中国地级以上城市工业创新效率空间格局研究   总被引：12，自引：4，他引：8  

杜志威  吕拉昌  黄茹 《地理科学》2016,36(3):321-327

以中国288个地级以上城市为研究对象,运用2008年第二次全国经济普查工业创新活动数据,综合考察城市工业创新效率的空间格局及其影响因素。首先,从投入和产出两方面构建了中国城市工业创新效率评价体系,运用DEA包络分析方法,从规模效率和纯技术效率两个维度对城市工业创新技术效率进行分析。然后,以聚类分析划分了3类工业创新效率城市,总结工业创新效率模式的空间特征,并分析了影响空间格局的原因。研究发现：中国城市工业创新效率呈现东强西弱,阶梯状减弱的总体空间格局,工业创新规模效率和纯技术效率的空间特征并不重合;全国尺度上,工业创新效率城市的空间分布与人口密度“黑河-腾冲”线的分布基本一致,区域尺度上,城市间呈现“核心-边缘”空间结构;城市工业创新效率空间格局受到工业发展基础与工业创新能力影响,提高城市工业创新效率关键在于提升工业创新中人力资本要素和优化工业创新投入规模。  相似文献   

夏季风等环流因子对黄河中游径流量周期变化的影响     

颜明  李夫星  贺莉  吕美朝  陈东 《地理科学》2016,36(6):917-925

基于黄河中游4个水文站1919~2010年还原的天然径流量、1873~2011年的夏季风强度指数、北大西洋涛动指数（NAO）和西太平洋副高指数等资料,利用Morlet小波方法分析了黄河中游河口镇-龙门区间（简称河龙区间）,龙门-三门峡区间（简称龙三区间）和三门峡-花园口区间（简称三花区间）径流量的周期变化,并探索了夏季风、中纬度西风与西太平洋副高等环流因子对黄河中游3个区间径流量周期性变化的影响。研究发现,黄河中游3个区间径流量的变化对夏季风、中纬度西风和西太平洋副高存在差异性响应,季风对于黄河中游的径流量不仅在时间上具有趋势性的影响,更为重要的是存在周期性的控制作用,在80 a长周期上对于整个黄河中游都有控制作用,但影响黄河中游降水-径流过程的不仅仅是夏季风,相关统计结果表明还受到西风带和西太平洋副高周期的影响。3个区间都存在一个中等尺度(25 a)的周期,这个周期在夏季风上没有得到体现,河龙区间和龙三区间的25 a周期是受西风带影响所致,而三花区间的中尺度25 a周期是西太平洋副高指数的强度和西界的作用所致。  相似文献   

An improvement of soil temperature simulations on the Tibetan Plateau     

SiQiong Luo  BoLi Chen  ShiHua Lyu  XueWei Fang  JingYuan Wang  XianHong Meng  LunYu Shang  ShaoYing Wang  Di Ma 《寒旱区科学》2018,10(1):80-94

The simulation of soil temperature on the Tibetan Plateau (TP) plays a dominant role in the performance of both global climate and numerical weather forecast models. To improve the simulation of soil temperature on the TP, the Johansen soil thermal conductivity parameterization scheme was introduced into Community Land Model 3.5 (CLM3.5) and Regional Climatic Model 4 (RegCM4). The improved CLM3.5 and RegCM4-CLM were utilized to conduct offline and regional simulation experiments on the TP. Comparison of the new and old schemes revealed that CLM3.5 provides high thermal conductivity parameters of mineral soil solid on the TP. The Johansen scheme is more practical for the TP than the soil thermal conductivity parameterization in CLM3.5. The simulation of soil temperature and liquid water content was improved in offline experiment. The improved parameterization scheme can also reduce the simulation error of soil temperature in winter throughout the entire TP.  相似文献   

Effects of aluminum toxicity induced by acid deposition on pine forest ecosystem in Longli of Guizhou Province,Southwestern China     

ZHANG Jing  LYU Zhipeng  SHAO Siya  LI Fangfang  YANG Shengtian  SONG Wenlong  LI Wei  LI Shun-jiang 《中国地理科学(英文版)》2016,26(4):495-507

The effects of acid deposition on pine forest ecosystems in Longli of Guizhou Province, southwestern China are studied using indoor experiments and model simulations. Indoor experiments are designed to explore the aluminum toxicity on pine seedlings, and the long-term soil acidification model（LTSAM） and a terrestrial biogeochemistry model（CENTURY） are used to simulate the influences of acid deposition on pine forest ecosystems. The indoor experiment results of aluminum toxicity show that aluminum ions in solution limit plant growth and acid deposition enhances this effect by facilitating the release of aluminum ions from the soil. Pine seedling biomass and root elongation decrease as the aluminum concentration increases. The results of model simulations show that the soil chemistry varies significantly with different changes in acid deposition. When the acid deposition increases, the pH value in the soil solution decreases and the soil Al³⁺ concentration increases. The increased acid deposition also has negative impacts on the forest ecosystem, i.e., decreases plant biomass, net primary productivity（NPP） and net CO₂ uptake. As a result, the soil organic carbon（SOC） decreases because of the limited supply of decomposition material. Thus acid deposition need be reduced to help protect the forest ecosystems.  相似文献   

广西昆仑关A型花岗岩地球化学特征及构造意义   总被引：12，自引：2，他引：10  

谭俊  魏俊浩  李水如  王忠铭  付乐兵  张可清 《地球科学》2008,33(6):743-754

昆仑关岩体位于广西南丹-昆仑关燕山期花岗岩带西南端, 岩石类型为黑云母花岗岩.岩相学及化学成分显示其属高钾钙碱性岩系, 具高硅、富碱和铝、低磷和钛的特点, SiO₂含量为68.13~72.61, K₂O/Na₂O比值介于1.28~1.69之间, 铝指数A/CNK=0.72~1.28, 属准铝质一强过铝质岩石.富集Ga、Rb、Th、U、Pb等元素, 而强烈亏损13a、Nb、Sr、P和Ti.稀土元素具明显负Eu异常, 总体呈现轻稀土富集的右倾"V"形配分模式.昆仑关古民单元锆石LA-ICP-MSU-Pb定年结果为93±1Ma, 形成于晚白垩世.矿物组成及地球化学特征确定了南丹-昆仑关花岗岩带是华南西南端一条重要的铝质A型花岗岩带, 控岩断裂构造为NW向南丹一昆仑关深大断裂.岩石学及主量和微量元素(含稀土)特征表明岩体侵位于后碰撞阶段的张性构造环境.结合研究范围在晚白垩世的构造背景及区域应力场匹配组合关系, 认为其与印度板块在该时期北移所引起的古太平洋板块高角度俯冲所导致的弧后拉张有关, 与浙闽沿海A型花岗岩或碱性岩分别代表了匹配构造体制下的两条A型花岗岩带.   相似文献   

中药熏蒸治疗腰椎间盘突出症的用药规律探析          下载免费PDF全文

周稆  梁玉婷  邱辕鑫 《应用海洋学学报》2023,39(4):31

目的：分析中药熏蒸治疗腰椎间盘突出症（LDH）的用药规律。方法：计算机检索2017年1月1日至2022年7月31日中国知网（CNKI）、万方数据(WANFANG DATA)、维普中文科技期刊数据库（VIP）中关于中药熏蒸治疗LDH的处方,借助中医传承辅助平台（V2.5）分析药物的频次、性味、归经,基于关联规则和复杂系统熵聚类分析核心药物组合等遣方规律。结果：共纳入处方150首,涉及中药171味。使用频.次≥30次的药物有18味,排前10位的分别为红花、伸筋草、透骨草、川芎、当归、威灵仙、独活、牛膝、桂枝和川乌。药性以温、平、寒为主;药味以辛、苦、甘、咸为主;归经主要归肝、心、肾、脾和膀胱经。关联规则分析得到常用药物组合19组。复杂系统熵聚类分析得到核心药物组合12组与新处方6首。结论：中药熏蒸治疗LDH多采用祛风湿、活血化瘀之药,兼以补益肝肾药。  相似文献   

Enhanced hysteresis of suspended sediment transport in response to upstream damming: An example of the middle Yangtze River downstream of the Three Gorges Dam     

Yiwei Lyu  Sergio Fagherazzi  Shan Zheng  Guangming Tan  Caiwen Shu 《地球表面变化过程与地形》2020,45(8):1846-1859

The peak in sediment transport in alluvial rivers generally lags behind the peak in discharge. It is thus not clear how the hysteresis in the sediment/discharge relationship may be impacted by damming, which can fundamentally alter the water and sediment regimes in the downstream reaches of the river. In this study, a total of 500 flood events in the Yichang–Chenglingji Reach (YCR) of the Middle Yangtze River immediately downstream of the Three Gorges Dam (TGD) are analysed to study the impacts of dam operations on the hysteresis of suspended sediment transport. Sediment rating curves, hysteresis patterns, as well as lag times, are investigated to determine the relationship between suspended sediment concentration (SSC) and flow discharge (Q) at different temporal scales, from inter-annual to individual flood events, for the pre- and post-TGD period from 1992 to 2002 and from 2003 to 2017, respectively. The results showed that the TGD operation decreased the frequency and magnitude of floods. The decrease in peak flow and increase in base flow weakened the flood contribution to the annual discharge by nearly 20%. However, the relative suspended sediment load contribution during flood events was much higher than the discharge contribution, and was little impacted by the dam. At seasonal and monthly scales, more than 80% of the suspended sediment was transported by ~65% of the water discharge in the summer and early autumn. The monthly SSC–Q relationship changed from a figure-eight to an anti-clockwise pattern after the construction of the TGD. For single flood events, the TGD operations significantly modified the downstream SSC–Q hysteresis patterns, increasing the frequency of anti-clockwise loops and the lag time between peak Q and peak SSC. These adjustments were mainly caused by differences in the propagation velocities of flood and sediment waves and the sediment ‘storage–mobilization–depletion’ process, whereas the influence of lateral diversions was small. © 2020 John Wiley & Sons, Ltd.  相似文献   

Prospects of interventions to alleviate rural–urban migration in Jiangsu Province,China based on sensitivity and scenario analysis     

H. Lyu  Z. Dong  M. Roobavannan  J. Kandasamy 《水文科学杂志》2020,65(13):2175-2184

ABSTRACT

Rural–urban migration is an adaptive response to location-specific environmental or socio-economic stressors. Jiangsu Province, China is witnessing rapid economic growth fuelled by manufacturing and services sector. Rural–urban migration in Jiangsu, which brings higher stress to resource-carrying capacity of urban areas, is driven by rural “push” factors, principally labour surplus and unemployment in agriculture. This study investigates possible policy interventions aimed at relieving the rapid rural–urban migration in Jiangsu based on a sensitivity analysis of driving factors in rural agricultural production. It shows that rural–urban migration is sensitive to input elasticities of precipitation and labour. Two groups of scenario analysis corresponding to possible policy interventions are implemented. The first policy focuses on providing government subsidies to rural non-agricultural industries then compensate for the shrinking agricultural production. Another policy supports education in rural areas to provide more skilled labour resource which can be absorbed by non-agricultural industries. Both two policies are effective in reducing rural unemployment and alleviating rural–urban migration.  相似文献   

黄土高原地区乡村性空间特征及其与可达性格局关系   总被引：1，自引：0，他引：1  

吕敏娟  曹小曙 《地理科学》2020,40(2):248-260

在乡村转型重构的关键时期以及城乡融合背景下,可达性作为驱动乡村地域特征改变的直接媒介,对乡村减贫及可持续发展产生重要影响。以县域为基本空间单元,构建了刻画乡村性和可达性的指标体系,定量测度了1990年、2000年、2010年、2015年黄土高原地区243个县域乡村性与可达性指数,探索黄土高原地区县域乡村性和可达性的时空演变特征,采用探索性空间数据方法,引入空间计量经济模型,对乡村性与可达性的集聚特征及关系进行计量分析。结果显示：① 研究区乡村性整体呈减弱态势、差异不断增大,呈现“西高东低”分布格局;可达性整体呈增强趋势、差异不断缩小,“东高西低”的分布格局基本不变。② 乡村性与可达性空间分布均呈较强的正空间自相关,以“榆林-庆阳”一线为界分布,但集聚态势总体不断减弱;其次,可达性的提升对乡村性呈负向影响且波动增强,低可达性-高乡村性类型主要分布在西北的青海、甘肃、宁夏境内,高可达性-低乡村性类型主要分布在东部经济发展水平较高的地级市周边县市。③ 乡村性的空间溢出效应显著,表现出显著的空间滞后和空间误差溢出效应,区域乡村性会受到周边地区乡村性的显著影响;可达性的提升会使得乡村人口变化率、一产产值比重降低;使农业劳动生产率、农村人均纯收入、农业土地生产率提高,且可达性对农业土地生产率的影响最大,而对农村居民人均纯收入的影响提升最大。  相似文献   

Spatial and Temporal Changes of Wetlands on the Qinghai-Tibetan Plateau from the 1970s to 2010s     

Zhenshan Xue  Xianguo Lyu  Zhike Chen  Zhongsheng Zhang  Ming Jiang  Kun Zhang  Yonglei Lyu 《中国地理科学(英文版)》2018,28(6):935-945

Wetlands on the Qinghai-Tibetan Plateau (QTP) perform a dazzling array of vital ecological functions and are one of the most fragile ecosystems in the world. Timely and accurate information describing wetland resources and their changes over time is becoming more important in their protection and conservation. By using remote sensing data, this study intended to investigate spatial distribution and temporal variations of wetlands on the QTP at different watershed scales from 1970s to 2010s. Results show that wetlands on the QTP have undergone widespread degradation from 1970s to 2010s, with nearly 6.4% of their area being lost. Areas of freshwater marsh, salt marsh and wet meadow declined by 46.6%, 53.9% and 15.6%, respectively, while lake area increased by 14.6%. The most extensive losses of natural wetlands have occurred in endorheic basins, such as in the Kunlun-Altun-Qilian Drainage Basin and Qiangtang Basin, which shrank by 44.5% and 33.1%, respectively. A pronounced increase in temperature tends to facilitate the evaporation process and reduce water availability for wetlands. One-third of the wetlands on the QTP are under threat of being submerged due to lakes rising in recent years. More research is needed to gain insight into the interaction mechanisms behind observed variations and potential impacts from further warming in the future.  相似文献