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Search Results: 1 - 10 of 165261 matches for " 周志翔 "
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林茶间作下的光照条件与茶树生理生态研究综述

生态学杂志 , 1995,
Abstract: ?
顺序图与状态图的递归语义一致性研究
,清?
计算机科学 , 2010,
Abstract: 建模面向对象的软件系统是uml的动态图的重要应用,采用顺序图描述消息传送,动态图描述活动。在大型系统开发过程中,往往存在大量顺序图和状态图,由于语义的缺失,导致这些图形表达涵义模糊不清,特别是在递归的信息传送上,由于表达方式的特点,状态图很容易造成实现过程的歧义甚至死锁。提出了基于asm的多agen、实时控制方法,结合形式化的规则定义,通过多个层次;agent控制状态的跃迁,保证状态图在描述复杂信息传送时,能够和顺序图的时序保持一致,这对提高系统的可靠性具有一定的现实意义。
绿色屋顶径流调控研究进展
陈小平,黄佩,**
应用生态学报 , 2015,
Abstract: 绿色屋顶在屋顶径流调控方面发挥着重要作用,能够有效减少径流量、延缓产流时间、降低径流峰值和改善径流水质.本文从绿色屋顶的分类及界定、绿色屋顶对径流的调控机制、绿色屋顶对径流量和水质的调控作用及其影响因素等方面阐述了国内外的研究现状,并从绿色屋顶植物的选择、高效绿色屋顶构建模式筛选、绿色屋顶径流调控规律研究、绿色屋顶截流能力的价值评估、绿色屋顶径流污染物的源汇解析及缓解措施等方面提出了绿色屋顶径流调控的研究趋势,以期为城市绿色屋顶的建设提供理论和方法支持.?
康集生态农场废窑地开发方式与经济效益分析
,钟懋功
中国生态农业学报 , 1996,
Abstract: 对山东省成武县康集乡生态农场废窑地开发方式与经济效益分析表明,采取农林牧副渔相结台的综合开发措施,有利于废弃窑地的整治与利用,经济效益显著,生态环境得到了保护和改善,并为社会提供了丰富的农副产品,是华北平原废地开发的有效途径。
漓江流域1973-2013年景观格局动态变化研究
Dynamic Changes of Landscape Pattern in Lijiang River Basin from 1973 to 2013

胡金龙,罗楠,
- , 2017, DOI: 10.3969/j.issn.1001-7461.2017.04.36
Abstract: 基于1973-2013年Landsat遥感影像数据,借助3S技术,分析漓江流域景观格局演化特征。结果表明,40 a间漓江流域林地、建设用地、裸地持续增加,农田不断减少,水域先增后减,草地先减后增,2000-2013年整体动态度达最高值,景观变化剧烈,类型转化频繁;从景观水平上看,1973-2000年景观破碎度不断加剧,斑块复杂性升高,2000-2013年景观破碎度降低,斑块趋向于规则化;从类型水平看,林地和建设用地破碎度先升后降,斑块间距离减少,聚集程度增加;农田破碎化加剧,趋向分散经营;水体的聚集度较高,以集中分布为主;草地斑块空间关系变化不明显,分布较为均衡;裸地趋向于集中分布。受退耕还林、林果种植以及城镇扩张和旅游开发等因素的驱动,各景观类型主要向林地和建设用地转移。
Based on remote sensing images of Lijiang River basin in 1973,1986,2000 and 2013,dynamic changes of landscape pattern were studied by 3S techniques.The results showed that woodland,construction land and bare land increased while farmland decreased,and water body increased first and then decreased,whereas the grassland decreased first,and then increased in the past 40 years.The peak value of comprehensive dynamic degree appeared at 2000-2013,indicating dramatically changes of landscape in the study area.From the view of the landscape level,the fragmentation degree and patch complexity increased during 1973-2000,while during 2000-2013,the trend was opposite.From the view of landscape type level,the fragmentation degree of woodland and construction land decreased after increasing,the distance between different patches reduced and aggregation degree increased; the fragmentation degree of farmland increased and tended to be managed separately; water body presented higher aggregation index,and in concentrated distribution; grassland had little changes in spatial relationship,and presented balanced distribution; and bared land tended to present concentrated distribution.Different landscape types mainly converted into the woodland and construction land because of the influences of the factors such as the implementation of policy of converting farmland into forestland,the planting non-timber forest trees,urbanization,and tourism development
The Spatial Structures and the Dust Retention Effects of Green-land Types in the Workshop District of Wuhan Iron and Steel Company
武钢厂区绿地景观类型空间结构及滞尘效应

ZHOU Zhi-Xiang,

生态学报 , 2002,
Abstract: The landscape green lands has an important role on maintaining the balance of urban or industrial district ecosystem, especially, smoothing away air pollutant and improving air quality of air pollution area. However, the ecological functions of green lands has a closed relation with the landscape types and the spatial structures of green lands when the percentage of green land coverage is less than 40%. In this paper, the green lands in the workshop district of Wuhan Iron and Steel Company are classifi...
The different urban green-land spatial patterns and their environmental effects:A case of the central district of Yichang city,Hubei Province
城市绿地空间格局及其环境效应——以宜昌市中心城区为例

ZHOU Zhi-Xiang,

生态学报 , 2004,
Abstract: The urban green-land system plays an important role in improving the quality of urban environment and maintaining the balance of urban ecological system. However, the whole ecological benefit of green-land system is mainly determined by green-lands' internal structures and spatial patterns when the percentage of green-land coverage is less than 40%. So far there hasn't been any research on the relationship of urban green-land spatial pattern and its environmental effect. In this paper, the four types of lan...
茄子植株中α-茄碱释放途径研究
,宝利,,张 平
中国生态农业学报 , 2010,
Abstract: 本文模拟了茄子在根系分泌、残体分解、雨水淋溶以及种子萌发情况下向环境中释放α-茄碱的过程, 利用HPLC测定了茄子通过不同途径向周围环境释放的α-茄碱含量。结果表明, 茄子可通过根系分泌、残体分解和种子萌发途径向环境中释放α-茄碱, 其中残体分解和种子萌发是主要途径, 根系只能主动分泌极少量的α-茄碱。茄子生长期不同, 根系主动分泌α-茄碱的量不同, 从茄苗现蕾到四面斗果实成熟是根系分泌α-茄碱的主要时期, 门茄坐果后至对茄成熟, 茄子根际土壤中α-茄碱含量增加最显著。植株不同部位残茬腐解后释放出的α-茄碱量不同, 大小顺序为: 叶>根>茎, 随着残株分解时间的延长, 土壤中α-茄碱含量显著增高。茄子种子萌发过程释放的α-茄碱含量与种子萌发密切相关, 该生物碱可抑制茄子种子萌发。紫茄“辽茄7号”和“超九叶茄”通过不同途径释放的α-茄碱量显著高于绿茄“通杂2号”和“西安绿茄”。
LycogarubinC和LycogalicAcidA的全合成有机化学
妮妮, 史倩,
有机化学 , 2014, DOI: 10.6023/cjoc201403025
Abstract: LycogarubinC和LycogalicacidA是用于研究DNA拓扑异构酶I(TopoI)抑制剂的重要海洋天然产物.我们以叔丁基二甲硅基(TBS)保护的3-丁炔-1醇为起始原料,以二甲基1,2,4,5-四嗪-3,6-二羧酸酯与炔的杂/逆Diels-Alder反应为关键反应,经1,2-二嗪还原,Swern氧化,Fischer吲哚合成等八步反应实现了LycogarubinC的全合成,再将LycogarubinC以氢氧化钾处理得到LycogalicacidA.
基于GIS的关中-天水经济区地形起伏度与人口分布研究
,李晶,
地理科学 , 2012,
Abstract: 地形起伏度作为影响人口分布的重要因素之一,是人居环境自然评价的一个重要指标,在小尺度人居环境自然评价方面也具有较高的准确性和实际应用价值。基于关中-天水经济区栅格数字高程模型,采用窗口分析等方法,利用ArcGIS软件空间分析模块中的邻域分析,提取了基于栅格尺度的关中-天水经济区地形起伏度,并从比例结构、空间分布和高度特征3个方面系统分析了关中-天水经济区地形起伏度的分布规律及其与人口分布的相关性。研究结果为①关中-天水经济区的地形起伏度以中低值为主,地形起伏度小于2.4的区域占总面积的96.66%,其中平地比例占总体的32.4%;地形起伏度越高的地区,平地比例越低,反之亦然。②关中-天水经济区的地形起伏度呈现南北高中间低的空间格局,最高值为宝鸡市太白县,最低值为关中平原;经度上的变化规律不是很明显,纬度上的地形起伏度无论从南到北还是从北到南都是先下降后增高的。③随着海拔高度的增加,地形起伏度呈现逐渐升高趋势,但变化幅度不大。④地形起伏度对区域人口分布有较强的影响,关中-天水经济区近90%的人口居住在地形起伏度小于1.5的地区,人口密度与地形起伏度的曲线拟合度非常高。
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