土壤类型和添加有机物料对铵态氮回收的影响

探讨NH4+-N回收率在不同因素下的变化规律。【方法】以黄土高原从北向南不同地区的典型土壤类型为对象,采用Bremner浸取法,研究了土壤类型、植被类型、施肥模式及添加有机物料对铵态氮回收率的影响。【结果】不同类型土壤及不同类型植被间NH4+-N回收率存在极显著差异(P<0.01)。黄土正常新成土的NH4+-N回收率最高(88.8%),极显著大于其他土壤,土垫旱耕人为土的NH4+-N回收率最低(81.0%),简育干润均腐土和干润砂质新成土介于二者之间;不同类型植被间,林地土壤的NH4+-N回收率(91.0%)极显著高于其他类型植被土壤,其他类型植被土壤的NH4+-N回收率表现为农田(85.5%)>裸地(83.8%)>草地(83.6%),但三者之间差异不显著。添加有机物料后,土壤NH4+-N回收率极显著增加(P<0.01),不添加有机物料对照土壤的NH4+-N回收率为84.3%,添加长毛草和苜蓿后的NH4+-N回收率分别为86.6%和85.9%。长期施肥对土壤NH4+-N的回收率无显著影响(P=0.436 5>0.05)。【结论】NH4+-N回收率与粘粒含量呈弱负相关,与有机质含量呈正相关,粘土矿物对N...

沙地樟子松天然林和人工林中针叶养分含量比较(英文)

为了诊断沙地樟子松人工林的衰退原因,我们比较分析了沙地樟子松天然林和人工林中的叶片养分含量。结果表明,天然林中的樟子松叶片内氮、磷含量均比人工林中低,而钾含量比人工林高。樟子松人工林叶片中 N:P, P: K 和N: K在45年前随年龄增加而增加,从植物养分含量的角度来看,这一结果表明氮或磷可能不是沙地樟子松生长的绝对限制因子。然而,天然林和人工林叶片中的钾含量比以前报道过的松属植物中的含量都要低。天然林叶片中的N: P比值在正常的范围内,但人工林的则在该范围以外。这些结果表明天然林具有比人工林更好的养分平衡状况。如果只从樟子松的生长地来考虑,我们可以认为樟子松人工林的衰退现象可能是因其它的矿物元素或者氮和磷的有效性,而不是氮和磷的绝对含量不足造成的。养分的不平衡状况和人工林内针叶快速分解可能也是衰退的重要因素。图3表3参42。

生殖物候与草甸草地多年生植物的消长

尽管草地管理研究较多,但从物候学进行的研究很少。目前尚未见到关于开花期和结实期如何影响科尔沁草原植物地位的报道。报道了科尔沁草甸草原34种多年生植物的始花期和果实始成熟期与其在割草和放牧利用下的消长关系。结果表明:(1)3种植物在4月1、3种在5月、10种在6月、7种在7月、1种在8月开始开花。3种在5月、14种在6月、11种在7月、5种在8月1、种在9月开始出现成熟果实。(2)与割草草地相比,始花期晚的植物在自由放牧草地中频度和多度趋于减少,果实始成熟期晚的植物也表现同样的趋势。(3)当将具有营养繁殖能力的植物排除后,与割草草地相比,始花期和果实始成熟期晚的植物在自由放牧草地中频度和多度减少的趋势更强。(4)为了使植物完成生活史,割草应在秋季大多数植物结实期结束时实施。(5)为保证大多数禾本科植物顺利完成生活史,应在大多数植物开始分蘖时开始放牧,进入花蕾期停止放牧,至结实期晚期又开始放牧。

外源硒对大豆产量、植株氮磷含量及土壤酶活性的影响

利用盆栽试验 ,研究了不同浓度、不同价态外源Se对大豆产量、N、P含量及与N、P代谢密切联系的土壤脲酶和磷酸酶活性的影响 .结果表明 ,施用浓度为 0 .2 5和 0 .5 μg·g-1土的Se4+ 和Se6+ 后 ,大豆产量、含N量及土壤脲酶活性增加 ,大豆含P量和土壤磷酸酶活性降低 .当Se6+ 浓度为 0 .5 μg·g-1土时 ,大豆植株含N量与土壤脲酶活性呈极显著的抛物线相关关系 ;Se6+ 浓度为 0 .2 5 μg·g-1土时 ,大豆植株含P量与土壤磷酸酶活性呈极显著的抛物线相关关系 .Se4+ 处理的大豆N、P含量和土壤脲酶和磷酸酶活性均无显著相关关系 .

中国杯形无隔担子菌研究1:分枝管菌属(英文)

目前我国共发现分枝管菌属的真菌4种,其中微小分枝管菌Henningsomyces minimus为中国首次报道,该种发现于广西壮族自治区的弄岗自然保护区和陇瑞自然保护区。根据中国的材料对该种进行了详细描述和显微结构绘图,给出了中国该属种类的检索表,并对其他三个种进行了概要描述。

Pyrrolide-ligated organoyttrium complexes. Synthesis, characterization, and lactide polymerization behavior

The N,N-bidentate ligand 2-{(N-2,6-diisopropylphenyl)iminomethyl)}pyrrole (L-1) and the N,N,P-tridentate ligand 2-{(N-2-diphenylphosphinophenyl)iminomethyl)}pyrrole (L-2) have been prepared. Their reactions with homoleptic yttrium tris(alkyl) compound Y(CH2SiMe3)(3)(THF)(2) have been investigated. Treatment of Y(CH2SiMe3)(3)(THF)(2) with 1 equiv of L-1 generated a THF-solvated bimetallic (pyrrolylaldiminato)yttrium mono(alkyl) complex (1) of central symmetry. In this process, L-1 is deprotonated by metal alkyl and its imino CN group is reduced to C-N by intramolecular alkylation, generating dianionic species that bridge two yttrium alkyl units in a unique eta(5)/eta(1):kappa(1) mode. The pyrrolyl ring behaves as a heterocyclopentadienyl ligand. Reaction of Y(CH2SiMe3)(3)(THF)(2) with 2 equiv of L-1 afforded the monomeric bis(pyrrolylaldiminato)yttrium mono(alkyl) complex (2), selectively. Amination of 2 with 2,6-diisopropylaniline gave the corresponding yttrium amido complex (3). In 3 the pyrrolide ligand is monoanionic and bonds to the yttrium atom in a eta(1):kappa(1) mode. The homoleptic tris(eta(1):kappa(1)-pyrrolylaldiminato)yttrium complex (4) was isolated when the molar ratio of L-1 to Y(CH2SiMe3)(3)(THF)(2) increases to 3:1. Reaction of L-2 with equimolar Y(CH2SiMe3)(3)(THF)(2) afforded an asymmetric binuclear complex (5).

七-(2,6-二-O-甲基)-β-环糊精对薄荷醇对映体手性识别的电喷雾质谱研究

利用电喷雾质谱研究了七-(2,6-二-O-甲基)-β-环糊精(DM-β-CD)作为手性识别试剂对薄荷醇对映体的手性识别效应。实验结果表明,在气相条件下,DM-β-CD可以与薄荷醇形成特异性结合复合物,化学计量比为1∶1。对复合物的串联质谱研究表明,DM-β-CD对薄荷醇对映体有较强的手性识别能力,手性识别率为Rchiral=1.81。DM-β-CD与(-)-薄荷醇形成的复合物比与(+)-薄荷醇形成的复合物稳定。

Synthesis of bis [bis (tert-butylcyclopentadienyl) neodymium chloride] and structural trend of bis[bis(tertbutylcyclopentadienyl) lanthanide chloride]

The reaction of NdCl3 with 2 equiv. of Na-(BuC5H4)-C-t in THF(tetrahydrofuran) gives blue crystals [((BUC5H4)-C-t)(2)NdCl](2), C36H52Cl2Nd2(M-r = 844.11) Which crystallizes in the triclinic system with space group . The crystal data are a=11.978 (1), b=12.671(4), c=12.706(2)Angstrom, alpha=105.47(2), beta=99.38(1)? gamma=93.15 (2)degrees, V=1825 (3) Angstrom(3), Z = 2 , D-c = 1.53g/cm(3), F(000) = 450 , T = 298K , lambda(MoK alpha) = 0.71069 Angstrom, , mu = 14.97cm(-1). Final R = 0.0390, R-w = 0.0376 for 4329 reflections with I greater than or equal to 3 sigma(I-o). The molecule has a dimer structure with two certrosymmetrical chlorine bridges. The structural trend of these analogous complexes is discussed.

Investigation of oxygen- and hydrogen peroxide-reduction on platinum particles dispersed on poly(o-phenylenediamine) film modified glassy carbon electrodes

Composite membrane modified electrodes were prepared by electrochemical deposition of platinum particles in a poly(o-phenylenediamine) (PPD) him coated on glassy carbon (GC) electrodes. The modified electrodes showed high catalytic activity towards the reduction of oxygen and hydrogen peroxide. A four-electron transfer process predominated the reduction process. The pH dependence and the stability of the electrodes were also studied.

The synthesis, characterization and photophysical properties of binary and ternary rare earth complexes with N-phenylanthranilic acid and l,l0-phenanthroline

Some novel binary and ternary complexes of rare earth(Gd, Eu,Tb) with N-Phenylanthranilic acid and 1,10-Phenanthroline were synthesized by homogenous precipitation and their compositions were characterized by,elemental analysis, IR spectra and UV-Vis spectra, The triplet state energies of N-Phenylanthranilic acid was determined to be 24 330 cm(-1) with the phosphorescence spectra of its gadolinium complexes and the energy match between the ligand and the central rare earth ions was studied. The photophysical properties such as luminescence properties and intramolecular energy transfer match between rare earth ions and ligands and between ligands were discussed. The result indicates that terbium complexes with N-Phenylanthranilic acid and 1,10-Phenanthroline have excellent luminescence properties.

稀土N-苯基邻氨基苯甲酸-1,10-邻菲咯啉二元、三元配合物的合成、表征及其光物理性质

合成了几种新型的稀土（钆，铕，铽）的Ｎ－苯基邻氨基苯甲酸－１，１０－邻菲咯啉的二元、三元配合物．以元素分析、红外光谱和紫外光谱进行了表征，确定了组成．同时以低温磷光光谱确定了配体的三重态能级为２４３３０ｃｍ－１，研究了配体与稀土离子的能级匹配．详细讨论了配合物的光物理性质如发光性能和配体与稀土离子之间以及有机配体之间的分子内能量传递机制，结果发现，铽的Ｎ－苯基邻氨基苯甲酸－１，１０－邻菲咯啉配合物的发光性能良好.

热致性液晶聚酯酰亚胺高分子的合成

本文以己二胺，癸二胺和对－亚苯基－双苯偏三酸酯二酐为单体通过溶液聚合反应制备了聚酯酰亚胺系列共聚物．采用ＩＲ，ＷＡＸＤ，ＤＳＣ和偏光显微镜研究了共聚物的结构和液晶性能，结果表明，聚合物具有热致液晶性，且随二胺单体摩尔组成的变化，共聚物的熔点Ｔｍｌ和玻璃化转变温度Ｔ８呈规律性变化．

PREPARATION AND CHARACTERIZATION OF A MULTICYLINDER MICROELECTRODE COUPLED WITH A CONVENTIONAL GLASSY-CARBON ELECTRODE AND ITS APPLICATION TO THE DETECTION OF DOPAMINE

A multi-cylinder microelectrode coupled with a conventional glassy carbon disc electrode (MCM/GC) was prepared and characterized using cyclic voltammetry and chronoamperometry. It was demonstrated that in the same way as one observed a steady-state current at closely spaced microelectrodes when redox recycling takes place, the same effect can be obtained with the MCM/GC device. The experimental results obtained with K3Fe(CN)6 solutions were compared with a previously developed theory. Further, it was demonstrated that with a carbon fibre MCM/GC device, the voltammetric behaviour of dopamine is greatly improved by virtue of redox recycling, hence giving high sensitivity. The steady-state collection current was linearly related to dopamine concentration in the range 1 X 10(-4) to 5 x 10(-7) Mol l-1, and the detection limit was 2 x 10(-7) mol l-1. The influence of coexisting ascorbic acid was also investigated. This device was applied successfully in the determination of dopamine hydrochloride in pharmaceutical preparations.

界面层结构对填充聚丙烯力学性能及流变行为的影响

本文采用各类偶联剂处理填充改性聚丙烯的无机填料。实验结果表明,硅烷类 KH-550偶联剂在界面层形成刚性架的有机硅烷膜复盖层结构,使填充聚丙烯屈服强度明显提高,断裂面形貌为界面结合较好的脆性断裂。TSC,NDZ-201,OLT-671和 DL-411等酯类偶联剂在界面形成线型柔性链的单分子层结构,使填充聚丙烯冲击强度、断裂仲长率提高,加工流动性能明显改善。