Dominant factors controlling glacial and interglacial variations in the treeline elevation in tropical Africa

IEECAS SKLLQG

微控制器MSP430F149在烤箱控制系统中的应用

介绍了美国Texas Instruments新一代16位Flash型MSP430F149系列微控制器的结构、特性和功能,阐述了基于该控制器的烤箱控制系统的硬件组成和软件架构,具有功能强、结构简单、可靠性高、抗干扰能力强、不需扩展外围器件等特点,满足了烤箱控制系统中对温度的测控要求。

彩绒革盖菌固体发酵生产木质素酶工艺优化研究

采用均匀设计U15( 5 8)和双温度培养法进行彩绒革盖菌固体发酵生产木质素酶 ,对漆酶、愈创木酚酶、多酚氧化酶的活力进行回归分析。结果表明 :应用双温度培养法进行彩绒革盖菌固体发酵生产木质素酶时 ,在自然补给氧气 ,培养基pH自然 (约 6 5 ) ,并保持环境湿度约 60 %的条件下 ,2 0d是适宜的发酵周期 ;玉米浆、麸皮、 (NH4 ) 2 SO4 、水分适宜作为固体培养基的成分 ;少量的Tween 80有利于木质素酶的生产。

长白山北坡植物群落α多样性及其随海拔梯度的变化

通过不同海拔高度的系统取样 ,研究了长白山北坡植物群落α多样性及其沿海拔梯度的变化规律 .结果表明 ,不同林层的乔木种 ,乔、灌、草各生活型类群 ,以及所有植物种的丰富度及多样性随海拔上升均表现出较明显的线性下降趋势 .乔木种从海拔 70 0m时的 19种至林线时下降为 1种 ;灌木和草本植物也分别从 2 0种和 6 1种 ,至山顶时下降为 2种和 15种 .乔木种和草本植物丰富度随海拔变化出现的几个峰值正是各植被带的分界 ,体现出过渡区物种丰富度较高的特点 .

大气CH_4中碳稳定同位素组成的PreCon-GC/C-IRMS系统测定

利用预浓缩装置-气相色谱/燃烧-同位素比值质谱仪(PreCon-GC/C-IRMS)联用系统,建立了就采样、浓缩和在线质谱分析大气CH4中稳定碳同位素组成的测定方法。通过多组试验对比,分析并讨论了利用PreCon-GC/C-IRMS联用技术测定大气CH4中碳稳定同位素比值的试验条件、系统线性、稳定性及准确度和精密度等。结果表明,在本研究方法条件下,当离子流强度在1.0~20 V时,系统线性良好(斜率S=0.04‰/V),在4.0~15 V内其线性(斜率S=0.03‰/V)优于总体线性;系统测量稳定性可靠,δ13C值的测定结果的S.D<0.3‰,最大偏差<0.5‰,回收率达99.99%,准确度和精度均符合分析与研究要求。利用该系统对室内和室外草坪地空气中CH4的碳稳定同位素组成做初步测试,其碳同位素的平均值分别为-31.358‰和-33.085‰,且相同地点区域空气中CH4的1δ3C值,在1 d内和不同日期间的变化均在0.5‰以内,重现性良好。

大兴安岭北坡火烧迹地森林郁闭度恢复及其影响因子(英文)

1987年发生在大兴安岭北坡的特大森林火灾,总过火面积达1.33×106hm2,形成了各种火烧强度区与未火烧区构成的异质镶嵌体。火烧强度、地形以及火后人类的恢复干预都不同程度地对火后森林恢复产生了影响。研究目的有二:一是为了揭示火后森林恢复状况;二是探寻火烧强度、地形以及火后更新措施等因素对火后森林恢复的影响程度。选取了位于火烧区的图强林业局中部的育英和图强两林场为研究区,选取反映森林景观质量的郁闭度指标作为研究对象,利用地理信息系统软件,将1987年火前与2000年的郁闭度等级分布图叠加,分析火后森林质量的恢复状况;利用多元线性回归法对火烧强度、海拔、坡度、坡向、坡位等地形因子以及各种更新方式对郁闭度恢复的影响程度进行了定量研究。结果显示,2000年郁闭度等级与火前相比发生了明显变化,2000年各林型郁闭度优势等级均由较高的等级4,5降为等级3;而等级1的比重也有所降低。表明,火后森林总体生长状况良好,无林地比重降低,但由于恢复时间较短,具有较高郁闭度的森林所占比重仍较低。多元线性回归显示,各因子均对火后郁闭度恢复产生了显著性影响。其中,海拔影响最大,与郁闭度等级呈正相关;其次是火烧强度,呈负相关;其它地形因子以及更新方式影响较小。

Boundary Characterization Experiment Series Overview

Ocean acoustic propagation and reverberation in continental shelf regions is often controlled by the seabed and sea surface boundaries. A series of three multi-national and multi-disciplinary experiments was conducted between 2000-2002 to identify and measure key ocean boundary characteristics. The frequency range of interest was nominally 500-5000 Hz with the main focus on the seabed, which is generally considered as the boundary of greatest importance and least understood. Two of the experiments were conducted in the Mediterranean in the Strait of Sicily and one experiment in the North Atlantic with sites on the outer New Jersey Shelf (STRATAFORM area) and on the Scotian Shelf. Measurements included seabed reflection, seabed, surface, and biologic scattering, propagation, reverberation, and ambient noise along with supporting oceanographic, geologic, and geophysical data. This paper is primarily intended to provide an overview of the experiments and the strategies that linked the various measurements together, with detailed experiment results contained in various papers in this volume and other sources

农田防护林体系结构优化配置研究

农田防护林体系结构优化配置研究范志平，姜凤歧，林鹤鸣，朱教君（中国科学院沈阳应用生态研究所沈阳１１００１５）为达到农田防护林防护效益和经济效益最大并永续利用，防护林体系必须具有在空间上布局的合理性及树种、群落和林分的多样性和稳定性特征。因此，构筑大面...

土地利用方式对土壤有机质的影响

通过对地带性常绿阔叶林、杉木人工林、农田、竹林等不同土地利用方式下土壤有机质总量、活性有机质及其组分的研究,发现土地利用方式对土壤有机质和活性有机质各组分的影响差异显著,其中阔叶林含量最高,杉木人工林低于阔叶林,竹林和农田最低。这些差别主要是由于凋落物的数量、质量以及各种管理措施不同所致

中国东北西部地区沙质荒漠化过程与植被动态关系的生态学研究:植被的分类

根据东北沙质荒漠化地区呼伦贝尔沙地、科尔沁沙地的 72个沙地植物群落样地、2 76种植物的调查数据 ,进行双向指示种分析 (TWINSPAN) ,结合DCA排序得到符合客观实际的分类结果 ,初步建立了中国东北沙质荒漠化地区植被分类系统 ,6个植被型 ,11个植被亚型 ,40个群系 ,5 5个群丛

Carbon-supported Pd–Ir catalyst as anodic catalyst in direct formic acid fuel cell

It was reported for the first time that the electrocatalytic activity of the Carbon-supported Pd-Ir (Pd-Ir/C) catalyst with the suitable atomic ratio of Pd and Ir for the oxidation of formic acid in the direct formic acid fuel cell (DFAFC) is better than that of the Carbon-supported Pd (Pd/C) catalyst, although Ir has no electrocatalytic activity for the oxidation of formic acid. The potential of the anodic peak of formic acid at the Pd-Ir/C catalyst electrode with the atomic ratio of Pd and Ir = 5:1 is 50 mV more negative than that and the peak current density is 13% higher than that at the Pd/C catalyst electrode.

Electrolytic Deposition and Diffusion of Lithium onto Magnesium-9 Wt Pct Yttrium Bulk Alloy in Low-Temperature Molten Salt of Lithium Chloride and Potassium Chloride

The electrolytic deposition and diffusion of lithium onto bulk magnesium-9 wt pct yttrium alloy cathode in molten salt of 47 wt pct lithium chloride and 53 wt pct potassium chloride at 693 K were investigated. Results show that magnesium-yttrium-lithium ternary alloys are formed on the surface of the cathodes, and a penetration depth of 642 mu m is acquired after 2 hours of electrolysis at the cathodic current density of 0.06 A center dot cm(-2). The diffusion of lithium results in a great amount of precipitates in the lithium containing layer. These precipitates are the compound of Mg41Y5, which arrange along the grain boundaries and hinder the diffusion of lithium, and solid solution of yttrium in magnesium. The grain boundaries and the twins of the magnesium-9 wt pct yttrium substrate also have negative effects on the diffusion of lithium.