期刊文献+
共找到24篇文章
< 1 2 >
每页显示 20 50 100
Geological structure of the yellow sea area from regional gravity and magnetic interpretation 被引量:37
1
作者 Zhang Minghua Xu Deshu Chen Jianwen 《Applied Geophysics》 SCIE CSCD 2007年第2期75-83,共9页
Regional gravity and aeromagnetic data covering the area of 32°- 38° N, 118°-127° E at the scale of 1:1,000,000 are coordinated and integrated in a synthetic study of the South China Yellow Sea an... Regional gravity and aeromagnetic data covering the area of 32°- 38° N, 118°-127° E at the scale of 1:1,000,000 are coordinated and integrated in a synthetic study of the South China Yellow Sea and adjacent areas. Depth to magnetic crystalline basement and its structure are determined by magnetic anomaly inversion. Depth to and thickness of the Paleozoic rock are also revealed by gravity anomaly inversion with constrains of the basement and known seismic information from several profiles. Structure units, main faults, basin boundaries, and sub-suppressions are outlined on the basis of gravity data interpretation. 展开更多
关键词 Yellow Sea gravity and magnetic interpretation regional structure oil basins.
下载PDF
URBAN REGIONAL STRUCTURES TRANSFORMATION AND SUSTAINABLE DEVELOPMENT: CASE STUDY OF NANJING MEGALOPOLIS 被引量:1
2
作者 XU Yi-lun WU Qi-yan REN Dong-ming 《Chinese Geographical Science》 SCIE CSCD 2000年第4期32-38,共7页
s: Since 1978, many changes have happened on the background of urban regional structure in China, such as the economy system restructuring, the social transforming including the population flow accelerating and social... s: Since 1978, many changes have happened on the background of urban regional structure in China, such as the economy system restructuring, the social transforming including the population flow accelerating and social demand diversifying and individualizing, the political and economic systems reforms, the rise of the real estate market and the changing relationship between human and nature. From the macroscopic view, these changes make the national urban system to be a newer pattern with a widening gap among the cities in spite of the rising of the cities as a whole. At the same, the urban land use structures are changing with both the trends of intensification and diversification, and the trends of the regional diversification and the economic integration. Besides, urban structures with multiple centers are emerging in several metropolitan areas in China. These changes and trends mentioned above are confirmed by a case study of Nanjing City, a growing metropolitan area in east China. The case study also points out some problems in urban regional structure reforming, especially the poor social and ecological considerations. We should pay more attention to some ideas like balance of intensification and decentralization, development of suburban centers and a reasonable mixing of the functional activities to develop a sustainable urban regional structure. 展开更多
关键词 urban regional structure Nanjing megalopolis sustainable development
下载PDF
Study on the causes and countermeasures for the dislocation of industrial structure in Three Gorges Region 被引量:1
3
作者 Zhou Yinzhen Lu Yaobin 《Ecological Economy》 2006年第1期81-88,共8页
In this paper, the dislocation of industrial structure refers to the inconsisency benveen employment structure and output structure in three industrles. Dnring the past over ten years, with the development of the Thre... In this paper, the dislocation of industrial structure refers to the inconsisency benveen employment structure and output structure in three industrles. Dnring the past over ten years, with the development of the Three Gorges regional social and economic, the industrial structure has optimized and upgraded constantly. However, for kinds of reasons, employment structure transference has lagged far behind output structure transference. In This paper, we try to analyze the causes of dislocation of the Three Gorges Regional industrial structure in analytical method of dislocation of industrial structure, and put forward the fundamental measures to optimize industrial stracture and promote sustainable development of the regional economy. 展开更多
关键词 Three Gorges region (TGR): Dislocation of industrial structure CAUSE COUNTERMEASURE
下载PDF
An Empirical Research of Producer Services' Cluster Development To Regional Industrial Structure Optimization And Upgrading --Based on the Research of 16 central cities' Panel Data in Yangtze River Delta
4
作者 LI Zhen-bo ZHANG ming-dou 《International Journal of Technology Management》 2015年第10期80-87,共8页
Based on the 16 central cities' Panel Data in Yangtze River Delta, location quotient index is used in this paper to measure and analyze the current cluster situation of producer services in Yangtze River Delta, fixed... Based on the 16 central cities' Panel Data in Yangtze River Delta, location quotient index is used in this paper to measure and analyze the current cluster situation of producer services in Yangtze River Delta, fixed effects model of Panel Data model is also used in this paper, and the industrial structure is taken as the dependent variable, while the core explanatory variables is the degree of producer services' cluster development, which is calculated by location quotient, moreover, three control variables introduced in this paper and they are technology advantage, education level and R&D spending, and the mentioned above is to empirically study the impacts of producer services' cluster development to the regional industrial structure. As a result, producer services' cluster development has a significant positive role in promoting the regional industrial structure optimization and upgrading, though the extent is not yet a big push and is still to be further strengthened. In this paper, it has provided a strong evidence that under China' s new normal economy, producer services is badly needed to promote regional industrial structure, and finally it makes specific suggestions based on the current cluster situation of producer services in Yangtze River Delta. 展开更多
关键词 producer services location quotient regional industrial structure optimization and upgrading
下载PDF
Structure and Kinematics of Emission Line Regions in AGN
5
作者 Wolfram Kollatschny 《天文研究与技术》 CSCD 北大核心 2003年第S1期32-41,共10页
I will review some key aspects of the physical conditions of the line emitting regions in AGN. The innermost BLR extends at radii of light days to light weeks from the central ionizing source. There are strong indicat... I will review some key aspects of the physical conditions of the line emitting regions in AGN. The innermost BLR extends at radii of light days to light weeks from the central ionizing source. There are strong indications that the BLR clouds are connected to the outer region of an accretion disk. Trends of radial acceleration of the line emitting clouds have been found in the extended narrow line region. Ⅰ will concentrate on observations taken in the optical wavelength range. Finally, Ⅰ will discuss different methods to determine the mass of the central supermassive black hole from the emission lines. 展开更多
关键词 structure and Kinematics of Emission Line regions in AGN 110 FIGURE
下载PDF
STRUCTURE AND RESTRUCTURING OF BEIJING-TIANJIN-HEBEI MEGALOPOLIS IN CHINA 被引量:1
6
作者 YU Tao-fang 《Chinese Geographical Science》 SCIE CSCD 2006年第1期1-8,共8页
Scott proposes to use the term global city-regions to designate the phenomena that bear some resemblance to the "world cities" firstly identified by Hall and Friedmann and Wolff, and to the "global citi... Scott proposes to use the term global city-regions to designate the phenomena that bear some resemblance to the "world cities" firstly identified by Hall and Friedmann and Wolff, and to the "global cities" of Sassen but whose essential social logic and contextual characteristics have evolved considerably since these pioneering studies were published. In simple geographical terms, a global city-region can be refered to comprise any major metropolitan area or any contiguous set of metropolitan areas together with a surrounding hinterland of variable extent-itself a locus of scattered urban settlements-whose internal economic and political affairs are bound up in intricate ways in intensifying and far-flung extra-national relationships. Scott refers to these extra-national relationships as a symptom of "globalization". As economic motors and political actors, the global city regions have been regarded as crucial parts of development strategies in China. In the "Eleventh Five-year Plan" issued by the National Development and Reform Commission of P. R. China, the Beijing-Tianjin-Hebei Province (Jing-Jin-Ji) region, one of the typical megalopolises or global city regions in the East Coastal China is paid more attention. This paper first analyzes the regional structure of the Jing-Jin-Ji region based on data of the fifth national population census of China. And then through the changes of the population growth, the dynamic process and mechanisms of the regional restructuring in the Jing-Jin-Ji is explored and discussed. 展开更多
关键词 regional structure regional restructuring Beijing-Tianjin-Hebei (Jing-Jin-Ji)
下载PDF
Features of isostatic gravity anomaly and seismic activity in the Central Asian region
7
作者 方盛明 冯锐 +3 位作者 田长征 孙桂香 王志理 李长法 《Acta Seismologica Sinica(English Edition)》 CSCD 1997年第6期105-109,共5页
In this paper, the lithospheric isostatic gravity anomaly with its distribution features in the Central Asian region (30°~70°N, 50°~140°E), according to the research of the lithospheric isostati... In this paper, the lithospheric isostatic gravity anomaly with its distribution features in the Central Asian region (30°~70°N, 50°~140°E), according to the research of the lithospheric isostatic principle, is discussed. Moreover, some primary structures and seismic activities in this region are discussed. 展开更多
关键词 isostatic gravity anomaly regional structure seismic activity the Central Asian region
下载PDF
Prokaryotic Expression and Immunogenicity of Dominant Epitope Region of Goose Parvovirus Structural Protein VP3
8
作者 Li Shuguang Cheng Likun +4 位作者 Li Feng Zhang Na Zhao Jialei Yang Lifang Shen Zhiqiang 《Animal Husbandry and Feed Science》 CAS 2018年第1期68-71,共4页
[Objective] The paper was to develop a subunit vaccine candidate for prevention and control of goose parvovirus infection. [Method]Based on the prokaryotic expression system, the antigenic epitopes and locations of th... [Objective] The paper was to develop a subunit vaccine candidate for prevention and control of goose parvovirus infection. [Method]Based on the prokaryotic expression system, the antigenic epitopes and locations of the structural protein VP3 were predicted by software analysis,and the region displaying a large portion of antigenic epitopes was amplified by PCR. The target VP3 DNA fragment was inserted into pET-30 a-VP3 vector, was transformed into Escherichia coli BL21 competent cells for protein expression and animal test. The SPF chickens were immunized with the recombinant protein and the antisera were collected for neutralization test by using a goose embryo fibroblast. [Result] The recombinant plasmid was constructed, and the target region of VP3 protein was expressed efficiently in a soluble form. The neutralizing titers of antisera could reach up to-2.608. [Conclusion] The target region displaying a large portion of antigenic epitopes of the structural protein VP3 could be expressed efficiently in soluble form, and the expressed protein could induce neutralizing antibodies in SFP chicken. 展开更多
关键词 Goose parvovirus Structural protein VP3 Dominant epitope region Neutralization titer
下载PDF
四川北部地区三次中强历史地震补充考证 被引量:12
9
作者 袁道阳 杨青云 +2 位作者 雷中生 苏琦 吴赵 《地震工程学报》 CSCD 北大核心 2016年第2期226-235,共10页
四川北部地区位于南北强震构造带的中北段,区内活动断裂众多、构造关系复杂、历史及现今地震活动频繁。其中,早期历史地震因时间久远、史料记载简略等原因,其地震基本参数确定和发震构造分析难度较大,存在较大的不确定性。通过对地震史... 四川北部地区位于南北强震构造带的中北段,区内活动断裂众多、构造关系复杂、历史及现今地震活动频繁。其中,早期历史地震因时间久远、史料记载简略等原因,其地震基本参数确定和发震构造分析难度较大,存在较大的不确定性。通过对地震史料的系统梳理和实地考证,对该区1900年以前的3次中强破坏性地震(公元638年松潘地震、1738年南坪地震和1748年松潘北地震)进行补充考证,对其震中位置、震级和烈度等基本参数进行重新核定,并综合分析其发震构造特征。研究结果对分析该区地震活动特征及判定未来强震危险区等均具有重要参考意义。 展开更多
关键词 四川北部地区 历史地震考证 发震构造
下载PDF
Time analysis of regional structure of large-scale particle using an interactive visual system
10
作者 Yihan Zhang Guan Li Guihua Shan 《Visual Informatics》 EI 2022年第2期14-24,共11页
N-body numerical simulation is an important tool in astronomy.Scientists used this method to simulate the formation of structure of the universe,which is key to understanding how the universe formed.As research on thi... N-body numerical simulation is an important tool in astronomy.Scientists used this method to simulate the formation of structure of the universe,which is key to understanding how the universe formed.As research on this subject further develops,astronomers require a more precise method that enables expansion of the simulation and an increase in the number of simulation particles.However,retaining all temporal information is infeasible due to a lack of computer storage.In the circumstances,astronomers reserve temporal data at intervals,merging rough and baffling animations of universal evolution.In this study,we propose a deep-learning-assisted interpolation application to analyze the structure formation of the universe.First,we evaluate the feasibility of applying interpolation to generate an animation of the universal evolution through an experiment.Then,we demonstrate the superiority of deep convolutional neural network(DCNN)method by comparing its quality and performance with the actual results together with the results generated by other popular interpolation algorithms.In addition,we present PRSVis,an interactive visual analytics system that supports global volume rendering,local area magnification,and temporal animation generation.PRSVis allows users to visualize a global volume rendering,interactively select one cubic region from the rendering and intelligently produce a time-series animation of the high-resolution region using the deep-learning-assisted method.In summary,we propose an interactive visual system,integrated with the DCNN interpolation method that is validated through experiments,to help scientists easily understand the evolution of the particle region structure. 展开更多
关键词 Visual analytics Frame interpolation INTERACTIVE Particle region structure
原文传递
Identification and characterization of adult alpha-and beta-globin genes and their genomic arrangement in Pseudosciaena crocea 被引量:1
11
作者 CHU Wuying QIAN Ronghua +3 位作者 WANG Lianshen YU Xiameng YOU Zhenqiang YU Lian 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2006年第4期65-76,共12页
The α- and β-globin genes from Pseudosciaena crocea were cloned by rapid amplification of cDNA 3 '-end ( 3 '-RACE). The cDNA of the α-globin is 595 bp with the ATG start codon located at Position 37, the TAA st... The α- and β-globin genes from Pseudosciaena crocea were cloned by rapid amplification of cDNA 3 '-end ( 3 '-RACE). The cDNA of the α-globin is 595 bp with the ATG start codon located at Position 37, the TAA stop codon at Position 469 and the AATAAA polyadenylation signal at Position 560, which codifies 145 amino acids. The entire open reading frame of the β-globin gene is 447 bp long, which encodes 148 amino acids. Amino acid identity of the α- globin or β-globin gene compared with those reported in other fish species, ranged from 31.9% to 76.4%. When comparing with human α- and β-globins, three important alterations in the structural regions can be noted: ct39 Thr→Gln, α113 His→Tyr and β117 His→Lys. The α-globin has a unique inserted amino acid residue in the 47th position. To understand the process of globin gene duplication and identify the regulatory elements present in the intergenic and intragenic regions of globin genes, the genomic arrangement of α- and β-globin genes was investigated. The results showed that the orientation of the two genes was head-to-head relative to each other. The intergenic region between the translation initiation codons of the linked α- and β-globin genes contains classical promoter elements and the length of it is much shorter than that reported in other fish. 展开更多
关键词 Pseudosciaena crocea GLOBIN gene cloning structural region HEAD-TO-HEAD regulatory elements
下载PDF
Experimental Observation of the Ore-Forming Fluid NaCl-H_2O System in the Earth Interior 被引量:5
12
作者 ZHANG Ronghua and HU Shumin Open Research Laboratory of Geochemical Kinetics, Chinese Academy of Geological Sciences,26 Baiwanzhuang Road, Beijing 100037, China 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 1999年第1期47-64,共18页
The NaCl-H_2O binary system is a major component of solutions coexisting with ores. Observation ofsaturated solutions of NaCl-H_2O by using the method of hydrothermal diamond anvil cell (HDAC) is a new approach tothe ... The NaCl-H_2O binary system is a major component of solutions coexisting with ores. Observation ofsaturated solutions of NaCl-H_2O by using the method of hydrothermal diamond anvil cell (HDAC) is a new approach tothe study of ore-forming fluids. The salinities of NaCl-H_2O solutions in experimental observation are in a range of 32-55%. The observed temperature range is 25℃-850℃, and the pressure range 1 atm-10 kb. In this temperature-pressure range, the supercritical single phase, two phases (L,V) close to the critical state and two-phased (L+V) immis-cible region were observed. And for the salinity of 35% the two phase L+V immiscible region of NaCl-H_2O solutionwas observed in a range of 253-720℃. Another temperature range, 400-817℃, was observed for the immiscible two-phased region of 50% salinity solution. In the high-temperature part of the two-phased immiscible region, the phase na-ture is very unstable. A "critical phenomenon" was observed when the heating path was very close to the critical state.It is possible to observe a 'critical phenomenon': an "explosion" occurred almost constantly at the interface between theliquid and vapour and the interface is rather obscure. A continuous transition between phases L and V could be foundin the immiscible L+V phase while heating continuously. Moreover, as the NaCl-H_2O solution was separated into liq-uid and vapour phases, static charges surrounding each vapour bubble could be seen, and these bubbles were attractedtogether by the static charges to form a special solution structure. Besides, critical states of different salinities of NaCl-H_2O were observed in order to study the properties of the fluids occurring in the rocks in the earth interior, the origin ofore-bearing fluids and the significance of supercritical fluid with respect to the ore formation. The comparison of the sa-linity data of the fluid inclusions in the minerals of ore deposits with observations of NaCl-H_2O under HDAC in theconditions of high temperatures and pressures, combined with further thermodynamic analysis of ore-formation condi-tions would explain in depth the factors determining the ore formation. 展开更多
关键词 critical phenomenon solution structure of the two-phased immiscible region ore-forming hydrothermal solutions
下载PDF
The Unascertained Comprehensive Evaluation on Rationalization of Regional Industrial Structure 被引量:1
13
作者 Xiaoguo Ma Fengqiu Du Kaidi Liu 《Journal of Systems Science and Information》 2006年第3期609-620,共12页
The index system of regional industrial structure is set up. There are two delaminated levels, the top layer evaluation and the bottom one on which the top evaluation is based. That is the characteristics of the evalu... The index system of regional industrial structure is set up. There are two delaminated levels, the top layer evaluation and the bottom one on which the top evaluation is based. That is the characteristics of the evaluation of regional industry structure. The distinction between the two evaluation levels involves the two essentially different two index weights, the unsscertalned comprehensive evaluating model together with division weight are used in the bottom evaluation, and expert weight in the top layer evaluation. In view of the evaluation of regional industrial structure, a sort of comparatively reasonable utility evaluation model is set up. Take the case of Beijing and other six provinces and cities is positively analyzed, which reflects the actual regional industrial structure. 展开更多
关键词 regional industrial structure index system unascertained comprehensive evaluation division weight expert weight
原文传递
Advances in Research on Urban Green Spaces from the Perspective of Urban Geography
14
作者 PENG Danlu 《Journal of Landscape Research》 2021年第1期58-63,共6页
The construction of urban green space has attracted extensive attention of researchers under the background of urban sustainable development and ecological civilization construction.The research of urban green space i... The construction of urban green space has attracted extensive attention of researchers under the background of urban sustainable development and ecological civilization construction.The research of urban green space involves ecology,geography,economics,sociology and other disciplines,among which geography has played an important role in promoting the study and practice of green space in terms of research perspectives,methods and techniques,planning and management.In this paper,the important role of urban geography in green space research is analyzed from defi nition,classifi cation to multidisciplinary background,and the research and practice progress of green space in urban geography are summarized in four aspects:characteristics and division of green space,relationship between green space and urban regional structure,service function of urban green space,and the relationship between green space and urban development.Finally,the practical achievements of green space research are illustrated from the perspective of urban geography. 展开更多
关键词 Urban geography Green space CHARACTERISTICS regional structure Service function
下载PDF
AIM Study on the Reaction of CH2SH Radical with Fluorine Atom
15
作者 Cui-hong Suna Yan-li Zeng +1 位作者 Ling-peng Meng Shi-jun Zheng 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 北大核心 2008年第2期123-130,共8页
The reaction of CH2SH radical with fluorine atom was studied at the levels of B3LYP/6-311G(d,p) and MP2(Full)/6-311G(d,p). The computational results show that the reaction has three channels and proceeds by the ... The reaction of CH2SH radical with fluorine atom was studied at the levels of B3LYP/6-311G(d,p) and MP2(Full)/6-311G(d,p). The computational results show that the reaction has three channels and proceeds by the addition of fluorine atoms on carbon or sulfur sites of CH2SH, forming initial intermediates. The calculated results show that the channel, in which fluorine attaches to the carbon atom to form CH2S and HF, is the most likely reaction pathway. Topological analysis of electron density was carried out for the three channels. The change trends of the chemical bonds on the reaction paths were discussed. The energy transition states and the structure transition regions (states) of the three channels were found. The calculated results show that the structure transition regions are broad in unobvious exothermic reactions or unobvious endothermic reactions, and are narrow in obvious exothermic reactions or obvious endothermic reactions. 展开更多
关键词 Radical reaction Energy transition state structure transition state structure transition region Topological analysis of electronic density
下载PDF
STRUCTURE IN THE PRECORE REGION OF HEPATITIS B CORE GENE AFFECTING ITS EXPRESSION IN E.coil
16
作者 马贤凯 丁广治 +4 位作者 石成华 左平 逯好英 卢秀桂 黄翠芬 《Science China Chemistry》 SCIE EI CAS 1987年第11期1190-1198,共9页
Restriction fragments of HBV-DNA, cleaved by endonuclease HhaI,containing HBcAg gene were trimmed by BAL-31 exonuclease to remove different lengths of the precore sequence.They were inserted into plasmid pUR222 at Eco... Restriction fragments of HBV-DNA, cleaved by endonuclease HhaI,containing HBcAg gene were trimmed by BAL-31 exonuclease to remove different lengths of the precore sequence.They were inserted into plasmid pUR222 at EcoRI site through synthetic linker ligation. Transformants in E.coli BMH7118 showing different levels of HBcAg gene expression were screened and analyzed for their nucleotide sequences in the junction region both by Maxam and Gilbert's chemical degradation method and by M13 chain termination method. Results of sequence analysis of different transformants revealed a partial palindromic (loop and stem) structure, at -7 to -35 nucleotide with regard to ATG of the HBcAg gene as position +1, which has dramatic effect on the level of expression of the inserted gene using the same promoter,SD sequence and identical N-terminus.The amount of HBcAg synthesized differed from 9% in the high expressing plasmid to less than 0.01% of the total cell proteins in the low expressing transformants.The findings were compared to results obtained by other workers in studies of HBcAg expression in procaryotes and their significance in the expression of eucaryotic genes in procaryotic cells were discussed. 展开更多
关键词 HBeAg HBcAg structure IN THE PRECORE region OF HEPATITIS B CORE GENE AFFECTING ITS EXPRESSION IN E.coil
原文传递
Security Structure Transformation in the Asia-Pacific Region and the ASEAN Role
17
作者 Ren Yuanzhe 《Peace》 2016年第4期47-59,共13页
After the end of the cold war, the Asia-Pacific security structure has experienced great changes, especially on the occasion of the current "power-sharing" and "power-shifting" between China and th... After the end of the cold war, the Asia-Pacific security structure has experienced great changes, especially on the occasion of the current "power-sharing" and "power-shifting" between China and the United States in the Asia-Pacific region, the Asia-Pacific security structure adjustment is especially significant. On the one hand, the Alliance structure with the United States as the pivot has experienced transformation from a hub-spokes system to a network, has formed the hierarchical layout of new alliance, quasi-alliance and potential alliance, On the other hand, emerging economies represented by China and Russia, while reinforcing the existing coordinate security framework, reshape the Asia-Pacific and even the whole Eurasia geopolitical posture through strategic initiatives such as the Belt and Road Initiative, the Eurasian Economic Union. As the third force in the Asia-Pacific security architecture, the Association of South-East Asian Nations(ASEAN) with the construction of a series of multilateral security mechanisms provides dialogue platform for the two security architectures led by major countries, and has also become one of the feasible paths to realize the future holistic security architecture in the Asia-Pacific region. Meanwhile, the major countries strategic competitions have intensified, which has gradually eroded the ASEAN ‘s cohesion, neutrality and even the central position in a holistic security architecture. The future's reconstruction of the Asia-Pacific security architecture needs to find new strategic consensus and reconfirm the ASEAN central position. 展开更多
关键词 ASEAN ASIA Security structure Transformation in the Asia-Pacific region and the ASEAN Role
原文传递
Understanding spatial structures and organizational patterns of city networks in China: A highway passenger flow perspective 被引量:17
18
作者 陈伟 刘卫东 +1 位作者 柯文前 王女英 《Journal of Geographical Sciences》 SCIE CSCD 2018年第4期477-494,共18页
The use of multi-perspective and multi-scalar city networks has gradually developed into a range of critical approaches to understand spatial interactions and linkages. In particular, road linkages represent key chara... The use of multi-perspective and multi-scalar city networks has gradually developed into a range of critical approaches to understand spatial interactions and linkages. In particular, road linkages represent key characteristics of spatial dependence and distance decay, and are of great significance in depicting spatial relationships at the regional scale. Therefore, based on highway passenger flow data between prefecture-level administrative units, this paper attempted to identify the functional structures and regional impacts of city networks in China, and to further explore the spatial organization patterns of the existing functional regions, aiming to deepen our understanding of city network structures and to provide new cognitive perspectives for ongoing research. The research results lead to four key conclusions. First, city networks that are based on highway flows exhibit strong spatial dependence and hierarchical characteristics, to a large extent spatially coupled with the distributions of major megaregions in China. These phenomena are a reflection of spatial relationships at regional scales as well as core-periphery structure. Second, 19 communities that belong to an important type of spatial configuration are identified through community detection algorithm, and we suggest they are correspondingly urban economic regions within urban China. Their spatial metaphors include the administrative region economy, spatial spillover effects of megaregions, and core-periphery structure. Third, each community possesses a specific city network system and exhibits strong spatial dependence and various spatial organization patterns. Regional patterns have emerged as the result of multi-level, dynamic, and networked characteristics. Fourth, adopting a morphology-based perspective, the regional city network systems can be basically divided into monocentric, dual-nuclei, polycentric, and low-level equilibration spatial structures, while most are developing monocentrically. 展开更多
关键词 space of flows city network urban economic region urban system monocentric structure polycentric structure community detection
原文传递
Altitude of the upper boundary of AAR based on observations of ion beams in inverted-V structures:A case study 被引量:2
19
作者 CUI YanBo FU SuiYan +5 位作者 ZONG QiuGang XIE Lun SUN WeiJie ZHAO Duo WU Tong George PARKS 《Science China Earth Sciences》 SCIE EI CAS CSCD 2016年第7期1489-1497,共9页
Outflowing ion beams forming four successive inverted-V structures in the energy-time spectrograms of H+, He+, and O+ were observed at an altitude of 3.4 RE by Cluster satellites travelling above the auroral accelerat... Outflowing ion beams forming four successive inverted-V structures in the energy-time spectrograms of H+, He+, and O+ were observed at an altitude of 3.4 RE by Cluster satellites travelling above the auroral acceleration region (AAR) in the southern hemisphere on February 14, 2001. Energization by negative U-shaped potential structures in the AAR is believed to be responsible for the formation of these outflowing ion inverted-V structures. Thus, utilizing the different motion properties of the three ion species, the altitude of the upper boundary of the AAR is estimated to be ~11100 km. Moreover, based on multi-satellite observations, each of these U-shaped potential structures involved in this event crosses the latitudinal direction at ~0.4°–1° invariantlatitude (ILAT), moving poleward at an average speed of ~0.2° ILAT per minute, before disappearing at ~71.5° ILAT. 展开更多
关键词 Outflowing ion beams Inverted-V structure Auroral acceleration region U-shaped potential structure Altitude of upper boundary
原文传递
A LINEAR HYBRID MODEL OF MSE AND BEM FOR FLOATING STRUCTURES IN COASTAL ZONES 被引量:2
20
作者 ZHANG Jun MIAO Guo-ping 《Journal of Hydrodynamics》 SCIE EI CSCD 2006年第6期649-658,共10页
A linear hybrid model of Mild Slope Equation (MSE) and Boundary Element Method (BEM) is developed to study the wave propagation around floating structures in coastal zones. Both the wave refraction under the influ... A linear hybrid model of Mild Slope Equation (MSE) and Boundary Element Method (BEM) is developed to study the wave propagation around floating structures in coastal zones. Both the wave refraction under the influence of topography and the wave diffraction by floating structures are considered. Hence, the model provides wave properties around the coastal floating structures of arbitrary shape but also the wave forces on and the hydrodynamic characteristics of the structures. Different approaches are compared to demonstrate the validity of the present hybrid model. Several numerical tests are carried out for the cases of pontoons under different circumstances. The results show that the influence of topography on the hydrodynamic characteristics of floating structures in coastal regions is important and must not be ignored in the most wave period range with practical interests. 展开更多
关键词 hybrid model Mild Slope Equation (MSE) Boundary Element Method (BEM) marine floating structures coastal regions wave propagation wave force
原文传递
上一页 1 2 下一页 到第
使用帮助 返回顶部