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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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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Balanced populations of black-fly larvae on artificial substrates are not to attain. During the initial phase of colonization the numbers of individuals increase relatively continuous, during the following period they decrease by drift induced by different environmental factors. On account of this fact a straight line is proposed as best and simplest fitting to the course of the colonization curve in the initial phase. This is in contrast to the steady-state model recommended by different authors. The exposition-times applied for different investigation purposes with foils of polyethylen are presented in tabular form. The adventages and disadvantages of different artificial substrates are compared with one another. 相似文献
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Assessment of frost damage to leafless stem tissues of Quercus petraea: A reappraisal of the method of relative conductivity 总被引:6,自引:0,他引:6
Leafless Quercus petraea stems 1.45.0 mm in diameterwere exposed to freezing temperatures before assessing frostdamage visually and by two methods where electrolyte leakagefrom tissues was examined. Visual assessment could not discriminatelethal from non-lethal damage, whereas electrolyte leakage could.Assessments based on the rate of electrolyte leakage took almosttwice as many man hours to obtain, but were more consistentthan those produced using the method of relative conductivity.Full equilibration of electrolyte leakage following exposureto freezing temperatures required at least 5 days at 4°C. Autoclaving the tissues at 121°C for 15 min failed to releaseall diffusible electrolytes even after 10 days equilibration,but complete release was achieved 24 h after autoclaving for120 min. Unless full equilibration is achieved, it is impossibleto define a value of relative conductivity that is indicativeof lethal damage. The use of predefined lethal values of relativeconductivity is inad visable because the relative conductivityof undamaged (unfrozen) shoots varies substantially with thephysiological state of the tissues. Allowing 57 days after freezing to permit full electrolyteequilibration, followed by autoclaving for 90120 minat 121°C and allowing 24 h before measurement provides areliable method for assessing freezing injury by the methodof relative conductivity in small pieces of leafless stem tissues.Differences between treatments can then be assessed using standardstatistical procedures. 相似文献
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In 2010, the first, and so far only, infestation of the Hungarian spruce scale (Physokermes inopinatus) and accompanying sooty mould occurred in Scania, southernmost Sweden. About 1000?ha of Norway spruce (Picea abies) were affected, and the trees suffered from the sucking of the insects as well as from the dense sooty mould that covered the needles. Salvage cuttings were carried out in many of the massively attacked forest stands, both in response to the fear that the trees otherwise would die, e.g. from secondary bark beetle attacks and to prevent spreading of the infestation. The aim of this study was to provide basic, quantitative knowledge on the aftermath response of trees that were heavily infested, but not exposed to salvage cutting. Growth characteristics, in terms of needle weight, shoot length and tree-ring size were measured on infested and uninfested trees to compare and contrast the spruce growth before, during and after the scale outbreak. The infestation resulted in dwarf annual shoots, stunted needles and thin tree rings. The needle weight returned to normal the following year, whereas shoot length and tree rings required one growing season before full recovery. 相似文献
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鼎湖山亚热带季风常绿阔叶林蒸散研究 总被引:14,自引:1,他引:14
运用Penman蒸散力公式和理论上导上导出的计算森林生态系统蒸散公式,对亚热睦带性群落鼎湖山季风常绿阔叶林的蒸散力和蒸散逐日进行计算,其结果表明:鼎湖山季风常绿阔叶林蒸散力年平均为987.5mm占同期降雨量的47%,蒸散力最大的月分是7月,最小的月份是2月,这样基本上与近地面层的气温度变化规律相一致,而与同期的降雨量有所延迟。林外自由水面蒸发年平均为1194.5mm干季林内蒸散力明显小于林外自由水面的蒸发,而湿季两者又十分接近,因此,两者相比可用来作为该地区划分干湿季的一个参指标,理论公式法所计算出该系统的蒸散年平均为951.9mm,与蒸散力相当,占同期降雨量的45.3%。鼎湖山季风常绿阔叶林总径流量年平均为1103.8mm,径流系数为0.52,研究期间系统贮水量的变经年平均为38.9mm.水量平均法所得的蒸散年平均为960.1mm与公式法计算所得的蒸散非常接近,3年的系统误差不到15,因此,初步得出此公式是计算森林生态系统蒸散的一种值得推广的方法。 相似文献
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杨树是我国北方造林绿化的主要树种,但由于抗盐碱能力较差,导致盐碱地区尤其是滨海重度盐渍区发展缓慢,人们担心杨树在该地区的长期适应性及其生长效果。作者对天津港区多年生的杨树绿地进行了全面调查,结果表明:①在客土绿化条件下,杨树生长表现良好,土壤盐害降低、肥力增强的变化趋势明显,提高了杨树在滨海盐渍区的长期适应性和稳定性。②毛白杨和欧美杨表现突出,年均生长量树高〉1.1m,胸径〉1.2cm;新疆杨冠幅小、生长量低、效益差。③杨树的生长状况与立地条件关系密切,毛白杨的年均生长量与土壤有机质呈显著正相关、与土壤全盐量呈显著负相关关系。因此,增加土壤有机质和降低含盐量的技术措施均能促进其生长,提高绿化效果。 相似文献
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黄菠萝(Phellodendron amurense Rupr.)属于芸香科(Rutaceae)、黄柏属(Phelloden-dron),是我国东北地区著名的三大珍贵阔叶树种之一,第三纪孑遗物种,特别是以生产地道中药材关黄柏而备受重视。我们通过对黄菠萝的结实规律研究,认为黄菠萝结实有明显的周期性,每隔3-4年出现一次丰产年;人工林种子产量比天然林产量高出近两倍,浆果大,种子大而饱满;人工林与天然林的种子发芽率均超过85%,人工林种子发芽率高出天然林发芽率的1.4%。 相似文献
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高纯度竹醋液的生产技术 总被引:1,自引:0,他引:1
通过对炭窑、炭材、燃料、收集工艺、储存条件和精制方法等的分析研究。结果表明:在砖土窑里用无化学污染,立地条件一般的老龄竹、竹材加工剩余物作燃料,收集温度90~160℃,静置8个月,再经精馏处理,能获得高纯度竹醋液。该竹醋液为棕黄色透明的液体,烟焦味淡,密度1.001g/cm3~1.008g/cm3,pH值2.6~3.2,有机酸含量7.5%~10.0%,甲醇和苯酚含量均小于0.01%,可溶解焦油含量0.5%~2.0%。 相似文献
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