999 resultados para 1995_01150505 TM-23 4301102


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大范围、实时、准确地监测典型草原地区草场退化或健康状况对于草原生态系统的保育、农牧业的可持续性发展具有非常重要的意义。比起传统的群落学研究方法,遥感技术对于监测大尺度的植被状况具有无可争议的优越性,并且已经被广泛引入监测植被覆盖变化的研究中。本项研究系统地分析、综述了过去用非遥感手段对放牧和草场退化的关注和研究,介绍了遥感技术应用于植被研究的理论基础、主要途径(植被指数)、有关领域的研究进展。特别是本文提出草场退化状况或整体健康状况可以由基干相互独立的层面表示,而过去监测植被变化主要依赖的NDVI等植被指数只能监测草原植被的个别层面(总量层)。 本文以草场放牧退化比较典型的内蒙古锡林河流域为研究对象,在进行了大量的野外样方调查的基础上,提出一种结合群落样方调查和遥感技术的监测草场健康状况的新方法。本文引入主成份分析方法(PCA),从包含12个反映群落各方面信息的变量中提取出3个有特定生态学意义的主成份,并进一步对其进行分析组合,得出一个能比较敏感、全面反映群落健康状况的新指标-草场健康指数(GHI)。 从6波段的植被光谱反射数据中比较理想地提取出2个主成份:可见光因子和红外光因子。表征群落总量、放牧退化的主成份和GHI与样方光谱反射值有相当的相关性,由此得到GHI与可光、红外光因子的回归模型。 应用此模型到卫星遥感数据(TM),得到GHI影像,并与同一数据的NDVI影像作对比研究,发现GHI在反映放牧等人为干扰对草原植被的影响效应方面比NDVI有明显的优点。此外,GHI影像对植被分布格局,特别是斑块结构有更好的显示效果。应用GHI到历史TM数据,对所研究地域的植被覆盖变化、农牧业的变迁模式等进行了定性研究。研究还发现有较长放牧史的过度放牧区的植被类型没有沿牧压梯度的规律性分布,而是呈随机斑块分布模式。

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This report of the cruise along the Sofala Bank (Mozambique) describes the catch composition and catch distributions of the shallow water shrimp. Biological data are given for Penaeus indicus and Metapenaeus monoceros which represent 77% of the total catch.

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Catch composition and bathymetric distribution of demersal fish caught along the coast of Mozambique between parallels 16 degree 20' and 19 degree 30' S at depths of 11 to 180 metres are given. The shrimp by-catch was also studied.

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This report of the research cruise (7 to 23 June 1981) surveying pelagic marine resources of the Sofala Bank (Mozambique) describes the size composition, distribution, length-weight relationships and sex-ratio of the fish captured. Decapterus russellii, D. macrosoma, Selar crumenophthalmus and Rastrelliger kanagurta represented 21.7% of the total catch. The by-catch was also studied.

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Przewalskin A (1), a novel C-23 terpenoid with a 6/6/7 carbon ring skeleton, was isolated from Salvia przewalskii. Its structure was determined by comprehensive 1D NMR, 2D NMR, and MS spectroscopic analysis and subsequently confirmed by a single-crystal X

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Participants were exposed to concepts and information about EAFM using a structured, participatory method of delivery. The learning strategy involved pre- and post-course assessment as well as 4-6 month follow up at outcome level to assess improves EAFM practices. The report outlines methodology details of content and the daily feedback process.

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Objectives of the workshop included: presentation of research to stakeholders; briefing of stakeholders on project objectives, contents and activities; to get stakeholder perceptions and suggestions.

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On page OP 175, U. Steiner and co-workers destabilise polymer trilayer films using an electric field to generate separated micrometre-sized core-shell pillars, which are further modified by selective polymer dissolution to yield polymer core columns surrounded by a rim and micro-volcano rim structures. When coated with gold and decorated with Raman active probes, all three structure types give rise to substantial enhancement in surface-enhanced Raman scattering (SERS). Since this SERS enhancement arises from each of the isolated structures in the array, these surface patterns are an ideal platform for multiplexed SERS detection.

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We demonstrate mode-locking of a thulium-doped fiber laser operating at 1.94 μm, using a graphene-polymer based saturable absorber. The laser outputs 3.6 ps pulses, with ∼0.4 nJ energy and an amplitude fluctuation ∼0.5%, at 6.46 MHz. This is a simple, low-cost, stable and convenient laser oscillator for applications where eye-safe and low-photon-energy light sources are required, such as sensing and biomedical diagnostics. © 2012 Optical Society of America.