共查询到20条相似文献,搜索用时 62 毫秒
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木棉(Gossampinus malabarica)又名攀枝花、红棉、英雄树、烽火树,属木棉科木棉属落叶高大乔木.木棉广泛分布在我国四川、云南、贵州、广西、广东,生长在江河沿岸、山地阳坡及村边道路旁,喜光、耐高温,对土壤要求不苛刻.在四川攀枝花地区木棉树于1月-2月份开花,先花后叶,花色艳丽,有红色、金黄、淡黄色等颜色,树形高大伟岸,是优良的园林绿化树种.木棉树现是攀枝花市市花和广州市市树,在园林绿化中常作行道树、庭荫树、景园树、盆景树等.木棉经嫁接后2 a-3 a开花,嫁接苗可作盆景矮化栽培,观赏价值高.本文介绍了木棉的嫁接育苗技术. 相似文献
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One compound approach combining factor-analytic model with AMMI and GGE biplot to improve multi-environment trials analysis 总被引:1,自引:0,他引:1
To improve multi-environmental trial(MET)analysis,a compound method—which combines factor analytic(FA)model with additive main effect and multiplicative interaction(AMMI)and genotype main effect plus genotype-by-environment interaction(GGE)biplot—was conducted in this study.The diameter at breast height of 36 open-pollinated(OP)families of Pinus taeda at six sites in South China was used as a raw dataset.The best linear unbiased prediction(BLUP)data of all individual trees in each site was obtained by fitting the spatial effects with the FA method from raw data.The raw data and BLUP data were analyzed and compared by using the AMMI and GGE biplot.BLUP results showed that the six sites were heterogeneous and spatial variation could be effectively fitted by spatial analysis with the FA method.AMMI analysis identified that two datasets had highly significant effects on the site,family,and their interactions,while BLUP data had a smaller residual error,but higher variation explaining ability and more credible stability than raw data.GGE biplot results revealed that raw data and BLUP data had different results in mega-environment delineation,test-environment evaluation,and genotype evaluation.In addition,BLUP data results were more reasonable due to the stronger analytical ability of the first two principal components.Our study suggests that the compound method combing the FA method with the AMMI and GGE biplot could improve the analysis result of MET data in Pinus teada as it was more reliable than direct AMMI and GGE biplot analysis on raw data. 相似文献
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近年来,绿色建筑成为国内乃至国际建筑界、房地产界的一个热点话题,绿色建筑的发展也越来越受到关注,许多国家都开展了绿色建筑的研究和实践,取得了很多的研究成果.尤其在去年经历了一场与"非典"的斗争之后,人类更加深刻地认识到绿色建筑在生活中的重要性,由此也引发了一场关于绿色建筑的革命,将绿色建筑向更深入、更科学的方向推进. 相似文献
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Natural spruce-fir mixed stand is one of the main forest types in the world,and also has huge ecological,economic and social benefits.According to the structural characteristics and succession laws of natural spruce-fir forest,it is urgent and significant to develop scientific management measures for natural spruce-fir mixed stand in line with local conditions.The article outlined the characteristics of the distribution and structure, regeneration and succession laws of natural spruce-fir forest,and analyzed the current situation and existing problems of natural spruce-fir forest management.The following recommendations were eventually made:1) In no cutting area,all logging activities should be banned.In a restricted cutting area,the cutting intensity should be generally controlled within 15%of the stock volume before cutting.On the commodity forest management area, the appropriate cutting intensity should be determined according to the volume per hectare,determine and classification management should be implemented in accordance with the characteristics of forest,to ensure the scientific selective cutting.2) Closure for afforestation,planting and repair planting should be adopted on vegetation-intensive land,sparse shrubs covered land and harvesting slash,in order to accelerate natural regeneration.3) The in situ conservation should be conducted in nature reserves and scientific experiment stations of rare and endangered species,such as Abies chensiensis,Picea neoveitchii,Abies vuanbaoshanensis,to reduce human destruction.4) It is supposed to collect seeds in time,establish nursery,actively establish forest, expand artificial population and promote natural regeneration. 相似文献
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《技术与市场》2007,(1):23
当前现代化的航天、航空、汽车、机械、电子、民用建筑、化工等行业迫切要求具备很高的力学性能及耐热、耐磨、耐化学性能的材料.因此高分子材料发展的一个重要方向就是通过对现有聚合物进行物理和化学改性,使其进一步高性能化、结构化、工程化.北京化工大学研制的聚氯乙烯合金是通过挤出机的力学、化学作用及接枝、复合技术使聚氯乙烯塑料工程化,成为物理性能可与ABS相比拟的新材料.聚氯乙烯合金具有高流动性、高韧性,完全可以代替ABS注塑计算机、电视机、冰箱、照相机、仪表等外壳.聚氯乙烯合金还具有良好的耐寒性,可制作各种规格的异型材,包括门窗、上水管道等.产品市场前景好,具有很强的竞争力,有很好的经济效益和社会效益. 相似文献
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溶氧超标"毒水症" 危害及症状:水体中因施放过多未经发酵的肥料,生肥在塘底分解出很细小的甲烷和硫化氢的小气泡,鱼苗误当食物吞入.其主要症状是:鱼鳃上会粘附许多小气泡,使鱼体上浮或游动失去平衡.鱼的肠道中有白色气泡,或鱼的体表、鳍条、鳃丝上附有较多的气泡,鱼体漂浮水面,沉不下去,严重的可致鱼类成批死亡. 相似文献
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浙江省重点公益林松类生物量模型研究 总被引:2,自引:0,他引:2
根据浙江省森林群落和树种分布特点,在浙江省200万hm^2重点公益林范围内,按气候区、林分类型、林龄组成、立地条件、林分组成等设置松类树种(包括马尾松、黄山松、湿地松、华南松和火炬松)典型样地122个,实测标准木255株。通过相关分析表明,树干干重、木材干重、皮干重、枝干重、冠干重、根干重与胸径和树高的相关系数较大,其冠干重、枝干重、叶干重则与胸径和树高以及枝下高有较大的相关系数,从变量得到的简洁性和准确性考虑,经不同模型的拟合和检验,确定了松类生物量各器官的独立模型,总量、木材、树皮、树根、树干的模型结构为W=c1D^c2H^c3,树叶、树枝、树冠的模型结构为W=c1D^c2L^c3;拟合了浙江省重点公益林松类生物量各器官及总量的独立模型和相容性模型,经检验,各模型均具有较好的拟合精度和预估水平,样本总体预估精度指旨标(P%)在多数分量中以相容性模型最高,而且相对误差绝对值指标(E2%)最小,总量、木材,树干、树皮的预估精度超过了独立模型,其他分量仍保持了独立模型的水平;而且相对误差绝对值均略高于或等于独立模型。 相似文献
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This paper proposes an automatic method of pore combination recognition,which is an important feature to hardwood recognition.After extracting edge from wood microscopic cross-section, based on area histogram of the similar circle regions,the method classifies all regions into two classes with maximum between-class variance,so as to distinguish the pore from other textures,which are similar in shapes but different in sizes.Meanwhile, second objective function about average area of closed regions is used to improve the pore segmentation performance.At last,the method uses adjacency degree of pore set to judge pore combination.The experiments demonstrate that the task of pore segmentation can be completed successfully for all kinds of pore distribution and combination,and also the correct combinations of pores are given. 相似文献
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According to the unification principle of system structure and system function of the Water Resource Conservation Forests,seven factors were selected from stand spatial structure,trees structure and healthy of woods,the multifunction management optimization model target was confirmed by using nonlinearity multi-objective programming approach, and the target function-stand spatial structure homogeneity index was defined to establish spatial optimization models with restraining conditions set up in diversity of stand structure and spatial structure.The spatial structure of available typical stand in the wet land area in southern Donting Lake was optimized by means of selective cutting and reinforcement planting.The results showed that the spatial structure was improved obviously and trees diversity and stand health were not weakened.It’s suggested that the established optimization model can effectively guide multifunction management,stand structure optimization and the steadiness of ecological ecosystem and it is convenient and operable in practice,and it’s very important to protect and recover ecosystem of Water Resource Conservation Forests. 相似文献
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通过对太原市区具有代表性的道路绿化带、公园绿化区、草坪绿化区和专用绿地等绿化类型园林植物主要虫害的系统调查,得到本地区园林植物的害虫目录,共有82种,并对每种害虫的寄主植物、为害程度、分布地点进行了介绍. 相似文献
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With the interpreted IKONOS4 satellite images collected in 2005,a 1:10 000 forest map,the data collected in ClassⅡforest survey in 2007,and surface runoff data obtained in the permanent runoff monitoring station,six site factors of slope gradient, slope position,soil thickness,soil thickness of A layer,soil type and soil water content were selected to establish a matter element model suitable to 297 forest sub-compartments.Further,the AHP was applied to modify the spatial structure and form the spatial para allocation of the protection forest system. The results showed that:1) the area allocation of different vegetation types was irrational,the area of a mixed coniferous and broad-leafed forest was 124.39 ha,accounting for 14.97%of the forested land,the mixed forest was consisted of two coniferous species accounted for 27.37%of the total forest land,and the pure forest was consisted of one coniferous species accounted for 42.48%.2) After optimization,the area allocation of different vegetation types in the protection forest system ranked as:the mixed coniferous and broad-leafed forest(31.12%)>shrub land(15.5%)>the economic tree crops(12.28%)>the mixed forest consisting of two coniferous species(11.46%)>the pure broad-leafed forest(11.41%)>the pure coniferous forest(9.51%)>grass land(8.70%). Besides,the annual surface runoff could reduce 43 171 mm or 62.15%,annual soil erosion could decrease 465.97 t or 79.66%.3) The following suggestions for spatial para allocation of the small watershed protection forest system were proposed: (1) Reducing pure cypress or pine forest,and increasing alder-cypress,oak-cypress or pine-cypress mixed forest.As for the current cypress and pine pure forests,alder or oak could be introduced to develop a mixed forest.(2) The canopy closure of pure cypress forest and alder-cypress forests should be maintained within 0.60-0.75,and the canopy closure of oak-cypress,pine-cypress or oak-pine forests should be controlled within 0.60-0.80. (3) For improvement of current pure 相似文献
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This paper focuses on how to build the model of precision fire hazard divisions in the level of forest resources sub-compartment.Based on 3D GIS technology and characteristics of forest fires in collective forest of southern China,this study utilized Lin’an City,Zhejiang Province as the experimental area.Forest fire factors were divided into 11 indexes from the three categories(social and economic factors,forestry characteristics,and meteorological characteristics) and weighted for analysis.Next,three eigenvectors(one for each category) were created to build a nonlinear mathematical model called precision fire hazard divisions for forests.Then,the model was used to optimize and test forest fire hazard divisions with the least squares.Results showed that experimental and theoretical values of error were less than 0.1. Thus,in the experimental area this model and the fire occurrence history matched. 相似文献
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本文采用综合逆境法测定了樟子松、华北落叶松、油松、华山松、白皮松等5种松对种子的活力及其综合逆境活力,结果表明:樟子松、油松、华北落叶松的种子发发芽率分别为69%、78%和41%.综合逆境活力分别为62.7%、64.3%和61.7%.樟子松、油松的发芽率较高,种子活力也较高. 相似文献
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"发案少,秩序好,群众满意"是社区警务的目标和努力方向.一个社区内发生案件的多少直接反映出该社区的治安状况,也是衡量一个社区民警是否称职的重要标准. 相似文献