气候变化条件下东北森林主要建群种的空间分布

全球气候模型HADCM2SUL和CGCM1分别预测100a后全球年均温增加3.7℃和5.2℃,年降水增加30.7%和25.1%。为了研究东北森林对这两种预测方案的反应,使用logistic回归模型分析了东北森林8个建群种与11种环境因子之间的相关关系。结果表明,除了山杨和蒙古栎之外,年均温是决定其它树种存在与否的重要因子。采用模型结果预测现行气候条件下8个树种的分布并与其现实分布比较,发现针叶树种的总正确率、敏感度、指定度和错误肯定率均比阔叶树种的要高,而错误否定率比后者低,说明模型对针叶树种的拟合程度要优于对阔叶树种的拟合程度。在此基础上,预测了8个树种在两种气候变化方案下100a后的分布图。结果表明,在HADCM2SUL方案下,兴安落叶松、白桦、冷杉和云杉的覆盖率分别下降91.2%、67.4%、11.9%、10%;长白落叶松、红松和蒙古栎的覆盖率分别增长87.8%5、4.6%、31.3%;在CGCM1方案下,兴安落叶松、白桦、云杉、冷杉和红松的覆盖率分别下降99.2%8、9.9%、85.9%、83.2%、4.9%;长白落叶松、蒙古栎的覆盖率分别增长93.3%、27.5%;山杨在这两种方案下数量不变。

树木根际pH环境与氧化还原状况

以3年生红松、核桃楸、水曲柳、椴树苗木为试材，运用琼脂─指示剂法对长白山地区有代表性的4种苗木的根际pH环境与氧化还原状况进行了研究，试验结果表明：红松和核桃楸根际的pH值在5.2和6.0之间，呈酸性；水曲柳和椴树根际呈碱性（pH值大于7.5）。红松根系分泌质子的部位，主要表现在根尖以上4.5～8.0cm的范围内，这是反映根系吸收养分的部位，也是根系生命活动最旺盛的区域，4种苗木根际均为氧化型（态）。

亚热带地区阔叶林与杉木林土壤活性有机质比较

通过对亚热带3个地区地带性阔叶林和杉木林土壤活性有机质的比较,分析森林类型变化及杉木连栽对土壤有机碳和养分含量的影响.结果表明:地带性阔叶林转变为杉木林后,土壤总有机碳含量下降27.8%～52.1%、腐殖酸碳下降32.2%～52.8%、胡敏酸下降36.4%～59.0%、富里酸下降29.7%～50.0%;杉木连栽也使土壤总有机碳和腐殖质含量下降.森林类型改变和杉木连栽对土壤活性有机质的影响更明显.杉木林取代阔叶林后,土壤微生物生物量碳、微生物生物量氮、可溶性有机碳和可溶性有机氮含量的最大降幅分别为61.8%、38.2%、43.3%和69.0%;与第1代杉木林相比,第2代杉木林土壤微生物生物量碳、微生物生物量氮、可溶性有机碳和可溶性有机氮含量的最大降幅分别为34.7%、29.3%、30.4%、18.4%.经相关性分析,除冷水浸提有机氮外,土壤活性有机质与养分含量之间具有密切的相关关系.

章古台沙地樟子松人工林土壤盐分动态变化研究

通过应用电导率法,对不同密度和不同年龄沙地樟子松人工林分内土壤盐分总量和各种阳离子含量进行一个生长季的观测,结果表明:各标准地不同土层土壤盐分含量都很小,且在7~9月变化幅度较小,波动范围在5%~27%之间;表层土壤盐分含量季节变化规律基本一致,最大值均出现在8月份,其它层次土壤盐分含量季节变化各标准地间差异很大。各标准地土壤剖面盐分垂直变化幅度均不大,但在整个观测季节基本表现出了随着土壤深度增加而增大的趋势,土壤中K+含量很低,变化幅度小;土壤中其它阳离子的含量及变化趋势与K+相似。因此,综合可以推断,在目前密度和年龄条件下,章古台沙地樟子松人工林土壤盐分总量及其各阳离子与林分密度和年龄几乎无关;沙地樟子松人工林衰退与土壤盐分没有直接的关系。

中国东北西部地区荒漠化发展前沿区域的遥感研究

依据 1 996年 7～ 9月和 1 988年 8～ 1 0月两个时期的LandsatTM遥感信息 ,分别对中国东北西部地区荒漠化发展前沿的典型区域吉林省乾安县的盐渍化、吉林省梨树县土地沙化变化和乌尔吉木伦河与新开河间的土地利用状况 ,进行遥感解译和实地调查。分析研究结果表明 ,东北西部这三个区域的生态环境 1 996年比 1 988年有所恶化 ,主要表征为盐渍化和沙化土地向东有较强发展和蔓延 ,撂荒地显著扩大 ,与沙化土地面积量级接近。由此东北西部应该成为我国荒漠化和生态环境治理的重点区域

Chiral Salan Aluminium Ethyl Complexes and Their Application in Lactide Polymerization

Synthetic routes to aluminium ethyl complexes supported by chiral tetradentate phenoxyamine (salan-type) ligands [Al(OC6H2(R-6-R-4)CH2)(2){CH3N(C6H10)NCH3}-C2H5] 7: R = H ; 5, 8: R = Cl; 6, 9: R = CH3) are reported. Enantiornerically pure salan ligands 1-3 with (R,R) configurations at their cyclohexane rings afforded the complexes 4, 5, and 6 as mixtures of two diastereoisomers (a and b). Each diastereoisomer a was, as determined by X-ray analysis, monomeric with a five-coordinated aluminium central core in the solid state, adopting a cis-(O,O) and cis-(Me,Me) ligand geometry. From the results of variable-temperature (VT) H-1 NMR in the temperature range of 220-335 K, H-1-H-1 NOESY at 220 K, and diffusion-ordered spectroscopy (DOSY), it is concluded that each diastereoisomer b is also monomeric with a five-coordinated aluminium central core.

Determination of reserpine in urine by capillary electrophoresis with electrochemiluminescence detection

A fast and sensitive approach to detect reserpine in urine using micellar electrokinetic capillary chromatography with electrochemiluminescence (ECL) of Ru(bpy)(3)(2+) detection is described. Using a 25 mum i.d. capillary as separation column, the ECL detector was coupled to the capillary in the absence of an electric field decoupler. Field-amplified injection was used to minimize the effect of ionic strength in the sample and to achieve high sensitivity. In this way, the sample was analyzed directly without any pretreatment. The method was validated for reserpine in the urine over the range of 1 x 10(-6) - 1 x 10(-4) mol/L with a correlation coefficient of 0.996. The RSD for reserpine at a level of 5 mumol/L was 4.3%. The LOD (S/N = 3) was estimated to be 7.0 x 10(-8) mol/L. The average recoveries for 10 mumol/L reserpine spiked in human urine were 94%.

Surface-enhanced Raman scattering of silver-gold bimetallic nanostructures with hollow interiors

Surface-enhanced Raman scattering (SERS) activity of silver-gold bimetallic nanostructures (a mean diameter of similar to 100 nm) with hollow interiors was checked using p-aminothiophenol (p-ATP) as a probe molecule at both visible light (514.5 nm) and near-infrared (1064 nm) excitation. Evident Raman peaks of p-ATP were clearly observed, indicating the enhancement Raman scattering activity of the hollow nanostructure to p-ATP. The enhancement factors (EF) at the hollow nanostructures were obtained to be as large as (0.8 +/- 0.3)x10(6) and (2.7 +/- 0.5)x10(8) for 7a and 19b (b(2)) vibration mode, respectively, which was 30-40 times larger than that at silver nanoparticles with solid interiors at 514.5 nm excitation. EF values were also obtained at 1064 nm excitation for 7a and b(2)-type vibration mode, which were estimated to be as large as (1.0 +/- 0.3)x10(6) and (0.9 +/- 0.2)x10(7), respectively. The additional EF values by a factor of similar to 10 for b(2)-type band were assumed to be due to the chemical effect. Large electromagnetic EF values were presumed to derive from a strong localized plasmas electromagnetic field existed at the hollow nanostructures.

Field-amplified sample stacking capillary electrophoresis with electrochemiluminescence applied to the determination of illicit drugs on banknotes

Capillary electrophoresis (CE) with Ru(bpy)(3)(2+) electrochemiluminescence. (ECL) detection system was established to the determination of contamination of banknotes with controlled drugs and a high efficiency on-column field-amplified sample stacking (FASS) technique was also optimized to increase the ECL intensity. The method was illustrated using heroin and cocaine, which are two typical and popular illicit drugs. Highest sample stacking was obtained when 0.01 mM acetic acid was chosen for sample dissolution with electrokinetical injection for 6 s at 17 kV. Under the optimized conditions: ECL detection at 1.2 V, separation voltage 10.0 kV, 20 mM phosphate-acetate (pH 7.2) as running buffer, 5 mM Ru(bpy)(3)(2+) with 50 mM phosphate-acetate (pH 7.2) in the detection cell, the standard curves were linear in the range of 7.50 x 10(-8) to 1.00 x 10(-5) M for heroin and 2.50 x 10(-7) to 1.00 x 10(-4) M for cocaine and detection limits of 50 nM for heroin and 60 nM for cocaine were achieved (S/N = 3), respectively. Relative standard derivations of the ECL intensity and the migration time were 3.50 and 0.51% for heroin and 4.44 and 0.12% for cocaine, respectively.The developed method was successfully applied to the determination of heroin and cocaine on illicit drug contaminated banknotes without any damage of the paper currency.

新型笼状同多钒酸盐[Ni(1,10′-phen)_3]_2·[V_2~ⅣV_8~ⅤO_(26)]的水热合成和晶体结构

尽管多金属氧酸盐 (POMs)的研究已有180多年的历史,但大量的POMs结构在最近几十年才被陆续解析出来[1～4].其中 ,同多钒酸盐由于钒配位几何形状的多样性,结构最为丰富 ,例如:[V4 O12 ]4-[5],[V5O14 ]3-[6],[V10 O2 8]6-[7] ,[V15O4 2 ]9-[8],[V13 O3 4 ]3-[9].值得注意的是,在这些化合物中,钒的化合价均处于最高氧化态+5价.由于+4价钒不易在溶液中(尤其是水中)稳定存在,因此在以往的常压溶液合成中具有混合价态的同多钒酸盐报道很少.与饱和价态的同多钒酸盐相比,混价多钒酸盐具有更为新奇的电荷分布和拓扑学几何构型,并且在 POMs的理论研究和抗病毒药物、电存储材料以及磁性材料等应用领域有特殊的研究和开发价值[1,10,11].因此,制备具有混价的新型同多钒酸盐一直倍受关注.近年来,水热合成技术的引入使同多钒酸盐合成化学迅速发展.水热体系提供了一个特殊的反应环境 [12 ],使制备各种具有混合价态的同多钒酸盐成为可能.Müller等[13]对这一领域开...

含柠檬酸配体的钼硫簇合物的合成与晶体结构的测定

合成了含有Mo—S簇阴离子 [Mo2 O2 ( μ S) 2 (C6H5O7) (C6H4 O7) ]5-柠檬酸簇合物 ,并通过元素分析、红外光谱、紫外 可见光谱和X射线光电子能谱对配合物进行了表征 ,用X射线衍射法测定了该化合物的晶体结构 .结果表明 ,该簇合物属于单斜晶系 ,空间群P2 1/c,a =2 3 766( 5)nm ,b =1 3 2 74 ( 3 )nm ,c =2 2 4 71 ( 5)nm ,α=γ =90°,β=1 1 8 2 1°,V =6 2 4 7( 2 )nm3 ,Z =8,一致性因子R =0 0 83 1 ,R2 ,w=0 1 536.该簇合物阴离子中每一个Mo原子都采取扭曲的八面体结构 ,柠檬酸通过羟基、α 羧基、一个 β 羧基与Mo配位 .晶体结构表明在一个结晶学上不对称的结构单元内有两个结晶学上独立的分子.

Analysis of mussel standard reference material by inductively coupled plasma atomic emission spectrometry and inductively coupled plasma mass spectrometry

A method for the analysis of mussel standard reference material by inductively coupled plasma atomic emission spectrometry( ICP-AES) and inductively coupled plasma mass spectrometry(ICP-MS) was developed. K, Na, Ca, Mg, P, Al, Fe, Zn, Mn and Sr were determined by ICP-AES and As, B, Cd, Co, Cr, Cu, Ga, Ge, Mn, Mo, Ni, Pb, Se, Sr, U and V by ICP-MS, The interference coefficients at the Mn-55, Se-78, Cu-63, Co-59, Ni-58, Ni-60, As-75, Se-77, V-51, Cr-53 and Cr-52 originating from polyatomic ion of the matrix elements (KO)-K-39-O-16, K-39(2), (ArNa)-Ar-40-Na-23, (CaO)-Ca-43-O-16, (CaO)-Ca-42-O-16, (CaO)-Ca-44-O-16, (PO2)-P-31-O-16, (ArCl)-Ar-40-Cl-35, (ArCl)-Ar-40-Cl-37, (ClO)-Cl-35-O-16, (ClO)-Cl-37-O-16 and (ArC)-Ar-40-C-12 were determined under the selected operation parameters. The major matrix elements, such as K, Na and Ca, result in the suppression of analytes signals. The apparent concentration at the significant biological element which was produced by the different digestion methods, (.) HNO3 + H2O2 (3 + 2), HNO3 + HClO4 (3 + 0.5) and HNO3 + H2SO4 (3 + 0.5),was determined. The sample digested by HNO3 + H2O2 did not give rise to interfere on the analyte, and the backgrounds of Se-77, Ga-69, Zn-67, As-75, V-51, Cr-53 and Cr-52 were increased by HNO3 + HClO4 digestion method, that affected the determination of these elements, especially the monoisotope As and V. Sample digested by HNO3 + H2SO4 increased the backgrounds at Cu-65, Zn-64 and Zn-67. Detection limits of ICP-AES are 0.001 similar to 0.75 mg/L and those of ICP-MS are 0.005 similar to 1.01 mu g/L. The relative standard derivations of ICP-AES and ICP-MS are 2.7% similar to 12.8%, 3.4% similar to 24.8%, respectively.

STRUCTURE OF [LA(NO3)(3)(OH2)(2)(OHME)(BIPY)].15-CROWN-5

[La(NO3)(3)(OH2)(2)(OHMe)(bipy).15-crown-5 is monoclinic, P2(1)/n, with a = 11.239(6), b = 19.302(7), c = 14.458(8) Angstrom, beta = 92.47(5)degrees, and D-calc = 1.63 g cm(-3) for Z = 4. In the complex, two nitrogen atoms (from bipy) and nine oxygen atom

悬浮液进样石墨炉原子吸收光谱测定贻贝样品中铅、镉和铜

本文采用直接进样原子吸收光谱法测定贻贝标准物质中的Pb、Cd和Cu。首先将样品配制成悬浮液,然后直接注入石墨原子化器进行分析。由于不经样品消解,分离和富集等操作,节省了大量时间,文章讨论了基体改进效应和酸度影响。当Pb、Cd和Cu含量分别为2.02,4.98和7.46μg/g时,相对标准偏差分别为8.2％、4.2％和7.5％;加入回收率处于93～115％之间。最后与酸溶样法和标准值进行了对照,得到了一致结果。

Simultaneous determination of four phases of copper in geological samples

According to the specific property of respective phases in copper ore, optimal extracting condition for, tour phases of copper with five infusion was examined. After a series of experiments, for example, different weight Of sample, artificial mixed single phases sample and repeated experiment, the extracting ratio constants foil all phases in different infusions were obtained. The mathematical model which is on the basis of the stable extracting constant is established. Based on the purpose-control genetic algorithms, we only need to determine the total copper in the sample in different infusions under the selected condition, then the value of respective phase could be calculated. The-relative standard deviation are (%) free oxidized copper phase:1.5, conjunction oxidized copper phase: 17.6,, secondary copper sulfide phase: 1.9, primary copper sulfide phase : 2.7,total copper: 0.8.