共查询到20条相似文献,搜索用时 62 毫秒
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我国木材干燥技术与发展探讨 总被引:7,自引:3,他引:4
详细论述了目前我国各种木材干燥方法的特点、技术水平及生产应用情况。从计算机技术,节能和环保、新技术材料的应用等角度,提出了我国木材干燥技术的发展方向。 相似文献
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<正> 我县硬杂木资源丰富、用途广泛、分类复杂,因此根据产品含水率的需要,对硬杂木混合干燥进行了干燥试验,并达到了工艺技术的要求,最终技术指标完全达到了产品的要求,炉次干燥合格率达到了95%左右。对于硬杂木混合干燥工艺技术来讲,是采用侧向通风,在室内强制干燥进行的技术手段,并按如下三个阶段进行测试的: 相似文献
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南方阔叶树材干燥初期应变特点的研究 总被引:6,自引:2,他引:6
在不同温度和平衡含水率条件下研究南方阔叶树材干燥初期应变特点。试验结果表明,干燥初期表层呈现伸张弹性应变和塑性应变,内层为压缩应变。伸张弹性应变的最大值是产生表裂的主要原因,塑性应变而引起的表层固定变形是产生内裂的原因。 相似文献
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木材干燥应力的研究对丰富和完善木材干燥理论、建立和完善干燥工艺、提高干燥质量和经济效益具有重要意义,许多研究者从不同角度对木材干燥应力应变进行了试验测定及数值计算.本文对其中的主要研究方法进行了较详细的归纳,并对今后的研究提出了看法和建议. 相似文献
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本文研究木材真空干燥。内容包括木材真空干燥机的研制和木材真空干燥工艺的研究。试验结果表明,干燥机设计合理,技术性能良好,能够满足科学研究和小型生产的需要。通过实验,提出榆木、水曲柳、桦木和椴木的干燥基准,证明用真空干燥法干燥厚阔叶树材,具有干燥时间短、干燥质量好的优点。真空干燥具有研究价值,值得在一定范围内推广应用。 相似文献
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We present a new approach for selecting seed sources of Eucalyptus to be grown on saline land. We evaluated our method using 22 seed sources, 11 tree-form species and 11 mallee-form species.
We found that the commonly used strategy of selecting seed sources on the basis of average productivity was inappropriate,
as average productivity was poorly correlated with the relationship between productivity and salinity that was actually observed.
Using our new approach, we categorized seed sources as salt-sensitive or salt-tolerant based on the strength of the observed
relationship between salinity and productivity. Seed sources defined as sensitive were associated with relatively large (−24.8
to −64.2%) productivity losses, while the changes in productivity for tolerant seed sources ranged from −17.1 to 10.5%. On
average, reductions in height due to increased salinity were about 30% greater for sensitive seed sources than tolerant ones,
although the effect was smaller for mallee-form and greater for tree-form seed sources. The difference between sensitive and
tolerant seed sources was similar after 1, 2 and 4 years of growth. 相似文献
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王珊子 《绿色中国(A版)》2006,(15):66-68
“民以食为天”,“人命关天”,这两句古话阐明了食品安全无以复加的重要性。实际上,食品安全的重要性还远不止于此,这个问题不仅关系到人的健康和生命,而且关系到经济发展、社会稳定,乃至公民对整个社会和政府的信心。 相似文献
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王珊子 《绿色中国(综合版)》2006,(8):66-68
“民以食为天”,“人命关天”,这两句古话阐明了食品安全无以复加的重要性。实际上,食品安全的重要性还远不止于此,这个问题不仅关系到人的健康和生命,而且关系到经济发展、社会稳定,乃至公民对整个社会和政府的信心。[编者按] 相似文献
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《Journal of Sustainable Forestry》2013,32(3-4):307-316
Concerns for maintaining biodiversity have led to the adoption of ecosystem management as the paradigm for federal land management. This approach will identify desired future conditions as the goal for management, based on ecological objectives for a given landscape. Some management efforts attempt to identify desired future conditions based on existing successional stages as defined by a classification of overstory vegetation types. Such an approach ignores most of the underlying ecological parameters of the landscape, and is inadequate for identifying past disturbance regimes and future successional pathways. An assessment of desired future conditions based on an ecological classification system is essential to overcome these inadequacies. The strategy proposed in this paper uses an appropriate ecological land classification, based on either ecological land types or habitat types, included in a broader hierarchical classification system. It also uses a vegetation map of existing overstory vegetation. These two maps are overlaid to generate polygons of ecological units that can then be used to create an ecosystem diversity matrix. Each polygon (stand) can be evaluated as to its composition and structure relative to its possible placement within the ecosystem diversity matrix through comparisons with historical ranges of variability. The overall ecosystem diversity matrix can then be examined in terms of the distribution of successional stages within each habitat type or ecological land type. The goal should be to maintain at least adequate ecological representation of all successional stages within each habitat type that occurred historically, based on past disturbance regimes. Adequate ecological representation is defined as sufficient size and distribution of inherent ecosystems to maintain viable populations of all endemic species dependent on these ecosystems. This approach can maintain and enhance regional biodiversity, but also maintain flexibility in land management options. 相似文献
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12个桃品种的花芽休眠需冷量和开花需热量 总被引:3,自引:0,他引:3
在浙西南地区研究12个桃品种花芽休眠需冷量和开花需热量生态指标.犹他模型测定结果显示:12个桃品种中,花芽休眠需冷量低的品种为春蜜、超红、中油11号、中油7号、中油4号,约为550~650 cu;其次是丽油5号、仓方早生、燕红、丽油3号、早凤凰,约为650~ 800 cu;需冷量高的品种为新川中岛和赤月,约为900~ 950cu.同一地区不同品种需热量差异较大,同一品种年际间差异相对较小.以生长度天模型试验结果表明:开花需热量低的品种为赤月和丽油3号,大约400 ~ 500 d·℃;其次是新川中岛,大约500~600 d·℃;春蜜、丽油5号、早凤凰、中油4号、中油7号、仓方早生和燕红大约600 ~ 700 d·℃;需热量较高的是中油11号和超红,约为700~800 d·℃.12个桃品种花芽休眠需冷量与开花需热量之间呈乘幂函数曲线显著负相关. 相似文献