利用异氰酸酯树脂胶和农业剩余物制造人造板的若干问题讨论   总被引：4，自引：0，他引：4  

顾继友  高振华 《林业研究》2002,13(1):74-76

在我国森林资源缺乏的形势下,利用农业剩余物制造人造板更加必要,农业剩余物是最具潜力的替代纤维资源。本文基于作者大量的研究经历,总结和讨论了在利用异氰酸酯和农业剩余物制造人造板时,应重视的一些主要问题,包括原料准备、热压工艺、胶接技术、防止霉变等问题,以及相应的解决办法。研究认为,利用稻秸和麦秸制造人造板,最合适的胶粘剂是异氰酸酯树脂胶,同时还应选择合适的工艺、胶接办法和处理办法。表1参9。  相似文献   

Dynamic properties of three types of wood-based composites     

Yingcheng Hu  Tetsuya Nakao  Takahisa Nakai  Jiyou Gu  Fenghu Wang 《Journal of Wood Science》2005,51(1):7-12

This study used a vibration test method to show that grain angles of face veneer have substantial effects on sound velocities and dynamic Youngs moduli of three types of wood-based composites. The sound velocity at 0° grain angle of face veneer was the highest, and it decreased with increasing grain angle in the range of 0° to 90°. This tendency was similar to that for dynamic Youngs modulus. The relationship between the grain angle of face veneer and the sound velocity of three types of wood-based composites can be expressed in the form of Hankinsons equation or a second-order parabolic equation. This study also showed that the application of orthotropic elasticity theory was valid for the three types of wood-based composites. The relationship between the grain angle of the face veneer and the Youngs modulus of three types of wood-based composites can be expressed in the form of the Jenkin equation, Hankinsons equation, or a second-order parabolic equation. Rule of mixture can also be used to predict the Youngs modulus of wood-based composite from the Youngs moduli of the two elements.Part of this study was presented at the 53rd Annual Meeting of the Japan Wood Research Society, Fukuoka, Japan, March 2003 and the 15th Annual Meeting of Chugoku Shikoku Branch of the Japan Wood Research Society, Higashi-Hiroshima, Japan, September 2003  相似文献   

Simultaneous determination of six isoflavonoids in commercial Radix Astragali by HPLC-UV   总被引：5，自引：0，他引：5  

Wu T  Annie Bligh SW  Gu LH  Wang ZT  Liu HP  Cheng XM  Branford-White CJ  Hu ZB 《Fitoterapia》2005,76(2):157-165

A HPLC-UV method for the quantification of six major isoflavonoids, calycosin 7-O-beta-D-glucoside (1), formononetin 7-O-beta-D-glucoside (2), (6alphaR, 11alphaR) 3-hydroxy-9,10-dimethoxypterocarpan-3-O-beta-D-glucoside (3), 7,2'-dihydroxy-3',4'-dimethoxyisoflavan-7-O-beta-D-glucoside (4), calycosin (5) and formononetin (6), in Radix Astragali (Huangqi) was developed and validated. The method was proven to be sensitive, specific, accurate and precise, as well as effective and easy.  相似文献   

Change of trunk sap flow of Ginkgo biloba L. and its response to inhibiting transpiration treatment     

Shoujia Sun  Runze Gu  Richen Cong  Shaochen Che  Junping Gao 《Frontiers of Forestry in China》2007,2(3):316-322

For this paper, GREENSPAN sap flow system was used to monitor the dynamics of trunk sap flow of Gingkgo biloba. Results indicate that sap flow velocity is significantly different among different heights, depths, and directions of the trunk. Sap flow velocity at the upper position of the trunk is higher than that of the middle and lower position, but cumulative flux is not significantly different among the upper, middle and lower sections. Sap flow velocity at 10 mm reached the most and that at 20 mm the least. However, sap flow velocity at 5 mm and 15 mm was similar and was second among the four depths. Results also showed that sap flow velocity of the south was the highest, and that of the west was next. An Automatic Weather Station of HOBO was synchronously applied to measure these meteorological parameters, and the relationship between these parameters and the changes of trunk sap flow velocity were analyzed. We found that the change of sap flow velocity was a single-crest curve on clear days and multi-crest curve on cloudy and rainy days. In addition, it is also revealed that by stepwise regression analyses photosynthetical active radiation (PAR), temperature and wind speed are the main environmental factors affecting sap flow velocity. The efficient methods of reducing water transpiration of trees, including leaf pruning, overshadowing and antitranspirant spraying, were found by investigating the effects on inhibiting transpiration, which indicated that spraying of antitranspirants, leaf pruning and overshadowing could significantly reduce transpiration but the effects of leaf pruning and overshadowing were far better than that of antitranspirant spraying. Translated from Scientia Silvae Sinicae, 2006, 42(5): 22–28 [译自: 林业科学]  相似文献   

酵母对亚急性瘤胃酸中毒绵羊缓解效果及作用机制研究     

韩郭皓  高晓莎  段晋伟  张慧琴  郑岩  何金鑫  丁建安  霍乃蕊  裴彩霞  李红丽  古少鹏 《畜牧兽医学报》2022,53(5):1475-1485

旨在探究一株酿酒酵母和两株瘤胃源褶皱假丝酵母对亚急性瘤胃酸中毒(subacute ruminal acidosis,SARA)绵羊的缓解作用及其机制,为研制防治SARA微生态制剂提供优良菌株和理论依据。选取60只2月龄同期断奶的杜泊羊(♂)×湖羊(♀)F₁代作为试验动物。通过逐步递增饲粮精粗比成功诱导40只绵羊发生SARA,将SARA绵羊随机分为4组,每组10只,分别为：SARA组、酿酒酵母组(Saccharomyces cerevisiae,SC)、褶皱假丝酵母一组(Diutina rugosa 1,DR1)、褶皱假丝酵母二组(Diutina rugosa 2,DR2),各组均饲喂精粗比为90∶10的日粮,酵母组于每天晨饲后分别灌服100 mL酿酒酵母ACCC 21162、褶皱假丝酵母N09、褶皱假丝酵母N07。对照组(Control,CON)饲喂50∶50饲粮。分别于第1、3、7、10天测定各组瘤胃液pH,第10天测定瘤胃与血液异常代谢产物、血气指标、瘤胃菌群。结果显示：1)灌服酵母组第3天后瘤胃液pH显著高于SARA组(P<0.05),灌服酵母可使SARA得有效缓解。2)瘤胃菌群相对丰度发生变化,SC组最优菌属为乳杆菌属,CON组最优菌属为普雷沃氏菌科未确定菌属,SARA、DR1、DR2组最优菌属为瘤胃菌科未确定属;灌服酵母组中,SC组丰富度指数最高,DR2组多样性指数最高。3)灌服酵母组瘤胃液和血液乳酸、瘤胃液组胺显著低于SARA组(P<0.05)。4)SC、DR2组血液pH、全血碱剩余极显著高于SARA组(P<0.01),灌服酵母组血液二氧化碳分压、二氧化碳总量、实际碳酸氢盐显著高于SARA组(P<0.05)。5)瘤胃液pH与血液实际碳酸氢盐呈现显著正相关(P<0.05),瘤胃液乳酸与瘤胃菌群Chao 1指标呈现显著负相关(P<0.05)。结果提示,3株酵母均可提升瘤胃菌群丰富度、降低瘤胃液和血液乳酸、减轻瘤胃炎症、缓解机体酸中毒。  相似文献   

毛白杨多功能新品种选育研究          下载免费PDF全文

顾万春  归复  于志民  穆吕钦  孙翠玲  张继华 《林业科学研究》1998,11(3):299-305

观测北京、河北、河南３地点的１３年生毛白杨无性系试验林,无性系间的树高、胸径、木材密度、纤维长度等性状的差异均极显著;无性系的遗传稳定性、生长适应性、主干通直系数、树体形态系数、抗病虫指数等性状存在一定差别。材积生长量无性系×地点交互作用极显著,无性系间生长型不同（“广适型”、“高产型”、“低产型”）。无性系的材积生长量、木材密度、主干通直系数、树体系数和抗病虫害指数的重复率分别为０．５８０、０．５３６、０．３９０、０．４１１和０．５００,性状经济权重分别为０．３５、０．２５、０．１０、０．１０和０．２０,建立多功能型无性系的选择指数,其综合育种增益比对照品种≥１５％为中选优良无性系新品种。为北京、河北、河南分别选育出８个、７个和６个优良无性系,平均综合增益分别提高２３．９％、２４．９％和２１．０％;３个地点都中选的３７、３５１、９８３２和１０１２等优良无性系的平均综合育种增益提高２５．１％。所选无性系皆为雄性,显著提高了城乡绿化效应。  相似文献   

刨花板厚度方向变形研究Ⅲ.刨花板厚度方向变形模型及规律的确定     

顾继友  高振华  王逢瑚  李治国  程瑞香 《林业科学》2002,38(4):134-140

对不同密度杨木刨花板、落叶松刨花板及不同厚度杨木、落叶松在不同方向的吸水厚度膨胀率进行追踪测试 ,然后进行回归拟合 ,结果表明 ,刨花板和木材的吸水厚度膨胀率方程与理论推导结果能很好的吻合 ,方程的数学形式都为 :TS(t) =a -be-t τ。由此得到刨花板的粘弹变形方程和胶接点破坏引起的变形方程的数学形式也与上式相同 ,对于机械吸附蠕变方程通过数学级数变换 ,也可得到相同的近似式。研究还表明用刨花板的吸水厚度膨胀率方程描述刨花板的尺寸稳定性 ,可得到该刨花板的最大吸水厚度膨胀率和衡量关于刨花板厚度膨胀速率的参数等信息 ,因此它更合理和实用  相似文献   

苦楝中国分布区的物候区划   总被引：15，自引：1，他引：15  

程诗明  顾万春 《林业科学》2005,41(3):186-191

苦楝 (Meliaazedarach)是我国优良的乡土树种 ,它具生长快、材质优良、驱虫、耐腐、吸附烟尘能力强等特性 ;根、皮、花、果均可入药 ,对昆虫具有很强的杀伤力 ,有“天然杀虫剂”之美誉 ,是高效、低毒的广谱生物农药的原材料之一 ;苦楝也是良好的蜜源植物 ,同时苦楝果实是榨油和  相似文献   

BL-甲醛消纳剂在竹地板上的应用研究     

李琴  何奇江  杨伟民  蔡博  顾波 《竹子研究汇刊》2004,23(4):42-45,50

针对我国竹地板销售价格连年走低、环保要求日益严格的现状,提出了将无毒、高效、低成本、生产和使用方便的BL-甲醛消纳剂应用于竹地板生产的设想.作者使用BL-甲醛消纳剂分别在竹地板上进行了小试和中试,并分析了BL-甲醛消纳剂在竹地板上的应用前景.结果表明,使用BL-甲醛消纳剂完全可以生产出高强度、低成本、环保的竹地板;BL-甲醛消纳剂和芬兰太尔化工有限公司生产的Aerolite UP4116胶配制使用时,较佳的添加量为20%～30%;BL-甲醛消纳剂在竹地板行业应用前景广阔.  相似文献   

刨花板的厚度膨胀率平行性现象     

顾继友  高振华  谭海彦  李治国 《林业科学》2002,38(5):128-134

本文利用落叶松刨花和自制的异氰酸酯胶粘剂 ,通过正交重复实验研究了刨花板制造工艺参数中的密度、热压温度、热压时间、刨花含水率、施胶量和施蜡量对“2 4h吸水厚度膨胀率”与“不可逆厚度膨胀率”差的影响 ,同时通过单因素重复实验对刨花板制造常用的胶种和刨花种类对厚度膨胀率差也进行了研究。结果表明 ,在上述热压参数中 ,只有板的密度和刨花种类是影响刨花板“厚度膨胀率平行性”规律的显著性因素 ;结合和分析部分学者的实验结果发现 ,刨花形态和刨花预处理也是影响刨花板“厚度膨胀率平行性”规律的显著因素。研究表明前者对刨花板“厚度膨胀率平行性”规律影响的实质是不同密度刨花板在 2 4h的吸湿膨胀的速率与程度差异所致 ,后者则是由于这些因素影响了木材的吸湿膨胀特性所致  相似文献