港珠澳跨海大桥收费模式研究     

娄彦江  马艳丽 《森林工程》2006,22(2):65-67

由于港珠澳跨海大桥联通三个不同体制的区域，故大桥的合理收费管理模式对大桥的建设有较大影响。本文着重研究了拟建的港珠澳跨海大桥收费模式的基本特征，包括大桥的收费制式、收费方式和收费广场设置情况，为大桥建成后能够顺利运营收费提供了科学的方法。  相似文献   

灵香草浸膏系列产品的研究   总被引：5，自引：0，他引：5  

朱凯  王庆六 《林产化学与工业》1995,15(2):67-71

以报春花科珍珠菜属植物灵香草为原料，采用不同的工艺，制取各类浸膏的研究结果。首先采用各种剂对灵香草进行浸提试验，并对得到的乙醇浸膏进行脱色浸膏、净油的研制；对得到的各类产品的物性数据进行研究测试，结果表明乙醇浸膏、脱色浸膏和净油具有许多优良特性，对它们的进一步研究开发有重大意义。  相似文献   

生态学中关键种与物种重要性的概念(英文)     

陆兆华  马玲  国庆喜 《林业研究》2001,12(4):250-252

在本文中,对关键种的概念进行了讨论,并介绍了关键种的典型特征及其在群落和生态系统中的判别。在对关键种的研究基础上,首次提出了物种重要性(SI)概念。物种重要性可以简单地理解为生态系统中物种的重要值,它由三个指数构成,即物种结构重要值(SIV)、功能重要值(FIV)和动态重要值(DIV)。本文同时评价了三大硬阔森林生态系统中乔木树种的物种重要性。  相似文献   

Fine roots refilling process in an artificial gap in a Picea mongolica forest     

Zou Chun-jing  Ma Yong-liang  Zhang Chao  Xu Wen-duo 《中国林学(英文版)》2007,9(1):19-26

Picea mongolica is an endemic but endangered species in China. The spruce forest is only found in sandy forest-steppe ecotones. In this study, we examined the initial response of the quantity and refilling process of fine roots in an artificial canopy gap with a diameter of 36 m in a P. mongolica forest. Under the canopy, the fine root length densities of trees, shrubs and herbs were 2,622, 864 and 3,086 m·m–2, respectively. The fine root biomass of trees, shrubs and herbs were 148, 62 and 65 g·m–2, respect...  相似文献   

Studies on the population frequency of insects and mites causing galls on the leaves of the sycamore maple<Emphasis Type="Italic"> Acer pseudoplatanus</Emphasis> L. in southern Poland     

Ma?gorzata?SkrzypczyńskaEmail author 《Journal of pest science》2004,77(1):49-51

Species composition of galls on the leaves of Acer pseudoplatanus L. was analysed in 2002 in three localities: the Wolski Forest, near an urban agglomeration of Kraków, the Ojców National Park and the Andrychów Forest District. A total of 12,013 galls were found. The galls were caused by six insect or mite species. The species composition of the galls was identical in the three localities. Artacris cephaloneus (Nalepa) was the most abundant species. The index of occurrence frequency and Agrells index of species co-occurrence were calculated. The index of occurrence frequency (F) value was highest in the case of A. cephaloneus (1.277) and the lowest value, i.e. 0.00005—both from the Wolski Forest. The highest value for Agrells index of species co-occurrence, i.e. 0.900, was found in the case of Eriophyes pseudoplatani Corti and Drisina glutinosa Giard (Ojców National Park), and the lowest,0.050, for D. glutinosa and Coptophylla gymnaspis (Nalepa) (Wolski Forest; Andrychów FD) and for D. glutinosa and Dasineura irregularis (Bremi) (Andrychów FD).  相似文献   

长白落叶松地理变异与种源区的划分     

彭宏梅  杨传平 《林业科技》1992,17(3):1-5

通过长白落叶松种源试验的结果,揭示了长白落叶松的地理变异规律与模式。主要特点是:呈现纬向为主,经向为辅,经纬双重正向的渐变模式。影响长白落叶松地理变异的主导气候因子是温度,其次为水份。利用长白落叶松种源生长与其环境因子线性相关显著的性状,采用主分量分析方法,将长白落叶松划分成四大种源区,即白刀山种源区(编号Ⅰ)、小北湖种源区(编号Ⅱ)大石头种源区编号(Ⅲ)、和白河种源区(编号Ⅳ)。  相似文献   

竹类植物花粉的生活力和自然授粉   总被引：8，自引：1，他引：8       下载免费PDF全文

张文燕  马乃训 《林业科学研究》1990,3(3):250-255

对12种开花竹类植物花粉的败育、生活力和自然授粉进行了观察和试验研究，花药和花粉在离体后生活力保存时间较短，尤其是离体花粉的生活力在1－2h会丧失贻尽，适宜竹花粉萌发的培养液的10％蔗糖液，若再加入5ppm硼酸能明显提高花粉发芽率。篌竹和斑苦 花分别属于花药合并粘连和无花粉的二类雄性不育型，其余10个竹种的花粉中均有三种类型的败育花粉，低温、干旱等不育环境使竹花粉发育受阻，不育花粉率增高，竹花的自然授粉不良，在盛花的竹株上接受不到花粉的竹花占33．3％，在部分开花的竹株上花粉自然授粉率公10％。  相似文献   

Evaluating effects of benzene–ethanol extraction on molecular weight of lignin isolated from pretreated bamboo substrate     

Xiaojuan Ma  Xin Zheng  Ling Lin  Lihui Chen  Shrikant Survase  Liulian Huang  Shilin Cao 《Wood Science and Technology》2015,49(5):945-955

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临夏州云杉苗圃病虫害及天敌调查研究   总被引：2，自引：0，他引：2  

马艳芳  张山林  常承秀  张永强  马慧  朱惠英 《甘肃林业科技》2015,40(1):50-53

对临夏州云杉苗圃病虫害种类、分布、危害及天敌情况进行了全面调查,初步查清了临夏州云杉苗圃主要发生的病虫害种类和天敌种类,在此基础上提出了当前云杉产业中病虫害防治的主要对象。  相似文献   

Pharmacokinetics of cefquinome in tilapia (Oreochromis niloticus) after a single intramuscular or intraperitoneal administration          下载免费PDF全文

Q. Shan  X. Zhu  S. Liu  Y. Bai  L. Ma  Y. Yin  G. Zheng 《Journal of veterinary pharmacology and therapeutics》2015,38(6):601-605

The pharmacokinetics of cefquinome was studied in plasma after a single dose (10 mg/kg) of intramuscular (i.m.) or intraperitoneal (i.p.) administration to tilapia (Oreochromis niloticus) in freshwater at 30 °C. Ten fish per sampling point were examined after treatment. The data were fitted to two‐compartment open models following both routes of administration. The estimates of total body clearance (CL/F), volume of distribution (Vd/F), and absorption half‐life (T_1/2ka) were 0.049 and 0.037 L/h/kg, 0.41 and 0.33 L/kg, and 0.028 and 0.035 h following i.m. and i.p. administration, respectively. After i.m. injection, the elimination half‐life (T_1?2β) was calculated to be 5.81 h, the maximum plasma concentration (C_max) to be 49.40 μg/mL, the time to peak plasma cefquinome concentration (T_max) to be 0.14 h, and the area under the plasma concentration–time curve (AUC) to be 204.6 μg h/mL. Following i.p. administration, the corresponding estimates were 6.05 h, 44.39 μg/mL, 0.17 h and 267.8 μg h/mL. The minimum inhibitory concentrations of cefquinome, determined for 30 strains of Streptococcus agalactiae isolated from diseased tilapia, ranged from 0.015 to 0.12 μg/mL. Results from these studies support that 10 mg cefquinome/kg body weight daily could be expected to control tilapia bacterial pathogens inhibited in vitro by a minimal inhibitory concentration value of ≤2 μg/mL.  相似文献