长白山阔叶红松林热量平衡和蒸散的研究

利用长白山阔叶红松林铁塔观测数据 ,采用鲍恩比—能量平衡法 (BREB )和布辛格普适函数法 ,计算出长白山阔叶红松林的热量平衡各分量与蒸散量 ,并利用长白山气象站的数据对蒸散的气候因子进行了分析 ,确认降水量、日总辐射、风速是影响长白山阔叶红松林蒸散的主要因子。

Nafion/PTFE composite membranes for fuel cell applications

Porous polytetrafluoroethylene (PTFE) membranes were used as support material for Nafion((R))/PTFE composite membranes. The composite membranes were synthesized by impregnating porous PTFE membranes with a self-made Nafion solution. The resulting composite membranes were mechanically durable and quite thin relative to traditional perfluorosulfonated ionomer membranes (PFSI); we expect the composite membranes to be of low resistance and cost. In this study, we used three kinds of porous PTFE films to prepare Nafion/PTFE composite membranes of different thickness. Scanning electron micrographs and oxygen permeabilities showed that Nafion resin is distributed uniformly in the composite membrane and completely plug the micropores, there is a continuous thin Nation film present on the PTFE surface. The variation in water content of the composite and Nafion 115 membranes with temperature was determined. At the same temperature, water content of the composite membranes was smaller than that of the Nafion 115. In both dry and wet conditions, maximum strength and break strength of C-325(#) and C-345(#) were larger than those of Nafion 112 due to the reinforcing effect of the porous PTFE films. And the PEMFC performances and the lifetime of the composite membranes were also tested on the self-made apparatus. Results showed that the bigger the porosity of the substrate PTFE films, the better the fuel cell performance; the fuel cell performances of the thin composite membranes were superior to that of Nation 115 membrane; and after 180 h stability test at 500 mA/cm(2), the cell voltage showed no obvious drop. (C) 2002 Published by Elsevier Science B.V.

Matrix-assisted laser desorption/ionization mass spectrometry using porous silicon and silica gel as matrix

Porous silicon powder and silica gel particles have been applied as inorganic matrices for the analysis of small molecules in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOFMS). In contrast to conventional MALDI-TOFMS, the signal interference of low-molecular analytes by the matrix has been eliminated. Almost no fragmentations of the analytes were observed. Effects of various factors, such as the particle and pore size, the suspending solution, and sample preparation procedures, on the intensity of mass spectra have been investigated. The pore structure of the inorganic matrix and penetration of the analytes into the pores must be optimized for effective desorption and ionization of the analytes. Matrices (DHB and HCCA) were covalently bound to silica gel for improvement of spectrum intensity. Copyright (C) 2001 John Wiley & Sons, Ltd.

黄河三角洲丹顶鹤适宜生境变化分析

以黄河三角洲生境分布图为基础 ,运用遥感和地理信息系统得出三个时期丹顶鹤 (Grusjaponensis)生境分布图。选取一系列的景观指数 ,通过APACK软件进行计算 ,结合土地利用动态度的概念对黄河三角洲地区 1 986～ 2 0 0 1年丹顶鹤生境的动态变化进行分析。结果表明 :适宜丹顶鹤栖息的生境面积不断减小 ,该地区的生境破碎化程度也不断升高 ;相应的适应丹顶鹤栖息的各生境类型的面积除了轻干扰深积水鱼类苇田 (人类活动造成 )的面积增加外 ,其余大多呈减少趋势 ,总的来说丹顶鹤栖息生境质量呈下降趋势。黄河三角洲丹顶鹤生境的变化是以人类活动为主要驱动力的

bridge the gap between software test process and business value: a case study

Chinese Academy of Sciences (ISCAS)

辽宁典型工矿区与污灌区土壤重金属污染状况及原因

对辽宁省几个典型工矿区以及污灌区土壤重金属污染状况进行调查研究,结果表明:调查区土壤重金属含量绝大多数高于土壤背景值,尤其工矿区附近土壤Cd、Pb、Cu和污灌区的Cd、Hg的污染状况应该引起足够的重视;重金属元素间存在着一定的伴生规律;土壤中重金属污染物主要来源于工矿开发、废岩、尾矿泥、大气飘尘以及污水灌溉等。

人工湿地及其在工业废水处理中的应用

论述了人工湿地污水处理技术的机理和优点 .人工湿地利用基质、植物和微生物这个复合生态系统的物理、化学和生物的三重协调作用 ,通过过滤、吸附、共沉淀、离子交换、植物吸收和微生物分解来实现对废水的高效净化 ,同时通过营养物质和水分的生物地球化学循环 ,促进绿色植物生长并使其增产 ,实现废水的资源化与无害化 ;人工湿地污水处理系统具有出水水质稳定、对营养物质去除能力强、基建和运行费用低、技术含量低、维护管理方便、耐冲击负荷强、适于处理间歇排放的污水和具有美学价值等优点 .该技术不仅能够在发展中国家和发达国家的城市生活污水处理中广泛应用 ,其在工业废水处理中的应用也正在不断受到重视 .根据人工湿地在工业废水处理中的研究和应用现状 ,指出了人工湿地处理特殊工业废水的前景及今后的研究方向 .

施用有机肥对棕壤和草甸土固钾作用的影响研究

通过室内恒湿和干湿交替培养试验 ,研究了沈阳地区耕地棕壤和草甸土的固钾特征 ,及其施用有机肥后对土壤固钾作用的影响。结果表明 ,在保持土壤处于田间持水量的恒湿条件下 ,两种土壤对外源钾都能够产生快速固定作用 ,经过 1d培养土壤的固钾作用就可以达到平衡 ,但干湿交替培养可以提高土壤固钾量 2 6 80 %～ 33 2 7% ;土壤施用有机肥后 ,在恒湿和干湿交替培养条件下均可以降低土壤的固钾强度 ,其中 ,施用有机肥 6 %处理的恒湿培养 15d后 ,棕壤和草甸土的固钾量分别降低了 2 5 71%和 36 6 2 %。

微团聚体的保肥供肥性能及其组成比例在评断土壤肥力水平中的意义

本文根据作者对黑土和棕壤的多年研究结果，论述了不同粒级的微团聚体在保肥和供肥方面的不同性能。鉴于肥地与复地、小粒级与大位级微团聚体间存在着保肥－供肥性能的明显差异，作者试以１０μｍ为界，划分＜和＞１０μｍ两类“特征微团聚体”，以其比例来界定高、低肥力土壤的微团聚体组成的数值范围和评断土壤肥力水平与培肥效果。结果表明，“特征微团聚体”的组成比例能较好地反映土壤肥力的现有状况及其调控的实际效果，是综合评价土壤肥力的新的有用指标。

Formation of Two Kinds of Hexagonally Arranged Structures in ABC Triblock Copolymer Thin Films Induced by a Strongly Selective Solvent Vapor

An order-order transition (OOT) in the sequence of a hexagonally arranged core-shell cylinder to a double-hexagonally arranged dot in polystyrene-block-poly(butadiene)-block-poly(2-vinylpyridine) (SBV) triblock copolymer thin films is reported to be induced upon exposure to a solvent vapor that: is strongly selective for the two end blocks. These two kinds of hexagonally arranged structures could form when the film thickness is 44, 3.23, and 223 nm. When the film thickness is decreased to 13 nm, the ordered structure is absent. The sizes of the cylinder structures formed with the same annealing time in films of different thickness are compared to address the effects of film thickness on the phase structure. The mechanism is analyzed from the total surface area of the blocks and the effective interaction parameter in the solvent vapor.