提高建筑工程预算的编制质量

建筑工程预算是施工企业的一项重要基础工作。随着经营管理和经济核算工作的逐步加强 ,施工企业对工程预算的要求越来越高 ,它要求工程预算准确、及时、适用。施工图预算编制 ,是一项繁重的经济技术工作。如何改革和加强这项工作 ,使之逐步简化 ,既有利于工程价款结算 ,又方便施工 ,这是基本建设战线的重大研究课题之一。本文探讨了这一问题。     

拟建混凝土结构的耐久性设计

对混凝土结构进行耐久性设计，提高结构的安全性和耐久性已成为全世界关注的重大课题。笔者提出在进行混凝土结构耐久性设计之前，首先要进行结构的工作环境分类，然后确定结构的设计使用寿命，最后利用极限状态对耐久性极限状态进行验算，科学地设计出既安全又适用，又耐久和混凝土结构，从而延长使用寿命，提高经济效益。     

谈亚布力林区红松的物候变化规律

分析红松生长过程中从树液流动到冬眠的物候变化规律,为研究红松果林丰产稳产技术措施提供条件。     

Ultrastructural implications of gamma-irradiation of wood

Summary An attempt is made in this study to relate the gamma-irradiation induced degradation of wood samples to their lignin content and distribution in the cell wall. Samples of Douglas-fir and yellow-poplar were submitted to increasing doses of gamma-irradiation and subsequently extracted with a dilute NaOH solution or with DMSO, prior to SEM observation. Other samples were observed in TEM. The irradiation-extraction procedure degraded the hardwood more than the softwood. In both species, the middle lamella was more resistant than the secondary wall. The S3 layer in Douglas-fir and the warty layer in yellow-poplar appeared to be more resistant than the other secondary wall layers. Some difference was also observed in radiation stability between tracheids or fibres and ray cells. This procedure is suggested as a method for studying lignin distribution in the wood cell wall.This research was conducted as part of a thesis submitted by the first author in partial fulfilment of the requirements for the Master of Science degree at the State University of New York College of Environmental Science and Forestry, Syracuse, New York. The authors wish to thank Dr. John A. Meyer who carried out the irradiation procedure. The first author also whishes to express gratitude to the Belgian American Educational Foundation, Inc., The Fondation Francqui and Mister Charles Berolzheimer, Research Director of the California Cedar Products Company, for having provided financial support for this study     

Effect of mat structure on modulus of elasticity of oriented strandboard

A model to predict bending stiffness of oriented strandboard (OSB) was tested with pilot plant experimental data. The experimental procedure developed in this study is unique in that it allows the model to be tested for extensive vertical configurations of strand angle distribution. After validation, the model was used to simulate a typical three-layer cross-oriented OSB panel with a vertical density profile and strand angle distribution measured on industrial panels. Analysis of the simulated vertical distribution of modulus of elasticity (MOE) indicated that the layers near the panel surfaces contributed much more to the effective parallel panel MOE than those close to the panel thickness center, with 80% of parallel MOE coming from the top 41% of weight and 32% of thickness. The effectiveness of methods to increase parallel bending stiffness through improving mat structure was evaluated. Increasing face/core weight ratio from 54/46 to 66/34 resulted in a 3.7% increase in simulated parallel MOE. Alignment of strands in face layers was identified having a greater potential to increase parallel MOE. Simulations with three improved strand angle distributions showed gains of 5.7, 12.0 and 19.8% in parallel MOE compared with a typical strand angle distribution of industrial OSB panels.     

A theory of the shrinkage of wood

Summary A relation describing the shrinkage properties of a fibre-composite is applied to a multilayered thin-walled model of wood. With the theory developed it is possible to specify shrinkage with respect to moisture content, as well as with factors involved in cell-wall geometry and composition. However, until more is known of the properties of the water-reactive matrix component of the composite it is only practicable to describe shrinkage with respect to the geometrical and compositional factors at the moisture-content of the stress free state.     

Dynamics of swaying of Picea sitchensis

Six 26-year-old Sitka spruce (Picea sitchensis (Bong.) Carr.) trees growing in a Scottish plantation were swayed manually to determine their mechanical dynamics. The natural frequency of sway of the intact trees (mean height 14.2 m and mean stem diameter 14.5 cm at 1.3 m) was on average 0.35 Hz. The variation of this frequency with tree size was found to be well described by engineering mechanics theory. In particular, shape parameters could be defined for both intact and branchless trees, which, along with stem size, density and elasticity, could predict the natural sway frequency using a simple formula. The damping of sway was found to consist of three components, (1) interference of branches with those of neighbors, (2) aerodynamic drag on foliage, and (3) damping in the stem. For the sample of six trees, which spanned the diameter range at the experimental site, the importance of these three components to overall damping was in the ratio 5/4/1 for the median sized tree. Interference between neighbors depended on the distance to neighbors, as well as on the sizes of the chosen tree and its neighbors. Aerodynamic damping was larger for larger trees and the energy lost to this force was similar in magnitude to that calculated to be lost using drag coefficients from published wind tunnel and other studies. The amount of damping from the stem was linearly related to stem diameter.     

林地抚育对板栗生长影响的试验研究

为探索板栗幼林抚育对生长的影响,通过板栗幼林中耕除草、间作与未间作对比试验。研究结果表明:中耕除草同龄的成活率以及树高、地径生长都比未中耕除草栗林有所增加,1次中耕除草效果差,中耕除草2~3次效果最好。间作薯类、豆类及谷类的板栗生长量比未间作的都有所增加,以间作薯类和豆类效果最明显。     

林业产业发展对策研究

本文从适应生态建设和市场变化的需要出发,提出必须加速构建现代林业产业体系,并根据国家总体部署、市场需求和本地比较优势,制订科学的产业发展计划;以大市场观念为指导,做大做强特色产业,突出区域发展重点,首力培育经营优势;充分发挥政府的作用,并通过行业协会,引导产业健康发展。     

Effects of Water State of Soil on Ecological Boundary of Leaf Surface of Populus davidiana

Intr0ducti0nThewaterstateofsoilasattimp0rtanti11dexforpIantmanageinentrestricteddirectIyplantproductiv-ity.I'-'lManyreportsdiscussedtheprocessoftl1ewaterabsorbedbyro0tsandtral1sportedtoairbyIeafAnOhm'slawanal0gywasfrequentlyusedtodiscusswaterreIati0nbetweenthepIantandtheel1-.l4-9lqVironment.l'-'lThewaterstateofsoilcanbere-flectedbytheIeafwaterstate,l"-"lbutfewreportsweref0undonevaIuationofsoilwaterbyecoIogicalboundaryofleafsurfacels.l14lTheeco-b0u11dary0nIeafsurfaceisathinnerairlayerwhic…     

华北香薷花期调控技术初步研究

华北香薷在野生环境下开花期在7~10月份之间,而在栽培条件下开花期在9~10月份之间,花期仅有57 d左右。为延长华北香薷在栽培条件下的花期,本研究利用短日照、植物生长调节剂GA3、NAA等处理,在5月下旬至6月中下旬对华北香蕾进行了30 d的处理。结果表明:(1)每天9 h的短日照可以促进华北香蕾花芽分化和花蕾形成,使其始花期提前至7月20日,花期长达97 d;(2)100 mg/L的赤霉素处理,可以使华北香薷始花期提前至8月12日,花期长达78 d;(3)300 mg/L的萘乙酸处理,可以使华北香薷始花期提前至8月15日,并推迟终花期至11月5日,花期长达80 d。     

Technologies of liquefaction of bamboo and preparation of adhesive

The technology of liquefying processed-waste bamboo with phenol is investigated by single factor trials and an orthogonal design. We studied the preparation technology and properties of adhesives from this phenol-liquefied bamboo with formaldehyde (BPF). The results show that temperature has a significant effect on liquefaction. The effect of the mass ratio of phenol to bamboo comes second and the catalyst dosage within the range of 2%–4% is the least effective. The optimum conditions of liquefaction are as follows: a mass ratio of phenol to bamboo 3.5, a catalyst dosage of 4%, liquefying temperature 145°C and liquefying time 60 min. The liquefaction rate of bamboo reached 99.1%. For the preparation of the adhesive, a mass ratio of liquefied bamboo products to formaldehyde (37%) is 100 to 164.8–199.5, while the ratio 100 to 108.2 is the best. This adhesive has a lower curing temperature than that of normal PF resin. At a hot-press temperature of 130 or 140°C, this new adhesive provides excellent bonding strength of plywood. The most favorable temperature for hot-pressing is 140°C. __________ Translated from Chemistry and Industry of Forest Products, 2007, 27(6): 65–70 [译自: 林产化学与工业]     

世界自然保护区发展概述

文章介绍了世界自然保护区的分布和近年来的增长情况,以及目前所采取的保护措施;论述了自然保护区加速发展的原因;分析了自然保护与保护区居民生产生活之间产生矛盾的根源;讨论了处理自然保护与社区发展之间关系的尝试;对自然保护事业的发展趋势进行了展望。     

我国农村土地流转的供求分析与现实论证

我国农村在大量农业劳动力外流和土地承包经营权流转不畅背景下,超小规模农户经营的局限性日益凸显,农地粗放经营和荒芜现象日趋加重。在介绍我国农村土地流转现状的基础上,通过对土地流转市场需求——供给模型的推导和分析,指出需求和供给因素怎样影响土地流转的数量和价格,并通过考察这些因素所对应的现实情况,分析出影响土地流转规模的农产品价格、生产资料价格、农业生产技术、农村劳动力转移难度、农村社会保障等方面的原因。在结合我国国情对以上因素进行现实的论证之后,提出提高农产品价格、降低生产资料价格、提高农业生产力、统筹城乡劳动就业和社会管理、健全农村社会保障体系等促进农村土地加快流转的建议。     

云南红豆杉优良单株初选

在收集整理有关资料的基础上,提出云南红豆杉优良单株初选标准,对形质指标提出定性要求;生物量指标拟合最优回归数学模型,得到优树选择最低基点和基线图;小枝叶紫杉醇含量根据预选群体计算其入选率与选择强度,以此为依据推算紫杉醇含量选择标准。     

凤眼莲动态模块化治理湖泊污染的设计

指出了环境生态工程采用生态学理论,强调将环境问题于系统内解决,使受污染的环境能够适时与周边的大自然友好和谐地融为一体,注重经济效益和生态效益的高度统一,已经逐步发展为最受欢迎的修复水体的技术之一。凤眼莲是修复污染湖泊的良好先锋植物,但其易泛滥成灾和含水量甚高的特性限制了人们对其大规模的使用。本着环境生态工程的理念,建立了凤眼莲动态模块化的浮床装置,利用风能为浮床装置提供电能,结合装置内的螺旋桨动力结构使浮床移动,通过旋转吊臂滑轮和底部尼龙网结构使凤眼莲机械化原位去水。此设计在实现低廉、高效治理水体富营养化和重金属等污染问题的同时,也有效解决了凤眼莲可能泛滥成灾的隐患,达到生态效益、经济效益和景观效益的协调统一。     

光合作用光响应曲线模型选择及低光强属性界定

采用抛物线、直角双曲线、非直角双曲线及直角双曲线修正式等数学函数对金沙江干热河谷3种不同类型植物材料的光合光响应曲线进行了拟合,提出一种分段函数用以拟合实测值并求算光合作用参数,构建了一种有关表观光合量子效率求算的弱光区域的确定方法,得到3点主要结论:(1)5种拟合方式中,分段函数与直角双曲线修正式对3种不同类型的光合光响应曲线均具有良好的拟合效果;(2)直角与非直角双曲线拟合得到的光合参数Pmax、LCP、Rd与实测值接近,但对LSP的估计值总是远低于实测值,直角双曲线修正式适合用于出现光抑制现象的曲线的模拟及其光合参数的求解,但无法得到饱和趋近型曲线的光合特征参数,分段函数求解的不同类型曲线的特征参数均与实测值较为接近; (3)以光合光响应曲线上光能利用效率的下降位点来界定植物表观光合速率随光强呈线性增长的弱光区域是可行的,且具相当的理论可释性。     

Limitation of XPS for analysis of wood species containing high amounts of lipophilic extractives

Chemical composition of Norway spruce and pine, two softwood species, has been investigated by X-ray Photoelectron Spectroscopy (XPS). Contrary to results previously obtained with beech wood, which allow to obtain information on bulk chemical composition from surface composition analysis, XPS analysis appears to be unsuitable for the characterisation of Norway spruce and pine wood chemical composition. Indeed, chemical compositions calculated from XPS data differ strongly from those obtained from microanalyses which are in good agreement with theoretical composition described in the literature. XPS analysis of both the softwood surfaces indicated high carbon contents explained by migration of lipophilic extractives to the surface under the influence of the vacuum necessary for XPS analysis. Nonvolatile extractives contained in wood were extracted and deposited on glass plates and analysed. Survey and detailed C1s spectra indicated similar signals to those recorded on wood surfaces. This phenomenon was not observed when samples had been previously extracted before analysis. These results strongly evidenced that extractives present in both species are able to migrate through resin canals from the bulk of the sample to the surface when put into ultra high vacuum. XPS presents, therefore, some limits in the case of the analysis of softwood species containing extractives able to migrate to the surface during analysis. This behaviour, difficult to control, could lead to erroneous interpretations due to extractives enrichment of the surface under the effect of vacuum.     

动漫产业民族化浅析

指出了随着文化市场的不断开放,越来越多的外来作品充斥着中国市场。面对咄咄逼人的外来动漫潮流,我们国产的动漫市场份额所占比重越来越少,甚至有江河日下之势。面对如此严峻形势,要如何奋起才能改变现在这种被动的局面呢？就动漫产业民族化的角度来分析、寻求答案,以求找到问题的突破口。试从动漫本质、国内动漫产业的问题、民族化实施途径等几个方面进行了阐述,以期能窥探冰山之一角,以起抛砖引玉之功效。     

美国薄壳山核桃果实发育研究

1995～ 1998年 ,在云南省林业科学院漾濞研究站从浙江引种的美国山核桃林内 ,对金华 1号、绍兴 1号、山站 2号、长林 13号 4个品种的果实发育进行了观测和解剖研究。结果表明 ,这 4个品种都具有明显的缓慢生长期、迅速膨大期、硬核期、果仁生长期 4个发育期 ;果实的体积和重量生长速率有 3～ 4次高峰 ,并与各发育期吻合 ;胚在硬核期出现 ,经历 18～ 19天基本定型 ,胚出现果实到采收需经历 5 2～ 5 9天 ,研究为正确制定丰产栽培措施提供了理论依据。通过对气温和降雨量的分析认为 ,美国山核桃为喜热树种 ,漾濞引种的美国山核桃发叶开花时间比浙江早 10天左右 ,果实进入迅速膨大期反而迟 10～ 15天。