期刊文献+
共找到1,153篇文章
< 1 2 58 >
每页显示 20 50 100
Impact of coupling coordination development of port and city environments on urban economic competitiveness:Evidence from the coastal port cities in eastern China
1
作者 LI Zhen-qiang YI Ying +2 位作者 LI Jia-li YOU Xiao-yue ZHOU Qiu-yang 《Ecological Economy》 2024年第1期53-71,共19页
Promoting the coupling coordination development of port and its hinterland city environments is an important way to improve urban economic competitiveness.Based on relevant data of 13 coastal port cities in eastern Ch... Promoting the coupling coordination development of port and its hinterland city environments is an important way to improve urban economic competitiveness.Based on relevant data of 13 coastal port cities in eastern China from 2000 to 2018,this study explores the coupling coordination development of port and city environments and its impact on urban economic competitiveness by constructing the coupling coordination degree model and the panel threshold model.The research results show that:(1)In terms of the coupling coordination development of port and city environments,most coastal ports and their hinterland cities are in a state of moderate or serious disorder.Overall,the degree of coupling coordination of port and city environments needs to be further improved;(2)The coupling coordination degree of port and city environments has a significant impact on urban economic competitiveness,and this effect gradually increases with the development of the ports and the urban economy.Among the variables that impact the urban economic competitiveness,fixed assets investment and foreign trade are significant factors that can enhance urban economic competitiveness.(3)At present,there is a“U-shaped”relationship between the coupling coordination degree of port-city environments and the urban economic competitiveness.This relationship lies on the right side of the inflection point of the“U-shaped”curve.Therefore,following the concept of assigning priority to ecological development,expanding fixed assets investment and actively developing foreign trade can further enhance the urban economic competitiveness. 展开更多
关键词 coastal ports city environments coupling coordination degree urban economic competitiveness threshold effect
下载PDF
Prospects and limitations of soil amendment and irrigation techniques for the water-saving public urban greenery and ephemeral weed management in the sandy soils of the United Arab Emirates
2
作者 Ayesha ALAM Elke GABRIEL-NEUMANN 《Journal of Arid Land》 SCIE CSCD 2024年第9期1288-1302,共15页
Public urban greenery greatly contributes to the residential and tourist value of cities in the Gulf Region,but due to the hyper-arid climatic conditions,the cost of irrigation and plant maintenance is very high.Exist... Public urban greenery greatly contributes to the residential and tourist value of cities in the Gulf Region,but due to the hyper-arid climatic conditions,the cost of irrigation and plant maintenance is very high.Existing strategies to reduce the monetary and ecological costs involve the cultivation of native xerophytic plantations,and/or the use of soil improvers to increase water-and nutrient-holding capacity of the sandy soils.Various soil improvers based on mineral,organic,or synthetic materials have entered the United Arab Emirates(UAE)market in recent years,but there is considerable uncertainty about how they should best be used in combination with ornamental plant stands involving xerophytic native plants.The present study investigated the effect of soil amendment and deep pipe irrigation on perennial ornamental plant stands involving native plants(Tephrosia appolinea(Gel.)Link in combination with Aerva javanica(Burm.f.)Juss.ex Schult.)and native-exotic plants(T.appolinea in combination with Ruelia simplex C.Wright)either or not topsoil and subsoil amendment with bentonite and hydrophobic sand under the irrigation water supply of less than 50%of reference evapotranspiration(ET0).After one year of cultivation,T.appolinea and A.javanica(native vs.native)produced high biomass and exhibited high water use efficiency(WUE)as compared with T.appolinea and R.simplex(native vs.exotic)combination given that no significant differences were found under the soil amendment treatments.All stands thrived under irrigation water supply far below what is usually supplied to exotic ornamental stands in public parks of the Al Ain City,the UAE.However,subsoil amendment in combination with deep pipe irrigation reduced the occurrence of weeds and increased the overall plant rooting depth.Our results suggest that subsoil amendment and irrigation up to 60-80 cm depth can potentially control ephemeral weed infestation,which is a great challenge in various plant production systems of the Gulf Region.The results of the present study suggest that the impact of soil amendment on the WUE of exotic plants is marginal and might not be economically justified.Replacing exotic with native ornamental plant species seems to have a far greater water-saving potential than the amendment of the soil,while weeds can be suppressed in the absence of topsoil moisture. 展开更多
关键词 native and exotic plant communities competitive strength soil improvers urban plantation subsoil amendment weed management
下载PDF
Relationship between urban eco-environment and competitiveness with the background of globalization: Statistical explanation based on industry type newly classified with environment demand and environment pressure 被引量:3
3
作者 KANGXiao-guang MAQing-bin 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2005年第2期344-349,共6页
Within the global urban system, the statistical relationship between urban eco-environment(UE) and urban competitiveness(UC)(RUEC) is researched. Data showed that there is a statistically inverted-U relationship betwe... Within the global urban system, the statistical relationship between urban eco-environment(UE) and urban competitiveness(UC)(RUEC) is researched. Data showed that there is a statistically inverted-U relationship between UE and UC. Eco-environmental factor is put into the classification of industries, and gets six industrial types by two indexes viz. industries' eco-environmental demand and pressure. The statistical results showed that there is a strong relationship, for new industrial classification, between the changes of industrial structure and evolvement of UE. The drive mechanism of the evolvement of urban eco-environment, with human demand and global work division was analyzed. The conclusion is that the development stratege, industrial policies of cities, and environmental policies fo cities must be fit with their ranks among the global urban system. At the era of globalization, so far as the environmental policies, their rationality could not be assessed with the level of strictness, but it can enhance cities' competitiveness when they are fit with cities' capabilities to attract and control some sections of the industry's value-chain. None but these kinds of environmental policies can probably enhance the UC. 展开更多
关键词 global urban system urban competitiveness urban eco-environment industry structure
下载PDF
Technological Innovation: A Primary Driver to Promote Global Urban Common Prosperity——An Analysis of Factors Influencing the Competitiveness of 1,007 Cities around the World 被引量:6
4
作者 Ni Pengfei Marco Kamiya +2 位作者 Li Bo Liu Xiaonan Li Qihang 《China Economist》 2020年第3期28-48,共21页
Common prosperity,an important goal of human development,increasingly has to be achieved through the common prosperity of cities.The research into and discovery of the determinants which create differences in urban ec... Common prosperity,an important goal of human development,increasingly has to be achieved through the common prosperity of cities.The research into and discovery of the determinants which create differences in urban economic competitiveness is of great signi ficance as,thereby,the research and expected discovery can help with the formulation of relevant policies for development,competition,and cooperation to promote win-win conditions among cities.However,such research is still rare.Based on the economic competitiveness data of 1,007 cities,this paper uses OLS regression and Shapley-value based decompositions regression to analyze factors affecting the economic competitiveness of global cities and differences that the cities made.Combined with quantile regression,studying the law of changing of each factor's effect on cities with different levels of economic competitiveness is of theoretical and practical signi ficance.The study findings are as follows.(1)The variability of global urban economic competitiveness is quite large.Cities in North America and Europe are still the benchmarks of global urban economic prosperity.(2)Financial services,technological innovation,industrial system,business environment,institutional environment,infrastructure,among other factors,have signi ficant impacts on the economic competitiveness of cities.(3)The primary factor that in fluenced the variability in economic competitiveness is technological innovation.(4)The ranking of the main in fluencing factors varied slightly between cities at different levels of economic competitiveness.These indicate that the international community should promote innovation in and diffusion of science and technology to achieve common prosperity by narrowing the gap between cities.The relevant decision-making departments,e.g.urban planning departments with strong economic and finance expertise of the cities in different development zones should adopt different measures in accordance with their actual situations. 展开更多
关键词 urban economic competitiveNESS common PROSPERITY Shapley value QUANTILE regression
下载PDF
Competitive adsorption and mobility sequence of heavy metals in urban soils of southeastern China 被引量:1
5
作者 ZHANG Ming-kui FANG Li-ping HUANG Chang-yong 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2006年第2期329-333,共5页
Heavy metals can be introduced into urban soils at the same time. Therefore, their selective retention and competitive adsorption by the soils become of major importance in determining their availability and movement ... Heavy metals can be introduced into urban soils at the same time. Therefore, their selective retention and competitive adsorption by the soils become of major importance in determining their availability and movement throughout the soil. In this study, the availability and mobility of six heavy metals in eight urban soils collected from different cities of Zhejiang Province, southeastern China were assessed using distribution coefficients(Kd) and retardation factor(Rf). The results showed that there were great differences in the Kd and Rfamong the tested soils. The adsorption sequences were Cr〉Pb〉Cu〉Cd〉Zn〉Ni, and the Kd decreased with increasing levels of metal addition. Ni generally has the lowest Rf values followed closely by Cd, and Zn whereas Cr and Pb reached the highest values. The results suggest that Ni and Zn have the highest mobility associated to the lowest adsorption, Cr and Pb present the opposite behavior. Correlation analysis indicates that soil pH, CaCO3 content, and cation exchange capacity (CEC) are key factors controlling the solubility and mobility of the metals in the urban soils. 展开更多
关键词 competitive adsorption mobility sequence heavy metal urban soil
下载PDF
Evaluation on Urban Tourism Competitiveness of Beibu Gulf Rim Based on the Entropy Approach
6
作者 Yafen HUANG Hua QUAN 《Asian Agricultural Research》 2019年第10期1-6,10,共7页
The tourism competitiveness of the cities around the Beibu Gulf was studied using the entropy method from the perspective of the 14 indexes of tourism current competitiveness,tourism support competitiveness and touris... The tourism competitiveness of the cities around the Beibu Gulf was studied using the entropy method from the perspective of the 14 indexes of tourism current competitiveness,tourism support competitiveness and tourism potential competitiveness.The results show that the cities of Sanya,Nanning and Haikou have the stronger competitiveness;the cities of Zhanjiang,Beihai,Chongzuo and Maoming have moderate competitiveness;and the cities of Yulin,Qinzhou,Yangjiang and Fangchenggang have the weak competitiveness.According to the analysis of the index weight and comprehensive ranking,almost each aspect contributes to the city competitiveness.The index weights of the tourism current competitiveness,tourism support competitiveness and tourism potential competitiveness are 0.27222,0.3938 and 0.33398,respectively.Based on the niche theory,the article put forward the strategies:dislocation development,balanced development and regional tourism competition and cooperation development. 展开更多
关键词 ENTROPY APPROACH urban AGGLOMERATION in Beibu GULF Rim tourism competitiveNESS NICHE theory
下载PDF
Putting Places First in Competitive Urban Transformation European Urban Creativity Perspectives and the City of Sarajevo
7
作者 Denis Zvizdic MejremaZatric Mirsad Mustovic 《Journal of Civil Engineering and Architecture》 2014年第5期649-662,共14页
The inter-urban competition seems to be of paramount importance for city-development today. The extensive reliance of competitiveness-oriented urban governance agendas on the knowledge-based, "new" economy, introduc... The inter-urban competition seems to be of paramount importance for city-development today. The extensive reliance of competitiveness-oriented urban governance agendas on the knowledge-based, "new" economy, introduced the notion of "creativity" into discussion on the future of urban development. Though still on the margins of serious urban theory, the discourse on "creative cities" that emerged in the early 2000s, has already had massive influence on the ways in which cities are managed and transformed in Europe. After examination of how the competitiveness-oriented strategies based on creativity and related to the qualities of place increase cultural and social sustainability of urban transformation and development, this paper briefly rethinks the current urban development policy of the city of Sarajevo in relation to the notion of "place", by leaning on the contemporary European urban development paradigm. The conclusion points out that the sustainable increase of urban competitiveness in Sarajevo should be pursued by the development projects of urban transformation promoting creative knowledge sector, based on the inclusive cultural urban narratives related to places, thus assuring simultaneous growth of creative knowledge industries and preservation of diverse social geography. 展开更多
关键词 PLACE urban competitiveness creative city social sustainability.
下载PDF
Competitive Aspects in the Metropolitan Region of Recife Bidding Terms for the Delegation of Its Urban Bus System
8
作者 Fernando Oliveira Rolim Enilson Medeiros dos Santos Leonardo Herszon Meira 《Journal of Traffic and Transportation Engineering》 2014年第2期72-84,共13页
This paper discusses aspects related to competitiveness in the ITB (invitation to bid) of the public tender for the concession of the urban bus public transport services in the RMR (Metropolitan Region of Recife) ... This paper discusses aspects related to competitiveness in the ITB (invitation to bid) of the public tender for the concession of the urban bus public transport services in the RMR (Metropolitan Region of Recife) in the Brazilian northeastern region. The bid was made public through a consortium formed by the two major cities of the RMR--Recife and Olinda, and the government of the State of Pernambuco. Throughout the paper, the basic features of the bidding terms are presented and some aspects of these characteristics that undermine competitiveness are pointed out and submitted to criticisms. Aspects such as the small number of lots, the lack of diversification of lot sizes and the possibility of forming consortia with unlimited number of participants were targeted. In order to prove the criticisms stated, a simulation of an arrangement amongst incumbents is presented, based on the rules of the tender, in which the allocation of incumbents ex post bidding does not differ from the ex ante scenario. Thus, the main objective of this article is to assess whether good practices that foster competition were followed by the ITB and the main conclusion is that competitiveness was put in jeopardy. 展开更多
关键词 COMPETITION competitive tendering urban buses public transport.
下载PDF
Study on the Role of Creative Industries in Urban Competitiveness
9
作者 Da Deng 《管理科学与研究(中英文版)》 2013年第3期31-34,共4页
关键词 摘要 编辑部 编辑工作 读者
下载PDF
Dynamic Evaluation on Regional Tourism Competitiveness:Urban Agglomeration of Shandong Peninsula,Eastern China 被引量:2
10
作者 Li Xue Dong Suocheng +1 位作者 Jin Xianfeng Zhang Guanghai 《Chinese Journal of Population,Resources and Environment》 2009年第3期30-41,共12页
The article establishes the appraisal index system for entire urban agglomeration and its interior cities individually,concretely including five aspects:driving forces for tourism development,the level of tourism deve... The article establishes the appraisal index system for entire urban agglomeration and its interior cities individually,concretely including five aspects:driving forces for tourism development,the level of tourism development,tourism impacts,tourism economic connection and tourism contributions of different cities to the whole urban agglomeration.As tourism competitiveness has the characteristics of comprehensiveness,systematicness and dynamicness,the article attempts to apply the structural prediction means of system dynamics to evaluating tourism competitiveness,aiming to provide some research methods and analysis ideas for tourism competitiveness measurement and trends analysis in urban agglomeration.Taking Shandong Peninsula urban agglomeration as the study area,the article simulates and analyzes the tourism competitiveness trend of the whole region and its interior cities from 2005 to 2020,and the result reflects that integrated development and regional combination of tourism are important means to upgrade tourism competitiveness in this region. 展开更多
关键词 regional tourism competitiveness system dynamics dynamic evaluation Shandong Peninsula urban agglomeration
下载PDF
Research on Impact Mechanism and Power System of Urbanization in West China 被引量:1
11
作者 WU Xiao, ZHANG Pei College of Architecture, Xi’an University of Architecture and Technology, Xi’an 710055, China 《Asian Agricultural Research》 2011年第12期56-61,共6页
Based on the current situation of urbanization development in West China, this paper analyses main factors responsible for sluggish urbanization in West China as follows: impact of environment factor, impact of popula... Based on the current situation of urbanization development in West China, this paper analyses main factors responsible for sluggish urbanization in West China as follows: impact of environment factor, impact of population quality and quantity, lagging of public product service, stagnancy of technological development, backwardness of slow growth, and rigidity of system building. And then this paper analyses the restriction mechanism of urbanization in West China: at the superficial level, the constraints of urbanization in West China arise from the shortage of capital; at the profound level, the backward culture contributes to the constraints of urbanization in West China. The thread of resolving restriction mechanism of urbanization in West China is put forward from system, economy and culture. On the basis of this thread, we construct the power system for the development of urbanization in West China. The power system for urbanization in West China should be propelled by "four forces", namely, pull of external forces, cohesive strength of regional market environment, expansion power inside countryside, traction of industrial structure adjustment. Innovation is the engine of impetus for urbanization in West China; spatial clustering and modernization of industry is the major driving force for urbanization; the government behaviour, driving of foreign investment, great projects and other forces are supplementary power. Via the main power, we should take the market as medium to achieve the role of power in promoting urbanization. 展开更多
关键词 WEST China urbanIZATION RESTRICTION MECHANISM powe
下载PDF
INFLUENTIAL FACTORS COMBINATION AND COMPETITIVE ADVANTAGES IN STAGES OF URBAN COMPETITIVENESS——Case Study of Suzhou in China
12
作者 yruTao-fang GUCHao-lin 《Chinese Geographical Science》 SCIE CSCD 2004年第3期202-208,共7页
The urban competitive advantages rely on the combination and interaction of influential factors. As a dynamic progressive process, the city at different time has different competition influential factors combination. ... The urban competitive advantages rely on the combination and interaction of influential factors. As a dynamic progressive process, the city at different time has different competition influential factors combination. Because of this, the urban competitive advantages take on time-series characteristics. Stages of urban competition can be summed up into three ones, the basic factor-driven, the investment-driven and the innovation-driven. The finding of the study on the stages of urban competitive advantages in Suzhou is that in the current stage of Suzhou its competitive advantage is the investment-driven. The investment, especially FDI, plays remarkable functions for Suzhou competition with other cities. 展开更多
关键词 Suzhou City urban competition competitive advantage influential factors combination
下载PDF
EXTERNAL SOURCES OF URBAN COMPETITIVE ADVANTAGES IN CHINA
13
作者 YUTao-fang GUChao-lin CHENXiu-ying 《Chinese Geographical Science》 SCIE CSCD 2005年第2期95-102,共8页
Urban competition refers to capacities of cities for attracting, capturing, controlling, dominating and transforming certain resources during urban development, and capacities for wealth creating, life-standard improv... Urban competition refers to capacities of cities for attracting, capturing, controlling, dominating and transforming certain resources during urban development, and capacities for wealth creating, life-standard improving and sustainable development maintenance. This paper first analyzes the external sources of urban competitive advantages: the global network-based advantages and the location-based ones. Then with the aid of method of principal component analysis in SPSS 10.0 for Windows, the Chinese urban global and local competitive advantages are explored. The finding is that the global network-and location-based advantages are remarkable for the cities in the eastern China. While for those in the western and the middle regions, affected by much lower regional competitive advantages and lower degrees of urban-regional integration, the urban competitive advantages are deeply influenced and weakened. 展开更多
关键词 urban competitiveness global network-based advantages location-based advantages Chinese cities
下载PDF
Evolution of Industrial Competitiveness Based on Evaluation of Urban Competitiveness of Dongguan City:A Case Study of Songshan Lake High-tech Zone
14
作者 TANG Shiyu LU Bin HE Dongran 《Journal of Landscape Research》 2020年第3期57-64,共8页
Based on the theoretical system of urban competitiveness,the evaluation model of urban competitiveness from the perspective of competition and cooperation was established.According to the significance index and explan... Based on the theoretical system of urban competitiveness,the evaluation model of urban competitiveness from the perspective of competition and cooperation was established.According to the significance index and explanatory index,the urban competitiveness was divided into urban comprehensive competitiveness(UC),urban internal node competitiveness(NC)and external competitiveness of urban network(EC).The scores and rankings of UC,NC and EC in 2006,2010 and 2015 were obtained by conducting the comprehensive evaluation of the urban competitiveness of Dongguan City with integrated usage of the principal component analysis and Technique for Order Preference by Similarity to an Ideal Solution and the data of other 20 cities in Guangdong province,Hong Kong and Macao.The research showed that the competitiveness of Dongguan City has been greatly improved during the decade of 2006–2015,and the regional cities in Guangdong Province had significant differences,which are reflected in the two dimensions of urban internal node competitiveness(NC)and external competitiveness of urban network(EC).Based on this,this study further analyzed Dongguan’s urban competitiveness from two dimensions of NC and EC,and took Dongguan Songshan Lake High-tech Zone as an example to study how to promote Dongguan’s urban competitiveness from the industrial level. 展开更多
关键词 Dongguan Songshan Lake High-tech Zone External competitiveness of urban network Improvement of comprehensive competitiveness
下载PDF
URBAN COMPETITIVE PATTERN AND ITS CHANGES IN CHINA 被引量:5
15
作者 DOU Wen-zhang LI Guo-ping +2 位作者 GAN Ying-jin WANG Li-ming YANG Kai-zhong(Department of Urban and Environmental Sciences, Peking University, Beijing 100871, P R. China) 《Chinese Geographical Science》 SCIE CSCD 2000年第2期105-112,共8页
With the national economy’s transition from a planning one to a market one, the factors affecting regional economic pattern has changed greatly. In this paper we first construct an index system for evaluating competi... With the national economy’s transition from a planning one to a market one, the factors affecting regional economic pattern has changed greatly. In this paper we first construct an index system for evaluating competitiveness of Chinese cities based on modern competitive advantage theory. With principal component analysis and cluster analysis methods, we compare the factors affecling cities’ integrated competitiveness in 1990 and 1997. We find that four major factors are capital (including investment, FDI and urban financial revenue ), urban ithestructure (transporiation and communication, urbanization level, education etc. ), industrial performance and structure, degree of market openness and that these factors have become more advanced and complicated since 1990. Most Chinese cities are transforming from productive factors-oriented type to investment-oriented type and a few are becoming innovation oriented. The integrated competitiveness is closely related to cities’ scale, urban function, regional policy and degree of market openness and displays an uneven spatial pattern. The difference between the south and the north and the difference between the west and the east co-exist bul the former has been more larger. Finally, we discuss the mechanism behind the pattern and attribute the unevenness to change of factors dominating the cities’ compehtiveness regional innovation capacity and geographical differenceof traditional culture. 展开更多
关键词 urban integrated competitiveNESS competitive PATTERN China’s CITIES
下载PDF
Conceptual Model for Urban Competitiveness 被引量:1
16
作者 Yongqiang Li 《Chinese Business Review》 2005年第9期6-9,14,共5页
Urban competitiveness is always the focus of researches on urban economy. The variety of definitions and evaluation systems of urban competitiveness are the results of lack of accurate and comprehensive understanding ... Urban competitiveness is always the focus of researches on urban economy. The variety of definitions and evaluation systems of urban competitiveness are the results of lack of accurate and comprehensive understanding on urban competitiveness. This paper reviews five groups of definitions on urban competitiveness and establishes a conceptual model for urban competitiveness. 展开更多
关键词 urban competitiveness conceptual model competitiveness
下载PDF
How to Improve Urban Competitiveness
17
作者 Yongqiang Li 《Chinese Business Review》 2005年第2期1-11,共11页
Urban competitiveness has been the hot topic for researches and studies over years. The aim of this paper is to elaborate urban competitiveness. First, definition of competitiveness is discussed in detail and then the... Urban competitiveness has been the hot topic for researches and studies over years. The aim of this paper is to elaborate urban competitiveness. First, definition of competitiveness is discussed in detail and then the differences of competitiveness of nations and enterprises are presented. In Section 2, urban competitiveness is defined. Since the assessment of urban competitiveness is the focus of many studies, Section 3 elaborates four models or frameworks for assessing urbancompetitiveness. Last, but by no means the least, Chengdu has been discussed as a case on how to improve urban competitiveness. Three suggestions are put forward, which are clustering strategy, more efficient governance and urban marketing campaigns respectively. 展开更多
关键词 urban competitiveness urban marketing clustering competitiveness
下载PDF
A field experimental study on the impact of Acer platanoides,an urban tree invader,on forest ecosystem processes in North America
18
作者 Wei Fang Xianzhong Wang 《Ecological Processes》 SCIE EI 2020年第1期93-107,共15页
Background:Invasive species affect community dynamics and ecosystem functions,but the mechanisms of their impacts are poorly understood.Hypotheses on invasion impact range from Superior Competitor to Novel Function,fr... Background:Invasive species affect community dynamics and ecosystem functions,but the mechanisms of their impacts are poorly understood.Hypotheses on invasion impact range from Superior Competitor to Novel Function,from Enemy Escape to Microbial Mediation.In this study,we examined the effects of an urban tree invader,Acer platanoides(Norway maple,NM),on a mesic deciduous forest in contrast to its native congener Acer rubrum(red maple,RM)with a split-plot design experiment.A total of 720 maple seedlings were transplanted to 72 plots under 24 trees of three canopy types.The three experimental treatments were removal of resource competition at above-and belowground and removal of leaf-litter effect.Soil moisture and nitrogen-related microbial activities were followed for each plot.Results:We found that partial canopy removal increased canopy openness and light transmission to the forest floor,but to a greater extent under NM than under RM trees.NM seedlings were more shade tolerant than RM seedlings in height growth.During the reciprocal transplantation in the mixed forest,biomass accumulation of NM seedlings under RM trees were twice as much as under NM,while that of RM seedlings under NM trees was 23.5%less than under RM.Soil net nitrification and relative nitrification were significantly higher,but mineralization rate was much lower under NM than under RM trees,which would lead to faster N leaching and lower N availability in the soil.Plots with litter removal had significantly higher seedling mortality due to herbivory by the end of 2 years,especially for NM seedlings under NM trees.Trenching enhanced soil water availability but there was no difference among canopy types.Conclusions:Our results demonstrated that invasion of NM not only altered forest canopy structure but also changed herbivory rate for seedlings and N dynamics in the soils.NM seedlings were more shade tolerant under NM canopies than RM seedlings and were more protected by NM litter under NM canopies than under RM canopies.These altered biotic and abiotic environments will likely facilitate further invasion of NM in the forests,hence positive feedbacks,and make it an increasingly serious tree invader in North America. 展开更多
关键词 Norway maple(Acer platanoides) urban tree Invasive species Red maple(Acer rubrum) Ecosystem processes Canopy and belowground competition Biomass production Soil N mineralization and nitrification Seedling herbivory Soil microbial communities
原文传递
数字普惠金融、横向税收竞争与城乡收入差距 被引量:1
19
作者 田时中 蔡雅冰 《山东财经大学学报》 2024年第1期41-55,共15页
缩小城乡收入差距是实现全体人民共同富裕的重要途径。基于2011—2020年中国内地31个省份的面板数据,运用面板Tobit模型和调节效应模型,揭示数字普惠金融和横向税收竞争对城乡收入差距的多重影响。研究发现:样本考察期内,中国城乡收入... 缩小城乡收入差距是实现全体人民共同富裕的重要途径。基于2011—2020年中国内地31个省份的面板数据,运用面板Tobit模型和调节效应模型,揭示数字普惠金融和横向税收竞争对城乡收入差距的多重影响。研究发现:样本考察期内,中国城乡收入差距整体呈“逐年下降”的时序特征,中西部城乡收入差距自“高—中高水平”向“中低—低水平”的格局演变,四种分项收入对城乡收入差距影响各异;基准回归表明,数字普惠金融和合理的横向税收竞争均显著缩小了城乡收入差距;调节效应显示,横向税收竞争在数字普惠金融缩小城乡收入差距中具有逆向调节作用。基于此,提出引导数字普惠金融向农村下沉、倡导合理税收竞争、破除城乡市场壁垒、完善公共服务普惠共享机制等政策建议。 展开更多
关键词 中国式现代化 数字金融 税收竞争 城乡收入差距 共同富裕
下载PDF
基于ICAE算法的城市群高速公路网布局优化研究
20
作者 裴玉龙 闻宇航 +1 位作者 王婉佼 潘胜 《重庆交通大学学报(自然科学版)》 CAS CSCD 北大核心 2024年第7期70-76,103,共8页
为提升城市群高速公路网通达程度和可达性水平,建立了体现城市群特征的优化模型,并改进了帝国竞争算法,以哈长城市群为案例,探究布局优化效果。采用高速公路出行时间确定城市群可达性等级,通过考虑可达性、距离等参数建立优化模型;引入... 为提升城市群高速公路网通达程度和可达性水平,建立了体现城市群特征的优化模型,并改进了帝国竞争算法,以哈长城市群为案例,探究布局优化效果。采用高速公路出行时间确定城市群可达性等级,通过考虑可达性、距离等参数建立优化模型;引入进化算子改进算法,构建进化帝国竞争算法;根据哈长城市群特征确定约束条件并求解,利用求解节点和周边道路网确定优化方案。研究表明:改进的算法收敛精度提高16.4%,时间缩短42.4%,共求解出6个节点,规划新建高速公路6条,改建高速公路14条,优化后的城市群高速公路2 h交通圈覆盖范围达到65.3%,14个县域交通圈等级上升,优化方案扩大了城市群2 h交通圈范围。 展开更多
关键词 交通工程 公路交通 高速公路网 帝国竞争算法 城市群可达性
下载PDF
上一页 1 2 58 下一页 到第
使用帮助 返回顶部