 86-90页

作者： YI ChengQi1 & HE Chuan1,2 1department of Chemistry,university of Chicago,Chicago,Illinois 60637,USA 2department of Chemical Biology,College of Chemistry and Molecular Engineering,peking university,beijing 100871,china 1. department of Chemistry University of Chicago Chicago Illinois 60637 USA2. Department of Chemical Biology College of Chemistry and Molecular Engineering Peking University Beijing 100871 China

*** AlkB is a direct DNA/RNA repair protein that oxidatively reverses N1 alkylated purines and N3 alkylated pyrimidines to regular *** crystal structures have revealed N1-methyl adenine(1-meA) recognition by AlkB and a unique base flipping mechanism,but how the AlkB active site can accommodate bulky base adducts is largely *** a previously developed chemical cross-linking technique,we crystallized AlkB with a duplex DNA containing a caged thymine base(cagedT).The structure revealed a flexible hairpin lid and a reorganized substrate recognition loop used by AlkB to accommodate *** observations demonstrate,at the molecular level,how bulky DNA adducts may be recognized and processed by AlkB.

关键词： DNA/RNA repair AlkB caged thymine disulfide cross-linking bulky base adduct

Bifurcation stabilization of nonlinear systems by dynamic output feedback with application to rotating stall control

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Science china(Information Sciences) 2012年第1期55卷 200-213页

作者： CHEN PengNian1,QIN HuaShu2,WANG Yong3&HONG YiGuang2 1department of Mathematics,china Jiliang university,Hangzhou 310018,china 2Institute of Systems Science,The Chinese Academy of Sciences,beijing 100080,china 3department of Mechanics,peking university,beijing 100871,china 1. department of Mathematics China Jiliang University Hangzhou 310018 China2. Institute of Systems Science The Chinese Academy of Sciences Beijing 100080 China3. Department of Mechanics Peking University Beijing 100871 China

The paper deals with the problem of stabilization of stationary bifurcation solutions of nonlinear systems via dynamic output *** is emphasized that the parameter of the system is not directly *** introduce the concepts of uniform observability of the inverse of a function of state and input and N-order-input-to-state bifurcation *** on the concepts,we propose a new method for designing dynamic compensators that guarantee bifurcation stability for the closed-loop *** an example,we apply the general theory to active control of rotating stall in axial flow compressors by designing a stabilizing dynamic compensator for the three-state Moore-Greitzer model with a class of cubic compressor characteristics.

关键词： bifurcation control uniform observability dynamic output feedback rotating stall

INTERACTION BETWEEN Cu AND LIQUID Sn(II)——SEM OBSERVATION OF INTERMETALLIC GROWTH

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Acta Metallurgica Sinica(English Letters) 1993年第8期6卷 81-86页

作者： ZHANG Qiyun LIU Shuqi XU Yaping peking university,beijing,china professor,department of Chemistry,peking university,beijing,100871,china

The features of Cu_6Sn_5 growing slowly at lower temperature and growing rapidly up over 350℃,and or Cu_3Sn growing at higher temperatures,bave been detailedly observed under *** increase of Pb content seems to inhib... 详细信息

关键词： Cu liquid Sn Cu_6Sn_5 Cu_3Sn lead wire solderability

MORPHOLOGICAL TRANSITION BETWEEN VESICLES AND TUBULES FOR A GLYCOPOLYMER-CONTAINING AMPHIPHILIC DIBLOCK COPOLYMER IN AQUEOUS SOLUTIONS

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Chinese Journal of Polymer Science 2001年第3期19卷 297-301页

作者： Zi-chen Li Yue Shen Yu-zeng Liang Fu-mian Li department of Polymer Science & Engineering College of Chemistry peking university beijing 100871, china beijing Univ Coll Chem Dept Polymer Sci & Engn Beijing 100871 Peoples R China

The morphological transition of molecular assemblies in aqueous solutions for a new amphiphilic diblock copolymer induced by changing the initial solvent conditions was studied by transmission electron microscopy (TEM). The copolymer was polystyrene(77)-b-poly[2-(beta -D-glucopyranosyloxy)ethyl acrylate (6)] (PSt(77)-b-PGEA(6)) and the solvent was a mixture of DMF and THF. PSt(77)-b-PGEA(6) yields vesicles and tubules when it is initially dissolved in THF and DMF respectively. The morphological transition between vesicles and tubules can be achieved by simply varying the amounts of THF and DMF, or changing the temperature at which the aggregates were prepared.

关键词： block copolymer amphiphile glycopolymer self-assembly tubule vesicle

On semisymmetric cubic graphs of order 6p^(2)

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Science china Mathematics 2004年第1期47卷 1-17页

作者： LU Zaiping, WANG Changqun & XU MingyaoLMAM, School of Mathematical Sciences, peking university, beijing 100871, china department of Mathematics, Zhengzhou university, Zhengzhou 450052, chinaPresent address: department of Mathematics, Qufu Normal university, Qufu 273165, china. 1. LMAM School of Mathematical Sciences Peking University 100871 Beijing China 3. department of Mathematics Zhengzhou University 450052 Zhengzhou China

A graph Γ is said to be G-semisymmetric if it is regular and there exists a subgroup G of A := Aut(Γ) acting transitively on its edge set but not on its vertex set. In the case of G = A, we call Γ a semisymmetric graph. The aim of this paper is to investigate (G-)semisymmetric graphs of prime degree. We give a group-theoretical construction of such graphs, and give a classification of semisymmetric cubic graphs of order 6p2 for an odd prime p.

关键词： (G-)semisymmetric graph, symmetric graph, bi-Cayley graph, regular covering, group action.

New color centers and luminescence of BaFI: Eu2+

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Science Bulletin 1997年第15期42卷 1268-1271页

作者： CHEN Wei and SU Mianzeng1. Laboratory of Semiconductor Materials Sciences, Institute of Semiconductor, Chinese Academy of Sciences, beijing 100083, china 2. department of Chemistry, peking university, beijing 100871, china Laboratory of Semiconductor Materials Sciences Institute of Semiconductor Chinese Academy of Sciences Beijing China department of Chemistry Peking University Beijing China

MANY publications have appeared on the photostimulated luminescence (PSL) of alkalineearth mixhalides. Color centers play a very important role in the PSL and X-ray storage imag-ing processes. The F centers, V centers and oxygen-related centers in this kind ofcrystals have been investigated. All these reports provide some useful information to the PSLmechanism and thus improve the practical applications of these materials. New color centers in

关键词： BaFI:Eu2+ color centers photostimulated luminescence.