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1.
赵魁浩 《中南林业科技大学学报(自然科学版)》2004,24(6):29-32
法治既是一种治国方式和手段,也是人民行使管理国家、管理社会的权利的途径.德治的核心内容是要建立社会主义的道德体系和弘扬优秀的民族精神.法治和德治既有区别,又有联系,是辨证统一的.法治、德治的辩证统一是贯彻"三个代表"重要思想和建设中国特色社会主义的内在要求. 相似文献
2.
Alfred J. Stamm 《Wood Science and Technology》1973,7(4):285-296
Summary Oven dry highly evacuated sticks of the sapwood of various hardwoods, 40 cm long by 1.0 to 1.2 cm in the radial and tangential directions, took up water to the extent of 44 to 82% of saturation by capillary flow in one minute. Heartwood sticks took up 15 to 38% of saturation in one minute. The initial rapid penetration was followed by a penetration in which the take up increase directly with the square root of elapsed time. In this range, the slope of toluene take up plots was about twice that of the water take up. This is close to the theoratical value on the basis of viscous flow control. The linear portion of the plots is followed by a curvilinear decrease in rate of take up to a final equilibrium value. Water take ups approached 100% of the theoretical values.Times to 0.99 of theoretical filling with water varied from 9 minutes for tupelo gum sapwood to 14.6 to 17.3 days for white oak heartwood. Complete filling with toluene was never attained. Diffuse porous hardwoods filled to the extent of 93.5 to 96.5% of saturation. Ring porous oaks filled to the extent of 88 to 92%, the lower values being for heartwood. Edge coating of the sapwood of yellow poplar and yellow birch with epoxy glue reduced the rate of penetration only slightly. End coating reduced the rate to a higher degree. Moisture gradients in the fiber direction for tyloses-free hardwoods were negligible at various stages of penetration, indicating that filling of the vessels was practically instantaneous. White oak heartwood gave an initial longitudinal gradient followed by a negligible gradient, indicating that longitudinal penetration is primarily through the lumen of the fibers rather than continously through the vessels. Longitudinal penetration was calculated to be 31.5 times as deep as transverse penetration in 100 minutes and 33.3 times as deep in 25 minutes for white oak heartwood. The ratios are of the same order of magnitude as for Loblolly pine. In both cases the ratios are smaller than values calculated from the fiber dimensions alone as ray cell penetration and cross grain effects tend to lower the ratios.Paper No. 3947 of the Journal Series of North Carolina State University Agricultural Experiment Station, Raleigh, N. C. 相似文献
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Summary The deformation processes involved in wedge indentation of wood are described. The behaviour of wood is compared to that of an elastic-plastic solid and that of a cellular body. It approximates towards the former when its density is high and towards the latter when its density is low. The hardness of wood is examined as a function of density and of wedge angle.We wish to thank the University Grants Committee and the New Zealand Forest Service for supporting this work 相似文献
4.
Forest buffer zones have recently been introduced in an attempt to suppress debris movement caused by mass wasting. There
are, however, many questions left unsolved regarding the role of forests in suppressing debris movement and damage to forests
by debris deposition. A number of debris avalanches occurred in southern Fukushima Prefecture and Hiroshima Prefecture in
August 1998 and June 1999, respectively. Suppression of debris movement by forests and damage to forests by debris deposition
were investigated in this study using aerial photographic interpretation and topographic analysis. Of the debris avalanches
delineated in the Fukushima and Hiroshima areas, 282 and 84 sites, respectively, were forested, and 43 and seven sites, respectively,
were nonforested. Topographic parameters, land use, and forest type at each site were surveyed by aerial photographic interpretation
and topographic analysis. Suppression of debris movement by forest vegetation was confirmed by higher equivalent coefficients
of friction and shorter average deposition zone length (about 28% and 55% shorter in the Fukushima and Hiroshima areas, respectively)
in forested sites compared with nonforested sites. While previous studies suggested that the width of the forest zone required
to prevent sediment outflow by surface erosion increases with increasing slope gradient, no clear relationship was found in
this study. While the length of deposition zone of debris material (this study) is strongly affected by the dynamic solid
friction coefficient and fluid friction of debris material, the length of deposition zone of the outflow of surface wash (past
studies) is mainly affected by the tractive force of water flow. Among the 65 trees that remained at the terminus of deposition
zones at five sites, 36 were alive and 29 were dead. Damage to the forest increases with increasing thickness of deposits
and decreases with increasing tree diameter. Such results are useful for designing forest buffer zones.
Received: June 18, 2001 / Accepted: August 21, 2002
Correspondence to:Y. Ishikawa 相似文献
5.
Tsutomu Yagihashi Mitsuhiro Hayashida Toshizumi Miyamoto 《Journal of Forest Research》2000,5(3):213-215
To evaluate what prevents seed germination and why ingestion by birds enhances germination, we carried out germination experiments
using bird-dispersed seeds of twoPrunus species (Prunus sargentii andP. ssiori) in the laboratory. Germination of seeds with following four treatments was compared: “Ingested seeds” excreted after feeding
of fruits to birds; “Extracted seeds” deliberately extracted from the fruit pulp; “Juiced seeds” which were supplemented with
the juice of the pulp after seeds had been deliberately extracted from the pulp; and “Intact seeds” in untreated whole fruits.
Many ingested (27%, 23% inP. sargentii, 18% inP. ssiori) and extracted seeds (24% inP. sargentii, 17% inP. ssiori) germinated, and difference in germination percentages between ingested and extracted seeds were not significant, for eitherPrunus species. The Juiced seeds rarely germinated (2% inP. sargentii, 6% inP. ssiori), and seeds within intact fruits did not germinate. These results suggest that the fruit pulp and the juice of the pulp inhibit
germination and the seeds could germinate without ingestion by birds once they had been manually extracted from pulp. Therefore,
it is considered that bird ingestion enahnces germination by removing pulp, especially juice of the pulp, in these twoPrunus species. 相似文献
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To clarify the inducing mechanism of kerf deviation caused by unsymmetrical set of the handsaw, we hypothesized that the moment
on the bottom edge of the saw blade, which is generated by the unsymmetrical set on handsaw teeth, bends the saw blade and
this deformation should be one factor of the kerf deviation. To verify this hypothesis, the bend of a saw blade was examined
by experiment and by calculation. In the experiments, a model tooth was attached to an actual handsaw. In the calculations,
a saw model with a rectangular prism as the model tooth was analyzed by the finite element method. Loads were applied on the
model tooth or the rectangular prism. From both the experiments and the calculations, the following results were obtained:
(1) the deformation of the handsaw was caused by the unsymmetrical set in the length direction and the height direction of
the saw blade; (2) the deformation and the inclination of the blade was larger at the front part of the saw than at the butt
part; and (3) comparing the saw handle fixing conditions, the kerf deviation in the sawing line was supposed to be larger
in the free handle condition and that kerf deviation in the depth direction was larger in the fixed handle condition. Based
on the above results, it is apparent that one of the kerf deviation mechanisms originated from unsymmetrical set on the saw
teeth.
Part of this report was presented at the 54th Annual Meeting of the Japan Wood Research Society, Sapporo, Japan, August 2004. 相似文献
8.
Non destructive methods for quantification of carbon seques-tration in tropical trees are inadequately developed. We described a stan-dardized method for estimating carbon stock in teak (Tectona grandi... 相似文献
9.
The aim of this research was to test the hypothesis that exposure to solar radiation increases the checking of wood exposed
to the weather, and to examine the causes and spectral dependency of such an effect. Lodgepole pine decking samples were exposed
outdoors under filters, which blocked selected regions of the solar spectrum while allowing other weathering factors to act
on samples. Surface checking in samples was quantified after 12, 24 and 36 weeks of exposure, and the chemical and micro-structural
changes occurring at weathered wood surfaces were examined. Check numbers and dimensions were greater in samples exposed under
a filter to the full solar spectrum than in samples exposed under filters that blocked the transmission of UV, visible or
infrared radiation. Samples that were shielded from more energetic wavelengths developed less checking and also showed less
delignification at the exposed wood surfaces. Checks developed at the margins of rays and propagated at the interface between
adjacent tracheids, close to the middle lamella. We conclude that exposure to UV and visible light increases the tendency
of wood to check during exterior exposure. Our findings point to a link between changes in cell micro-structure as a result
of photodegradation of lignin and the development of visible checks in wood exposed outdoors. 相似文献
10.
Tryptophol (an indole-3-ethanol analogue which is a major secondary metabolite produced by Zygorhynchus moelleri) stimulated the growth of 13 out of 18 isolates of Armillaria ostoyae in culture. Rhizomorph production of 16 out of 18 isolates of A. ostoyae was enhanced by the presence of Z moelleri in oak branch segments. Tryptophol can be considered as a growth-promoting substance stimulating the vegetative growth of A. ostoyae in culture, and Z. moelleri as a fungus stimulating the rhizomorph formation on oak wood. 相似文献
11.
孙彦珍 《内蒙古林业调查设计》2009,32(6):39-40
杨树杂交是选育优良品种最直接有效的途径之一,并能为现代高新技术育种提供原始材料。杨树杂交育种在全世界范围开展以来,选育出了大量的优良品种,对提高杨树生产力起到了非常重要的作用。文章就杨树切枝杂交技术作一简单的阐述,主要包括材料的准备、室内切枝杂交、播种育苗等。 相似文献
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分别以纤维素、木质素、杉木屑与核桃壳为原料,经过炭化后在Ni的催化作用下于1 400℃下进行了石墨化反应,并以X射线衍射(XRD)、Raman光谱和高分辨率透射电镜(HRTEM)分析了产物的石墨化程度。研究结果表明:纤维素在生物质的石墨化过程中起主要作用,在相同处理条件下,由纤维素得到的产物石墨化程度最高,由木质素得到的产物石墨化程度最低,杉木屑和核桃壳2种生物质原料得到的产物石墨化程度介于纤维素和木质素之间,不同原料石墨化程度的显著差异可能是由于原料结构的差异造成的。同时电导率测试结果表明:20 MPa条件下,由纤维素得到的产物的电导率为54 S/cm,而由木质素得到的产物仅为31 S/cm,与石墨化程度的高低相对应。纤维素/木质素混合物的石墨化程度介于纤维素和木质素之间,两者不同质量比对混合物的石墨化程度影响不大。 相似文献
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16.
青春双歧杆菌代谢低聚木糖机理研究 总被引：2，自引：0，他引：2
对青春双歧杆菌代谢低聚木糖的动力学行为进行了探讨,同时对青春双歧杆菌代谢低聚木糖时各组分的变化规律及代谢产物进行了研究.结果表明,青春双歧杆菌代谢低聚木糖48 h后,总糖质量浓度从最初的5.00g/L降至3.59g/L,菌体质量浓度从0.10g/L上升至0.35g/L,培养体系的pH值从7.00降至4.75.青春双歧杆菌代谢低聚木糖时,首先代谢木二糖至木五糖组分,此后,其分泌的α-L-阿拉伯呋喃糖苷酶将低聚木糖组分中的阿拉伯糖基侧链水解释放,并作为青春双歧杆菌的碳源.代谢过程中,青春双歧杆菌还能分泌β-D-木糖苷酶作用于低聚木糖的末端,释放出木糖,最终导致木糖在培养体系中累积.代谢产物分析结果显示,青春双歧杆菌代谢低聚木糖的代谢产物主要有乳酸、乙酸、丙酸和丁酸. 相似文献
17.
A stable cell suspension line of Catharanthus roseus producing anthocyanin was obtained. In this strain it was found that approximately 30% of cells regularly accumulated these metabolites and that anthocyanin accumulation occurred between the second half of log phase and the stationary phase of the culture growth cycle. The anthocyanins in the suspension cultures were compared with those biosynthetized in the flowers both of regenerated by somatic embryogenesis and field-grown plants. Six anthocyanins were identified in all the examined samples, three 3-O-glucosides and three 3-O-(6-O-p-coumaroyl) glucosides of petunidin, malvidin and hirsutidin. The hirsutidin coumaroyl glucoside has not been reported previously, and was predominat in all samples. The anthocyanin relative content was similar for cell suspensions and flowers from regenerated plants but different from field-grown plant flowers; instead, the total content was almost the same for the two flower types and higher compared to suspension culture content. 相似文献
18.
QIN Qing XU Hao WANG Jin-qiao DU Yun-ping CHEN Wen-wen ZHANG Zong-he HUANG Jia-ling 《林产化学与工业》2012,32(2)
以塔拉粉为原料,研究了不同溶剂对塔拉单宁提取的影响,并对塔拉单宁提取的最佳工艺进行了探索.结果表明,采用甲醇为提取剂,采用间歇法提取塔拉单宁,最佳工艺条件为:提取温度60℃,每次提取时间40 min,提取3次,每次1h,液固比依次为4.5∶1(mL∶g,下同)、4∶1、4∶1,塔拉单宁粗提物得率67.2％ ～68.4％,相对误差1.77％,单宁纯度66.0％～67.5％,相对误差2.25％,单宁提取率91.5％. 相似文献
19.
受铬矿尾矿库污水不合理排放的影响,铬金属在下游水源和土壤中超标现象较为严重。为治理铬污染,开展了电解法去除土壤中铬污染试验,结果表明：采用磷酸盐缓冲液作为电解质,在铬污染土壤两端加上低压直流电场,使铬污染土壤在电解液磷酸盐缓冲液介子中以离子态产生迁移,即以三价或六价铬向电极方向移动,从而使土壤中的离子态铬在阴极端得到富集,土壤中的金属铬得到有效去除。 相似文献