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1.
基于植被与温度条件的农业旱情遥感监测研究   总被引:2,自引:0,他引:2  
本文以山西省为实验区,利用2002-2005年作物生长期NOAA/AVHRR数据计算的TCI和VCI指数,取二者最大值(MTVI)作为旱情监测的指标进行旱情监测实验,并结合同期地面土壤湿度进行实验分析。分析结果表明利用TCI和VCI的最大值作为监测指标可以较好的反映农业旱情程度以及范围分布,与单个TCI和VCI监测结果相比,MTVI监测结果稳定可靠,在一定程度上弥补了单一指数监测时的不足。  相似文献   

2.
植被状态指数和温度条件指数的提取方法   总被引:6,自引:0,他引:6  
NDVI最大值最小值和地表温度最大值最小值分别是计算植被状态指数(VCI)和温度条件指数(TCI)的关键参数。本文在介绍国内外提取四个参数的研究应用情况的基础上,充分考虑了各地区温度、地形等的影响,提出了新的提取方法,以适应全国范围内的旱情监测。针对各影响因子的分析表明,本文提出的参数提取方法是合理可行的。  相似文献   

3.
本文以MODIS反演大气透射率,以HJ-1B/CCD分类结果反演地表比辐射率,并基于单窗算法,利用HJ-1B/IRS4数据反演地表温度.在此基础上,提取研究区的热场变异指数来分析重庆热岛空间分布特征,并就NDVI与NDBI对热岛效应的影响进行了分析.其结果如下:1)重庆城市热岛大致位于中梁山、铜锣山之间,呈东北、西南走向分布;2)热岛中心不在市中心,而是集中在大渡口工业园区、江北机场这些能耗大、人口密集区域,热岛强度范围在5?C-10?C之间;3)接近长江、嘉陵江水域的建筑用地密集区域,其热岛效应并不明显;4)NDVI与热岛强度呈负相关关系,NDBI与热岛强度呈现较为明显的正相关关系,二者对热岛都有重要影响,而NDBI的影响更大.因此,利用HJ-1B数据监测城市热环境,能较好地揭示重庆城市热岛空间分布特征,为城市环境监测与改善提供参考.  相似文献   

4.
地表热辐射场景动态变化模拟分析是热红外遥感领域研究热点之一.首先基于地表能量平衡方程和一维导热方程,建立地表温度二次谐波模型,模拟裸露地表温度日变化规律,并利用CUPID模型模拟植被冠层温度;其次利用高空间分辨率多光谱遥感影像的可见光-近红外光谱特征,提取植被、裸土、水体、不透水面等地物端元的覆盖比例及分布;最后结合地表温度模拟结果和典型发射率波谱,基于端元能量线性混合的假设,模拟地表热红外辐射动态场景.结果表明,地表温度日变化模拟值与实测值吻合较好,标准偏差在2.7℃以内;模拟场景可展现出清晰的纹理细节和较强的遥感成像真实感,场景热辐射特征与地物类型及其空间分布、成像时刻、观测角度均有关联.  相似文献   

5.
用低分辨率遥感数据计算地表蒸散通量时, 如何减小空间尺度误差是需要考虑的重要问题. 在用MODIS数据计算蒸散时尝试加入高分辨率中巴资源卫星CBERS-02提供的地表分类图像, 根据此分类信息在每个MODIS 1 km像元内统计各种地表类型所占的面积比例, 并分别计算各亚像元的热量通量, 然后用面积权重平均的方法得到MODIS像元的热量通量. 结果表明, 将CBERS高分辨率地表分类数据和MODIS低分辨率遥感数据结合, MODIS 1 km混合像元的土壤热通量、显热通量和潜热通量都有所改变. 进一步分析这种变化产生的原因, 结合地面实验观测数据的验证, 作者推断, 经过处理以后, 混合像元的显热通量和潜热通量的误差都有所减小.  相似文献   

6.
青藏高原热红外遥感与地表层温度相关性研究   总被引:1,自引:1,他引:1  
通过对青藏高原热红外遥感数据与地表层温度场分布规律的分析,确定影响地表层温度的陆面因素,采用神经网络技术建立通过热红外遥感反演陆面参数预测地表层温度的模型,利用该模型对各陆面参数与地表层温度的相关关系进行了分析.该方法为热红外遥感用于大面积地块缝合带监测以及研究构造热异常探索了一种新途径.  相似文献   

7.
根据两通道与温度无关的波谱指数的概念,并利用白天和晚上中红外和热红外的空间测量值,提出了一种用于提取方向比辐射率的物理方法,同时提出了一个用于描述反射率(或比辐射率)角度变化的三参数现像模型.把这种方法用于AVHRR数据,结果显示,地球表面并不是Lambert体.对裸露土壤,双向反射率的角度变化似乎与方位角无关,而植被具有很强的后向散射作用.至于方向比辐射率,植被的值很高而且与方向无关,相反,干旱地区的地表比辐射率的值较低并且具有显著的方向性.  相似文献   

8.
基于径向基函数神经网络,利用陆面参数和地表层不同深度的钻孔测温数据建立了地表各层温度的预测模型.采用各层预测模型级联递推的方法由陆面参数向下逐层预测地表各层温度.该方法为热红外遥感用于大面积地块缝合带监测以及研究构造热异常探索了一种新途径.  相似文献   

9.
植被含水量光学遥感估算方法研究进展   总被引:6,自引:0,他引:6  
利用光学遥感技术定量估测植被含水量,有助于森林火险评估、农业干旱监测和作物产量估计.本文评述利用光谱反射率、光谱水分指数和辐射传输模型方法反演植被含水量的研究进展,从观测数据和辐射传输模型评估了光谱水分指数估测植被含水量的可靠性.重点针对植被含水量的两个主要定义—可燃物含水量(FMC)和等效水厚度(EWT),分析了植被水分指数对FMC和EWT的反演精度.而且利用观测数据和数据库估算植被含水量,结果表明三类水分指数(WSI,NDII,NDWI1640,WI/NDVI)均与冬小麦冠层FMC有较好的相关性(n=45).最后,本文总结了光学遥感探测植被含水量进一步的发展方向.  相似文献   

10.
大气订正是遥感信息定量化研究中必不可少的一步,目前已有一些成熟的方法,但由于HJ-1A/B卫星CCD相机波段设置特点,常规的大气订正方法基本不适合于HJ-1A/BCCD影像.本文在大量分析HJ-1A/BCCD影像中不同地物的多种指数基础上,提出了改进暗目标法实现HJ-1A/BCCD影像的大气订正,该方法采用比值植被指数(RVI)、土壤调整植被指数(SAVI)和归一化水体指数(NDWI)的综合分析法确定暗像元自动提取,使之适用于环境减灾卫星CCD影像数据.为了客观地验证该方法的精度,本文选取地表平坦均一的敦煌校正场作为实验区,通过多次测量卫星过境时的地表反射率进行分析验证.  相似文献   

11.
This review attempts to rationalise what is known about bacterial phytotoxins and associate it with the ecology and possible evolution of the producing organisms. Study of non-toxin producing variants gives insight into the ecological role of the toxin. Elucidation of chemical structures of phytotoxins has shown that many exist as families of analogous compounds. Studies on the variation of chemical structures and how they are distributed across species and genera can lead to development of hypotheses on evolutionary relationships. Knowledge on biosynthetic pathways to tosins allows recognition of specific enzymatic steps involved in developing the characteristic features of the structures. Phytotoxins often have a potent biochemical activity, and in some cases the producing organism has associated mechanisms to prevent action of the toxin upon itself; in such cases toxigenesis is clearly not a chance event. The various aspects of bacterial toxigenesis indicate that bacterial phytotoxins are special secondary metabolic products that play beneficial roles to the producing organisms in their various ecological niches.  相似文献   

12.
This paper puts forward the hypothesis that the distinctive features of quantum statistics are exclusively determined by the nature of the properties it describes. In particular, all statistically relevant properties of identical quantum particles in many-particle systems are conjectured to be irreducible, ‘inherent’ properties only belonging to the whole system. This allows one to explain quantum statistics without endorsing the ‘Received View’ that particles are non-individuals, or postulating that quantum systems obey peculiar probability distributions, or assuming that there are primitive restrictions on the range of states accessible to such systems. With this, the need for an unambiguously metaphysical explanation of certain physical facts is acknowledged and satisfied.  相似文献   

13.
Summary It was found that some ciliates,Stentor, Spirostomum andBlepharisma, which can contract rapidly like the stalks of Vorticellidae, have Ca2+-binding proteins that are very similar to spasmins, in the immunological sense. The presence of spasmins in other Protozoa and in some Metazoa was also investigated.  相似文献   

14.
Defensive secretions (allomones) from first-instar nymphs of stink bugs in the subfamily Pentatominae contain (E)-4-oxo-2-decenal as a major constituent, whereas this compound is absent from later instars. In contrast, first instars ofEdessa meditabunda (Edessinae) produce allomones like those of later instars. The C6 and C8 (E)-4-oxo-2-alkenals are common, characteristic exocrine compounds of nymphal and adult Heteroptera, but (E)-4-oxo-2-decenal is previously unknown as a major natural product for which a biological role has yet to be established.  相似文献   

15.
A part of the gene coding for a halophilic serine protease from a halophilic archaeumHaloferax mediterranei R4 was amplified by PCR and its 672 nucleotide sequence was determined. Tentative translation to the amino acid sequence suggested that the enzyme was quite similar to halolysin produced by another halophilic archaeum strain 172P1. Nucleotide sequences of 16S rRNA encoding genes from 9 halophilic archaea were determined. Alignment of 19 sequences known so far showed that there are more than 20 positions carrying bases or deletions specific for each halobacterial genus:Halobacterium, Haloarcula, Haloferax, andHalococcus.  相似文献   

16.
What is the relationship between observations, predictions, texts, and instruments in ancient astrology? By distinguishing between two distinct kinds of observation claim in astrological texts, I show on the one hand the rhetorical and theoretical importance of each kind of observation claim to ancient astrological traditions, and on the other hand how practices of ancient astrology break from observation once astronomical phenomena become reliably predictable. We thus see a shift in practice from observationally derived predictions to a reliance on textual and instrumental authority, even though the rhetoric of ancient astrology still tries to maintain an emphasis on observation.  相似文献   

17.
Summary Recent data on the immunologication of regulatory peptides and related propeptide sequences in endocrine cells and tumours of the gastrointestinal tract pancreas, lung, thyroid, pituitary (ACTH and opioids), adrenals and paraganglia have been revised and discussed. Gastrin, xenopsin, cholecystokinin (CCK), somatostatin, motilin, secretin, GIP (gastric inhibitory beenrevised and discussed. Gastrin, xenopsin, cholecystokinin (CCK), somatostatin, motilin, secretin, GIP (gastric inhibitory polypeptide), neurotensin, glicentin/glucagon-37 and PYY (peptide tyrosine tyrosine) are the main products of gastrointestinal endocrine cells; glucagon, CRF (corticotropin releasing factor), somatostatin, PP (pancreatic polypeptide) and GRF (growth hormone releasing factor), in addition to insulin, are produced in pancreatic islet cells; bombesin-related peptidesare the main markers of pulmonary endocrine cells; calcitonin and CGRP (calcitonin gene-related peptide) occur in thyroid and extrathyroid C cells; ACTH and endorphins in anterior and intermediate lobe pituitary cells, -MSH and CLIP (corticotropoin-like intermediate lobe peptide) in intermediate lobe cells; met- and leu-enkephalins and related peptides in adrenal medullary and paraganglionic cells as well as in some gut (enterochromaffin) cells; NPY (neuropeptide Y) in adrenalin-type adrenal medullary cells, etc.. Both tissue-appropriate and tissue-inappropriate regulatory peptides are produced by endocrine tumours, with inappropriate peptides mostly produced by malignant tumours.  相似文献   

18.
Summary Monarch butterflies sequester cardenolides from their larval host plants in the milkweed genusAsclepias for use in defense against predation. Of 108Asclepias species in North America, monarchs are known to feed as larvae on 27. Research on 11 of these has shown that monarchs sequester cardenolides most effectively, to an asymptote of approximately 350 g/0.1 g dry butterfly, from plants with intermediate cardenolide contents rather than from those with very high or very low cardenolide contents. SinceAsclepias host plant species are distributed widely in space and time across the continent, monarchs exploit them by migration between breeding and overwintering areas. After overwintering in central Mexico, spring migrants east of the Rocky Mountains exploit three predominantAsclepias species in the southern USA that have moderately high cardenolide contents. Monarchs sequester cardenolides very effectively from these species. First generation butterflies are thus well protected against predators and continue the migration north. Across the northern USA and southern Canada most summer breeding occurs on a fourthAsclepias species and in autumn most of these monarchs migrate back to Mexican overwintering sites. The ecological implications of this cycle of cardenolide sequestration for the evolution of monarch migration are discussed.  相似文献   

19.
Summary In vitro and in vivo data on the benzimidazoline compound indicate anthelmintic potential when introduced directly into the abomasum.  相似文献   

20.
Cognition wars     
In what kinds of physical systems can cognition be realized? There are currently competing answers among scientists and theorists of cognition. There are many plant scientists who maintain that cognition can be realized in plants. There are biological scientists who maintain that cognition is materially realized in bacteria. In this paper, I will present the basis for such claims and evaluate them and discuss the future for theories of the metaphysical basis of cognition in the cognitive sciences.  相似文献   

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