不同施肥制度对潮棕壤微生物量碳的影响

利用长期定位试验研究了下辽河平原地区不同施肥处理下潮棕壤微生物量碳的变化。结果表明:不施肥处理的微生物量碳含量最低,化肥均衡施用和施用循环肥均能显著提高土壤微生物量碳含量(P<0.05),以化肥N、P、K+循环猪圈肥处理效果最好;各处理的微生物量碳均呈现出春冬季较低,夏秋季较高的趋势;化肥均衡施用配合循环肥能显著提高土壤微生物量碳的周转强度,缩短周转时间(P<0.05),以化肥N、P、K+循环猪圈肥处理土壤微生物量碳的周转时间最短,1年可周转1.03次。

生态稳定化污泥农用研究

污泥中的有机质及各项营养成分在农业生产中可起到重要的肥效作用,但未稳定的污泥在农用过程中会引起作物的不良反应,从而影响作物的产量.试验中以人工湿地积存污泥为肥料,与当地土壤按不同配比掺合,同时,以水稻草焚烧后的余灰作为补充钾源,混匀制成栽培基质进行小麦的盆栽试验.通过植株的生长状况及产量较直观地探寻此类污泥农用的稳定性.

The influence of nucleating agent on crystallization behavior and properties of polypropylene and its copolymer with ethylene

The influences of nucleating agent EDBS on crystallization behavior and properties of polypropylene UP) and its copolymer with a small amount (4. 48 %, molar fraction) of ethylene (CPP) were studied. DSC results indicated that the crystallization temperature of iPP and CPP samples with 0.5 % (mass fraction) EDBS obviously increased and the degree of crystallinity of these samples became higher. In addition, adding small amount of EDBS enhanced the crystallization of the low isotacticity and low molecular weight segments of the CPP. PLM results showed that their spherulite size decreased markedly, and as a result, the transmittance and haze of the films were all improved.

Syntheses and crystal structures of mononuclear rhodium hydrido complexes from the reactions of [Rh(H)(2)(PPh3)(2)(EtOH)(2)]ClO4 with various nitrogen ligands

Reactions of the Rh hydrido complex [Rh(H)(2)(PPh3)(2)(EtOH)(2)]ClO4 (1) With nitrogen ligands such as 2-(4-thiazolyl)benzimidazole (tbz). pyridazine (pdz), imidazole (im) and pyrimidine (pmd) in CH,Cl, afforded Various mononuclear Rh hydrido complexes, [Rh(H)(2)(PPh3)(2)(tbz)]CIO4 (2), [Rh(H)(2)(PPh3)(2)(pdZ)(2)]ClO(4)(.)2CH(2)Cl(2) (3). [Rh(H)Cl(PPh3)(2)(pdz)(2)](ClO4CH2Cl2)-C-. (4). [Rh(H)(2)(PPh3)(2)(im)(2)]ClO(4)(.)2CH(2)Cl(2) (5). [Rh(H)Cl(PPh3)(2)(im)(2)](ClO4CH2Cl2)-C-. (6). [Rh(H)(2)(PPh3)(2)(pmd)(2)](ClO4CH2Cl2)-C-. (7) and the Rh non-hydrido complex [RhCl2(pmd)(4)]ClO4 (8). The Rh complexes 2. 3, 5 and 6 were crystallographically characterized. The formation process was monitored by H-1 NMR and UV-Vis spectra. In all the Rh hydrido complexes, the Rh atom is coordinated by two PPh3. ligands in trans-positions and two nitrogen ligands in the cis-positions. The remaining sites Lire occupied by one or two hydride atoms to form a saturated 18-electron framework in a slightly distorted octahedral geometry. For complex 2 an appreciable inter-molecular pi interaction is observed between planes of tbz and PPh3 ligands, while an intra-molecular hydrogen bonding interaction between C-H and Cl atoms is found in complex 6.

成核剂对聚丙烯及其共聚物的结晶行为和性能的影响

研究了成核剂 1 ,3∶ 2 ,4-对二乙基苄叉山梨醇 (EDBS)对聚丙烯及其乙烯共聚物的结晶行为和结晶形态的影响 ,并对其薄膜进行了光学性能的表征 .结果表明 ,添加少量 (质量分数 0 .5 % )的成核剂 ,使聚丙烯样品的结晶温度大大提高 ,结晶度明显增加 .而对于乙烯共聚聚丙烯样品 ,添加少量 (质量分数 0 .5 % )成核剂 ,不仅使其整体结晶温度大大提高 ,结晶度增加 ,而且明显强化了低有序部分的结晶 .少量成核剂的加入 ,使聚丙烯及其共聚物的球晶尺寸明显缩小 ,薄膜的透光性和雾度显著改善

Monte Carlo simulation for the modification of polymer via grafting

Monte Carlo method has been applied to investigate the kinetic of grafting reaction in free radical copolymerization. The simulation is quits in agreement with that of theoretical and experimental results. It proves that the Monte Carlo simulation is an effective method for investigating the grafting reaction of free radical copolymerization. (C) 2000 Elsevier Science Ltd. All rights reserved.