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991.
Shigeru Yamauchi Yoichi Sakai Yasuo Watanabe Michael Kenya Kubo Hideaki Matsue 《Journal of Wood Science》2007,53(4):324-331
The distributions of boron in Japanese cedar (Cryptomeria japonica D. Don) sapwood blocks treated with aqueous or methanolic boric acid [B(OH)3] solutions were explored through Raman spectroscopy and prompt gamma-ray analysis (PGA). B(OH)3 was the sole boron species observed in Raman spectra of the wood blocks treated with either solution. Plots of weight gain
of the treated wood blocks versus boron concentration in treatment solutions were found to be linear. The results indicated
that the methanolic solution makes it possible to impregnate wood with much larger amounts of boron than the aqueous solution.
PGA confirmed that B(OH)3 was highly enriched near the end grains of the treated wood blocks. Raman measurements suggested that boron content in the
bulk of the wood block is not as large as expected from the weight gain of the treated wood blocks when an ordinary air-drying
method is used. It was concluded that the aqueous solution impregnates the cell walls of wood with boron more easily than
the methanolic solution.
Part of this report was presented at the 55th (Kyoto, March 2005) and 56th (Akita, August 2006) Annual Meetings of the Japan
Wood Research Society. This article follows the previous rapid communication “Analysis of boron in wood treated with boric
acid solutions using Doppler broadening method of prompt gamma-rays.” J Wood Sci (2006) 52:279–281 相似文献
992.
The effects of thermo-mechanical refining conditions on the properties of medium density fiberboard (MDF) made from black
spruce (Picea mariana) bark were evaluated. The bark chips were refined in the MDF pilot plant of Forintek Canada Corporation under nine different
refining conditions in which preheating retention time was adjusted from 3 to 5 to 7 min and steam pressure was set at either
0.6, 0.9 or 1.2 MPa. The resulting bark fibers were blended with 12% UF resin (based on oven-dry fiber weight) using a mechanical
blender. The resinated fibers were manually formed into fiber mats and hot-pressed into MDF panels using consistent parameters.
Two panels for each refining condition were produced, resulting in a total of 18 panels. Analysis of variance (ANOVA) was
used to analyze the significance of factors. Regression coefficients and 3D contour plots were used to quantify the relationship
between panel properties and the two test factors. The results from this study indicated that the preheating retention time
was a significant factor for both modulus of rupture (MOR) and modulus of elasticity (MOE), the steam pressure was a significant
factor for internal bond strength (IB), MOR and MOE, whereas both factors were insignificant for thickness swelling, water
absorption and linear expansion. The properties of MDF panels were quadratic functions of retention time and steam pressure.
Compared to the ANSI standard for 120-grade MDF, most panels with a nominal density of 950 kg/m3 had very high IB (>1 MPa) and acceptable MOR, MOE and dimension stabilities. These results suggest that black spruce bark
residues can be considered as a potentially suitable raw material for manufacturing MDF products. 相似文献
993.
Weston F. Mwase Åsmund Bjørnstad James M. Bokosi Moses B. Kwapata Brita Stedje 《New Forests》2007,33(3):297-307
Biodiversity is declining throughout southern African miombo woodlands due to poor land use practices that are detrimental
to soil, vegetation and habitat. We aimed at examining tree and shrub species diversity and distribution in Uapaca kirkiana-dominated woodlands under three land tenure types; forest reserves, customary and leasehold land. The study was conducted
at different forest sites within similar agroecological zone in southern Malawi. Study sites were located at a range of altitudes
between 900 and 1,200 m a.s.l. Three circular plots each with 32.60 m radius were established at each study site to sample
tree and shrub species composition, structure and distribution under three land tenure types. We found that forest reserves
had higher species diversity with an average of 16 tree families, 27 genera and 34 species as compared to only 10 tree families,
6 genera and 6 species on customary forest lands. Comparisons of diameter at breast height size class distributions showed
that customary land had significantly low numbers of small (5.0–10.0 cm) and very large (≥30 cm) diameter classes suggesting
lower levels of regeneration and high rate of anthropogenic activities. The high species diversity and richness in forest
reserves and leasehold land indicate high potential for protected lands to restore tree species diversity. It is concluded
that levels of human activities as influenced by land tenure type reduce tree species diversity, composition and distribution
at the different sites, and this confirms the hypothesis that open access lands are not compatible with conservation of tree
and shrub species diversity because of high anthropogenic activities. 相似文献
994.
巴山冷杉和秦岭冷杉树脂精油化学成分的研究 总被引:3,自引:0,他引:3
应用毛细管气相色谱标准样品叠加法和色谱—质谱—计算机联用技术研究了巴山冷杉和秦岭冷杉树脂中精油的化学成分。从巴山冷杉树脂精油中分离出的165个色谱峰中鉴定出29个成分,占精油总量的99.13%;从秦岭冷杉树脂精油中分离出的138个色谱峰中鉴定出22个成分,占精油总量的99.47%。两种精油被鉴定的成分均为香成分组成。 相似文献
995.
马尾松人工林施肥试验初报 总被引:3,自引:0,他引:3
本文通过对马尾松人工林施肥试验,表明在Ⅲ类地,适量施尿素和过磷酸钙可促进幼林树高、胸径生长。 相似文献
996.
本文作者根据二氧化氯自身特点及在水厂中的实践,论述了二氧化氯的主要物理性能,消毒氧化作用,制取方法,以及在水厂消毒中的应用。 相似文献
997.
银杏雄株开花生物学特性的研究 总被引:17,自引:0,他引:17
对从泰安和郯城共5050株银杏雄株中筛选出的26个优良单株的开花生物学特性进行了研究。这些单株具有花期长、花粉量大及花粉生活力强等特点。相关分析和方差分析结果表明,随海拔高度的增加,花期逐渐延长,但小孢子叶球数/短枝下降。每米长枝上的短枝数最高达45个。短枝长与小孢子叶球数/短枝呈极呈著的正相关。3年生枝段短枝开花率最高,达96%。每个短枝上小孢子叶球数最高达645个,每个小孢子叶球最多含花药58个,每个花药含有花粉粒最高达23×104个,平均每个小孢子叶球含花粉粒达65×104个。14#单株出粉率达683%。一株45年生雄株可产花粉165g。花粉生活力平均为92%。授粉后座果率90%,有胚率91%。 相似文献
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