基于HJ-CCD影像数据的新疆喀纳斯自然保护区植被叶面积指数估算     

昝梅  李登秋  居为民  王希群  陈蜀江 《冰川冻土》2013,35(4):892-903

以新疆喀纳斯自然保护区为研究区, 评价了HJ-CCD影像数据估算植被叶面积指数(LAI)的能力及其对大气订正方法的敏感性.分别利用6S和FLAASH两种大气订正模型对HJ1B-CCD2影像进行大气订正, 比较了大气订正前后不同植被(针叶林、阔叶林、针阔混交林和草地)反射率及5种植被指数(NDVI、SR、SAVI、MSR、ARVI)的变化, 进而建立了4种植被类型LAI的遥感估算模型, 分析了LAI的空间分布格局.结果表明: 大气订正后可见光波段的反射率降低, 6S模型订正后近红外波段的反射率上升, 而FLAASH模型订正后近红外波段的反射率下降.大气订正后NDVI、SR、SAVI(除针叶林)和MSR上升, 6S模型订正后所有植被类型的ARVI下降, FLAASH模型订正后针叶林和阔叶林的ARVI上升, 而针阔混交林和草地的ARVI下降.大气订正提高了植被指数与LAI之间的相关性, 对于针叶林、阔叶林、针阔混交林而言, 利用6S模型订正后的反射率建立的模型优于FLAASH模型订正后的反射率建立的模型, 而草地却相反.经过大气订正, HJ-CCD影像数据可应用于研究区植被LAI的估算.研究区LAI的高值集中在湖泊和河流附近, 低值分布在海拔较高处.山地森林草原带、亚高山森林带、高山灌丛草甸带、高山冻原、高山冰川带植被LAI的平均值分别为2.6、3.9、2.5、1.7和1.0.  相似文献   

湘西多民族山区耕地利用效率空间差异分析     

刘春腊  王鹏  徐美  刘沛林 《冰川冻土》2013,35(5):1308-1318

以县域为单元, 基于各行政区域2001-2010年的统计数据, 从耕地资源量、耕地集约利用水平、粮耕弹性系数3方面选取10项指标, 构建了耕地利用效率评价指标体系, 并引入"年变化率"的概念与方法, 对湘西多民族山区2001-2010年耕地利用效率的空间差异进行了分析. 结果表明: 总体而言, 湘西多民族山区耕地利用效率比较低, 近年虽有好转迹象, 但县域间的协调度仍处于基本协调或不协调状态. 耕地利用效率的年变化率为21%, 各单项指标的年变化率亦存在较大波动. 在影响耕地利用效率各因子中, 粮食单产、土地产出均为高度相关因素, 而耕地总面积的关联度排在最后. 从空间上看, 湘西北部以及东部地区耕地利用的空间分异较小, 而西部、中部和南部地区的空间分异较大, 可划分为高效高度协调型、高效基本协调型、高效不协调型、中效基本协调型、中效不协调型和低效不协调型等六类地区.  相似文献   

跨地方饮食文化生产的过程研究──基于符号化的原真性视角   总被引：4，自引：2，他引：2  

曾国军  刘梅  刘博  蔡晓梅 《地理研究》2013,32(12):2366-2376

全球化是去地方化,抑或在全新体系中定义新的地方性、凸显地方性,学术界对此一直存在争论。伴随全球化进程,地方性饮食追逐人口流动跨地方扩展,这些跨地方饮食在保持文化原真性和适应本地顾客需求方面挣扎。如何保持原真性,保持何种原真性成为跨地方饮食文化生产的焦点。本文通过对地方性与跨地方、原真性与符号化的相关研究进行梳理,基于饮食文化原真性的理论分析,揭示了“原真性的符号化”这一跨地方饮食文化生产的重要过程。与此同时,还阐述了在跨地方饮食文化生产过程中,原真性符号化的必然性及其循环过程,旨在为跨地方饮食文化生产提供理论依据和实践指引,同时也有利于理解地方性文化的跨地方传播、创新与发展。  相似文献   

An examination of the presence and topography of the D″ discontinuity under the Russia–Kazakhstan border region using seismic waveform data from a deep earthquake in Spain          下载免费PDF全文

Xuzhang Shen  Yuanze Zhou  Koki Idehara  Xiuping Mei  Kangsheng Xu 《地震科学（英文版）》2014,27(2):209-215

The D″ layer, which is located atop the core–mantle boundary, has long been an area of focus for global seismology studies. A widely used approach to study the discontinuities in the D″ layer involves the use of the SdS phases between the S and ScS phases, which requires that certain stringent conditions be satisfied with respect to an epicentral distance and earthquake depth. Therefore, this approach is only practical for investigating the presence and topography of velocity interfaces in certain local regions around the world. The Russia–Kazakhstan border region has been a “blind spot” with respect to this detection method. The seismic network deployed in the northeastern margin of the Tibetan Plateau has recorded relatively clear SdS phases for the M _S 6.3 earthquake that occurred in Spain on April 11, 2010, allowing this blind spot to be studied. This paper compares the observed waveforms and synthetics and uses the travel times of the relevant phases to obtain a D″ discontinuity depth between 2,610 and 2,740 km in the examined area. This study provides the first results regarding the depth of the D″ layer discontinuity for this region and represents an important addition to the global studies of the D″ layer.  相似文献   

Purification and identification of a clotting protein from the hemolymph of Chinese shrimp (Fenneropenaeus chinensis)     

WANG Baojie  PENG Hongni  LIU Mei  JIANG Keyong  ZHANG Guofan  WANG Lei 《中国海洋大学学报(英文版)》2013,12(3):477-483

The clotting protein (CP) plays important and diverse roles in crustaceans, such as coagulation and lipid transportation. A clotting protein was purified from the hemolymph of Chinese shrimp Fenneropenaeus chinensis (named as Fc-CP) with Q sepharose HP anion-exchange chromatography and phenyl sepharose HP hydrophobic interaction chromatography. Fc-CP was able to form stable clots in vitro in the presence of hemocyte lysate and Ca²⁺, suggesting that the clotting reaction is catalyzed by a Ca²⁺-dependent transglutaminase in shrimp hemocytes. The molecular mass of Fc-CP was 380 kDa under non-reducing conditions and 190 kDa under reducing conditions as was determined with SDS-PAGE. CP exists as disulfide-linked homodimers and oligomers. The N-terminal amino acid sequence of Fc-CP was identical to that of shrimps including Penaeus monodon, Farfantepenaeus paulensis and Litopenaeus vannamei; and similar to that of other decapods. The purified Fc-CP was digested with trypsin and verified on an ABI 4700 matrix-assisted laser desorption/ionization tandem time-of-flight (MALDI-TOF/TOF) mass spectrometry. Our results will aid to better understanding the coagulation mechanism of shrimp hemolymph.  相似文献   

矿山灾害链及其断链减灾模式分析     

刘磊  施龙青  孙红华  王敏  孙琪  邱梅  刘虎 《煤田地质与勘探》2013,41(5):40-44

为了揭示矿山灾害系统的复杂性规律和运动本质,运用系统理论观点,从灾害链的角度对矿山灾害链定义、分类、特点及链式发育机理进行了研究。提出矿山灾害链组合断链减灾模型,即"初次断链+预防断链+灾后重建"组合断链模型,并在华恒公司矿井水害防治中得到运用,可以有效的解决矿井水害特别是矿井西部老空水问题。矿山灾害链式效应在矿山灾害中普遍存在,组合断链减灾模型为最佳减灾方案,而通过对断链程度和各断链过程对总断链的贡献率的计算实现断链最优化将成为今后研究的重点。   相似文献   

Adjusting Chlorine Dosage and to Prevent Bio‐Growth and Minimize Trihalomethanes in Reverse Osmosis Filtrate in a Wastewater Reclamation Process     

Yi‐Che Hsu  Yu‐Hsuan Wang  Shuo‐Chuan Wu  Chuen‐Mei Wu  Ching‐Ping Chu  Yu‐Jen Chung  Yong‐Tang Huang  Kuo‐Liang Wang 《洁净——土壤、空气、水》2012,40(3):254-261

Feasibility of effluent reclamation for the Futian municipal WWTP in Taichung Taiwan was evaluated using an “SF‐UF‐RO” pilot plant. The optimal parameters of each unit were obtained during the pilot plant test. The pilot plant started the operation in late October 2008 and operated until January 2011. The reverse osmosis (RO) system produces 75 m³ water daily, and the produced water quality was comparable to the city water in Taichung. Chlorine dosed in the sand filtration (SF) inlet and ultrafiltration (UF) backwash had the most significant effect on the stability of system performance. When the chlorine was underdosed, biofilm clogged the bag filter (prefilter of UF) and led to the flow rate decay of the UF. The prefilter needed replacement every 1 or 2 weeks resulting in increased process cost. On the other hand, when the chlorine dosage was increased to mitigate the biofilm growth, the residual chlorine not only reacted with TOC and derived trihalomethanes (THMs) in the RO product water (more than 20 µg/L), but it also damaged the RO membrane. After trial and error, the chlorine concentration was optimized as 0.7 mg/L in SF inlet to prevent growth of biofilm as well as to control the residual chlorine in the RO inlet and THMs in the RO product water. It is suggested that cautiously adjusting chlorine dosage is essential for stably operating such a hybrid membrane system to reclaim the municipal wastewater.  相似文献   

Application of Dispersive Liquid–Liquid Microextraction Based on Solidification of Floating Organic Droplet Multi‐residue Method for the Simultaneous Determination of Polychlorinated Biphenyls,Organochlorine, and Pyrethroid Pesticides in Aqueous Sample     

Mei Zuo  Jing Cheng  Guzalnur Matsadiq  Lu Liu  Man‐Liang Li  Miao Zhang 《洁净——土壤、空气、水》2012,40(12):1326-1333

Dispersive liquid–liquid microextraction based on solidification of floating organic droplet (DLLME‐SFO) technique was successfully applied for simultaneous assay of eight polychlorinated biphenyls, two organochlorine, and four pyrethroid pesticides multi‐residue in aqueous samples by using GC‐electron capture detection. The effects of various parameters such as kind of extractant and dispersant and volume of them, extraction time, effect of salt addition, and pH were optimized. As a result, 5.0 µL 1‐dodecanol was chosen as extraction solvent, 600 µL methanol were used as dispersive solvent without salt addition, pH was adjusted to 7. Under the optimized conditions, the limits of detection (LOD) were ranged from 1.4 to 8.3 ng L^?1. Satisfactory linear range was observed from 5.0 to 2000 ng L^?1 with correlation coefficient better than 0.9909. Good precisions were also acquired with RSD better than 13.6% for all target analytes. The enrichment factors of the method were ranged from 786 to 1427. The method can be successfully applied to simultaneous separation and determination of three class residues in real water samples and good recoveries were obtained ranging from 76 to 130, 73 to 129, and 78 to 130% for tap water, lake water, and industrial waste water, respectively.  相似文献   

从3个科学理念简论沉积学中的 “白云岩问题”^*   总被引：4，自引：0，他引：4       下载免费PDF全文

梅冥相 《古地理学报》2012,14(1):1-12

作为碳酸盐岩的重要类型,白云岩的成因机理和时空分布规律,一直是沉积学重要的研究主题之一。沉积学家已经建立了众多的白云石化模式,并用来解释各种白云岩的成因。然而,白云石在地表条件下的形成过程和机理,一直没有得到实验室条件下的模拟和证实,所以白云岩的成因就成为沉积学的难题,即沉积学中的 “白云岩问题”。白云岩形成的作用被简称为白云石化作用,同时作为碳酸盐岩成岩作用机制的类型之一,代表了科学理念的第1个变化;立足于前寒武纪白云岩原生沉积组构的精美保存,从早先的 “原生白云石沉淀”的假设到后期的 “拟晶白云石化作用”模式的提出,代表了科学理念的第2个重要变化;微生物作用有助于白云石沉淀而出现的 “微生物白云石化作用”的模式,似乎代表了沉积学家对沉积学中的 “白云岩问题”的探索和研究之中的第3个重要的科学理念进步。追逐上述科学理念的变化和进步,将会更加深入了解科学家们对 “白云岩问题”研究和探索的重要进展。  相似文献   

山西省煤矿采空塌陷形成机制浅析   总被引：2，自引：0，他引：2  

韩文德  郭美萍  陈宇鹏  曹志强 《地质与资源》2004,13(3):167-168

煤矿采空塌陷是山西省地质灾害的主要灾种.采空塌陷的发育程度由内因、外因共同决定.自然地理地质环境背景条件为内因,人类工程活动为外因.内因决定了采空塌陷的分布区域,外因则控制它的发育程度.内因通过外因表现出来.  相似文献