利用MODIS数据反演气温监测夏季高温热害   总被引：1，自引：0，他引：1  

裴亮  王和斌  延昊 《安徽农业科学》2012,40(8):4777-4779,4817

[目的]研究利用MODIS数据反演气温来监测夏季水稻高温热害。[方法]介绍了一种新的反演我国东部地区白天气温的统计算法,并给出了一个监测2007年我国东部夏季水稻高温热害的例子。[结果]夏季在我国南部水稻的抽穗期期间,高温对水稻的产量起着关键性的影响。利用MODIS数据监测高温热害是减轻农业灾害的一个可行办法。[结论]该研究结果为我国夏季水稻高温热害的监测提供了方法。  相似文献   

光谱异质性参数优化方法及其在QuickBird影像中的应用     

孙小丹  侯阳青 《福建林业科技》2012,39(4):101-105,116

提出了一种光谱异质性参数优化方法,与现有方法相比,新方法的改进主要有:①在设置参与分割的波段数据时,通过引入派生波段数据来增强分割判据的数据支撑;②在设置各波段数据层的权值时,综合考虑了各波段数据层包含的信息量和相互间的信息相关度,以抑制波段数据层间的信息冗余对分割过程的不利影响.最后,通过分割对比实验证明:采用新方法设置的光谱异质性参数执行影像分割,“欠分割”现象有了较大幅度地减少,对象间的差异程度和对象内部的均质程度都得到了提高,分割质量有了明显地改善.  相似文献   

Coil embolization of patent ductus arteriosus via the carotid artery in seven dogs     

Sarah J. Miller  William P. Thomas 《Journal of Veterinary Cardiology》2009,11(2):129-136

This study was designed to evaluate the feasibility and limitations of transcatheter embolization coil occlusion of patent ductus arteriosus in dogs using a carotid artery approach. Seven dogs examined at the University of California, Davis Veterinary Medical Teaching Hospital in 2002-2003 for evaluation of heart disease had congenital patent ductus arteriosus diagnosed by characteristic physical, electrocardiographic, radiographic, and anatomic and Doppler echocardiographic findings. Dogs were anesthetized for transesophageal echocardiography and transcatheter coil embolization of the ductus via the right external carotid artery. Coil embolization was achieved in all seven cases, using one to four detachable embolization coils. There were no major complications. Minor complications occurred in two dogs (additional coils placed using a femoral arterial approach and coil embolization of a left femoral artery branch). One dog was examined only 24 h post-operatively and had no murmur and trivial residual ductal flow by Doppler echocardiography. The other 6 dogs were clinically healthy when examined up to three years post-intervention. One dog had a very soft continuous murmur and mild residual ductal flow; the other five had no audible continuous murmur, with only one dog having trivial residual ductal flow identified by Doppler echocardiography. Although technically challenging, coil embolization via the carotid artery is a viable alternative approach for transcatheter closure of patent ductus arteriosus in some dogs.  相似文献   

基于动变形试验的黄土剪切带特性研究     

李浩东  骆亚生  王志杰 《西北农林科技大学学报(自然科学版)》2012,40(2):227-234

【目的】分析动荷载条件下黄土局部化变形的判断依据和剪切带的特性,探究不同初始应力条件对非饱和黄土剪切带特性的影响。【方法】用动扭剪仪进行陕西杨凌非饱和黄土的动变形试验,分析其动本构关系曲线、动孔隙气压力和阻尼比的变化规律,探讨初始平均主应力和初始主应力方向角对剪切带倾角的影响。【结果】土样的动本构关系曲线、动孔隙气压力随时间变化曲线和阻尼比随动剪应变变化曲线皆为非线性型,其变化规律很好地体现了局部化变形的过程。当初始主应力方向角<45°时,土样的剪切带倾角随着初始平均主应力的增加而呈增加趋势;当初始主应力方向角≥45°时,剪切带倾角随着初始平均主应力的增加呈减小趋势。在初始主应力方向角<45°时,剪切带倾角随着初始主应力方向角的增大而减小;当主应力方向角为90°时,土样未出现剪切带。【结论】动荷载作用下,黄土会发生局部化变形,这种局部化变形的出现和发展可以用动孔隙气压力和阻尼比的变化规律来判别,该判别方法意义明确且合理可行;初始平均主应力、初始主应力方向角对黄土的剪切带倾角有一定影响。  相似文献   

用单片机控制单边带电台进行数字通讯的研究     

刘贵斌 《大连水产学院学报》1998,13(4):52-55

利用单片机控制技术，将单边带电台和ＧＰＳ这两台功能不同的设备进行综合控制和管理，使单边带电台自动报发船位及数字通讯，从而收到以较小的投入，达到扩展功能，提高自动化程度和管理水平之功效。  相似文献   

消化道出血的选择性血管造影诊断及介入治疗     

罗泽斌  吴剑波 《湛江医学院学报》1998,16(4):327-328,334

目的：用选择性腹部血管造影的方法评估不明显原因消化道出血的病因、造影表现，及介入治疗，方法：本组２１例全部经手术病理证实，先前均经消化道钡餐造影、纤维内镜及繁华吉肠镜检查，并分别行选择性肠系膜上动脉和肠系膜下动脉造影。９例行介入性治疗，采用血管收缩剂持续灌注和栓塞。结果：２１例出血的病因中，血管畸形７例，平滑肌瘤８例，溃疡性结肠炎４例，克隆氏病２例，血管造表现观血管不同程度异常分布为主，其中血管畸  相似文献   

Agronomic evaluation of precise mechanical hoeing and chemical weed control in sugar beet   总被引：1，自引：0，他引：1  

J J J Wiltshire  N D Tillett†  & T Hague† 《Weed Research》2003,43(4):236-244

Most herbicide applications to sugar beet (Beta vulgaris L.) are made to the whole crop area, but there is the opportunity to restrict applications to the crop row, decreasing the usage of herbicide by up to 70%. However, this would require greater use of mechanical weed control between rows. Experiments were performed in two seasons to evaluate the weed control performance of a novel, vision‐guided, inter‐row hoe in sugar beet crops grown on a peat fen soil. Hoe lateral placement was within ±30 mm. A precise hoeing and band spraying treatment was compared with overall herbicide use, and with treatments in which the herbicide applications were replaced by hand weeding to minimize competition between crop and weeds. Two hoe passes were made in each season, at crop growth stages of two and 10–12 true leaves in the first season and four and eight true leaves in the second season. Plant population density was not affected by treatment, indicating that none of the treatments caused crop plant loss. Use of the guided hoe controlled weeds better than overall spraying. Crop yields were not significantly different between treatments, indicating that weed control prevented competition with the crop in all treatments.  相似文献   

胰岛素抵抗机制及其营养干预作用研究     

孙智媛  谷雪玲  范志勇 《家畜生态学报》2021,32(1):1-6

胰岛素抵抗(Insulin resistance,IR)常会引发血脂异常、非酒精性脂肪肝等慢性代谢疾病,影响动物正常生长状态并降低养殖效益.机体存在多种能够诱发胰岛素抵抗的因素,如氧化还原状态、体脂代谢和肠道微生物的种类和数量等,明确这些影响因素的作用及其作用机制对寻找改善胰岛素抵抗的作用靶点和营养物质具有重大意义.目...  相似文献   

深圳市罗湖区围产儿出生缺陷监测干预的效果分析     

刘保华  陈晓红  曾红燕  周丽萍  刘晓芬 《湛江医学院学报》2006,24(5):459-460,465

目的:调查深圳市罗湖区出生缺陷发生情况,了解其相关危险因素,对近3年综合干预措施的效果进行评估,为预防决策提供依据。方法:将2000-2002年(未实行出生缺陷综合干预措施,为无干预组)与2003-2005年(期间采取出生缺陷综合干预措施,为干预组)围产儿出生缺陷情况进行比较,对2003-2005年干预效果进行评估。结果:罗湖区近6年共有围产儿44503例,发生出生缺陷657人,无干预组的缺陷发生率为1.53%,干预组为1.43%;通过综合干预措施,危险因素暴露率较干预前明显减少(P<0.001),常住人口出生缺陷发生率显著下降(P<0.05),且出生缺陷的顺位发生了变化,以先天性心脏病居首位。结论:罗湖区出生缺陷发生率较高,是引起围产儿死亡的首位原因,采取综合干预措施可达到降低出生缺陷发生率的目的。  相似文献   

Differential host residence of adult cryptomeria bark borer,Semanotus japonicus Lacordaire (Coleoptera: Cerambycidae), in relation to tree size of Japanese cedar,Cryptomeria japonica D. Don     

Kensuke Ito 《Journal of Forest Research》1999,4(2):151-156

To understand factors involved in tree-size dependent vulnerability ofCryptomeria japonica to damage bySemanotus japonicus, residence of adultSemanotus japonicus on host trees was assessed in twoCryptomeria japonica stands, using band trap method and mark-recapture techniques. Adult capture distributions among trees were analyzed in relation to diameter size of each tree. Female adults consistently exhibited more frequent residence on larger trees, under different field conditions. Females that made inter-tree movements preferentially chose larger trees as their destinations. Frequent residence by females on large trees was associated with high productivity of progeny adults. Male adults were also more frequently resident on larger trees. These results suggest that tree-size dependent oviposition accounts for the tree-size dependent vulnerability ofCryptomeria japonica to damage bySemanotus japonicus. Possible causes underlying the differential host residence of adultSemanotus japonicus are discussed.  相似文献