脲酶-硝化抑制剂对减缓尿素转化产物氧化及淋溶的作用

利用原状土柱模拟试验,研究了脲酶抑制剂氢醌(HQ),硝化抑制剂包被碳化钙(ECC)和双氰胺(DCD)以及它们的不同组合对尿素转化产物土壤持留、氧化以及淋溶的影响.结果表明,与其它抑制剂处理相比,HQ+DCD组合能有效抑制尿素水解产物的氧化,使其以交换态NH4+的形式在土壤中长时间持留;氧化作用的抑制不仅减少了氧化产物NO3-的累积,也降低了NO3-淋溶潜势,使其淋入下层土壤的深度仅限在5～10cm范围内,且淋溶量显著降低.

三工河流域新老绿洲发育度的比较

绿洲是干旱区最重要的景观单元之一。人工绿洲是在干旱条件下经长期人类活动改造而形成的特殊景观。随着人类对绿洲水土资源开发利用程度的不断加强,绿洲呈现出不同的发展阶段。从天然绿洲到人工绿洲,是人类适应和改造干旱区自然环境的历程。在这一人地相互作用的过程中,绿洲显示出明显的发育演化特征。从多学科综合的角度,提出绿洲发育度的概念,并从灌溉体系的建设状况、水资源的利用水平、植被与生态建设、农业发展程度、社会经济水平和绿洲景观结构等7个方面提出了绿洲发育度的评价指标体系,以天山北坡2个人工绿洲为例,从空间上定量比较2个绿洲的发育程度,其中阜康市绿洲发育度高于222团绿洲(阜北农场)。

森林生态系统粗木质残体生态功能研究(英文)

粗木质残体(CWD)是森林生态系统中重要的结构性与功能性单元。本文在对国内外CWD 研究历史进行简要回顾的基础上,对其生态功能及其分解过程进行了系统分析。指出了目前CWD 研究的热点及存在的问题,并建议加强对CWD生态服务功能的定量化研究,为其在维持生物多样性、生产力和其它生态过程方面的经营管理提供科学指导。参57。

森林生态系统健康评估Ⅱ.案例实践

结合样地调查和他人对阔叶红松林生态系统相关指标的研究资料数据,利用健康距离(HD)评估法和上文建立的阔叶红松林生态系统健康评估指标体系框架,对不同人为干扰影响的长白山阔叶红松林生态系统进行系统健康的评估实践.结果按顺序依次为20%强度择伐林021<50%强度择伐林044<白桦中成林067<白桦中幼林072<红松人工林074<人工落叶松林077.

生物有机肥对西红柿生长及品质影响效应初探

在西红柿上进行施用生物有机肥、有机无机配合施肥、三元肥的田间对比试验。结果表明,单施生物有机肥比单施无机三元肥的西红柿中硝酸盐含量低15.71%,维生素C含量高25.82%;种植后土壤中有机质含量提高11.21%。西红柿种植中施用生物有机肥可以提高西红柿品质,减轻病害,增加土壤中有机质含量,培肥地力;生物有机肥与无机三元肥配合施用与单施无机肥料间产量差异不大。

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。

资源型城市生态经济系统的能值分析

资源型城市是由于资源的开发而发展起来的特殊区域,是我国城市的重要类型之一。论述了用能量和货币评价资源型城市生态经济系统的不足;介绍了H.T.Odum的系统能值分析理论及能值分析方法的基本步骤和评价指标。最后以铜川市为例,对其生态经济系统进行分析与评价。结果表明:铜川市是资源输出型的生态经济区域,从1949年到2000年的51年间,铜川为外地输出了2541亿元的财富;经济发展的主要驱动力首先是当地的不可更新资源,其次是从外地输入的资源与产品,再次是当地的可更新资源;能值货币比值上升,能值利用强度下降,但仍然

基于遥感-过程耦合模型的1988～2004年青海三江源区净初级生产力模拟

三江源区不仅是地处青藏高原的全球气候变化的敏感区,也是我国甚至亚洲最重要河流的上游关键源区。作为提供物质基础的植被净初级生产力(Netprimaryproduction,NPP),是评价生态系统状况的重要指标。该文应用已在碳通量观测塔验证,扩展到区域水平的遥感-过程耦合模型GLOPEM-CEVSA,以空间插值的气象数据和1km分辨率的AVHRR遥感反演的FPAR数据为模型主要输入,模拟并分析了1988～2004年该区NPP时空格局及其控制机制。结果表明,该区植被平均NPP为143.17gC·m–2·a–1,呈自东南向西北逐渐降低的空间格局,其中,以森林NPP最高(267.90gC·m–2·a–1),其次为农田(222.94gC·m–2·a–1)、草地(160.90gC·m–2·a–1)和湿地(161.36gC·m–2·a–1),荒漠最低(36.13gC·m–2·a–1)。其年际变化趋势在空间上呈现出明显的差异,西部地区NPP表现为增加趋势,每10a增加7.8～28.8gC·m–2;而中、东部表现为降低趋势,每10a降低13.1～42.8gC·m–2。根据显著性检验,NPP呈增加趋势(趋势斜率b>0),显著性水平高于99%和95%的区域占研究区总面积的13.43%和20.34%,主要分布在西部地区;NPP呈降低趋势(趋势斜率b<0),显著性水平高于99%和95%的区域占研究区面积的0.75%和3.77%,主要分布在中、东部地区,尤以该区长江和黄河等沿线区分布更为集中,变化显著性也更高。三江源NPP的年际变化趋势的气候驱动力分析表明,整个区域水平上该地区植被生产力受气候变化的主导,西部地区暖湿化趋势,造成了该地区生产力较为明显的、大范围的增加趋势;但东、中部地区则主要受人类活动的影响,特别是长江、黄河等河流沿线,是人类居住活动密集的地区,造成这些地区放牧压力较大、草地退化严重,而该地区暖干化趋势加剧了这一过程。

Synthesis and properties of novel sulfonated polyimides containing binaphthyl groups as proton-exchange membranes for fuel cells

A novel sulfonated diamine monomer, 2,2'-bis(p-aminophenoxy)-1,1'-binaphthyl-6,6'-disulfonic acid (BNDADS), was synthesized. A series of sulfonated polyimide copolymers containing 30-80 mol % BNDADS as a hydrophilic component were prepared. The copolymers showed excellent solubility and good film-forming capability. Atomic force microscopy phase images clearly showed hydrophilic/hydrophobic microphase separation. The relationship between the proton conductivity and degree of sulfonation was examined. The sulfonated polyimide copolymer with 60 mol % BNDADS showed higher proton conductivity (0.0945-0.161 S/cm) at 20-80 degrees C in liquid water. The membranes exhibited methanol permeability from 9 x 10(-8) to 5 X 10(-7) cm(2)/s at 20 degrees C, which was much lower than that of Nafion (2 x 10(-6) cm(2)/s). The copolymers were thermally stable up to 300 degrees C. The sulfonated polyimide copolymers with 30-60 mol % BNDADS showed reasonable mechanical strength; for example, the maximum tensile strength at break of the sulfonated polyimide copolymer with 40 mol % BNDADS was 80.6 MPa under high moisture conditions. The optimum concentration of BNDADS was found to be 60 mol % from the viewpoint of proton conductivity, methanol permeability, and membrane stability.

A novel route to polyethylene-polystyrene blends through the fragmentation of porous polystyrene beads supported metallocene in ethylene polymerization

Polyethylene-polystyrene blends were synthesized by in situ ethylene polymerization with polystyrene porous beads supported metallocene; the influence of fragmenting support beads on the morphology and the mechanical performance of the blends was investigated.

Hydrothermal synthesis and crystal structure of a sulfur-bridged binuclear copper(II) coordination polymer generated by a spontaneous reduction

A simultaneous reduction SO42- to S2- by 2,5-pyridinedicarboxylate under hydrothermal conditions produced a new binuclear copper(II) coordination polymer [CuS(4,4'-bipy)](n) (4,4-bipy = 4,4'-bipyridine) (1). Single crystal X-ray analysis revealed that compound I consisted of sulfur-bridged binuclear copper(II) units with Cu-Cu bonding which were combined with 4,4-bipy to generate a three-dimensional network constructed from mutual interpenetration of two-dimensional (6,3) nets. Crystal data for 1:C10H8CuN2S, tetragonal 14(1)/acd, a = 14.0686(5) Angstrom, b = 14.0686(5) Angstrom, c = 38.759(2) Angstrom, Z = 32. Other characterizations by elemental analysis, IR, EPR and TGA analysis were also described in this paper.

Zn_4B_6O_(13)∶Ce~(3+),Tb~(3+)的合成与发光

高温固相扩散方法首次合成了Zn4 B6 O1 3:Ce3+ ,Tb3+ 光致发光材料。通过XRD分析获得晶胞参数 :a =0 7472nm ,V =0 .4172nm3,为立方晶系。研究Ce3+ 和Ce3+ ,Tb3+ 在Zn4 B6 O1 3中的激发和发射光谱 ,发现Ce3+ 在Zn4 B6 O1 3中的激发和发射带比Ce3+ 在其他基质中红移2 3 8～ 4.94KK ,Ce3+ 的发射带与Tb3+ 的 7F6 → 5G2 ,5D1 ,5H7吸收带有很好的重叠 ,使Ce3+ 对Tb3+ 有良好的敏化作用。Ce3+ ,Tb3+ 在基质中的能量传递机理为 :Ce3+ →Ce3+ 和Ce3+ →Tb3+ 之间的偶极子—偶极子的电多级相互作用的共振传递机理。色坐标为 :x =0 2 81,y =0 .619。SEM摄取产物的晶貌 ,颗粒均匀 ,平均粒度为 0 .2 3 μm ,接近纳米级。

Preparation and luminescence properties of ormosil material doped with Eu(TTA)(3)phen complex

The europium complex, Eu(TTA)(3)phen (TTA = thenoyltrifluoroacetone, phen = 1,10-phenanthroline) was successfully doped into organically modified silicate (ormosil) matrix-SiO2/(VTMOS+PMMA) (VTMOS = vinyltrimethoxysilane, PMMA = polymethylmethacrylate) via sol-gel process, and the luminescence properties of the resultant ormosil composite phosphors [ormosil: Eu(TTA)(3)phen were investigated compared with those of the pure Eu(TTA)(3)phen complex powder. The ormosil composite materials incorporated with Eu(TTA)(3)phen show the characteristic red emission of Eu3+ ion. The Eu3+ possesses fewer emission lines and longer lifetime in the hybrid phosphor than in the pure Eu(TTA)(3)phen complex. This has been explained from the viewpoint of the surrounding environment where the Eu3+ ion lies. (C) 2000 Elsevier Science B.V. All rights reserved.

Anodic voltammetric behavior of inosine on a glassy carbon electrode

The anodic voltammetric behavior of inosine (I) was investigated by linar-sweep voltammetry, differential-pulse voltammetry and cyclic voltammetry at a glassy carbon electrode. In a medium of 0.1 mol/L N2HPO4, inosine showed a well defined anodic peak. The peak potential was about 1.42 V (vs. Ag/AgCl). A linear relationship held between the peak current and the concentration of inosine in the rang of 5 x 10(-4) similar to 8 x 10(-2) g/L. The peak potential decreased with the decrease of the acidity of the solution. The four anodic peaks of inosine with hypoxanthine, xanthine and uric acid were obtained. Their peak potentials were about at 1.42, 1.07, 0.72 and 0.26 Vt vs. Ag/AgCl). The method has been used for the direct determination of inosine in injections. Recoveries of inosine in urine samples were about 85%. Experimental result proved that the electrode reaction was diffusion-controlled and irreversible.