共查询到20条相似文献，搜索用时 62 毫秒
1.
异氰酸酯胶芦苇刨花板生产工艺研究 总被引：11，自引：0，他引：11
芦苇的ＳｉＯ２含量高，使用脲醛胶（ＵＦ）难以获得良好的胶合结果，本研究采用二苯基甲烷二异氰酸酯（ＭＤＩ）胶粘剂压制芦苇刨花板，试验结果表明，当ＭＤＩ施胶量为４％和５％，刨花板的密度为０．７０ｇ／ｃｍ＾３时，其物理力学性能指标分别达到我国Ａ类刨花板优等品种和二等品的标准要求，如果ＭＤＩ单价由现在２０．００元／ｋｇ下降到１７．３０元／ｋｇ，ＭＤＩ芦苇创花板和ＵＦ芦苇刨花板的生产成本相同。 相似文献
2.
3.
异氰酸酯胶无毒低密度杉木刨花板的制造 总被引：1，自引：0，他引：1
本研究探讨了用异氰酸酯胶粘剂制造低密度杉木刨花板的工艺条件,讨论了施胶量、热压温度、热压时间、热压压力和刨花含水率对板材性能的影响。结果表明,当板材密度为０．４３～０．４８ｇ／ｃｍ＾２时,施胶量只需５％,刨花含水率适应范围广,所制成的刨花板无毒,耐水性好。 相似文献
4.
对废纸刨花板的制造工业进行了初步探讨,分析了废纸用量,施胶量,热压时间,热压温度４个变量因子对刨花板性能的影响。试验结果表明添加部分废纸制造刨花板是完全可行的,其产品主要物理力学性能,密度（ρ）０．７５ｇ／ｃｍ＾３,吸水厚度膨胀率（ＴＳ）３．８％,内结合强度（ＩＢ）０．６２ＭＰａ,静曲强度（ＭＯＲ）２２．４ＭＰａ弹性模量（ＭＯＥ）２５．４×１０＾３ＭＰａ均达到ＧＢ／Ｔ４８９７－９２中Ｂ类刨花板的技 相似文献
5.
本文对两家电厂的粉煤灰进行了粉煤灰刨花板制造工艺的研究。研究结果表明：１．助剂种类及添加量应根据粉煤灰化学成分和品质的差异而有所区别。２．灰木比是影响板材物理力学性能的最显著因素，灰木比的取值范围在２：１～４：１可制出合格板材。３．密度对板材强度的影响极为明显，粉煤灰刨花板密度不宜低于０．９０ｇ／ｃｍ￣３。４．增加施胶量虽然可以提高板材强度，但施胶量大于９％对强度的影响已不明显。本文还就生产性试验、初步经济分析、市场前景进行了简要说明。 相似文献
6.
改性UF麦秸均质刨花板的工艺研究 总被引：1，自引：1，他引：1
通过试验确定了麦秸均质刨花板的主要工艺参数。其结果表明：１０ｍｍ厚麦秸均质刨花板的较优工艺参数为热压温度１５０℃、热压时间８ｍｉｎ、表层麦秸刨花的施胶量为１０％、芯层麦秸刨花的施胶量为８％、板密度０．７５ｇ／ｃｍ３、表芯层刨花比例为３：７。按照以上工艺条件压制的麦秸均质刨花板性能已达到均质刨花板的要求。 相似文献
7.
酚醛胶亚麻屑刨花板生产工艺及其耐老化性能的研究 总被引：1，自引：0，他引：1
本文主要研究酚醛胶亚縻屑刨花板的生产工艺及其而加速老化性能。研究中采用正交设计安排试验，并对试验结果进行方差分析，最后通过分析，得出酚醛胶亚縻屑刨花板的生产工艺和利用该工艺生产的的板的耐加速老化性能结果。研究结果表明：密度为０．７５ｇ／ｃｍ＾３的酚醛胶亚麻屑刨花板性能不仅达到了德国室外用建筑刨花板标准ＤＩＮ６８７６３Ｖ１００型的要求，而且按美国ＡＳＴＭＤ１０３７加速老化标准检验，其静曲强度老化剩余 相似文献
8.
稻草原料酸碱性及稻草中密度纤维板的性能 总被引：8，自引：2，他引：8
测试分析了稻草原料的ｐＨ值和缓冲容量，分别使用脲醛树脂胶和异氰酸酯胶在特定工艺条件下压制了稻草中密度纤维板，并测试了板材性能。结果表明：１）稻草秸秆原料呈弱碱性，缓冲容量远高于普通木材；经热磨处理获得的稻草纤维呈弱酸性，其缓冲容量虽较稻草秸秆有一定幅度的下降，但仍高于普通木材；２）脲醛树脂或异氰酸酯稻草中密度纤维板的性能都明显优于相应的碎料板；在密度０．８０ｇ／ｃｍ３和施胶量１７％的条件下，脲醛树脂稻草中密度纤维板性能达到国标ＧＢ／Ｔ１７６５７－１９９９一等品的要求，在密度０．８０ｇ／ｃｍ３和施胶量６％的条件下，异氰酸酯稻草中密度纤维板性能达到国标ＧＭ／Ｔ１７６５７－１９９９优等品要求。 相似文献
9.
10.
马尖相思离体培养再生植株的研究 总被引：4，自引：0，他引：4
用马尖相思（Ａｃａｃｉａ ｍ ａｎｇｉｕｍ ）１０ 年龄树芽器官为外植体,通过组织培养直接诱导不定芽产生,并获得根茎叶齐全的试管苗。剪取当年枝条的自顶芽往下依次带节的茎段培养,以第二、第三节茎段诱导芽萌动率高而快;芽诱导培养基为改良ＭＳ＋ ６－ＢＡ ２ ｍ ｇ／Ｌ＋ ＮＡＡ ０．５ ｍ ｇ／Ｌ,芽诱导率９０％ ;芽增殖培养基为改良ＭＳ＋ ６－ＢＡ ０．５ ｍ ｇ／Ｌ＋ ＮＡＡ ０．２５ ｍ ｇ／Ｌ＋ ＶＢ２ ５ ｍ ｇ／Ｌ＋ Ｖｃ ４ ｍ ｇ／Ｌ,芽增殖倍数４．８ 倍;生根培养基为１／２ ＭＳ＋ ＡＢＴ ２ ｍ ｇ／Ｌ＋ ＩＢＡ ０．２ ｍ ｇ／Ｌ＋Ａｃ ０．１％ ,生根率９７．０％ ;黄心土为试管苗最佳移栽基质,成活率达到８５％ 。 相似文献
11.
《Scandinavian Journal of Forest Research》2012,27(5):427-435
In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads. 相似文献
12.
《Scandinavian Journal of Forest Research》2012,27(3):206-217
The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage. 相似文献
13.
《Scandinavian Journal of Forest Research》2012,27(1):53-61
This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland. 相似文献
14.
《Scandinavian Journal of Forest Research》2012,27(1):15-27
The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions. 相似文献
15.
本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。 相似文献
16.
《Scandinavian Journal of Forest Research》2012,27(2):131-138
The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided. 相似文献
17.
18.
《Scandinavian Journal of Forest Research》2012,27(5):472-479
Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken. 相似文献
19.
Srisuda Thippayarugs Banyong Toomsan Patma Vityakon Viriya Limpinuntana Aran Patanothai Georg Cadisch 《Agroforestry Systems》2008,72(2):137-148
In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic
or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts
(stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea
(Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content
as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest
N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized
to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea,
largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for
N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant
components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N
released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures
were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality
components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in
the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols.
Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest
age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its
components are mixed. 相似文献
20.
A. Rigueiro-Rodríguez M. R. Mosquera-Losada E. Gatica-Trabanini 《Agroforestry Systems》2000,48(3):245-256
The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste
disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization,
(2) milk sewage sludge at 40 kg N ha−1 target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two
pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha−1. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha−1) + Trifolium repens L. group Ladino (4 kg ha−1) + Trifolium pratense L. var. Marino (1 kg ha−1); (2) Lolium perenne L. var. Tove (25 kg ha−1) + Trifolium repens L. group Ladino (4 kg ha−1) + Trifolium pratense L. var. Marino (1 kg ha−1). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea
(Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m2, with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect
on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage
sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but
affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral
systems.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献