1960～2005年汕头500hPa高度变化

分析汕头气象站1960-2005年500hPa高度的气候变化特征，得出存在年际和年代

ZnO单晶的缺陷及其对材料性质的影响

利用X射线衍射技术、荧光光谱、霍尔效应和光学显微等方法分别研究了ZnO单晶的品格完整性、深能级缺陷、电学性质、位错和生长极性．通过比较ZnO单晶材料在退火前后的测试结果，分析了材料的缺陷属性和缺陷对材料性质、晶体完整性的影响．

Synthesis and magnetic characterization of nickel ferrite nanoparticles prepared by co-precipitation route

Magnetic nanoparticles of nickel ferrite (NiFe2O4) have been synthesized by co-precipitation route using stable ferric and nickel salts with sodium hydroxide as the precipitating agent and oleic acid as the surfactant. X-ray diffraction (XRD) and transmission electron microscope (TEM) analyses confirmed the formation of single-phase nickel ferrite nanoparticles in the range 8-28 nm depending upon the annealing temperature of the samples during the synthesis. The size of the particles (d) was observed to be increasing linearly with annealing temperature of the sample while the coercivity with particle size goes through a maximum, peaking at similar to 11 nm and then decreases for larger particles. Typical blocking effects were observed below similar to 225 K for all the prepared samples. The superparamagnetic blocking temperature (T-B) was found to be increasing with increasing particle size that has been attributed to the increased effective anisotropy energy of the nanoparticles. The saturation moment of all the samples was found much below the bulk value of nickel ferrite that has been attributed to the disordered surface spins or dead/inert layer in these nanoparticles. (c) 2008 Elsevier B. V. All rights reserved.

Cu胁迫对大麦幼苗生长及DNA损伤效应的研究

通过石英砂培养试验,采用AFLP分子标记技术研究Cu胁迫对大麦幼苗根系基因组DNA的损伤效应,同时比较基因组DNA损伤与幼苗根系生长、可溶性蛋白含量变化对Cu污染胁迫的敏感性。结果表明,12.5￣50mg·L-1Cu处理8d后,与对照相比根长显著变短,根系内的可溶性蛋白含量显著降低;基因组DNA的AFLP图谱与对照相比发生显著变化,具体表现为谱带的消失、新谱带的出现以及谱带荧光强度的改变。三者均对低浓度的Cu污染胁迫响应敏感,其中AFLP图谱变化是对Cu胁迫响应最为敏感的生物标记物,可用于土壤Cu污染的早期诊断和生态风险评价。

长白山北坡植被垂直带群落交错区的定量判定

以海拔梯度上的群落重要值和二元数据为指标 ,采用游动分割窗技术辨析了长白山北坡各植被带群落交错区的位置和宽度 .结果表明 ,采用平方欧氏距离 (SED)和Bray Curtis距离函数 (PD)计算的游动分割窗的峰值和峰宽有较好的重合性 ,其中基于灌木和草本物种重要值的平方欧氏距离更能准确地反映交错带植被的变异 .依据游动分割窗的分析 ,判定阔叶红松林和暗针叶林的交错区为渐变类型 ,位于海拔 112 0m ,宽度为 2 0 0m ,暗针叶林和岳桦交错区为急变类型 ,位于海拔 1790m ,宽度为 5 0m ,林线为急变类型 ,位于海拔 2 0 0 0m ,宽度为 4 0m .

长白山阔叶红松林土壤氮化亚氮和甲烷的通量研究

采用静态箱 /气相色谱分析方法对长白山阔叶红松林两个处理的N2 O和CH4通量进行了研究 .结果表明 ,凋落物对土壤N2 O排放和CH4吸收的影响是显著的 ,影响程度分别是 36 9%和 2 3 4 % .两个处理的N2 O排放通量季节变化趋势相似 :夏季 (6～ 8月 )的排放通量最高 ,春季 (3～ 5月 )次之 ,秋 (9～ 11月 )冬 (12～ 1月 )两季较低 .其日变化趋势也相似 :最大值都出现在 18:0 0 ,最小值都出现在 12∶0 0和 14 :0 0 .CH4吸收通量的季节变化趋势也很相似 :夏秋两季的吸收通量明显高于春冬两季的吸收通量 .其日变化趋势也相似 :从 14∶0 0开始持续上升到 18:0 0达到最大值 ,然后持续下降到早晨 6 :0 0达到通量的最小值 .研究还发现 ,长白山阔叶红松林土壤的N2 O排放和CH4吸收间存在着一种负线性相关关系 .

Mass resolved MPI spectra of methyl iodide in the 430-490 nm region

The mass resolved multiphoton ionization (MPI) spectra of methyl iodide were obtained in the 430-490 nm region using a time-of-flight (TOF) mass spectrometer. They have the same vibrational structure, which testifies that the fragment species, in the wavelength region under study, are from the photodissociation of multiphoton ionized molecular parent ions. Some features in the spectra are identified as three-photon excitations to 6p and 7s Rydberg states of methyl iodide. Two new vibrational structures of some Rydberg states are observed. The mechanism of ionization and dissociation is also discussed. (C) 2001 Elsevier Science B.V. All rights reserved.

辽河平原土壤退化及防治与修复技术

本文研究了辽河平原土壤退化现状、退化原因,提出了相应的防治及修复技术。