Regional forest cover estimation via remote sensing: the calibration center concept

A method for combining Landsat Thematic Mapper (TM), Advanced Very High Resolution Radiometer (AVHRR) imagery, and other biogeographic data to estimate forest cover over large regions is applied and evaluated at two locations. In this method, TM data are used to classify a small area (calibration center) into forest/nonforest; the resulting forest cover map is then used in combination with AVHRR spectral data from the same area to develop an empirical relationship between percent forest cover and AVHRR pixel spectral signature; the resultant regression relationship between AVHRR band values and percent forest cover is then used to extrapolate forest cover for several hundred kilometers beyond the original TM calibration center. In the present study, the method was tested over two large regions in the eastern United States: areas centered on Illinois and on the Smoky Mountains on the North Carolina-Tennessee border. Estimates of percent forest cover for counties, after aggregating AVHRR pixel estimates within each county, were compared with independent ground-based estimates. County estimates were aggregated to derive estimates for states and regions. For the Illinois region, the overall correlation between county cover estimates was 0.89. Even better correlations (up to r = 0.96) resulted for the counties close to one another, in the same ecoregion, or in the same major land resource region as the calibration center. For the Smokies region, the correlations were significant but lower due to large influences of pine forests (suppressed spectral reflectance) in counties outside the hardwood-dominated calibration center. The method carries potential for estimating forest cover across the globe. It has special advantages in allowing the assessment of forest cover in highly fragmented landscapes, where individual AVHRR pixels (1 km²) are forested to varying degrees.Managed by Martin Marietta Energy Systems, Inc., under contract PE-AC05-840R21400 with the U.S. Department of Energy     

呋甾烷研究进展

呋甾烷是食品、中药材（药品）储存和炮制以及人体内非酶糖基化反应（Mallard反应）的糖基化终产物之一,与食品营养、中药材（药品）品质和人体健康密切相关.因此,对呋甾烷进行全面、深刻研究具有重要意义.对呋甾烷生化特性与结构、生成机理、测试方法和抑制策略4部分进行简要综述,并在此基础上对呋甾烷研究前景进行展望,以期为呋甾烷后期研究提供一定参考.     

我国现代先进生产力发展的层次性、阶段性与党的"三个代表"作用

代表中国先进生产力的发展要求是"三个代表"的基础。我国现代先进生产力的发展具有多层次性和多阶段性。我国现代先进生产力的这一特点与中国共产党作为先进生产力主体力量先进部队的阶级特性,决定了党必然代表中国先进生产力的发展要求。面向新世纪,我们党坚定地站到先进生产力的前沿,大力推进理论创新与科技创新,从而进一步解决好了党在新世纪"如何代表"的问题。     

IWWIP冬小麦优良品系产量试验结果分析及利用评价

2004年兰州商学院小麦研究所引进国际冬小麦改良项目(IWWIP)半干旱地和水地兼性及冬小麦优良品系产量试验(8THEYT-SA,2004—2005和9THEYT-IRR,2004—2005)两套。每套试验实际参试品种(系)20个。试验结果表明,旱地试验中9906、9914、9916、9920和9921等5份材料在生产上有直接利用价值。水地试验中9806和9825等2份材料虽然产量低于对照,但与对照的产量差异不显著,可以考虑在生产上直接利用。试验中对在不同方面(抗锈性、抗旱性、丰产性和品质等)表现突出的材料,应扬长避短进行研究利用。     

高级氧化技术在微污染水源水处理中的应用

[目的]为了提高高级氧化技术对微污染水源水的处理效果。[方法]采用臭氧、紫外和臭氧/紫外3种高级氧化技术,处理微污染水源水。[结果]每种处理方法都对江水中氨氮和高锰酸盐指数有一定的去除效果,其中臭氧紫外混合投加使用效果最好。在臭氧投加量为3.9 mg/L、紫外灯开启35盏(光照强度为124μW/cm~2)、pH为7.6的条件下,水中氨氮和高锰酸盐指数的去除率分别为62.96%和62.85%。[结论]UV/O_3技术的氧化能力和污染物去除率均好于单独UV或O_3高级氧化技术。     

高级氧化技术修复萘污染土壤和地下水研究进展

多环芳烃是土壤和地下水中普遍存在的持久性有机污染物。其中，萘是结构最简单的多环芳烃，具有迁移性强的特点，可通过多种途径在土壤和地下水中富集，是焦化、化工等历史遗留地块重点关注的污染物之一。高级氧化技术高效、安全且经济，因此，基于高级氧化的萘污染土壤和地下水修复技术受到越来越多的关注。本文综述了芬顿和类芬顿氧化、臭氧氧化和过硫酸盐氧化的反应机理，重点阐述了二价铁、微纳级零价铁、铁矿物、铁螯合物等均相及非均相活化剂活化的氧化技术在修复萘污染土壤和地下水方面取得的研究进展，介绍了多种高级氧化技术联合修复以及高级氧化技术与生物降解技术协同修复的研究现状，指出了目前萘的高级氧化技术研究存在的问题，并对研究做出了展望。