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Study of spatial distribution of sandy desertification in North china in recent 10 years

Science china Earth sciences 2004年第Z1期47卷 78-88页

作者： WANG Tao, WU Wei, XUE Xian, SUN Qingwei & CHEN GuangtingKey Laboratory of Desert and Desertification, Cold and Arid Regions environmental and Engineering Research Institute, Chinese Academy of sciences, Lanzhou 730000, china Department of Environment Engineering, peking university, beijing 100871, china Key Laboratory of Desert and Desertification Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou China Department of Environment Engineering Peking University Beijing China

Sandy desertification is a land degradation characterized by wind erosion, mainly resulted from the excessive human activities in arid, semiarid and part of sub-humid regions in North china. It is one of main kinds of desertification/land degradation as well as water-soil erosion and salinization in china. Rapid and continuous spread of sandy desertification during last 50 years has created a major environmental and socio-economic problem in North china. Remote sensing monitored results in 2000 showed that the sandy desertified land area has been 38.57× 104 km2. The area of potential to slightly sandy desertified land is 13.93× 104 km2, moderately land 9.977×104 km2, severely land 7.909 ×104 km2 and very severely land 6.756×104 km2. Sandy desertification mainly occurs in the semi-arid mixed farming-grazing zone and its northern rangeland zone, semi-arid dryland rainfed cropping zone and arid oasis-desert margin zone. The average annually developmental rate of sandy desertified land increased from 2,100 km2 ·a-1 in 1976-1988 to 3,600 km2 · a-1 in 1988-2000. The basic status of sandy desertification in North china is 'overall deterioration, while local rehabilitation'. Already achieved rehabilitation results and monitoring assessment show that about 60% of desertified land in North china can be restored under the conditions of rational land-use ways and intensity.

关键词： sandy desertified land, spatial distribution, remote sensing monitoring, last 10 years, North china.

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On the Modular Version of the Gluck-Wolf Theorem

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Acta Mathematica Sinica,English Series 2002年第2期18卷 335-338页

作者： LU Zi Qun school of Mathematical sciences.peking university.beijing 100871.P.R.china E-mail:zqlu@*** school of Mathematical sciences Peking University Beijing P.R. China

Let N be a normal subgroup of a finite group *** be an irreducible Brauer character of *** π is a set of primes and (1)/(1)is a π'-number for any. X ∈IBr_p(G|).If p|G:N|, and N is p-solvable,then G/N has an abelia... 详细信息

关键词： ρ-Brauer character Lifting Brauer character ρ-length

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Developmental sequence of Cambrian embryo Markuelia

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Chinese Science Bulletin 2007年第7期52卷 929-935页

作者： DONG XiPing1,2 1 school of Earth and Space sciences, peking university, beijing 100871, china 2 Laboratory of Palaeobiology & Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of sciences, Nan-jing 210008, china (email: dongxp@***) school of Earth and Space sciences Peking University Beijing China Laboratory of Palaeobiology & Stratigraphy Nanjing Institute of Geology and Palaeontology Chinese Academy of Sciences Nanjing China

Based on more exquisitely preserved specimens of Markuelia hunanensis recently recovered from Middle and Upper Cambrian in western Hunan and in the light of Synchrotron radiation X-ray tomo-graphic microscopy, the developmental sequence from cleavage through organogenesis to the pre-hatching of Cambrian embryo Markuelia, especially the developmental sequence during the pre-hatching stage, i.e. from the earliest period when the scalids and tail spines only took shape to the latest period (just about hatching), is established. This developmental sequence provides a pattern of embryonic development during the pre-hatching stage, which has not been established in the living scalidophorans (priapulids, loriciferans and kinorhynchs). Thus, it not only enriches our knowledge on the embryonic development of the extant descendants of Markuelia, but also opens a new window to the evolution and development of the animal.

关键词：寒武纪蠕虫化石胚胎发育序列两侧对称动物胚胎

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The late Paleoproterozoic extension event:aulacogens and dyke Swarms in the North china craton

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Progress in Natural Science:Materials International 2006年第2期16卷 201-208页

作者： HOU Guiting, LI Jianghai, LIU Yulin and QIAN Xianglin (Key Laboratory of Orogenic Belts and Crustal Evolution, school of Earth and Space sciences, peking university, beijing 100871, china) Key Laboratory of Orogenic Belts and Crustal Evolution School of Earth and Space Sciences Peking University Beijing 100871 China

The extension structures and tectonic implication in the North china Craton ( NCC) are discussed in this paper based on the mafic dyke swarms and geochronology, combining with the geochronology of aulacogens. The late Paleoproterozoic time is the important turning point in the Precambrian evolution of the NCC. The extension system (e.g. aulacogens and dyke swarms) is widespread in the NCC, which marks the carbonization of the NCC with the rigid characteristic similar to the modern plate. The paleostress field modeling suggests that the dyke swarms and aulacogens are arogenic extension marking the start of the supercontinent, not synorogenic and post-orogenic extension. The mafic dyke swarms in the NCC mainly ranged from 1.83 to 1.77 Ga. The extension of the NCC is very limited brittle extension, the average extension ratio is only 0.35% given by mafic dyke swarms extension calculation, so most of extension in the NCC is contributed by the aulacogens. The mafic dyke swarms are related with the aulacogens in the origin.

关键词： North china craton late Paleoproterozoic aulacogens mafic dyke swarms extension.

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Weight hierarchies of linear codes satisfying the Near-Chain condition

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Progress in Natural Science:Materials International 2005年第9期15卷 784-792页

作者： LIU Zihui1** and CHEN Wende2(1. school of Mathematical sciences, peking university, beijing 100871, china 2. Laboratory of Systems and Control and Key State Laboratory of Information Security, Institute of Systems Science, Academy of Mathematics and Systems Science, Chinese Academy of sciences, beijing 100080, china) school of Mathematical sciences Peking University Beijing 100871 China Laboratory of Systems and Control and Key State Laboratory of Information Security Institute of Systems Science Academy of Mathematics and Systems Sciences Chinese Academy of Sciences Beijing 100080 China

The weight hierarchies of a linear [n,k;q] code C satisfying the Near-Chain condition are studied, almost all the weight hierarchies of such code are determined.

关键词： weight hierarchy Near-Chain condition difference sequence linear code.

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Mesozoic thrusts and extensional structures in the Daqingshan orogen, Inner Mongolia, and their temporal and spatial relationship

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Progress in Natural Science:Materials International 2007年第2期17卷 177-186页

作者： QI Guowei, ZHANG Jinjiang , WANG Xinshe and GUO Lei ( Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, china school of Earth and Space sciences, peking university, beijing 100871, china Institute of Geology, Chinese Academy of Geological sciences, beijing 100037, china) Key Laboratory of Orogenic Belts and Crustal Evolution MOE School of Earth and Space Sciences Peking University Beijing 100871 China Institute of Geology Chinese Academy of Geological Sciences Beijing 100037 China

Three large-scale thrusts developed in the Daqingshan orogen, Inner Mongolia, with a northeast-east trending from Louhuashan to Suletu are described in this paper. These northwest-directed thrusts, together with the four tectonic belts (or tectonic sheets) separated by these faults, formed a typical thrusting system. The originally defined Hohhot metamorphic core complex may be a tectonic sheet, making the uppermost tectonic unit of the thrusting system and truncated by the Daqingshan detachment fault on top. The existing tectono-chronological studies showed that the thrusting of this region possibly happened at the same time as the extension along the top detachment fault. This presents that the contraction and extension in Daqingshan orogen were probably simultaneous. The structural pattern of the Daqingshan orogen can be correlated to the Himalayan orogen, and models for simultaneous thrusting and detachment in Himalaya may give a hint for explaining the development of the Daqingshan orogen.

关键词： Daqingshan thrust metamorphic core complex detachment fault contraction-extension transform Himalaya.

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Another Construction of Cartesian Authentication Codes from Geometry of Clasical Groups

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Communications in Mathematical Research 1999年第1期 103-114页

作者： Feng Rongquan (school of Mathematical sciences, peking university, beijing, 100871)

§１．ＩｎｔｒｏｄｕｃｔｉｏｎＬｅｔＳ，ＥａｎｄＭｂｅｔｈｒｅｅｎｏｎ－ｅｍｐｔｙｓｅｔｓａｎｄｌｅｔｆ：Ｓ×Ｅ→Ｍｂｅａｍａｐ．Ｔｈｅｆｏｕｒｔｕｐｌｅ（Ｓ，Ｅ，Ｍ；ｆ）ｉｓｃａｌｅｄａｎａｕｔｈｅｎｔｉｃａｔｉｏ... 详细信息

§１．ＩｎｔｒｏｄｕｃｔｉｏｎＬｅｔＳ，ＥａｎｄＭｂｅｔｈｒｅｅｎｏｎ－ｅｍｐｔｙｓｅｔｓａｎｄｌｅｔｆ：Ｓ×Ｅ→Ｍｂｅａｍａｐ．Ｔｈｅｆｏｕｒｔｕｐｌｅ（Ｓ，Ｅ，Ｍ；ｆ）ｉｓｃａｌｅｄａｎａｕｔｈｅｎｔｉｃａｔｉｏｎｃｏｄｅ（ｓｅｅ［１］），ｉｆ（...

关键词： Authentication Code Finite Field Symplectic Group Unitary Group Orthogonal Group Pesudo symplectic Group

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Economic development and its impact on the environment in east coastal zone of china

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Journal of environmental sciences 1991年第2期3卷 121-126页

作者： Guan BorenCenter of Envirornmental sciences,peking university,beijing 100871,china

This paper discusses briefly the elementary characteristics of the east china economic developing zone, and analyses the condition of urban atmospheric pollution, water pollution and ecological damage in this zone at present. It was brought forward that we must pay great attention to the environmental factors, and make the environmental impact assessment and environmental planning in the process of economic development in this zone.

关键词： east coastal zone ecological environment environmental impact assessment environmental planning.

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Histological observation of some primitive euconodonts of Late Cambrian from Liaoning

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Progress in Natural Science:Materials International 2005年第12期15卷 1084-1088页

作者： GUO Wei,DONG Xiping,ZENG Xiaochun and ZHAO Le Department of Geology,College of environmental Science,peking university,beijing 100871,china Department of Geology Peking University Beijing 100871 China College of environmental Science Peking University Beijing 100871 China

The histology of some euconodonts of Late Cambrian from Benxi and Fuxian County,Liaoning Province is studied by the oil-immersion *** histological characteristics of six primitive species of euconodonts - Proconodontus muelleri,Proconodontus tenuiserratus,Granatodontus ani,Rotundoconus tricarinatus,Teridontus nakamurai and Cordylodus proavus are described in *** dentine and atubular (parallel- and wavy-lamellar) dentine are found in the basal bodies of the primitive euconodonts Proconodontus tenuiserratus and Proconodontus muelleri,*** tubular dentine and spherulitic dentine are also recognized from the basal bodies of Granatodontus ani and Rotundoconus *** the histological characteristics of the studied six species of euconodonts belonging to Proconodontus lineage and Teridontus lineage Sensu Miller (Univ Kansas Paleontol Contr,1980,99: 1-39) seems to be almost the same,euconodonts are proposed as possibly monophyletic herein.

关键词： histology primitive euconodonts Late Cambrian Liaoning

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Prediction, Synthesis and Antigenicity of the Antigenic Peptides of 26kDa Glutathione S-Transferasc of Schistosoma Japonicum (Sj26)

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Chinese Chemical Letters 1999年第1期10卷 27-28页

作者： Jia Xi XU Meng Shen CAI(College of Chemistry and Molecular Engineering, peking university, beijing 100871)(school of Pharmaceutical sciences, beijing Medical university. beijing 100083) Coll. of Chem. and Molec. Eng. Peking University Beijing 100871 China school of Pharmaceutical sciences Beijing Medical University Beijing 100083 China

Six antigenic peptides of 26 kDa glutathione S-transferase of Schistosoma japonicum(Sj26) have been predicted according to their hydrophilicity, flexibility. accessibility. chargedistribution and β -turn in the secondary structure by the determination of its primary structure andsynthesized by solid phase method. All of them showed antigenicity with anti-schistosomajaponicum immunoglobulin polyclonal antibody, anti-Sj-lgG PcAb by Dot-ELISA. Three of themshowed good antigenicity. They would serve as candidates of synthetic anti-schistosomal vaccine.

关键词： SchistosomajQPonicum glutathione S-transferase antigenic peptide peptide vaccine.

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