Alkaline degradation of spruce and beech wood

Summary The alkaline delignification of spruce and beech wood is accomplished in three phases. The first phase results in a decrease of yield down to 83...80%, the second one in a decrease from 83...80% to 64...61% and the third one in a yeld drop from 64...61% to 50...46%. The amount of polysaccharides removed in the first phase was 22%, in the second phase 5...6% and in the third phase 10% of the total polysaccharides in the original wood. The amount of lignin removed in the first phase of delignification was 9...11% in the second phase 53...54% and in the third phase 28% of the total lignin in the original wood. The polysaccharides extracted in the second and third phase amounted to 70...78% of the polysaccharides removed in the first delignification phase. For an entire characterization of the delignification reaction not only the course of lignin removal is of importance but also the course of the polysaccharide extraction. The results show that for a two-stage alkali-oxygen-cooking technology the optimum yield after initial partial alkaline delignification lies in the range of 64...61%.     

游离甲醛和人造板释放甲醛

甲醛是室内空气污染源，它常与甲醛系统粘接连在一起，本文根据国内外资料评述人造板甲醛释放量，分析了脲醛树脂的水解和人造板释放甲醛的机理，还介绍了甲醛的毒害，各国政府的有关法规以各种降低甲醛释放量的方法。     

华北落叶松边材透水性与叶面积空间分布的相关性的探讨

对华北落叶松林单木累积叶面积、树干边材面积、树干边材透水率及透水量的垂直分布规律及其相互关系进行了探讨。研究表明，引入树干边材面积与边材透水率的积可明显提高估测树冠叶面积垂直分布的精度，进而为精确估测林分的叶面积空间分布提供了新途径。     

Altitudinal patterns of the flora of seed plants of Dawei Mountain in Yunnan Province, south China

Altitudinal gradient incorporates multiple resource gradients, which vary continuously in different fashions. It is important to study the mountain floristic patterns along altitudinal gradients, which reveal the regular pattern of the flora along the environmental gradients, the changing trend of biodiversity patterns along the altitudinal gradient, and relevance of biological fitness. To explore the compositional characteristics and ecological significance of floristic patterns along altitudinal gradient in China National Nature Reserve of Dawei Mountain in the southeast of Yunnan Province, field investigations have been made to the flora along the two routes of the southwest slope and the northeast slope of the said reserve, including a vertical vegetation transect. Meanwhile, further investigations have also been made to the flora of Dawei Mountain, which has been accounted for in the literature, as Flora Yunnan, The Seed Plant in Yunnan, and so on. The structural characteristics of the flora and the altitudinal distribution pattern of its floristic components were analyzed. By applying systematic cluster analysis, the altitudinal position of the dividing line of floristic changes along altitudinal gradient was detected, and the effects of the montane climate on the vertical variation of floristic composition were studied. Conclusions were put forward. This paper can be summarized as follows: (1) The obvious boundary that differentiates tropical floristic elements is located at the altitude of approximately 1,500 m; it is reasonable to stipulate the boundary line between tropical rain forests and the evergreen broad-leaved forests. (2) The vertical vegetation spectrum made by cluster analysis shows that humid rain forests are below 700 m a.s.l, montane rain forests are between 700 and 1,500 m, monsoon evergreen broad-leaved forests are between 1,300 and 1,800 m, and montane mossy evergreen broad-leaved forests are above 1,800 m a.s.l. Nonrepresentative montane mossy dwarf forests (above 2,100 m) in the area are distributed in windward sides and in barren land on the mountain slopes. __________ Translated from Acta Phytoecologica Sinica, 2005, 29(6): 894–900 [译自: 植物生态学报]     

我国杨树杂交育种的现状和发展对策

在简要介绍了我国杨树资源并回顾了４０年来的杂交育种成就后，把我国杨树杂交育种过程划分成两个时期。第一个时期解决了北方杨树栽培的品种化问题，第二个时期在一定程序上用自己选育的无性系改变了黄河以南到长江中下游地区直接用引入无性系造林的现状。但由于两个时期是一个世代的短期育种活动，方法和程序上缺少改进，都把由种间杂种Ｆ１中选择无性系作为重点，加之基因资源有限，都存在推广无性系亲缘相近潜育的危险性，缺乏长     

砂质土肥力状况及其与毛白杨生长关系的研究

对黄河故道冲积砂质上的肥力状况和毛白杨生长因子之间的关系进行了研究，着重分析了土壤养分和水分在土体中的分布规律，及其与土壤质地的关系，以及不同生长季节毛白杨的叶片营养特征和树高、胸径生长量与砂质土水分、养分含量的相关性。结果表明：砂质土肥力低下；土壤质地、养分和水分变化状况与树木生长关系密切，尤其是土壤粘粒、水分和氮素含量与毛白杨生长呈明显的正和关。故可通过施肥、灌水、改善土壤保水保肥特性来调整和控制林木生长。     

城市道路网信息管理系统研究

针对国内城市交通规划缺乏完整的道路信息资料 ,提出了如何利用功能完善的EMME/2交通规划软件结合中国的交通特性 ,进行城市路网信息资料的获取 ,并提出相应的数据库记录规定 ,据此研制开发了城市道路网信息管理系统。     

装饰单板贴面胶合板与杉木复合制造地板技术

为了降低实木复合地板生产的材料消耗和成本,直接采用装饰单板贴面胶合板与杉木组合制造实木复合地板.结果表明,按改进工艺制造的复合地板不仅具有国标所要求的物理力学性能,而且可降低材料成本30%左右.     

Pyrolytic characteristics of burning residue of fire-retardant wood

In order to investigate the pyrolytic characteristics of the burning residue of fire-retardant wood, a multifunctional fire-resistance test oven aimed at simulating the course of a fire was used to burn fire-retardant wood and untreated wood. Samples at different distances from the combustion surface were obtained and a thermogravimetric analysis (TG) was applied to test the prrolytic process of the burning residue in an atmosphere of nitrogen. The results showed that: 1) there was little difference between fire-retardant wood and its residue in the initial temperature of thermal degradation. The initial temperature of thermal degradation of the combustion layer in untreated wood was higher than that in the no burning wood sample; 2) the temperature of the flame retardant in fire-retardant wood was 200°C in the differential thermogravimetry (DTG). The peak belonging to the flame retardant tended to dissipate during the time of burning; 3) for the burning residue of fire-retardant wood, the peak belonging to hemicellulose near 230°C in the DTG disappeared and there was a gentle shoulder from 210 to 240°C; 4) the temperature of the main peaks of the fire-retardant wood and its burning residue in DTG was 100°C lower than that of the untreated wood and its burning residue. The rate of weight loss also decreased sharply; 5) the residual weight of fire-retardant wood at 600°C clearly increased compared with that of untreated wood. Residual weight of the burning residue increased markedly as the heating temperature increased when burning; 6) there was a considerable difference with respect to the thermal degradation temperature of the no burning sample and the burning residue between fire-retardant wood and untreated wood. __________ Translated from Journal of Beijing Forestry University, 2006, 28(3): 133–138 [译自: 北京林业大学学报]