钝顶螺旋藻在LED光电板式光生物反应器中的培养研究   总被引：1，自引：1，他引：1  

徐明芳  李贻玲 《海洋科学》2001,25(2):42-46

分析研究了ＬＥＤ集成光电板光辐射强度对螺旋藻生物量浓度、螺旋藻比生长速率、藻光合放氧量及藻光合色素等螺旋藻生长特性的影响，并分析了ＬＥＤ集成光电板辐射红光及红、蓝组合双波长光质与冷白荧光灯光质对藻类各有效组成部分的影响。结果表明，在光辐射强度尚未达到饱和光辐射强度之前，光辐射强度决定螺旋藻的比生长速度；超过饱和光辐射强度，光合作用产氧量趋向恒定，说明螺旋藻光合器官具有光合稳定性；与冷白荧光日光灯组相比，ＬＥＤ集成光电板射红光及红，蓝组合双波长光质非常适合螺旋藻的生长并促进细胞干重、叶绿素、藻胆蛋白的增加，在相同的光辐射强度[275.9μmol/(m^2.s)]下，采用ＬＥＤ集成光辐射板辐射单色红光与冷白荧光日光灯组相比，藻胆蛋白、藻细胞干重吸绿素a分别增加４３．３９％、９８．４０％，５１．５６３％。  相似文献   

基于贫困分级的云南省城乡收入差距时空演化与影响因素研究   总被引：1，自引：0，他引：1  

杨子生  杨人懿  刘凤莲 《地理研究》2021,40(8):2252-2271

云南是中国贫困县最多的山区省份,同时也是中国城乡收入差距长期居高不下的典型省份。针对当前研究中未能深入探讨城乡收入差距与各地贫困程度关联性、未能深入探讨各影响因素空间相关性、忽视关键地理因素对城乡收入差距影响等问题和不足,本文将各县按照贫困程度的差异划分为4个类别,使用云南省129个县（市）2010—2018年产业、社会、经济、人口等维度的面板数据,并引入“地形-气候综合优劣度”作为非经济指标,在分析城乡收入差距时空演化和空间格局特征基础上,运用空间动态面板模型深入探析了其影响因素。基于研究结果,认为有必要将缩小城乡收入差距与国家精准扶贫战略、城乡融合发展战略和乡村振兴战略有效衔接。  相似文献   

高铁影响下的中国区域创新时空演化与效应分解     

刘国燕  李涛 《世界地理研究》2021,30(2):355-366

探究高速铁路对区域创新的影响机制将深远影响我国区域经济发展。运用ESDA、SDM和求偏微分等方法,测算了由高铁开通带来的时空压缩对区域创新产出产生的直接效应和间接效应,并通过分地区回归对异质性进行了深入分析。结果表明：我国创新产出具有显著的空间相关性,且集聚程度不断增强,“核心-外围”区域基本形成,创新活动具有一定的锁定特征;其中,R&D人员投入、FDI、政府财政科技支出和居民消费支出是影响区域创新产出的重要因素;高铁开通对创新的影响存在空间异质性,R&D人员全时当量对东部地区的影响最大,东北和中部地区则同时依赖于R&D人员和R&D资本投入,西部地区并未受到极化影响,反而因时空压缩产生了正向溢出效应。  相似文献   

基于模糊物元的中国城市群物流能力研究     

胡玉洲 《地域研究与开发》2016,(1):5-9

通过构造基于面板数据的模糊物元模型研究中国十大城市群的物流能力。研究结果表明:中国十大城市群整体物流能力总体呈上升态势,并经历了2次高速增长期;从时间上来看,中国十大城市群物流能力除在个别年份回落外,整体呈现逐年上升趋势,且发展基本同步;从空间上来看,中西部与东部城市群相比物流能力存在较大差距,区域差异明显,发展水平及速度均不及东部城市群。  相似文献   

Factors Driving the Expansion of Construction Land: A Panel Data Study of Districts and Counties in Ningbo City,China     

MOU Chufu  WANG Limao  QU Qiushi  FANG Yebing  ZHANG Hong 《资源与生态学报(英文版)》2018,9(4):365-373

This paper analyzes panel data from 2003-2012 to identify the factors driving the expansion of construction land in Ningbo city; it uses panel data, regional-level, and year-by-year regression models. The results indicate the following: (1) For each 1% increase in the size of the economy, urban population, and industrial structure adjustment coefficient, the amount of construction land increased by 0.35%, 0.52% and -1%, respectively. (2) The factors driving the expansion of urban construction land differed across regions. In more highly developed areas such as Yuyao, Cixi, Fenghua and the downtown area, population growth was the most obvious driving factor with coefficients of 4.880, 1.383, 3.036 and 0.583, respectively, in those areas. Here, the impact of industrial structure adjustment was lower than that of population growth (with coefficients of 1.235, 0.307, 0.145 and -0.242), while economic development was an increasingly insignificant factor (with coefficients of -0.302, 0.071, 0.037 and 0.297). On the other hand, economic development was the most important factor for the expansion of construction land in relatively less developed areas such as Xiangshan and Ninghai counties with coefficients of 0.413 and 0.195, respectively. Here, population growth (with coefficients of -0.538 and 0.132) and industrial structure adjustment (with coefficients of -0.097 and 0.067) were comparatively weaker driving factors. (3) The results of the year-by-year regression indicate the increased impact of economic development as a driving factor (from -1.531 in 2005 to 1.459 in 2012). The influence of the population growth factor slowly declined (from 1.249 in 2005 to 0.044 in 2012) and from 2009 on was less influential than the economic development factor. The industrial structure coefficient remained negative and its influence diminished from year to year (from -5.312 in 2004 to -0.589 in 2012).  相似文献   

中国城市能源消费碳排放的区域差异、空间溢出效应及影响因素   总被引：17，自引：2，他引：15  

王少剑  苏泳娴  赵亚博 《地理学报》2018,73(3):414-428

基于1992-2013年中国城市遥感模拟反演碳排放数据,采用空间自相关、空间马尔科夫矩阵和动态空间面板数据模型,在同时考虑碳排放的时空滞后效应和不同地理经济空间权重矩阵的条件下,对城市碳排放的演化路径和关键影响因素进行了定量识别和减排政策探讨。研究表明,中国城市能源消费碳排放的区域差异正逐步缩小,空间上呈现出明显的高排放俱乐部集聚特征,同时碳排放类型演化具有明显的路径依赖特征;面板数据模型估计结果表明经济增长与人均碳排放呈现显著的倒“U”型曲线关系,而绝大多数城市的人均碳排放处于随经济发展而增加的阶段,二产偏重的经济结构和投资的粗放增长共同正向作用于城市碳排放,而人口的集聚效应、技术水平的提升、对外开放度和公路运输强度的增加则共同抑制城市碳排放水平的提高。因此未来要抑制促增因素和发挥促降因素的作用才能有效降低城市碳排放;优化产业结构、精简粗放投资、增加研发强度以及提升公路通达性是未来实现中国城市节能减排的有效途径。  相似文献   

Analyzing Partially Correlated Longitudinal Data in Community Survey Research     

Hua Qin  Elizabeth Prentice  Kathlee Freeman 《社会与自然资源》2018,31(1):142-149

Community surveys have been widely used to investigate local residents’ perceptions and behaviors related to natural resource issues. However, most existing community survey research relies on cross-sectional data and is thus unable to capture the temporal dynamics of community processes. Longitudinal analysis has received increasing interest in recent natural resource social science literature. Trend and panel studies are two typical approaches in longitudinal community survey research. Due to limited sampling frames, research design, and respondent attrition, longitudinal community surveys often involve both paired and independent observations across different survey waves. Using previous survey data on community responses to forest insect disturbance in Alaska as an example, this research note shows that the corrected z-test is a more appropriate approach to analyze partially correlated longitudinal data than conventional statistical techniques such as the paired and independent t-tests.  相似文献   

中国新企业成立空间差异的影响因素——以金属制品业为例   总被引：3，自引：1，他引：2  

史进  贺灿飞 《地理研究》2018,37(7):1282-1296

新企业是产业空间重构的重要驱动力。采用1998-2007年中国工业企业数据库,以金属制品业为例,发现金属制品业新企业成立的活跃地区由东部沿海转向中西部地区,特别是中部地区。随后建立“全球链接、区域竞争和地方环境”的分析框架,通过城市层面的面板Tobit模型,考察新企业成立空间差异的影响因素,并突出企业效率在这些因素作用过程中的影响。研究发现：① 外向型城市有利于新企业成立;低效率的新企业只是追求劳动力的低成本,但是高效率的新企业还能兼顾劳动力的高质量。② 区域市场潜力大的城市有利于新企业成立。③ 市场化环境好的城市有利于新企业成立,地方化经济对新企业成立无显著影响,而适度的相关多样化能够促进高效率新企业成立。  相似文献   

Time domain simulation of side-by-side floating bodies using a 3D numerical wave tank approach     

《Applied Ocean Research》2016

The coupled system of two side-by-side fixed and/or floating bodies interacting with a large amplitude nonlinear wave is studied using a direct time domain solution method. The numerical model is based on a three-dimensional mixed Eulerian–Lagrangian (MEL) method under certain simplifying approximations permitting Rankine panel scheme to be implemented over a time-invariant boundary surface to solve the boundary value problem for the unknown velocity potentials. A 4th order Adams–Bashforth–Moulton scheme is used for time marching of rigid-body motion histories of the individual bodies and evolution of the free-surface including the gap region in which large resonant fluid motions occur. A systematic study has been carried out to evaluate the performance of the developed time domain method in simulating the forces and motions as well as the fluid motion in the gap region for the two body system under various arrangements and in different wave-headings. At first, the computed numerical results have been validated and verified with computational and experimental results available in literature for standard geometries such as vertical truncated cylinders and rectangular boxes. Secondly, effectiveness of the damping lid model which is introduced to suppress wave resonance in the gap region is investigated including its influence on maximum sway forces on fixed and floating rectangular barges in side-by-side configurations. Thirdly, comparative studies on absolute and relative motion response for two cases (two rectangular barges, and a FLNG-FPSO + shuttle tanker) in side-by-side arrangement are detailed to bring out the importance of nonlinearities arising due to steep nonlinear incident waves. Finally, coupled motions of the two-body system of an FPSO and a shuttle tanker floating in side-by-side configuration in a steep nonlinear wave field are studied in which the two bodies are connected through hawsers, and also the FPSO is moored to the ground. Additionally there is a fender between the two bodies.  相似文献   

环境质量与经济增长库兹尼茨关系空间计量分析   总被引：8，自引：2，他引：6  

苏梽芳  胡日东  林三强 《地理研究》2009,28(2):303-310

大多数学者研究环境库兹尼茨曲线(EKC)时,都隐含地假定一个地区人均污染与相邻的地区不存在空间相关性,因而其得到的估计结果可能出现偏误,进而将结论应用到环境政策方面也令人难以信服。为克服上述缺陷,利用中国28个省域1993~2005年的面板数据,应用考虑空间效应的空间面板数据模型,对中国的环境库兹尼茨曲线进行实证分析。结果发现:(1)我国的区域污染存在空间相关性,因此空间面板数据模型更适于研究EKC曲线;(2)区域污染排放不仅受本地区人均收入影响,而且相邻区域的污染物排放也对本地区有重大影响,即污染物排放具有空间溢出作用;(3)我国居民环境质量-收入弹性仍然处于较低的水平,环境质量在居民消费需求中比重并不高。  相似文献