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71.
72.
酸催化下苯酚液化木材的制备与表征 总被引:19,自引:3,他引:19
在硫酸作用下用苯酚对人工林杨木和杉木进行液化,考察反应时间、反应温度等对液化反应的影响,并对液化产物进行表征分析.结果表明:1)在硫酸催化下,杨木和杉木被苯酚液化的历程相似,但残渣含量稍有不同.酸性催化剂不仅对纤维素和半纤维素起作用,对木质素也起作用.2)反应温度比反应时间对液化效率的影响大,二者均能影响液化产物的分子量和分子量分布.通常杉木液化产物的重均分子量高于杨木.3)液化过程中,木质素和半纤维素首先被液化,最后是纤维素.木材组分的分解、酚化和再缩聚反应主宰整个液化动力学过程及液化产物的结构特征. 相似文献
73.
Jie Liu Rumi Fujita Michiko Sato Kuniyoshi Shimizu Fumiko Konishi Kiyoshi Noda Shoichiro Kumamoto Chie Ueda Hisatoshi Tajiri Shuhei Kaneko Yoshitaro Suimi Ryuichiro Kondo 《Journal of Wood Science》2005,51(2):189-192
The inhibitory effects of 102 methanol extracts of 40 mycelia, 9 culture fluids, and 53 fruiting bodies of 40 strains of Ganoderma lucidum on 5-reductase were investigated. The methanol extract of the fruiting body of each strain was found to show the strongest 5-reductase inhibitory activity among the extracts tested. 相似文献
74.
在气候干燥、寒冷的西北地区 ,引进具有耐干旱、贫瘠 ,抗寒冷 ,抗盐碱等多种优良特性的常绿或准常绿饲料灌木四翅滨藜 ,经过 2a生长全过程的栽培试验 ,观测结果表明 :在不同土壤类型下 ,新梢生长量、扦插育苗的成活率、保存率都表现出差异性。但移栽苗的成活率、保存率差异不大 ,表现出较强的适应性。而在中、强盐碱性土壤、(粗 )砂土中仍能正常生长 ,但新梢生长量低 ,分枝减少 相似文献
75.
The resin content in larch wood is usually determined by the traditionalBenzene-Alcohol Extract Method(BAEM).In order to meet the requirement of production prac-tice,the authors present two simple quick determination methods,IR lamp method and hydrogenperoxide solution method.Compared with the results of traditional method,the results of newmethods are nearly the same as former,therefore,both two methods can reflect the change condi-tion of resin content in wood. 相似文献
76.
77.
78.
S. Hauser 《Agroforestry Systems》1993,24(2):111-121
Root observations were carried out on a typic Paleudult in the humid forest zone of south eastern Nigeria in an alley cropping trial usingDactyladenia (Acioa) barteri andSenna (Cassia) siamea as hedgerow trees and the interrow space planted to maize/cassava intercrop. Rooting depth ofD. barteri andS. siamea exceeded 1.6 m. Lateral root propagation ofS. siamea was 15 m, and ofD. barteri was 5 m from the hedgerows. The whole no-tree control plot was within the range of roots of the adjacent hedgerows. Rooting density and depth ofS. siamea in the no-tree control plot was generally higher than of cassava.S. siamea and cassava root density were inversely correlated. Assuming radial symmetry of root propagation, water and nutrients were available from an area 6.1 and 2.3 times larger than the allocated plot size ofS. siamea andD. barteri, respectively. Data obtained in alley cropping trials, not considering lateral root propagation, can be invalidated through exploitation of the no-tree control treatment and nutrient acquisition by hedgerow species from a larger area than allocated, thus underestimating and overestimating the performances of the respective treatments. Possible alternative measures for avoiding root interference are discussed but no good solution can be given. 相似文献
79.
Summary The aim of the present study was to investigate whether the resistance of beech foliage(Fagus sylvatica) against oxidative stress was affected by soil quality, nitrogen or CO2 fertilisation, or lachnid infestation(Phyllaphis fagi). For this purpose young beech trees were grown for four years in reconstructed calcareous or acidic forest soils in open
top chambers under ambient or elevated CO2 concentrations with two levels of nitrogen fertilisation. At harvest lachnid colonisation was observed, preferentially on
leaves from trees in calcareous soil and on leaves from trees fertilised with the high nitrogen level. General leaf characteristics
such as pigment concentrations, dry mass, and leaf mass ber area were not affected by the soil type, nitrogen fertilisation
or CO2 regime. Leaves colonised with lachnids displayed slightly increased leaf mass per area. When the stress resistance was challenged
by exposure to paraquat — a herbicide inducing oxidative stress — leaves from trees grown on calcareous soil maintained significantly
longer membrane integrity and, thus, were better protected against stress than leaves from trees on acidic soil. Other experimental
variables had negligible or no effects on the resistance against oxidative stress.
相似文献
80.
Idaho locust (Robinia pseudoacacia 'Idaho') is an exotic multi-purpose tree used in landscaping, soil and water conservation, fodder sources and others. To improve its drought tolerance for reclaiming arid land, five lines of transformed mtl-D gene, as osmotic regulator in plant cells, have been selected and managed to determine their drought tolerance under experimental conditions.Qualitative and quantitative variables of transformed plants were studied. The critical value of drought tolerance was determined by detecting the 2,3,5-triphenyl tetrazolium chloride (TTC) reductants in roots and soil water content (SWC). The critical value for drought tolerance was SWC 6% while for the control plants the critical SWC was 8%; a moderate level of SWC is 13% and the highest SWC for plant endurance was 18%. The method proved to be reliable and sensitive in the evaluation of drought tolerance for forest trees. 相似文献