共查询到20条相似文献,搜索用时 109 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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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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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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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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近年来,银川市园林绿化建设发展较快,取得了可喜的成果,但在养护管理工作中仍存着不足和问题。本文从当前银川市园林绿化养护管理中存在的现实问题入手,分析问题存在的原因,提出科学规划、建立现代管理体制、增强全民绿化意识、依法治绿等提高城市园林绿化管理水平的措施与建议。 相似文献
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作者根据在江苏宜兴抽水蓄能电站工程从事工程造价管理的经验,论述了工程项目从开工的成本管理制度及原则、目标成本的分解、成本控制的方法、成本控制的奖惩到全员参与成本管理,实现管理目的体会。 相似文献
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中国森林资源采伐管理改革与发展 总被引:1,自引:0,他引:1
森林资源采伐管理制度,对促进森林可持续经营,保障森林经营者利益,以及有效保护森林资源具有重要作用。目前我国森林资源采伐管理制度主要由森林采伐限额管理制度,凭证采伐林木制度,年度木材生产计划几部分组成。我国的森林资源采伐管理在经历了统一管理严格控制阶段和经营管理调整阶段之后,当前正处于经营主体改变前提下的试点改革阶段。从2007年试点工作启动至今,改革取得了可喜的成绩,但目前森林资源采伐管理改革中存在一些问题。如:改革宣传力度不够,采伐限额编制不合理,采伐审批过程有待进一步简化,缺乏支持经营主体的信贷体系等。针对存在的问题,认为下一步的改革应该加大改革政策的宣传力度,确保采伐限额制定的准确性,简化采伐申请的审批程序,为林业的发展提供充足的财政支持等。 相似文献
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数字林业网格(DFG,digital forestry grid)也叫林业应用网格,其研究目标在于配合国家数字林业建设,针对林业与生态环境建设工程应用需求.结合网格的优点和大量的数字林业数据,可以使各种分布式的资源更好地整合在一起,并使用户和资源更好地协同工作.用户管理系统是应用网格中必不可少的组成部分,是保证网格安全的基础.应用网格中成千上万的用户有着不同的身份、不同的权限,他们在网格中的角色不同,所允许的操作也不同(Foster et al.,2001).如何保存和管理应用网格中的所有用户信息、权限信息以及数字凭证信息是用户管理系统所要解决的问题.权限控制对于应用网格门户和工作流系统提供了基本的支持,数字证书管理包括证书的申请、签发和管理,它提供了对用户身份的强认证,以实现对网格服务的安全调用. 相似文献
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国外工业用材林集约经营技术比较与借鉴 总被引:1,自引:0,他引:1
从经营理念、经营目标以及具体经营技术等方面, 介绍国外林业发达国家人工用材林集约经营概况; 结合我国速生丰产林建设的现状以及存在的问题, 针对如何提升速生丰产林集约经营水平, 从制定速生丰产林标准及相应的技术指南, 推动速生丰产林的专业化经营, 注重植被管理、环境管理和景观管理等方面提出意见和建议。 相似文献
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国有林区森林经营方案编制和实施中面临的问题与对策 总被引:2,自引:0,他引:2
林工茗 《内蒙古林业调查设计》2020,43(2):25-27
科学编制和实施好森林经营方案是实现森林可持续经营、确保森林质量精准提升的重要基础和措施。文章阐述了编制和实施好国有林区森林经营方案的必要性,通过分析云南省国有林区森林经营方案编制和实施中存在的问题,提出相应的对策。 相似文献
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美国的森林经营与森林认证现状及对我们的启示 总被引:2,自引:0,他引:2
美国是世界上森林经营水平较高的国家之一,从国家林业计划、森林生态系统经营、可持续经营标准和指标等方面分析了美国森林可持续经营状况,并介绍了美国森林经营及森林认证的有关情况,借鉴美国森林可持续经营的经验,提出了我国森林可持续经营和森林认证的对策。 相似文献