Impact of coupling coordination development of port and city environments on urban economic competitiveness:Evidence from the coastal port cities in eastern China

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.

一株桃褐腐病生防酵母菌活性冻干粉的制备及保鲜应用

为研究出一种能有效防治水蜜桃采后褐腐病的生防制剂,以一株间型假丝酵母菌Y-17为研究对象,通过单因素实验和响应面中心组合设计对间型假丝酵母菌Y-17冷冻干燥保护剂的配方进行筛选和优化,考察了所制备的活性冻干粉的生防效力和存放效力,并研究了其对水蜜桃的蜜桃采后贮藏的保鲜效果。结果表明,山梨醇5.43 g/100 mL、海藻糖12.45 g/100 mL、谷氨酸钠13.56 g/100 mL时,组合保护效果最好,酵母菌存活率可达84.21%±0.87%,且冻干后的菌粉仍具有较高的生防效力,-20℃贮藏180 d酵母存活率为34.66%。保鲜应用实验表明,酵母菌Y-17活性冻干粉能够有效抑制水蜜桃腐烂,25℃贮藏至第9 d时,腐烂指数仅为6.28%。酵母冻干粉还能减少桃果实贮藏期间水分流失,减缓果实软化速度,25℃贮藏7 d后,桃果实可溶性固形物含量、维生素C含量、可滴定酸含量分别为10.67%、2.15 mg/100 g、0.17%,均高于对照组,且能有效维持果皮细胞膜完整性,对水蜜桃采后的贮藏保鲜具有积极作用。

Assessing coordination degree of port development and urban environment and its influencing factors

Due to limited resources regarding port development,the contradiction between ports and cities has gradually become prominent.Taking China's coastal ports as an example,this paper measures the degree of coordination between port development and urban environment,and analyzes its influencing factors.We find that this coordination degree is relatively low and needs to be further improved.The regression results of the ordinary panel model show that the scale of port logistics,port infrastructure construction,and the quality of economic development play a significant role in promoting the coordinated development of the port and the urban environment.The regression results of the threshold panel model show that the expansion of the port logistics scale is only conducive to promoting the coordinated development of the port and the urban environment when the levels of port infrastructure are relatively high.In addition,the promotion effect of the port logistics scale on the coordinated development of the port and the urban environment differs depending on the quality of economic development.Therefore,the relevant departments should pay more attention to the construction of port infrastructure and the quality of economic development,making appropriate adjustments to both in order to better promote the coordinated development of the port and city environment.

长三角地区数字经济发展对城市间经济差距的影响研究——基于“中心—外围”视角的分析

基于我国长三角地区41个城市2011-2020年的面板数据,采用双向固定效应回归方法实证检验数字经济发展对中心城市与外围城市间经济差距的影响及作用机制。研究发现,整体来看,在长三角地区,数字经济发展有利于缩小中心城市与外围城市之间的经济差距。在这一过程中,改善要素错配是重要的作用路径。异质性分析结果显示,相比于产业结构升级水平较低和人力资本水平较低的城市,数字经济发展对产业结构升级水平较高和人力资本水平较高城市的积极作用更加显著。同时,数字经济发展对“宽带中国”试点城市的作用程度也明显强于非试点城市。此外,拓展性研究结果显示,数字经济发展对中心城市与外围城市间经济差距的影响存在显著的倒“U”型特征。进一步对拐点进行计算发现,在长三角地区,仍有一些城市位于曲线左侧,数字经济发展水平较低,未能对中心城市与外围城市间经济差距发挥积极的缩减效应。基于此,提出加强数字基础设施建设、持续优化要素市场配置机制、积极推进产业结构升级、提高人力资本水平等政策建议。