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991.
本文对林业企业电网实现最佳无功补偿问题进行了探讨,并提出了确定电网实现最佳无功补偿容量的计算公式及具体方法,为提高电网功率,缓解林区供电紧张的问题提供了依据。 相似文献
992.
993.
森林资源是国家最重要的自然资源,是国家富强、人民昌盛的重要物质财富。本文从森林资源资产评估的必要性和紧迫性入手,对森林资源资产评估理论、方法进行了探索,对森林资源资产评估过程中应注意的问题进行了分析,确立了符合实际的理论和方法,并应用于实践。 相似文献
994.
竹材具有明显的变异性,为了稳定产品的质量,需要统一采集和加工的方法.本文参照国标作法和国际标准(ISO)对毛竹的采集和加工方法作出统一的规定,其中包括竹材的采集地点、采集日期、采集数量、竹龄、竹材的胸径、长度、稍径、竹材的材质,以及竹材的分段方法,竹秆大小端的长径、短径、壁厚、圆度、削尖度提出具体的要求.根据统一方法加工的竹秆变异受到限制. 相似文献
995.
DemofsellecraneisthesmalleStoneofallcrans,ithasgreatdistributioninChinaandhasvarioushabitatThebredngareaismoStiylocatedineastInnerMongchaAUtonomousedOn,HeilowiirePrednceandWesternhlinPrOvince.ItwigratshereinthendddleofMarh,laysopboearyMaytothendddleofJune,andbonstondgratetothesouthinthelateoctobe.TherearelotsofreportSaboutecolOgicalndesOfbooiselecranes,butfewreportSabootthedeveoPInenofneshiop.TherehasbeenafewstUdiesaboutedngofdemoisel1ecranesinsomezoosinChina.msresearchmaterialisfrOm… 相似文献
996.
The wood powder ofTetracentron Sinense Olive was extracted with the benzene and alcohol (2:1 v/v). Then, the extractive is analyzed in Gc and Gc-Ms. Twenty chemical
constitutions of the extractive are separated and identified, which are as follows: calamenene; 2.6,10-trimethyldihexyl; 3-methoxybenzaldehyde;
Methyl-4-methox-ybenzoate; 4-methoxyphenylacetone; 3.4-dimethoxybenzaldehyde; 3.4-dimethoxyhypnone; methyl-3.4-dimethoxybenzoate; Methyl-4-methoxyphenylacrylate;
4,4′-dimethoxycabonyl-diphenylethane; Methyl-3, 4,5-erimethoxybenzoate; Methyl-3.4-dimethoxyphenylacrylate; Methyl-myristate;
Methyl-palmate; Methyl-zoomarate; Methyl-stearate; Methyl-oleate; Methyl-arachidate; Methyl-behenate; Dimethylazelate. 相似文献
997.
Xu Wei Deng Jun-tao Sun Bao-ping Zhu Guo-ping 《中国林学(英文版)》2005,7(4):49-54
The general situation of the total land resources in Wulushan, West China was studied by field investigations with the aid of a GIS software, called Region Manager. The current status of land use in Wulushan is described. The potential land productivity was evaluated by a fuzzy comprehensive method, We take each plot as a basic unit of evaluation on the basis of an index system of land resources in Wulushan which was developed from the investigation data. Evaluation of potential land productivity is the key part of land management. A guideline is presented in this paper for a proper utilization of the land resources and to develop the productive capacity of the land. 相似文献
998.
From January 1999 to May 2001, we investigated seasonal variations in the photosynthetic capacity of Taiwan spruce (Picea morrisonicola Hay.) growing in the subalpine region of subtropical Taiwan (23 degrees 29' N, 120 degrees 53' E, 2600 m a.s.l.). Photosynthetic capacity (near light-saturated net photosynthetic rate, Pnsat, chlorophyll fluorescence (Fv/Fm) and soluble protein concentration of needles all increased from mid or late spring to early winter. Even when minimum air temperature of the measuring day dropped to near 0 degrees C, Pnsat remained at about 20% of the highest value observed in winter. There was a curvilinear relationship between Fv/Fm and the minimum or mean air temperature of the measuring day. The increase in Fv/Fm with temperature was slowed when the daily mean air temperature was above 7 degrees C, or the minimum air temperature was above 3 degrees C; however, when air temperatures dropped below these values, Fv/Fm varied sharply. Seasonal variations in Pnsat paralleled those in Fv/Fm and needle soluble protein concentration. In early or mid spring when air temperature and Fv/Fm increased, Pnsat and soluble protein concentration remained low. Multiple regression analysis showed that seasonal variations in Pnsat were affected by Fv/Fm, air temperature and needle soluble protein concentration, and the multiple regression equation could be used to estimate Pnsat in different seasons. We conclude that the decrease in photosynthetic capacity of Taiwan spruce in winter and its subsequent recovery in spring were mainly caused by photoinhibition and its reversal, and changes in needle soluble protein concentration. Another possible explanation for the delayed recovery of photosynthetic capacity in spring may be associated with the slow increase in needle soluble protein concentration. 相似文献
999.
刨花板板坯表面增湿处理—缩短热压周期的有效途径 总被引:1,自引:0,他引:1
本文阐明,刨花板板坯表面增湿是缩短热压周期的有效途径及其原理,影响增湿效果的主要因素是热压板温度、增湿量、增湿层厚度比。 相似文献
1000.
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