共查询到19条相似文献,搜索用时 93 毫秒
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通过对比性试验和研究,提出用汽蒸法替代蒸煮法处理俄罗斯产进口山毛榉的新工艺。采用此工艺干燥处理后 的山毛榉,颜色鲜艳,干燥周期短,开裂和变形小,适用于木材加工业的批量生产。 相似文献
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最近,欧洲市场山毛榉胶合板和多种相关产品的价格继续下降,需求仍然比较疲软。去年同期需求强劲,供应紧张,价格上涨,交货拖延的情况完全不同了。 相似文献
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植物光响应曲线拟合,可以估算植物的表观量子效率、最大净光合速率和光饱和点等重要参数,这对弄清欧洲山毛榉的光合特性非常重要。采用Li-6 400XT型便携式光合测定系统,设定的光强梯度为2 500、2 000、1 500、1 000、500、200、150、100、80、50、20、0(μmol·m-2·s-1)。研究结果表明:光合作用对光响应的机理模型、直角双曲线模型、非直角双曲线和指数方程模型拟合曲线决定系数分别为R2=0.999、0.998、0.998和0.987,拟合程度均较高。4种光响应曲线模型拟合欧洲山毛榉光响应曲线得到的相关参数表明,虽然指数方程模型拟合系数最低,但指数方程模型求得的各项参数与实测值相吻合。因此,推荐采用指数方程模型对欧洲山毛榉光合作用光响应曲线最为适宜,这也为欧洲山毛榉选择适宜的区域栽植推广提供重要科学依据。 相似文献
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欧洲对美国的山毛榉出口一直处于上升趋势。在前半年,山毛榉锯材出口上升了71%,出口额达到1330万美元。出口量增长了94%,达到3.5万m^3。美国从奥地利的进口量增长336%,达到2125m^3。德国锯材厂销售量增长到一个新的纪录,3.3万m^3。 相似文献
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小径原木干燥工艺初探 总被引:2,自引:0,他引:2
本文是在桦木(Betulaplatyphylla)、刺槐(Robiniapseudoacacia)与水曲柳(Fraxi-nusmandshurica)等小径原木干燥可行性分析与干燥特性研究等工作的基础上,总结出了小径原木的干燥工艺过程。生产实践证明,该工艺过程对小径原木的干燥是可行的。 相似文献
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《Wood material science & engineering》2013,8(1-2):71-77
Abstract Discolouration during the drying of non-steamed beech is a major industrial concern. The generally preferred yellow-white colour can easily develop a reddish or dull grey appearance during drying. In this study, the influences of log storage time and kiln drying climate on the colour of non-steamed sawn beech have been investigated and quantified. Samples 27×87 mm in cross section were dried in laboratory kilns and the average colour, in CIELAB colour space was measured on dry planed surfaces using a photoelectric colorimeter. Log storage for 13 weeks under low-temperature conditions had no visible effect. The reddish discolouration is mainly temperature related while the greyish discolouration is mainly controlled by the equilibrium moisture content (EMC) during the initial drying. Within the investigated climate interval, the EMC was twice as important as temperature for the final colour. Regression models developed show that, as long as the EMC is kept below 15%, a temperature of up to 37°C can be allowed without any visually detectable discolouration. 相似文献
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采用介电式含水率仪对山毛榉常规干燥材及热处理材的含水率进行了测量,并与烘干法测量结果进行了对比分析,采用最小二乘法,分别拟合出了180℃、195℃和210℃山毛榉热处理材的校正曲线。180℃、195℃和210℃山毛榉热处理材的介电式含水率仪校正曲线分别为, y=1.2923 x+0.2783, y=1.3920 x+0.7473, y=1.6445 x+1.4892。结果表明,常规干燥材的电测法结果能很好地反映其实际含水率水平,而热处理材的电测法结果则普遍大于烘干法,3种热处理材均呈现出随含水率的增高,差值随之增大的趋势,且随着处理温度的升高,差值愈大。 相似文献
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《Scandinavian Journal of Forest Research》2012,27(1-4):220-232
The genetic structure in Danish indigenous and introduced provenances of beech (Fagus sylvatica L.) is described. Ten stands are analysed based on variation revealed by seven enzyme systems. The present study reveals significant allele frequency differences between populations with a small absolute amount of genetic differentiation, with no pattern related to geographic distance. The genetic differentiation between indigenous populations measured by Wright's F ST‐statistic does not deviate significantly from zero, and only 2.9% of the total genetic variation in the foreign populations was due to interpopulation differences, The allele frequencies in relatively small and isolated populations do not differ from the frequencies found in larger areas with beech forest. The low genetic differentiation of isozyme level between indigenous and foreign populations was opposed by significant differences in foliation performance measured on three pairs of neighbouring stands. Foliation performance in adjacent stands of indigenous and introduced beech indicates that quantitative characteristics must be considered separately from neutral variation at single loci. 相似文献
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Der pH-Wert und das Vorkommen niedermolekularer Fettsäuren im Naßkern der Buche (Fagus sylvatica L.)
M. Von Walter 《Forest Pathology》1993,23(1):1-10
The pH-value and the occurrence of fatty acids in wetwood of European Beech (Fagus sylvatica L.). At the border of the wetwood area pH-value of the capillary liquid was altered from acid to neutral conditions. Fatty acids frequently occurred in wetwood. Probes with pH-values higher than 6.8 often were deeply black stained. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(1-4):333-342
Seasonal changes in the N and P content of foliage in a young forest of Fagus sylvatica were measured. Leaves from branches of the upper and lower crown of dominant trees and from suppressed trees were compared. Nutrient retranslocation rates during senescence differed considerably between trees. This variation appeared not to be related to any differences in environmental factors or tree vigour, and was probably genetically induced. In dominant trees the most efficient retranslocation of N was recorded in the upper crown and probably resulted from higher leaf temperatures and a longer senescent period in the sun leaves than in the shade leaves. Phosphorus retranslocation efficiency was higher in suppressed trees than in dominant ones, but no such tendency was observed with N. The most obvious difference between leaves at different crown levels concerned the time at which P translocation began; an outflow of P from leaves in the lower crown began in June, while in the upper crown this outflow did not begin until September/October. 相似文献
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为了提高番龙眼地板毛坯干燥质量,对25mm厚的番龙眼地板毛坯进行低温低湿干燥工艺的研究.探讨了番龙眼木材干燥工艺基准的制订,并通过番龙眼木材干燥工艺的实施对其干燥结果进行分析,为进一步研究制订番龙眼木材干燥工艺提供了思路和方法. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(1-4):215-225
A general model for comparing the profitability of natural regeneration in beech (Fagus sylvatica L.) with planting of Norway spruce (Picea abies L.) is developed. The model is basically a method of comparing a series of net present values. An example of using the model is given: BEECH (90–110) denotes a cyclic regime in which regeneration is initiated at age 90 of a stand, and the canopy trees are cleared at age 110. This regime is compared with the alternative of planting Norway spruce. Economic data used for the comparison are representative of the southeastern regions of Denmark. The conclusion of the comparison is as follows: BEECH (90–110) is superior to planting of Norway spruce for required real rates of return up to 3–4%. For higher required rates of return planting of Norway spruce is preferable. 相似文献
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以菲律宾桃花芯木为研究对象,探索30 mm厚菲律宾桃花芯木锯材干燥工艺。通过百度试验法得知其初期开裂为3级、内裂为2~3级、截面变形为1级;通过密度测定实验得知其气干密度为0.562 g/cm^3、全干密度为0.517 g/cm^3和基本密度为0.465 g/cm^3。根据该木材密度和干燥特性制定3种30 mm厚菲律宾桃花芯木锯材干燥基准并分别进行常规干燥工艺试验。通过对3次工艺试验结果的综合分析表明:在3次工艺实验所用执行基准均能满足2级干燥指标。其中,第一次工艺实验所用执行干燥基准为本研究中最佳干燥基准。第一次工艺实验的初始温度为60℃,末期温度为80℃、初含水率为66.97%、终含水率为7.79%的锯材干燥周期为185 h。 相似文献
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《Scandinavian Journal of Forest Research》2012,27(1-4):263-271
Exchangeable Al and acidity of Swedish beech (Fagus sylvatica L.) forest soils are documented and discussed on the basis of known changes in soil chemical properties during recent decades. It is concluded that the pH and base saturation decrease, which has occurred in most forest soils of the region, has been accompanied by increases in the amount of exchangeable and soil solution Al and a greater decrease of the Ca: AI ratio, particularly in the B horizon. An adverse nutritional state now seems to prevail in most beech forest B horizons. Conditions are more favourable in the topsoil due to the formation of Al‐humus complexes which are less available to plant uptake, and in the case of very acid mor layers, a low Al content. However, in A (mull) horizons of intermediate acidity with a rather high clay content and low in humus, conditions approaching those of the B horizon may be found. 相似文献