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1.
苗圃转让     
今年顺义区苗圃绿化、美化苗木达1120多种、1.12亿株。其中油松、白皮松、华山松、雪松、桧柏、侧柏等常绿树13157亩,1650万株,占育苗总面积的23%;连翘、碧桃、榆叶梅、紫叶李、紫蔽、紫荆、月季、玫瑰、黄刺梅、黄杨、女贞等花灌木5468亩,1455万株,占育苗总面积的10%;白腊、元宝枫、栾树、国槐、银杏、合欢、龙爪槐、杜仲、千头椿、金丝柳、各种品种杨等落叶乔木37375亩,8095万株,占育苗总面积的67%。  相似文献   

2.
大丽花块根繁育和栽培技术   总被引:2,自引:0,他引:2  
大丽花(Dahlia pinnata Cav)菊科,大丽花属,多年生草本,原产墨西哥,又名大丽菊、大理花、天竺牡丹、西番莲、地瓜花,具有植株粗壮、花期长、花朵硕大,品种繁多、花色鲜艳、适应性强等特点。是美化公园,布置庭院、花坛、花境以及切花陈设的较好花卉材料。大丽花为世界名花之一,目前世界约有3万多个品种,我国有500余品种。  相似文献   

3.
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   

4.
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   

5.
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   

6.
蚊子、苍蝇、螳螂、臭虫、蜘蛛、蚂蚁之类害虫,在家庭、工厂、办公室、医院、学校、酒店等地,随处可见,无处不入.这些昆虫不但给人们的生活带来很多烦恼,更重要的是,他们导致疾病传播,从而严重危害人们的身体健康.所以,根除害虫,改变居住环境,早已成为人们关注的问题.  相似文献   

7.
肥胖是一种常见的慢性疾病,它是由于生理化机能的改变而引起的体内脂肪沉积量过多,造成体重增加,导致机体发生一系列病理、生理变化的病症.肥胖症是一种全身性代谢疾病,除引起身体外形的改变外,过多的脂肪可带来物理性的负荷,还是各种疾病的"培养箱".肥胖人群平均寿命明显低于正常体重的人群,同时肥胖症还是心血管疾病、糖尿病、脂肪肝、肿瘤的温床,它是一种营养代谢性疾病.减肥首先必须从能量的摄入入手,减少热能的吸收.  相似文献   

8.
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   

9.
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   

10.
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   

11.
本文对单管顺流式“垂直失调”的原因进行分析,并提出相应的防治措施。  相似文献   

12.
市政排水管网是城镇市政管网建设的重要组成部分,随着城镇规模的扩大,排水管网的规模和投资也随之增大,从几个方面介绍城镇排水管网设计过程中的一些重点和难点,以及注意事项。  相似文献   

13.
在室外管网施工中,工艺管道的安装是其过程中最基本的组成部分,也是最重要的环节。作者依据工程实际,对建龙公寓室外管网工程的工艺管道施工安装程序进行了详细论述。  相似文献   

14.
论述了水泵出水管路设计的几个问题,并在线路布置、管材选择等方面提出了注意事项。  相似文献   

15.
本文作者通过参与小区的给水施工、设计与监理工作,对小区给水设计提出个人的一点经验。  相似文献   

16.
本文介绍了流向逆流冲洗法在解决供暖系统堵塞问题中的应用,此法可作抢修、维修之用。  相似文献   

17.
作者通过哈尔滨高科技开发区大口径球磨铸铁管道的施工,介绍了大口径球磨铸铁管道的施 工程序、要求及注意事项。  相似文献   

18.
根据现在户式小型采暖炉供暖的特点,并结合供暖工程和应用实例对比,对单管水平系统加跨越管及散热器如何合理分布进行了分析,阐明了选择合理的布置方式可节约投资、并能满足供暖要求的设计理念。  相似文献   

19.
传统气力输送系统设计通常依靠人工计算实现,设计内容主要是确定各管段管径及阻力损失。随着气力输送装备日趋多样化、大型化以及系统复杂性增加,各管段管径、阻力计算过程繁琐重复,计算量大且容易出错,传统的人工设计方法已无法满足现代设计要求。本研究把计算机数据处理软件MATLAB和EXCEL应用到设计中,为高效准确地设计气力输送系统提供了一种简单可靠的计算机辅助设计方法。  相似文献   

20.
中国长江三峡地区花岗岩坡面管流运动特性   总被引:2,自引:0,他引:2  
人们早就认识到土体内的水分运动 ,在很多时候并不都遵从达西定律所描述的呈层流流态 ,只有当雷诺数Re≤ 10时 ,土壤水分运动才遵从达西定律 .该文通过观察位于中国长江三峡地区湖北省秭归县花岗岩坡面下部开挖的一长度为 2 9m、深度为 2 13 2 6 0m的土壤剖面 ,发现土管主要分布在B层 (花岗岩风化程度较高的层次 )和C层 (花岗岩风化程度较低的层次 )的过渡带附近 .在坡面下部坡脚部位垂直于坡长方向上 ,每米宽度大约分布有土管 5 7个 .通过连续观测实验坡面的土管在多场降雨过程中的管流现象 ,发现管流流速与沿程水力坡降呈现非线性关系 ,而呈一定的抛物线关系 .结合土壤、地质和土地利用状况等调查结果 ,经对多场降雨及管流观测数据进行整理分析 ,建立了研究地点的管流模型 .由管流模型计算的管流流速VP、流量QP 和土管半径r,与 4个管流的实测值具有较好的相似性 .尤其是依据模型模拟的土管长度X ,反映出不同土管由于所处剖面位置的差异 ,其长度差别较大 ,所模拟的 4条土管长度分别为研究集水区最长距离的 98 1%、2 7 6 %、11 0 %和 3 0 % .管流模型建立过程及模拟结果均反映出管流是土壤水分运动的一种特殊形式 ,它遵从Darcy Weisbach定律所描述的土壤水分运动 .其水分通量远大于一般意义上的土壤  相似文献   

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