木浆纸生产剩余物--木屑制造刨花板的工艺探讨

试验表明,利用木浆纸生产剩余物－－木屑为原料,采取相应的工艺措施,可制造出合格的刨花板,取得良好的经济效益。     

实木地板块标准的讨论

叙述了实木地板块的木材树种、生产过程、品种、使用方法的变化和问题。对1994年发布、实施的实木地板块国 家标准提出了一些修改意见。     

遂川天然次生林干材收获模型

根据天然次生林中收集的样本资料,以样地中检尺乔木树干材积为基准变量Ｙ,以平均林龄,平均胸径,株数、乔木种数、郁闭度为说明变量,建立不同的干材收获模型。『     

Molecular genetic strategies for species identification

This paper probes into the molecular genetic mechanism of the formation of species, subspecies and variety in evolving progression, and brings forward 5 criteria of an ideal strategy in species identification: stating the specific characteristics at species, subspecies and variety level without any interference of too high polymorphism at individual or population level; keys should be distributed as 0 or 1, e. g. yes or no; satisfying repeatability and simple operation; high veracity and reliability; adaptability to widely various specimen. Respectively, this paper reviews two strategies focusing on detecting the fragment length polymorphism and base replacement and lays out some detail methods under above strategies. It demonstrates that it is not possible to solve all species problems by pursuing identification with only a single gene or DNA fragment. Only based on thorough consideration of all strategies, a method or combined several methods could bring satisfying reliability. For advanced focuses, it requires not only development and optimization of methods under above strategies, but also new originality of creative strategies.     

Bending creep behavior of hot-pressed wood under cyclic moisture change conditions

This study examined the bending creep behavior of hot-pressed wood during cyclic moisture changes. Sugi (Cryptomerica japonica D. Don) specimens were pressed in the radial direction under six combinations of nominal compressive strain (33% and 50%) and press temperatures (140°C, 170°C, 200°C). Creep tests were conducted at 20°C with three cyclic relative humidity changes between 65% and 95% under 25% of short-breaking stress. The effect of moisture content (MC) change on elastic compliance and mechanosorptive (MS) compliance was investigated. The relation between MS compliance and thickness swelling was studied. The results indicated that total compliance increased over the history of cyclic moisture changes; and its behavior was closely related to the changes in MC and thickness swelling. The total compliance increased during adsorption and decreased during desorption. Elastic compliance increased linearly with MC and was dependent on press temperature and compression. With increasing MC change, MS compliance increased during adsorption and decreased during desorption. The first adsorption led to greater MS compliance than did the subsequent adsorption with the same amount of MC change. In general, the elastic parameterK _E and the MS parameterK _Mincreased with compression and decreased as the press temperature increased. The MS parameterK _M was apparently greater than the elastic parameterK _E. The MS parameterK _M increased with swelling coefficient K_SW of the hot-pressed specimen during adsorption and decreased with an increasing shrinkage coefficientK _SH during desorption.     

Decontamination of synthetic solutions containing heavy metals using chemically modified sawdusts bearing polyacrylic acid chains

New materials containing carboxylate groups have been synthesized by grafting polyacrylic acid onto sawdust. These new adsorbents were subjected to continuous extraction of different metal ions using packed columns to determine their maximum binding capacities. They exhibit binding capacities 15–40 times higher than unmodified sawdusts for removal of Cu²⁺, Ni²⁺, and Cd²⁺ chosen as representative heavy metal ions. Cation desorption and adsorbent regeneration could be effected by elution with a diluted HCl solution; water as an eluent has no effect on metal desorption.     

Damage to residual stands from thinning with short-span tower yarders: Re-examination of wounds after five years

The current status of wounds on residual trees was investigated and compared with the wound status from five years ago when the stands were thinned and logged. Wound status was defined according to the four levels of severity based on appearance. Several damaged trees were cut for inspection of the wounded areas. Most wounds of a lighter severity level had already healed by occlusion and were no longer evident. Wounds reflecting heavy damage but had healed, were smaller in the horizontal dimension, or width, than those not yet healed. Slight wounds, but with a current status reflecting persistent damage were smaller in the vertical dimension, or length. An inspection of wound sections revealed the development of discoloration in the wood. Only the slight wounds that healed early had no or small discolored areas. The width of discolored areas of wounds in which cambium was still exposed was greater than the original width of the wound. In conclusion, wound width rather than length significantly affects healing or occlusion of wounds.     

《猪生产学》课程教学改革与创新研究

《猪生产学》是动物科学专业的重要专业课之一。本文主要探讨了《猪生产学》课程的教学内容、教学改革原则以及教学中存在的问题,从教学内容改革、教学方法改革和加强师资队伍的培养等方面入手,提出了《猪生产学》课程改革的措施。通过这些实施改革措施,旨在培养适应现代化、集约化、自动化的和信息化养猪生产的高素质专业人才。     

火炬松纸浆林材性变异和优质原料培育期的确定*

１６年生火炬松纸浆材性状研究表明：管胞长度径向呈递增稳定的模式，纵向呈递减变化；其长宽比变异类似于管胞长度的变化；管胞长度变化范围为１．４０３～４．４５６ｍｍ，长宽比为４６．７～７０．１，腔径比为０．７１１～０．７８６，壁腔比为０．３８１～０．４９６。基本密度径向由０．３２４ｇ／ｃｍ３递增到０．４２８ｇ／ｃｍ３；纵向递减，其均值变动于０．３１４～０．４０１ｇ／ｃｍ２；株间木材密度均值与管胞长度两性状不相关。纤维素含量由髓心附近３７．０４％递增到树皮附近４３．９１％，木素、多缩戊糖含量分别由２８．７８％、１４．５９％递减到２５．７４％、１２．０５％，其苯醇抽出物含量变化在２．１２％～８．３８％之间。火炬松木材幼龄期约为１０～１３ａ。基于火炬松木材各树龄材性的变化，结合生长量指标，确定其短周期纸浆林适宜采伐树龄约为１２～１３ａ。     

广西特色农业资源型产业发展的科技问题探讨

【目的】分析广西特色农业资源型产业科技发展现状和存在的科技问题,提出促进广西特色农业资源型产业发展的科技对策,为广西特色农业资源型产业发展提供决策参考。【方法】在阐述广西蔗糖、木薯、桑蚕等特色农业资源型产业科技发展现状、存在问题的基础上,通过系统分析广西特色农业资源型产业发展对科技的需求,提出科技支撑广西特色农业资源型产业发展的思路、重点任务及对策。【结果】明确了保障国家食糖安全、发展非粮生物质能源、优化产业经济结构及提高产业效益、产业与生态环境协调发展等对科技的需求及广西特色农业资源型产业发展面临创新能力不强、科技有效供给不足、科技成果转化与推广应用体系尚不完善、科技技术应用水平不高等科技问题。【建议】应加强顶层设计,科学制定广西资源型农业产业的发展规划;依靠科技进步转变农业资源型产业的生产发展方式;加快农业优势特色产业技术创新体系建设,增强产业科技创新能力;培育和扶持农业产业科技型企业的发展;大力实施名牌战略,打造农业优势产业品牌;构建多元化的科技投入体系;培育创新团队,建设一支农业科技创新人才队伍等,以促进广西特色农业资源型产业可持续发展。