Moisture movement and thickness swelling in oriented strandboard. Part 2: Analysis using a nuclear magnetic resonance imaging body scanner

The previous paper in this series demonstrates the use of a nuclear magnetic resonance (NMR) micro-imaging system to observe the movement of liquid water through small specimens (11 × 16 mm² cross-section) of oriented strandboard (OSB) and solid wood. In the present paper, a NMR body scanner is utilized to obtain images of moisture penetration into ASTM D 1037–99 standard sized (152 × 152 mm²) thickness swelling specimens at different intervals during water soaking. As with the micro-imaging study, silicone was applied to the surfaces and edges of some of the specimens in order to observe the directional characteristics of moisture movement through OSB. Specimens with commercially applied edge sealant were also included in the study in order to observe the effectiveness of the sealant of reducing moisture penetration and thickness swelling. The presence of voids and areas of low density were shown to contribute significantly to moisture penetration into the specimens.     

林业企业会计信息披露模式的构建

林业会计信息披露是林业会计中主要和基本的问题。从林业会计信息的基本特征出发,剖析了现行林业企业会计信息披露的局限性,主要存在会计信息披露目标过分强调为国家宏观管理服务、披露内容不充分,披露方式不科学等问题。在此基础上探讨了林业企业会计信息披露的模式。     

金沙江干热河谷区退耕还林适宜造林树种筛选研究

金沙江干热河谷上段退耕还林区适宜造林树种筛选结果:甜酸角、山毛豆、苏门答腊金合欢、新银合欢、久树、印度黄檀等适宜在海拔1400m以下地带造林,构树、木豆、坡柳、余甘子、川楝等适宜在海拔1600m以下地带造林,山合欢、黑荆树、墨西哥柏、干香柏等适宜在海拔1400～1600m地带造林。木豆、坡柳、山毛豆等可进行直播造林,山合欢、黑荆树、川楝、苏门答腊金合欢、新银合欢、久树等采用百日容器苗造林,甜酸角、墨西哥柏、干香柏、印度黄檀等采用1年生容器大苗造林效果更好。块状整地(规格40cm×40cm×40cm),施有机肥加一定量的N、P肥作基肥,塘底施放高丙体粉防治白蚁危害,于雨季初期择时取苗造林,造林后应防止种植塘积水。造林苗木选用充分木质化的粗大壮苗;造林后和雨季中、后期及时清除种植塘周围杂草。     

黄土半干旱区集水造林条件下林木生长适宜的土壤水分环境

2000年在山西方山，采用LI－6200光合测定系统和LI－1600稳态气孔仪，对不同集水措施试验地的刺槐、侧柏和苹果的生理指标进行了实地观测，并辅以相同树种实地盆栽苗木水分胁迫条件下的林木生理指标观测，研究了林木净光合速率、羧化效率、水分利用效率与土壤含水量的定量关系。结果表明：维持刺槐、侧柏和苹果净光合作用的最佳土壤含水量分别为17.13%、15.9%和16.11%，三树种维持叶片水分利用效率的最佳土壤含水量依次为13.23%、10.66%和12.38%；羧化效率最高时的土壤含水量临界值依次为15.7%、15.5%和15.8%；土壤水合补偿点分别为4.55%、3.91%和4.49%。上述三树种蒸腾速率所适宜的土壤含水量分别为18.82%、19.70%和16.33%。根据集水造林的基本构思，可选取维持最佳叶片水分利用效率的土壤含水量临界值作为集水造林林木密度调控的土壤水分阈值和林木需水量的低限计算条件。这一指标可量化为刺槐10％－13％，苹果10％－12.5%，侧柏9.5%-11%。     

尾叶桉胚状体植株诱导与增殖研究

本文报导了用尾叶桉种子下胚胎诱导体细胞胚胎发生，获得根苗齐全的胚状体再生植株，经过５～６代增殖培养，获得大量丛生苗，已完成移栽，炼苗的全套生产技术流程，是迄今世界松树组培由下胚轴产生胚状体小苗成功的第三例，在木本植物的同类组培成功研究中也是数例之一，在科学和林木良种快速选育与繁殖上有重要价值。     

Genetic diversity of sea buckthorn (Hippophae rhamnoides) populations in northeastern and northwestern China as revealed by ISSR markers

As a N₂-fixing tree species, sea buckthorn (Hippophae rhamnoides) is well adapted to arid regions and is utilized for multiple purposes in China. Current knowledge of genetic variability of H. rhamnoides is limited in terms of rangewide distributions. Eleven natural populations of sea buckthorn in northeastern and northwestern China were analyzed to detect genetic variation among and within populations, by use of ISSR (inter-simple sequence repeats) markers. Using eight primers, 207 polymorphic loci were observed, ranging in size from 250 to 2500 bp. The coefficient of gene differentiation (Gst = 0.0679) showed that the total molecular variance of 11 populations was mainly existed within populations. The genetic variation within and among the 11 populations was 93.21 and 6.79%, respectively. No significant correlation between genetic and geographic distances of the populations was found using ISSR markers. Our study provides a population-level genetic profile for further investigation and conservation of genetic diversity of sea buckthorn.     

以酶解渣为碳源制备木聚糖酶的研究

以里氏木霉（Tichoderma reesei)Rut C-30为产酶菌，低聚木糖制备过程中酶解渣为碳源可透导产生含低纤维素酶活（0.106IU/mL)的木聚糖酶（154.67IU/mL)，两种酶活的比值达1459，与粗木聚糖为碳源产木聚糖酶相比，木聚糖酶活提高了1.67倍，而纤维素酶活没有增加。此酶在50℃条件下酶解粗木聚糖和酶解渣时，pH值5时酶解效率最高，酶解产物通过HPLC分析，主要是木糖。该酶系的组成主要是外切-β-木糖苷酶。     

Factorial analysis on forest canopy density restoration in the burned area of northern Great Xing＇an Mountains, China

The restoration of forest landscape has drawn much attention since the catastrophic fire took place on the northern slope of Great Xing‘an Mountains in 1987. Forest canopy density, which has close relation to forest productivity, was selected as a key factor to find how much the forest quality was changed 13 years after fire, and how fire severity, regeneration way and terrain factors influenced the restoration of forest canopy density, based on forest inventory data in China, and using Kendall Bivariate Correlation Analysis, and Distances Correlation Analysis. The results showed that fire severity which was inversely correlated with forest canopy density grade was an initial factor among all that selected. Regeneration way which did not remarkably affect forest canopy density restoration in short period, may shorten the cycle of forest succession and promote the forest productivity of conophorium in the future, Among the three terrain factors, the effect of slope was the strongest, the position on slope was the second and the aspect was the last.     

三种薇菜产品营养成分的分析与比较

以南薇菜干、北薇菜干、水煮薇菜为原料,对它们的水分、灰分、粗蛋白、粗纤维、粗脂肪、胡萝卜素、Vc、K、Na、Ca、Mg、Fe、Cu、Se等营养成分进行了分析。结果表明:水煮薇菜含水量最高达到85.7%,两种薇菜干的水分含量差异不显著,但与水煮薇菜水分含量有极显著差异。南北薇菜干灰分和K含量差异显著,水煮薇菜含量最低与两种菜干均有极显著差异;水煮薇菜的粗脂肪和胡萝卜素含量最低与南薇菜干都有极显著差异,南北薇菜干间只有粗脂肪含量差异显著。三种菜样间Ca含量都有极显著差异,但Fe含量差异都不显著。粗蛋白、粗纤维、Vc、Na、Mg、Se、Cu南北薇菜干间无显著差异,水煮薇菜含量最低与两种菜干都有极显著差异。     

鹤庆县金沙江干热河谷地区几个适宜造林树种育苗技术研究

根据鹤庆金沙江流域的气候、土壤和社会经济等条件,选用苏门答腊金合欢、新银合欢、黑荆作为主要的造林树种。采用不同的处理方法分别在昆明的实验室和造林区进行发芽试验,结果表明：用始温90℃浸种24h后播种,出苗效果好,苗圃出苗率分别为49．69％、65．74％、58．64％,室内试验发芽率分别为66．5％、83．0％、87．0％。在苗木定植后半年和一年内分别进行调查,分析造林效果,认为所选树种适合在鹤庆金沙江干热河谷地区种植,值得推广。