辽河下游平原不同水分条件下稻田氨挥发

应用通气密闭室法,研究了辽河下游平原不同水分条件下潮棕壤稻田生态系统施用氮肥后的NH3挥发.结果表明:稻田施用氮肥后有明显NH3挥发损失,整个生长期间总挥发量为11.64~34.01 kg N.hm-2,占施氮量的4.66%~11.66%;不同施肥时期的损失量为分蘖期>孕穗期>移栽前,挥发高峰出现在施氮肥后的2~4 d内.稻田水分状况对NH3挥发损失具有重要影响,田面积水条件下NH3挥发总量和肥料氮损失率都较大,且不同施氮水平间差异显著(P<0.05),挥发量随施氮量的增加而增加;田面不积水条件下NH3挥发量相对较小.氮肥用量、田面水NH4+浓度和pH是影响NH3挥发的重要因素;氮肥用量为180 kg N.hm-2时,不同磷水平对NH3挥发的影响不显著.

水蚀条件下硝酸铵施用对黄绵土氮素流失的影响

研究结果表明不同坡度谷子地 ,高 N处理小区径流中铵态氮、硝态氮和有效氮浓度平均为 1.0 6、0 .76和1.82 mg/kg,低 N分别为 0 .6 4、1.2 9和 1.93mg/kg;高氮处理土壤铵态氮、硝态氮和有效氮平均流失量分别达到17.90、12 .93和 30 .84kg/(km2 · a) ,低 N流失量为 11.90、2 3.86和 35 .77kg/(km2 · a)。高氮处理小区泥沙中有机质和全氮浓度平均为 5 .2 1和 0 .5 36 g/kg,而低氮处理分别为 4.94和 0 .481g/kg;高氮和低氮处理土壤有机质流失量分别为 5 70 2和 5 743kg/(km2 · a) ,土壤全氮流失量为 498和 5 5 9kg/(km2 · a)

南方丘陵人工林林下植物种间关系分析

在2×2联列表的基础上,应用χ2检验和联结系数,检测南方丘陵人工林林下植物种间关系,以期分析南方丘陵人工林植被恢复程度及其稳定性.结果表明,灌草两层联结程度达到显著的种对很少;灌木层极显著的有12种对,显著的有19种对,其余200种对联结程度不显著;草本层极显著和显著各有11种对,其余83种对联结程度不显著.按组间联系及种间的正负关联性,灌木层植物可分为2个种组:Ⅰ.四川红淡比、三叶赤楠、乌饭树、满树星、长托菝葜、格药柃;Ⅱ.大叶胡枝子、白马骨、牡荆.种组Ⅰ与种组Ⅱ之间许多种群间存在显著负关联.优势种往往在种间关系中起着关键作用.草本层优势种狗脊蕨、暗鳞鳞毛蕨、扇叶铁线蕨之间存在极显著正关联,且与多种群存在极显著或显著正关联;灌木层中2个种组均以优势种为联结核心.灌草层中正负关联的比例反映了灌木层和草本层物种处在动态变化中.灌木层正负关联比例为125/106,草本层42/63.最后分析了种间联结方法的几个缺陷,并对该方法的使用提出建议.

沈阳市郊耕地土壤交换性Ca含量的空间异质性特征

利用地统计学和地理信息系统相结合的方法研究了沈阳市郊耕地土壤 (0～ 2 0cm)交换性钙含量的空间异质性特征 ,绘制了交换性钙含量的空间分布图。结果表明 ,土壤交换性钙含量经对数转换后基本符合正态分布 ,变异函数的最佳理论模型为球状模型 ,交换性钙含量具有很强的空间相关性 ,空间自相关距离为 15 8km ,其空间异质性主要受成土母质和土壤类型等结构性因子的影响

沈阳市行道树树种的选择与配置

采取典型抽样的方法对沈阳市行道树进行了全面的群落调查。结果表明 ,研究区内行道树共 13科 ,2 4属 ,2 2 91株 ,森林覆盖率为 15 13%。胸径 <0 2 5m(1级胸径 )和 0 2 5～ 0 5m(2级胸径 )的树木分别占 4 3 0 %、17 9% ;树高 <4 6m (1级 )的树木占 4 9 8% ,介于 4 6～10 7m(2级 )为 4 3 3% ;健康状况为中等以上 ,沈阳市行道树处于种群稳定时期 ,但树种多样性指数不高 ,结构单一。根据城市的自然条件和行道树的选择标准 ,提出了沈阳市行道树树种选择与配置的对策与建议。

施肥对油松刺槐混交林土壤微生物种群和酶活性的影响

通过对比试验研究了尿素、磷酸铵及复合肥处理对油松刺槐混交林土壤微生物种群和酶活性的影响。结果表明 :复合肥和尿素处理能够显著促进土壤微生物种群数量的增加 ,与对照相比 ,生长季平均增加了 4 2 1%和 18 4 %。复合肥有利于提高固氮菌和钾细菌数量 ,磷酸铵促进了磷细菌数量的增长。施肥处理增强了土壤酶活性 ,且季节变化明显。

施用泥炭对风沙土改良及蔬菜生长的影响

通过盆栽试验比较了施用不同剂量的泥炭 (0 %、2 %、5 %、8%及 10 % )对风沙土改良的效果和对白菜生长及产量的影响。结果表明 ,泥炭能增强风沙土的持水能力 ,降低土壤的pH值 ,增加土壤中有机质、全氮、速效氮和速效磷等的含量 ;白菜根系长度、生物量、高生长和地上部分的生物量均有增加 ,其中 8%泥炭处理为最佳 ,其根系长度、根鲜重、干重、高生长、地上部分鲜重、干重依次比对照增加 71%、4 0 2 %、4 6 4 %、10 7%、84 7%和 10 0 1% ;同时施用泥炭还有利于提高白菜干物质的积累及其品质

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 %。

Synthesis, structure and photochromic properties of a novel 1,6-hexanediamine trimolybdate supramolecular compound

A novel supramolecular compound 1,6-hexanediamine trimolybdate ((C6H18N2[Mo3O10], denoted as HDAMo) has been synthesized by a hydrothermal method and its structure has been characterized by elemental analyses, Fourier transform infrared (FT-IR) spectra, single-crystal X-ray diffraction (XRD) technique. This single crystal compound consists of protonated 1,6-hexanediamine (HDA) cations and polyoxometalate [Mo3O10](2-) anions. Its crystal structure belongs to monoclinic system (space group P2(1)/n) with a = 7.7508(14), b = 11.467(2), c = 16.167(3) angstrom, beta = 92.689(3)degrees, V = 143 5.3(5) angstrom(3), Z = 4 and D-ealc = 2.619 g cm(-3). The final statistics based on F-2 are GOF = 0.980, R-1 = 0.0261 and wR(2) = 0.0506 for I > 2 sigma(I). XRD analysis revealed that in the crystal structure of HDAMo, novel infinite [Mo3O10](2-) chains parallel to a axis are made up of distorted MoO6 octahedra connected by corners and edges. The protonated HDA cations occupy channels formed by [Mo(3)O3(10)](2-) Chains and exhibit strong hydrogen bond interactions to terminal and bridging oxo groups of the chains. The [Mo3O10](2-) chains linked through protonated HAD cations formed a one-dimensional network. The HDAMo compound shows novel photochromic properties, i.e., its color changes from white to reddish brown gradually under UV irradiation. XRD, FT-IR, ESR spectra and XPS are used to investigate the photochromic behavior of the compound.

Structural diversity of lanthanide-amino acid complexes under near physiological pH conditions and their recognition of single-stranded DNA

We reported here four structures of lanthanide-amino acid complexes obtained under near physiological pH conditions and their individual formula can be described as [Tb-2(DL-Cys)(4)(H2O)(8)]Cl-2 (1), [Eu-4(mu(3)-OH)(4)(L-Asp)(2)(L-HAsp)(3)(H2O)(7)] Cl center dot 11.5H(2)O (2), [Eu-8-(L-HVal) (16)(H2O)(32)]Cl-24 center dot 12.5H(2)O (3), and [Tb-2(DL-HVal)(4)(H2O)(8)]Cl-6 center dot 2H(2)O (4). These complexes showed diverse structures and have shown potential application in DNA detection. We studied the interactions of the complexes with five single-stranded DNA and found different fluorescence enhancement, binding affinity and binding stoichiometry when the complexes are bound to DNA.

Synthesis and characterization of white-light-emitting polyfluorenes containing orange phosphorescent moieties in the side chain

Two orange phosphorescent iridium complex monomers, 9-hexyl-9-(iridium (III)bis(2-(4'-fluorophenyl)-4-phenylquinoline-N, C-2')(tetradecanedionate-11,13))-2,7-dibromofluorene (Br-PIr) and 9-hexyl-9-(iridium(III)bis(2-(4'-fluorophenyl)-4-methylquinoline-N, C-2')(tetradecanedionate-11,13))-2,7-dibromofluorene (Br-MIr), were successfully synthesized. The Suzuki polycondensation of 2,7-bis(trimethylene boronate)-9,9-dioctylfluorene with 2,7-dibromo-9,9-dioetylfluorene and Br-Plr or Br-MIr afforded two series of copolymers, PIrPFs and MIrPFs, in good yields, in which the concentrations of the phosphorescent moieties were kept small (0.5-3 mol % feed ratio) to realize incomplete energy transfer. The photoluminescence (PL) of the copolymers showed blue- and orange-emission peaks. A white-light-emitting diode with a configuration of indium tin oxide/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/PIr05PF (0.5 mol % feed ratio of Br-PIr)/Ca/Al exhibited a luminous efficiency of 4.49 cd/A and a power efficiency of 2.35 lm/W at 6.0 V with Commission Internationale de L'Eclairage (CIE) coordinates of (0.46, 0.33). The CIE coordinates were improved to (0.34, 0.33) when copolymer MIr10PF (1.0 mol % feed ratio of Br-MIr) was employed as the white-emissive layer. The strong orange emission in the electroluminescence spectra in comparison with PL for these kinds of polymers was attributed to the additional contribution of charge trapping in the phosphorescent dopants.

Organic thin-film transistors in sandwich configuration

Organic thin-film transistors (OTFTs) having source/drain electrodes sandwiched between copper phthalocyanine (CuPc) and cobalt phthalocyanine (CoPc) layers, CuPc/CoPc SC OTFTs, are investigated. Comparing their properties with that of CuPc-based top-contact OTFT, field-effect mobility increases from 0.04 to 0.11 cm(2)/Vs, threshold voltage shifts from -13.8 to -8.9 V, and the current on/off ratio maintains at a level of 10(5). A top-contact OTFT with a layer of CuPc and a layer of CoPc (10%)-CuPc mixture reveals that the combination of CuPc and CoPc enhances charge injection from the source electrode into the active layer and increases the off-state current. The sandwich configuration increases the field-effect mobility, reduce the threshold voltage, and improve the on/off ratio at the same time. Our results indicate that using a double-layer of active organic materials in sandwich configuration is an effective way to improve OTFT performance.

Charge carrier mobility and electroluminescence in a green-emitting alternating block copolymer with a methoxy Bi-substituted chromophore

We determine the mobility of positive and negative charge carriers in a soluble green-emitting alternating block copolymer with, a methoxy bi-subsbituted conjugated segment. The negative charge carrier mobility of 6 x 10(-11) cm(2)/V.s is directly determined using space-charge-limited current analytical expressions. Positive charge carrier transport is also space-charge-limited, with a mobility of I x 10(-8) cm(2)/V.s. The electron trap distribution is exponential, with a characteristic energy of similar to 0.12 eV. A hole trap with energy similar to 0.4 eV was observed. This copolymer is used as emissive material in organic light-emitting diodes that present brightness of similar to 900 cd/m(2) at 12.5 V.

Hydrothermal synthesis and structure of a bi-capped Keggin polyoxoanion, [(As2AsMo8V4O40)-As-III-Mo-V-O-IV](5-)

The title compound, [NH3CH2CH2CH2NH2][NH3CH2CH2CH2NH3](2)[As-2(III) As-v Mo-8 V-4(IV) O-40] (.) 5H(2)O, was hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction. Crystal data: monoclinic, C2/c, a = 45.375(9) Angstrom, b = 11.774(2) Angstrom, c = 23.438(5) Angstrom, beta = 96.62(3)degrees. X-ray crystallographic study showed that the crystal structure was constructed by bi-capped alpha -Keggin fragments [(As2AsMo8V4O40)-As-III-Mo-v-O-IV](5-) polyoxoanion. (C) 2001 Elsevier Science B.V. All rights reserved.

Crystal structure of mixed sodium-potassium paradodecatungstate 6-hydrate

The crystal structure of K7Na3[H2W12O42]3 . 6H(2)O was determined by X-ray crystallography,and refined to R=0.0864 based on 7024 observed reflections (I>2 sigma(I)). The crystallographic parameters are a=11.755(2), b=13.0493(3), c=16.289(3) Angstrom; alpha=77.13(3)degrees, beta=82.92(3)degrees, gamma=89.65(3)degrees, triclinic, space group, P (1) over bar, V=2416.7(8) Angstrom(3), Z=2, M-r=3330.98, D-cal=4.578Mg/m(3), F(000)=2904; mu (MoK alpha)=29.170mm(-1), T=293K. Two independent polyanions are centered respectively at 1,1,1/2 and 1/2, 1/2, 0, approximately perpendicular to each other with dihedral angle between the equatorial planes of the molecules at 96 degrees. K+ and Na+ respectively occupy the clefts of the two discrete polyanions.