中国旅游资源绿色转换效率的时空演化及影响因素研究

文章基于2000—2019年中国省际面板数据,运用EBM模型、GIS技术和Tobit回归方法对旅游资源绿色转换效率的时空演化及影响因素进行实证分析,结果表明:(1)旅游资源绿色转换效率经历了初步发展期(2000—2006年)、粗放式增长期(2007—2015年)和高质量转型期(2016—2019年),旅游资源绿色产出能力由30.4%提高至55.3%,处于中等水平;(2)研究期间,三大经济带效率水平显著提升,中部地区效率增速最快,居于首位,西部地区效率水平落后于东中部地区;(3)从空间分布看,效率高值区主要分布在天津、江苏、上海等东部地区,低值区主要分布在宁夏、新疆、青海等西部地区,各省份之间存在马太效应;(4)旅游资源高阶化、经济发展水平、产业结构、产业集聚、交通水平、科技水平和市场化水平显著促进了旅游资源绿色转换效率的提高,而旅游产业接待规模、碳排放结构、对外开放水平对效率的提升具有抑制作用。

Efficient expression of green fluorescent protein (GFP) mediated by a chimeric promoter in Chlamydomonas reinhardtii

To improve the expression efficiency of exogenous genes in Chlamydomonas reinhardtii, a high efficient expression vector was constructed. Green fluorescent protein （GFP） was expressed in C. reinhardtii under the control of promoters： RBCS2 and HSP70A-RBCS2. Efficiency of transformation and expression were compared between two transgenic algae： RBCS2 mediated strain Tran-Ⅰ and HSP70A-RBCS2 mediated strain Tran-Ⅱ. Results show that HSP70A-RBCS2 could improve greatly the transformation efficiency by approximately eightfold of RBCS2, and the expression efficiency of GFP in Tran-Ⅱ was at least double of that in Tran-Ⅰ. In addition, a threefold increase of GFP in Tran-Ⅱ was induced by heat shock at 40℃. All of the results demonstrated that HSP70A-RBCS2 was more efficient than RBCS2 in expressing exogenous gene in C. reinhardtii.