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991.
选用广西马尾松龄施肥材料(连续观测13年),根据国际《木材物理力学试验方法》,研究了施肥对木材密度和干缩率的影响,结果表明:N、P、K三要素中,以N、P肥对木材密度和干缩率的影响较大。⑴总的来说P增加木材密度和干缩率,N肥降低木材密度木材干缩率。N、P肥降低木材差异干缩。施K肥对木材密度和干缩率的影响规律性不明显。⑵N、P、K施肥对木材密度和干缩率的影响及其变化程度,与肥种、施肥量、树干部位、木纹方向、气干或全干状态有关。施P肥木材密度具有增加的趋势,而且树干下部基本密度方差分析各处理间差异显著。N、K肥对木材密度的影响,规律性不明显。P肥使木材干缩率增加,P肥主要增加的是全干干缩率和径向气干干缩率,特别是树干下部径向气干干缩率各处理间差异显著。K肥对干缩率的影响规律性不明显,有待进一步研究。⑶为了保证木材质量,对于纤维用材林,主要施P肥;对于结构用材林,可施P肥,适当考虑N肥、K肥施用应慎重。 相似文献
992.
993.
M. R. Dove 《Agroforestry Systems》1992,17(1):13-41
This study suggests that one of the most productive (and most neglected) uses of social science research in forestry development projects is to examine foresters' beliefs regarding rural peoples. This suggestion is illustrated with data from the Forestry Planning and Development Project, Pakistan's first nation-wide social forestry project.The operational component of this project, intended to assist small farmers to cultivate trees on their farmlands, ran into immediate difficulties. Many of the foresters involved insisted that small farmers were simply not interested in tree cultivation. A comprehensive base-line study subsequently was carried out to examine the validity of this belief. The results of this study (confirmed by the subsequent experience with the project in the field) varied markedly from the foresters' beliefs.While many of the foresters believed small farmers were opposed to having trees on their farms and would not agree to plant trees under the project, most farmers already had trees on their farms and expressed interest in planting more; while many foresters believed farmers would only be interested in planting large blocks of market-oriented exotics, most farmers requested small plantings of multi-purpose native trees; while many foresters believed farmers would plant trees only for market sale, most farmers requested trees to meet household needs for fuel and timber; and while many foresters did not think that increasing supplies of fuelwood could reduce the burning of dung, all of the evidence provided by the farmers suggested that it would.The disparity between farmer reality and forester belief is attributed to failures on the part of both foresters and social scientists — failure by foresters to distinguish their non-empirical beliefs about farmers from their empirically-based knowledge of trees, and failure by social scientists to recognize the belief systems of foresters as a legitimate and important object of study. Their study comprises three parts: finding out what the foresters think the farmers want, finding out from the farmers what they actually want, and then analyzing and explaining the differences. 相似文献
994.
The main purpose of this study was to investigate the changes in heat flux and temperature after the subject's palm was in contact with interior decorating materials. The relations among heat flux, temperature, and sensation of cold/warm during contact were studied. Ten men and ten women were selected and introduced to 21 materials for the contact test. They were in contact with the specimens for 30min without seeing them in a climate-controlled room at 25°±1°C and 65% RH. Changes in the heat flux and temperature of the specimens were determined by a heat flux meter. A sensory evaluation test was applied to evaluate the cold-warm contact. Results indicated that the heat flux and temperature increased with increasing time after the subject's palm was in contact with the specimens. The heat flux (Q
30) and temperature (T
30) 30min after the subject's palm contacted the specimens were greater for male subjects than for female subjects. A positive linear regression equation existed between the values for Q30 andT
30, whereas a negative linear regression formula existed the sensation of cold-warm by contact (5) and the values of ln(Q
1·). Therefore, the sensation of cold/warm by contact could be estimated simply by using the thermal physical properties of the interior decorating materials.Part of this report was presented at the International Conference on Effective Utilization of Plantation Timber, Chi-Tou, Taiwan, ROC, May 1999 相似文献
995.
The nitrobenzene oxidation method was modified to obtain more reproducible data and more structural information about lignin, not only by gas chromatography (GC) but also by proton nuclear magnetic resonance (1H-NMR) spectroscopy for quantitative determination of the oxidation products and to simplify the procedures. The nitrobenzene oxidation mixture was directly extracted after acidification without preextraction of by-products. The direct extraction made the extractive step easy and gave reproducible data. 5-Iodovanillin was selected as a new internal standard. The reason for this selection was that 5-iodovanillin did not exist in the nitrobenzene oxidation products from any plant species and had an aldehyde group whose peak did not overlap with the other aldehyde peaks on an1H-NMR spectrum. Thus, the use of 5-iodovanillin enabled us to quantifyp-hydroxybenzaldehyde, vanillin, and syringaldehyde in oxidation products on the basis of1H-NMR analysis as well as GC. Furthermore, more information about the condensed structure of lignin was derived by comparing the1H-NMR and GC analyses.Part of this work was presented at the 42nd Annual Meeting of the Lignin Symposium, Sapporo, October 1997 相似文献
996.
Bruchidius andrewesi Pic. has been recorded as a serious pest of pods and seeds of Acacia tortilis in the Thar desert of India. Pest infestation on developing pods and its relationship with morphological traits is reported. Pod infestation varied from 5 to 19% with 5–29% infestation of seeds. Infestation of pods is directly related to infestation of seed (r = 0.72**), and both pod and seed infestation are also directly correlated with loss in seed biomass (r = 0.79** and R = 0.88**). The infestation of pods starts in November and increases steady until harvest. Seeds kept in the laboratory for further studies were found to be 100% infested with B. andrewesi, as the insect multiplied faster under these conditions. The heavy infestation is damaging not only to A. tortilis but also to other leguminous trees of the desert. Bruchidius andrewesi has also been found on pods and seeds of Prosopis cineraria, an important indigenous tree of the region. 相似文献
997.
A method to estimate the content of -carbonyl structures in lignin was developed. This method consists of two successive treatments: NaBD4 treatment of pulp to reduce an -carbonyl structure in lignin, and nitrobenzene oxidation. NaBD4 was used to convert an -carbonyl structure to a deuterium-labeled hydroxymethine structure. The ratio of D-vanillin [(HO)(H3CO)C6H3CDO] to H-vanillin [(HO)(H3CO)C6H3CHO] or that of their syringyl analogues obtained by nitrobenzene oxidation was used as the measure of the content of -carbonyl structure. Model experiments demonstrated that when sodium hydroxide was used as alkali for the nitrobenzene oxidation, the retention of deuterium at the side chain -position was very low due to the displacement of deuterium with hydrogen by an unknown reaction mechanism. In order to depress this unexpected displacement, the reaction conditions of the nitrobenzene oxidation were modified. The modified nitrobenzene oxidation employs 0.5mol/l of lithium hydroxide as a reaction medium instead of 2.0mol/l sodium hydroxide. By this modification, this method could successfully trace the formation and the degradation of the -carbonyl structure in milled wood lignins.This paper was presented in part at the 11th International Symposium on Wood and Pulping Chemistry, Nice, France, June 2001 and at the 46th Lignin Symposium, Kyoto, Japan, November 2001 相似文献
998.
999.
惠德华 《林业机械与木工设备》2004,32(3):12-15
连续生产中、高密度薄板的方式是采用连续双钢带冷热压机,而国内人造板设备制造行业尚无制造连续双钢带冷热压机的能力。本文依据木纤维薄板矫直原理,提出采用简易连续热辊压压机加矫直机的方案,探索低成本连续生产中、高密度纤维薄板和异型板的方式,以解决实际生产问题。 相似文献
1000.