林火因子对大兴安岭森林植被演替的影响

森林火灾因火烧强度、频率及大小等方面的不同,形成了许多不同的火烧迹地,对火后演替有重要的影响 不同火烧程度的迹地上残存的活植被繁殖体的多度及其空间分布等方面有很大的不同,且直接影响火后植被的初始演替格局及动态 相对于中轻度火烧迹地而言,重度火烧迹地由于残留的活植被繁殖体很少等因素,极大地增加了演替的不确定性 火烧频率随着林分位置、类型、林龄以及林分的疏密度等方面的不同而有很大的差异,火烧频率的增加会阻碍植被向森林演替,甚至导致森林向灌木草本演替 一般面积大的火烧迹地相对于中小火烧迹地而言,火后森林物种的丰富度低,灌木草本的盖度低,外来物种多 火烧程度、频度和大小等林火因子往往相互作用共同影响火后植被,增加了演替的复杂性及其不可预测性

螺旋藻的开发及应用前景

综述了螺旋藻的营养价值、保健功效、生产及应用,并展望了开发前景。

蚯蚓对土壤中杀虫剂的回避行为——一种用于土壤健康质量快速诊断的装置和方法

通过设计一套试验装置,研究了蚯蚓对土壤中杀虫剂的回避行为。结果显示,蚯蚓对某些杀虫剂非常敏感,土壤中杀虫剂含量达到其半致死浓度(LC50)的1/5～1/25时,即出现明显的逃逸或迁移行为。

沈阳市建成区树种结构分析

通过对沈阳市建成区城市树木的调查分析发现 ,沈阳市的各土地利用类型中的树木种类和数量分布不均匀 ,其中 ,被调查的256块样地中每公顷树种≤5种的样地有113块 ,占总调查样地的44.14% ;每公顷≤10株的样地共43块 ,占总样地的16.80%。利用树种多度重要性排序及累积贡献率获得了不同土地类型中的主要树种 ,多个生物多样性指数表明 ,公园性质绿地的树种多样性最高 ,企事业单位用地与居住区用地次之 ,街道类用地较低 ,而商业金融用地最低。在此基础上对沈阳市的树种发展提出建议

施肥对黑土土壤微生物生物量碳的作用研究

长期施肥对黑土耕地表层土壤微生物生物量碳 (MBC)的作用研究结果表明 ,NPK化肥配施可保持休闲地土壤微生物生物量碳含量至 1.6g/kg水平 ;高量有机肥与无机肥配施可比休闲地土壤微生物生物量碳含量提高 1.96～ 2 .75倍 ;长期耕种与施肥对土壤微生物生物量碳含量产生衰减影响 ;各处理土壤微生物生物量碳含量增加依次为M2 +NPK(+14 1.2 5 % ,1990年始处理 ) >M4+NPK(+12 6 .88% ) >M2 +NPK(+10 1.2 5 % ,1980年始处理 ) >M4+CK(+80 .6 3% ) >(M1+NPK)× 1.5 (+13.13% ) >NPK(+8.12 % ) ,各处理土壤微生物生物量碳含量减少依次为M0+NPK(- 3.75 % ) >M1+NPK(- 17.5 0 % ) >M2 +CK(- 30 .6 3% ) >CK(- 4 7.5 0 % ) >M0 +CK(- 6 1.88% )。

四川栲树心材腐朽病研究

根据野外调查,四川青城山和峨嵋山地区栲树心材腐朽病的病原菌为淡黄木层孔菌(Phellinusgilvus(Schwein:Fr.)Pat.),造成心材白色腐朽,最终导致受害树木枯死或风折。本文对此病害的症状进行了报道,并对采集的病原菌标本材料作了详细描述,对该菌的种内分化进行了探讨。

外来杂草入侵的化学机制

由外来杂草入侵引发的严重生态和经济问题已倍受关注 .外来杂草在新生境成功入侵 ,除了具备一些基本的生物生态学特征外 ,还应具备一些特有的入侵机制 .阐明外来杂草的各种入侵机制可以为入侵杂草的预测和控制提供科学依据 .外来杂草只有在新生境中与原产地生物种间的相互作用中取得优势 ,才能定植并扩增种群而成功入侵 .在这些外来杂草和原产地生物种间的相互作用关系中 ,化学关系是不可忽视的方面 .目前研究已经证实 :植物的化感作用在外来杂草成功入侵中发挥着重要的作用 .事实上 ,植物也可以通过合成和释放特定的化学物质防御或抑制新生境的动物、植物和微生物 .外来杂草入侵的化学机制涉及到植物化学生态学的各个方面 .因此 ,外来杂草的化学生态学特征应作为入侵种预测的重要指标之一 ,外来杂草入侵的化学机制应是今后重要的研究方向

下辽河平原不同土地利用方式下土壤微节肢动物群落结构研究

20 0 0年 10月～ 2 0 0 1年 10月对下辽河平原地区撂荒、林地、旱田、水田 4种不同土地利用方式的土壤微节肢动物进行了调查 .应用个体数密度、类群丰富度、多样性指数和均匀度 4个群落参数 ,研究了土壤微节肢动物的群落结构和季节变化 .结果表明 ,撂荒中土壤微节肢动物的 4个群落参数均为最高 ,旱田均为最低 ,季节变化影响土壤微节肢动物的群落结构 ,但土地利用方式不影响群落结构的季节变化型 .下辽河平原地区不同土地利用方式共鉴定出土壤微节肢动物 12个类群 ,撂荒、林地、旱田中弹尾目 (Collem bola)和蜱螨目 (Acarina)为优势类群 ,双翅目 (Diptera)、鞘翅目 (Coleoptera)和膜翅目 (Hymenoptera)为常见类群 ,水田中弹尾目、蜱螨目和双翅目为优势类群 ,鞘翅目为常见类群 .各土地利用方式、各季节均在表层土壤出现的类群最多、密度最高 ,中层次之 ,底层最少

下辽河平原稻田非生长季碳排放观测研究

应用静态箱 /气相色谱法对下辽河平原稻田非生长季碳排放动态变化规律进行了测定。结果表明 ,非生长季 (10月至翌年 4月 )稻田CH4、CO2 和N2 O排放总体上随气温变化而发生变化。在冻融期 (3月中下旬 )CO2 和N2 O有明显的排放。非生长季节的稻田是大气CO2 和N2 O的源 ,作为大气CH4的源或汇的作用不明显。

中国西藏合叶苔属(合叶苔科)一新种——片毛合叶苔

描述了采自中国西藏的苔类植物新种片毛合叶苔ScapaniamacroparaphylliaT .Cao ,C .Gao&J.Sun。新种与腋毛合叶苔S .bolanderiAust.相近 ,区别特征为 :植物体小 ,叶腋内假鳞毛状附属物大 ,呈长片状 ;叶缘齿细胞单列 ,通常 1 - 3个细胞长 ;叶表面角质层粗糙 ,具圆密疣 ,疣大 ,直径达 6- 7μm。

Aglacins I-K, three highly methoxylated lignans from Aglaia cordata

Further chemical investigation of the stem bark of Aglaia cordata has led to the isolation and identification of three new lignans, namely, aglacins I-K (1-3), all of which contain two contiguous trimethoxylated phenyl systems. Among them, aglacins I and J (1 and 2) are new members of the aryltetralin cyclic lactol class, while aglacin K (3) is a new example of tetralrydrofuran lignan. The structures of these compounds were established on the basis of spectroscopic data interpretation.

Molecular cloning and expression analysis of Ch-penaeidin, an antimicrobial peptide from Chinese shrimp, Fenneropenaeus chinensis

A new member of antimicrobial peptide genes of the penaeidin family, Ch-penaeidin, has been cloned from the haemocytes of Chinese shrimp, Fenneropenaeus chinensis, by reverse transcription PCR (RT-PCR), 3'-rapid amplification of cDNA end (3'-RACE) and smart cDNA methods. The Ch-penaeidin cDNA was 655 bp and the open reading frame of the cDNA encoded a 71 amino acid peptide. Ch-penaeidin contained a putative NH2-terminal signal Sequence (1-19) followed by a mature peptide (20-71). The sequence identify with other penaeidins from Litopenaeus vannamei and Litopenaeus setiferus is between 48% and 71%. The signal sequence of Ch-penaeidin is almost completely identical to that of other penaeidins, while differing relatively in the N-terminal domain of the mature peptide. Ch-penaeidin was designated as a novel member of class penaeidin 3 according to phylogenetic analysis. The Mature peptide. with a predicted molecular weight of 5589.32 Da, and a pI of 9.77, has eight positively charged amino acids and no negatively charged amino acids. The expression and distribution of Ch-penaeidin in Unchallenged shrimps were studied by RT-PCR, Northern blot and in situ hybridisation. The results showed that the Ch-penaeidin transcripts were detected in haemocytes (granular haemocytes), heart, gill, intestine, and subcuticular epithelia of the shrimp. and that Ch-penaeidin was constitutively expressed mainly in haemocytes. (C) 2003 Elsevier Ltd. All rights reserved.

Size hierarchies affecting the social interactions and growth of juvenile Japanese flounder, Paralichthys olivaceus

Japanese flounder Paralichthys olivaceus (T. & S.)juveniles were size-graded and divided into three groups (small, large, and mixture of small and large flounder), and their social interactions (feeding, aggressive attacking and activity) and growth were investigated. The growth of the small flounder was markedly suppressed by the presence of the large flounder. Large flounder did not significantly suppress the overall food intake of the small flounder but exhibited high aggressive attacking on them and consequently inhibited their activity. Size dominance showed little influence on the aggressive behavior, feeding, activity and growth of the large flounder. The large flounder could not effectively defend the food in excess during the experiments ruling out disproportional food acquisition as the primary mechanism responsible for the size hierarchy effect. Aggressive interaction of the large flounder on the small flounder might be an important cause for the growth retardation of the small flounder. In culture, size grading could markedly improve the growth and survival of the early juvenile flounder. (C) 2004 Elsevier B.V. All rights reserved.

Determination for the different combined-form inorganic carbon in marine sediments

Marine sediment is the important sources and sinks of carbon. The inorganic carbon(IC) in marine sediments plays an important role in carbon cycling. In order to understand IC function in carbon cycling, sequential extraction method based on IC combined chemical strength difference were established to get five phases: NaCl phase (step I), NH3 - H2O phase (step II), NaOH phase (step III), NH2OH . HCl phase (step IV) and HCl phase(step V). The best extraction conditions were obtained by a series of experiments. Extractants were added into plastic centrifuge tubes in Step I - M, the capped tube were placed on a shaker table to keep the solids suspended for two hours. The suspended solution was separated by centrifugal, the residues were washed with water. The two supernatant were combined and the CO, was finally determined by volumetric analysis. The residues were transferred into conical flask in step IV and V, and then the extractants were added. The produced CO2 was adsorbed by saturated Ba(OH)(2) solution, and determined by volumetric analysis. This method for IC has a good precision in the analysis sediment samples.

超高压输电线路巡检机器人的视觉监控系统研究

超高压输电线路智能巡检机器人是输电工程技术发展的重要内容．介绍了一种应用于500 kV 超高压输电线路带电巡检智能巡检机器人系统．重点介绍了该巡检机器人系统的视觉监视与检测方法及应用技术．此类机器人系统可在输电线路上实现监控状态下的自主行走与视觉监视,跨越杆塔等作业,可在野外环境下完成连续巡检作业．这种作业方式,将大大减轻输电维护人员的劳动强度与难度,提高巡检效率与质量．对输电工程的安全可靠运行具有重要意义．