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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,{2. Department of Environment Engineering, peking university, beijing 100871,{2. Chinese Acad Sci Cold & Arid Reg Environm & Engn Res Inst Key Lab Desert & Desertificat Lanzhou 730000 Peoples R China peking Univ Dept Environm Engn Beijing 100871 Peoples R 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 {2. and socio-economic problem in North china. Remote sensing monitored results in 2.00 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 1988-2.00. 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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Categories and characteristics of urban villages by GIS-based analysis:A case study of the Shenzhen Special Economic Zone

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Science china(Technological sciences) 2010年第S1期53卷 150-157页

作者： TONG De1,FENG ChangChun2.LI GuiCai1 & CHEN Peng1,2.1S henzhen Graduate School,peking university,Shenzhen 518055,{2. 2.ollege of Urban and environmental Science,peking university,beijing 100871,{2. 1. Shenzhen Graduate School Peking University Shenzhen 518055 China 2. College of Urban and environmental Science Peking University Beijing 100871 China

Studies on the characteristics of urban villages have attracted much interest in urban ***,how to advance the development of further theoretical analysis and quantitative methodologies,especially in the era that GIS and digital-urban technologies develop rapidly and provide precious resources on spatial issues,has always been a heated debate and *** this paper,a mathematical model based on spatial analysis is introduced to deal with the categorization and characterization of urban villages.A total of 89 urban villages in the Shenzhen Special Economic Zone(SEZ)are used in this case *** ArcGIS tools on buffer analysis,distance and density calculation,and socio-economic and spatial attributes conjunction,urban villages’31 spatial variables in 4 aspects—social,economic,locational,and physical—are extracted,and 6 principal factors are concluded by principal components analysis to indicate the spatial characteristic of urban *** on the 6 principal factors,6 types of urban villages,including rapidly sprawling,large,rapidly industrializing periphery,overcrowded,intensively mobile and economically backward,are divided through the Hierarchical Clustering ***,the spatial features and formation mechanisms of each type of urban villages are ***,the advantages and the shortcomings of the methodology for this specific application are also ***,several guidelines on urban village management and renewal are provided based on the result of type *** outcome of the paper depends on the informational and technological support from the development of digital-city management,and is able to in turn provide basis on monitoring and improving urban villages which can further digital urban framework.

关键词： urban villages GIS-based analysis principal component hierarchical cluster the Shenzhen Special Economic Zone (SEZ)

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The variation in the magnetic fluctuation anisotropy across the front boundaries of magnetic clouds and its geomagnetic response

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Chinese Science Bulletin 2002年第10期47卷 863-867页

作者： LIU Rui & WEI FengsiDepartment of Geophysics, peking university, beijing 100871,{2. Lab for Space Weather, center for Space Science and Applied Research, Chinese Academy of sciences, beijing 100080,{2. Department of Geophysics Peking University Beijing China Lab for Space Weather Center for Space Science and Applied Research Chinese Academy of Sciences Beijing China

A statistical study of magnetic fluctuations near the front boundaries of magnetic clouds is approached with the method of Minimum Variance Analysis, based on the data of ImpS and Wind spacecraft. New discoveries are that (1) fluctuation anisotropy tends to increase across the front boundaries of magnetic clouds; (2. there is a good correlation between the fluctuation anisotropy and the geomagnetic activity indices; and (3) in some cases, although there is southward field component immediately after the front boundary, Kp index descends (or Dst index ascends) with a corresponding decrease of the fluctuation anisotropy; in other cases with no distinct southward field component, Kp index ascends (or Dst index descends) with a corresponding increase of the fluctuation anisotropy. Thus we suggest that the fluctuation anisotropy might be a useful indicator in diagnosing the magnetic activities of magnetic clouds.

关键词： front boundary of magnetic clouds geomagnetic activity fluctuation anisotropy.

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Straight river: its formation and speciality

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Journal of Geographical sciences 2002年第1期12卷 72-80页

作者： WANG Sui-ji1, NI Jin-ren2.(1. Institute of Geographic sciences and Natural Resources Research, CAS, beijing 100101,{2. 2. center for environmental Science, peking university, beijing 100871,{2.) Institute of Geographic sciences and Natural Resources Research CAS 北京 100101 center for environmental Science Peking University 北京 100871

Straight river is generally regarded as one of the typical river patterns in conventional classifications in terms of their channel plain landforms. However, very few straight patterns were found to be distributed in wider spatial and temporal spans in the self-adjusted fluvial rivers. Thus, the questions occur such as that is it possible for a channel takes on a stable straight pattern? What are the main factors controlling the processes of the river pattern formation and transformation from a straight to other patterns? Various theories and hypotheses including geomorphic threshold hypothesis, the extreme hypothesis on energy dissipation rate, the stability theory, etc. have been developed to explain the aforementioned questions, but none of them is sound for the explanation to the straight-river formation. From the modern fluvial plain patterns, the straight patterns are not as stable as other typical patterns which occurred in nature; from the historic records of the river sedimentation, no apparent evidence was found to support the stable straight river evolution. Based on the analysis of existing theories, observations, evolvement processes of the channel patterns in the experimental results, this paper concluded that the straight pattern should not be included as one of the typical patterns that are self-formed and developed. This study is of importance to understanding of the river pattern formation and transformation.

关键词： straight river formation cause evolvement sedimentation

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Effect of external and internal phosphate status on arsenic toxicity and accumulation in rice seedlings

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Journal of environmental sciences 2009年第3期21卷 346-351页

作者： WANG Lihong,DUAN Guilan Research center for Eco-environmental {2.,Chinese Academy of {2.,beijing 100085,china [a]Research center for Eco-environmental {2. Chinese Academy of Sciences Beijing 100085 China

Phosphorus （P） deficiency is thought to exacerbate the arsenic （As） phytotoxicity in paddy rice. The experiments were conducted to investigate the effects of external phosphate supply on As accumulation in rice and its toxicity under phosphate deficiency conditions. Rice seedlings pretreated with a phosphorus deficient nutrient solution （-P） for 14 d accumulated more As than those pretreated with a normal phosphorus supply nutrient solution （＋P）. Rice protreated with -P showed As toxicity symptoms after being exposed to 50 μmol/L arsenate for 4 h, while ＋P rice did not show any toxicity symptoms. Arsenic toxicity symptoms can be alleviated by increasing external P concentrations. The arsenate uptake rate and accumulation corresponded with the As toxicity in rice plants. Arsenic concentrations in rice roots decreased with increasing external phosphate concentrations. The lowest As accumulation and the highest P accumulation were found when the external P concentration reached 100μmol/L. In short, P deficiency increased the sensitivity of rice to arsenate and increasing of external phosphate supply could alleviate As toxicity.

关键词： phosphorus arsenate arsenic toxicity arsenic accumulation rice seedlings

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Population pharmacokinetic model of valproate and prediction of valproate serum concentrations in children with epilepsy

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Acta Pharmacologica Sinica 2004年第12期25卷 10-17页

作者： De-chun JIANG, Li WANG2.Department of Pediatrics, peking university First Hospital, TherapeuticDrug Monitoring and Clinical Toxicology, center of peking university, beijing 100034, china Department of Pediatrics Peking University First Hospital Therapeutic Drug Monitoring and Clinical Toxicology Center of Peking University Beijing 100034 China

AIM: Using sparse data of valproate (VPA) serum concentrations to build a population pharmacokinetic (PPK) model of VPA in Chinese children with epilepsy and to predict serum concentrations for new patients using a Bayesian approach. METHODS: Two hundred epileptic children, whose VPA serum concentrations were collected, were divided randomly into two groups (A and B, n=100 each). The PPK parameter values of group A were calculated to establish a PPK Model by using the NPEM Program of USC*PACK software. Based on it, VPA serum concentrations of group B were predicted with the Bayesian Fitting Program of the USC*PACK software. To assess the accuracy and precision of prediction, a paired-comparisons t-test was run between predicted and ob- served concentrations, and then the mean prediction error (MPE), mean square prediction error (MSPE), root mean square prediction error (RMSPE), and coincidence rates for different percentages of prediction error were all calculated. RESULTS: Optimum PPK parameters were: Ka, 2.52.±2.743 h-1; Vs, 0.32.±0.496 L/kg; and Kel, 0.0438±0.0384 h-1. For group B, there was no significant difference between predicted and observed concentrations. MPE was -0.43 mg/L, MSPE was 115.40 (mg/L)2. and RMSPE was 5.47 mg/L. The coincidence rates for percent- ages of prediction error, which were less than 5 %, 10 %, 15 %, 2. %, 2. %, and 30 %, were 62.%, 74 %, 82.%, 85 %, 89 %, and 93 %, respectively. CONCLUSION: A PPK model of VPA in epileptic children was successfully established. Based on it, VPA serum concentrations can be predicted accurately with a Bayesian approach.

关键词： pharmacokinetics valproic acid epilepsy Bayes theorem USC*PACK software

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β2.Adrenergic receptor on T lymphocytes and its clinical implications

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Progress in Natural Science:Materials International 2009年第1期19卷 17-23页

作者： Xuelai Fan a,Yuedan Wang b,a peking university,School of Pharmaceutical sciences,{2. 100083,china b peking university,School of Basic Medical sciences,{2. 100083,china [a]peking university School of Pharmaceutical Sciences Beijing 100083 China [b]Peking University School of Basic Medical Sciences Beijing 100083 China

Sustained complex cross-talk between the immune system and the nervous system plays a vital role in retaining homeostasis in a healthy *** of the central regulatory mechanisms involved is the existence and functions of β2.adrenergic receptors(β2.R) on T *** article reviews research progress made recently,including the expression of adrenergic receptors on T lymphocytes,the structure and intracellular pathways of β2.R,the activation of β2.R by either endogenous or exogenous agonists,and the effect of β2.R stimulation on T cells which alters T cell proliferation,differentiation,cytokine production and T-helper-mediated antibody ***,we discuss the roles of β2.R played in the pathogenesis and treatment of autoimmune diseases.

关键词： Neuroimmunology β2.adrenergic receptor T cell Autoimmune

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Retrospect and prospect of watershed hydrological model

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Communications in Nonlinear Science and Numerical Simulation 2001年第3期6卷 172-177页

作者： B. CHEN, L. Z. XIA, Z. F. YANG and G. Q. CHEN State Key Laboratory for Studies of Turbulence and Complex Systems / center for environmental {2., peking university, beijing 100871, china Institute of environmental {2., beijing Normal Universitg, State Key Lab. Studs. T./C.S. Center for Environmental Sciences Peking University Beijing 100871 China Institute of environmental sciences Beijing Normal University Beijing 100875 China

A brief review is presented of the development of watershed hydrological models. Conventional Hydrological Model, Grey Hydrological Model, Digital Hydrological Model and Intelligent Hydrological Model are analyzed. The frameworks of Fuzzy Cognitive Hydrological Model and Integrated Digital Watershed Hydrological Model are presented.

关键词： watershed hydrological model digital watershed complex system

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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 {2.,beijing 100871,china Department of Geology College of Environmental Science 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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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,{2. 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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