共查询到20条相似文献,搜索用时 78 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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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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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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森林工程与森林生态系统保护 总被引:4,自引:3,他引:1
森林工程体系的基本框架包括木材采伐工程、迹地更新造林工程、抚育采伐工程、低效林改造工程、林内路桥工程和装备系统工程。策划和实施森林工程时应遵循的两个基本原则,一是森林工程活动将森林生态系统保护置于首要位置,二是森林工程工艺系统要与作业区域的生态系统保持一致。由于森林生态系统群落结构及其生态过程决定森林生态系统功能,所以森林工程实施时,森林生态系统群落结构保护要着眼于群落结构的连续性和多样性,生物多样性保护要着眼于目的树种、珍稀濒危物种保护和生境保护,森林生态系统环境保护要着眼于水土流失、土壤和地质性灾害。 相似文献
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林业工程建设监理存在的问题及发展思考 总被引:2,自引:0,他引:2
通过对林业工程建设监理现状及特点阐述,分析林业工程建设监理与一般民用建筑工程监理的不同及当前林业工程建设监理存在的问题,结合生态林业工程发展现状,提出今后林业工程建设监理的发展的基本思路。 相似文献
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本文通过对设计阶段工程造价控制原则的分析,提出了工程造价控制的目标,运用价值工程原理,采用层层分解工程投资的方法达到限额设计,论述了技术与经济的有机结合,最终达到合理、有效地控制工程造价。 相似文献
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基因工程在林业生产中的应用 总被引:3,自引:0,他引:3
基因工程是现代生物技术的代表。近10年基因工程的发展迅猛,林业上已经有20多个树种的品系得到了转基因植物。基因工程在林业生产上的应用主要包括以下方面:提高植物的光合效率;增强植物抗病虫害的能力;生物固氮;增强和改良种子贮藏蛋白;培育抗除草剂作物等。 相似文献
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混凝土工程施工过程中 ,经常发生一些质量通病 ,影响结构的安全 ,如何最大限度的消除质量通病 ,保证工程结构安全 ,是工程技术人员急需掌握的 ,本文就结合工作实际 ,对混凝土工程的质量通病的产生和防治进行探讨。 相似文献
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建设工程施工质量是工程建设的核心,是决定工程安全性能的关键,是实现工程施工三大控制目标(质量、投资、进度)的重点,特别是业主方由于是建设工程项目实施的总集成者,因此,在建设工程项目管理中业主方科学有效地进行质量控制是十分必要的。 相似文献
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地下工程渗漏现象较为普遍且后果严重,因此防渗堵漏技术应用在工程实践中作用显著;本 文结合具体工程分析了地下工程渗漏原因,提出了防渗堵漏针对性较强的技术措施。 相似文献
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建设工程价格的合理确定关系着整个工程项目的建设质量,因此说工程造价管理问题是建设工程的核心问题。科学有效的制定建筑工程造价,可以保证建筑工程的顺利完工和建设质量。因此,建筑企业必须要重视建设工程造价问题。文章从建设工程造价合理确定的意义入手,探究我国建设工程合理确定价格的方法与途径。 相似文献
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在工程建设中,只有把造价管理工作作为一项核心工作,才能真正降低工程造价,提高经济效益.本文对如何提高工程造价管理质量,如何加强工程造价的全过程管理的实施提出了几点建议. 相似文献