温带森林土壤溶液溶解性N_2O和CO_2含量特征及其影响机制

利用陶瓷头土壤溶液收集器采集2006年7月～2007年8月间长白山阔叶红松天然林不同深度(15cm和60 cm)土壤溶液,探讨应用气液萃取平衡-气相色谱法测定森林土壤溶液中溶解性气体N_2O和CO_2浓度的可行性,并利用此方法研究林地不同深度土壤溶液中两种气体含量特征及其影响机理。研究结果显示观测期内林地15 cm和60 cm深度土壤溶液中溶解性CO_2浓度的变化范围分别为5.26～10.71μg·mL~(-1)(C)和3.13～6.16μg·mL~(-1)(C),溶解性N_2O浓度的变化范围分别为2.44～13.40 ng·mL~(-1)(N)和3.23～27.98 ng·mL~(-1)(N)。阔叶红松天然林土壤溶液中溶解性CO_2和N_2O浓度均呈现出明显的季节性变化。春融后的降水促进了土壤溶液中溶解性N_2O产生,尤其在60 cm深度。与60 cm深度相比,林地15 cm深度溶液中溶解性CO_2浓度的季节性变化更明显,尤其在植物生长旺季。逐步回归分析显示,水溶性有机碳含量可以解释林地不同深度溶液中溶解性CO_2浓度变化的29%;水溶性有机氮含量可以解释林地60 cm深度溶解性N_2O浓度变化的34%。因此,水溶性有机碳和有机氮分别是长白山阔叶红松林土壤溶液溶解性CO_2和N_2O形成的重要因子。同时研究结果表明本文实验方法对于测定林地不同深度土壤溶液中溶解性N_2O和CO_2含量均有较好的适用性,连续三次萃取后所获得的气体浓度可有效反映溶液中的实际气体浓度。

中国北方半干旱区机械化坐水种技术研究

机械化坐水种已成为中国半干旱区作物抗旱播种的有效措施。本文探讨了机械化坐水种的技术原理,研究了作物出苗的适宜土壤底墒,分析了2BQMS-2型坐水播种机的性能优点,提出了应用机械化坐水种技术需要解决的问题,为中国北方半干旱区发展机械化坐水种提供技术依据。

中国东北西部地区沙质荒漠化过程与植被动态关系的生态学研究:植被的排序

根据东北沙质荒漠化地区呼伦贝尔沙地、科尔沁沙地的 72个沙地植物群落样地、2 76种植物的调查数据进行DCA排序 ,排序结果充分反映了沙地植被与地理因子、气候因子、地形因子、水文因子、干扰因子的关系 .DCA排序的第 1轴反映沙地植被分布的水分梯度 ;第 2轴反映土壤梯度 ;第 4轴主要反映热量梯度 ;DCA的1、4轴排序图和 1、2、4轴排序图 ,反映沙地植被与沙质荒漠化的生态规律 .采用定性因子评价赋值与定量因子相结合的方法 ,经双重筛选逐步回归分析 ,建立了沙地植被DCA排序坐标与地理、气候、地形、水文、干扰等诸多生态因子的线性回归模型 .

Electrochemical surface plasmon resonance detection of enzymatic reaction in bilayer lipid

In this paper, electrochemical surface plasmon resonance (SPR) method was first used to detect enzymatic reaction in bilayer lipid membrane (BLM) based on immobilizing horseradish peroxidase (HRP) in the BLMs supported by the redox polyaniline (PAn) film. By SPR kinetic curve in situ monitoring the redox transformation of PAn film resulted from the reaction between HRP and PAn, the enzymatic reaction of HRP with H2O2, was successfully analyzed by electrochemical SPR spectroscopy.

Synthesis and structural characterization of a new molecule-based complex constructed from dodecamolybdophosphoric acid and imidazole

A new compound, (CH5N2)(3)(PMo12O40CH4N23H2O)-C-.-H-. (1), was synthesized and structurally characterized by elemental analyses, IR spectra, UV spectra, NMR spectra and ESR spectra. This is, to our knowledge, the first example of an imidazole-polyoxometalate species. The compound was recrystallized from N,N-dimethylformamide (DMF), and then black block-like crystals of (C3H5N2)(4)((PMoMo11O40)-Mo-V-O-VI)(.)4C(3)H(7)NO(.) 2H(2)O (2), were obtained. It crystallizes in a triclinic space group P (1) over bar with n=12.423(3) Angstrom, b=12.666(3) Angstrom, c=13.341(3) Angstrom, alpha=70.56(3)degrees, beta=71.16(3)degrees, gamma=64.18(3)degrees, V= 1742.3(6) Angstrom(3), Z=1, R1 = 0.0585, wR2 = 0.1885. An X-ray crystallographic study showed that the crystal structure is constructed by electrostatic attractions and hydrogen bonds between a dodecamolybdophosphoric anion and an imidazole. The imidazole and DMF molecules occupy cavities in a polyoxometalate lattice ordered along a c-axis. The structure of (2) is similar to that of (1) from a comparison of both IR spectra and TGA Curves.

Studies on the structure of tricyclohexyltin-2-(1,2-dithioethylene)methylene-3-oxo-5-aryl-4-pentenicate

Three title compounds were prepared and the structure of title compound 2 was characterized by IR, H-1 NMR, C-13 NMR, Sn-119 NMR spectroscopy and the crystal structure of compound 2a was determined by X-ray analysis with the final R indices[I >2 sigma (I)] R-1 = 0.0350 and R-2,R-omega = 0.0888. The crystal of compound 2a belongs to triclinic system, space group P1 with a = 1.0598(6) nm, b = 1.307 4(10) nm, c = 1.378 6(10) nm, alpha = 62.666(7)degrees, beta = 72.530(2)degrees, gamma = 80. 680(2)degrees, V = 1.618 0 nm(3), D-x = 1. 444 g (.) cm(-3), Z = 1, F (000) = 728. The bond length of Sn1-O1 is 0. 2076 nm and Sn1 . . . O2 distance is 0.301 3 nm. The coordination about the tin atom can be considered as a distorted tetrahedral. The detail values of H-1 NMR, C-13 NMR, Sn-119 NMR, (2)J(119Sn-1H) and J(119Sn-13C) were obtained. delta (119Sn) = 23.836, (2)J(119Sn-1H) = 88.0 Hz, (1)J(119Sn-13C) = 347.1 Hz, (2)J(119Sn-13C) = 45.6 Hz.

Several new phenomena in the formation of ring-banded spherulites of poly(epsilon-caprolactone) and poly(styrene-random-acrylonitrile) blends

Ring-banded spherulites in crystallization of poly(epsilon-caprolactone) and poly (styrene-random-acrylonitrile) blends were observed with polarizing optical microscopy and digital image analysis technique was applied directly to the image obtained by polarizing microscope, Several new interesting phenomena were found. One is that the ring-banded structure is still clearly seen after the analyzer was removed and this astonished phenomenon couldn't result from the general concept about formation mechanism of ring-banded spherulite - lamellae twisting, Another one is that there is a slight, dark line in the bright band when cross polars were added, which may be related to the formation process and mechanism of ring-banded spherulites in the blends of poly (epsilon-caprolactone) and poly (styrene-random-acrylonitrile).

聚己内酯和丙烯腈-苯乙烯无规共聚物的共混物生成环带球晶中的几个新现象

聚己内酯（ＰＣＬ）和丙烯腈－苯乙烯无规共聚物（ＳＡＮ）的共混物的相容性和形态曾被广泛研究［１～４］．ＰＣＬ的结晶形成球晶结构，其和ＳＡＮ共混，在熔体中结晶时不但可观察到Ｍａｌ－ｔｅｓｅ十字消光，而且存在非常明显的明暗交替的周期性环带状结构，称之为“环…

La_(0.9)Ni_2储氢合金的电化学性能

本文研究了稀土AB_2型非整比储氢合金La_(0.9)Ni_2的结构和电化学性能。结果表明,与LaNi_2储氢合金相比,La_(0.9)Ni_2合金显示了更易活化、更高的放电容量和突出的倍率性能,但荷电保持率较低。此外,合成工艺,退火处理和球磨对储氢合金的电极性能有很大影响。

稀土富勒烯提取液的解析电子轰击质谱

采用解析电子轰击质谱对电弧法合成的稀土富勒烯衍生物的提取液进行了质谱分析，有效地检测到富勒烯，稀土富勒烯单电荷、双电荷的分子离子峰。利用同位素贡献确证了某些稀土富勒烯的生成。采用高电流瞬间解析样品，使得谱图中的谱峰强度更加真实地反应出提取液中各组分的相对含量。

NMR Spectra of polyimides: Interpretation and local chain motion study

Three kinds of high-performance polyimides 1 (poly(ketone-imide) PKI), 2 (poly(ether-imide) PEI) and 3 (poly(oxy-imide) POI) were studied using nuclear magnetic resonance (NMR). The NMR spectra of the polyimides were assigned according to the comprehensive consideration of the substitution effect of different substituting groups, viz. distortionless enhancement by polarization transfer (DEPT), no nuclear Overhauser effect (NNE), analysis of relaxation time, and two-dimensional correlated spectroscopy (COSY) techniques. The structural units of these three polyimides were determined. Carbon-13 and proton relaxation times for PEI and PKI were interpreted in terms of segmental motion characterized by the sharp cutoff model of Jones and Stockmayer (JS model) and anisotropic group rotation such as phenyl group rotation and methyl group rotation. Correlation times for the main-chain motion are in the tens of picosecond range which indicates the high flexibility of polyimide chains. Correlation times for phenyl group and methyl group rotations are more than 1 order of magnitude lower and approximately 1 order of magnitude higher than that of the main chain, respectively.

新的稀土锂钒酸盐的合成、结构和发光

本文首次报道了在６００℃的烧数小时合成出新的稀土锂钒酸盐Ｙ＿（０．５－ｘ）Ｌｉ＿（１．５）ＶＯ＿４：ＲＥ＿ｘ（ＲＥ＝Ｓｍ￣（３＋），Ｅｕ￣（３＋），Ｄｙ￣（３＋），Ｈｏ￣（３＋），Ｅｒ￣（３＋），Ｔｍ￣（３＋））（０．０１＜ｘ＜０．１）多晶粉末。比通常钒酸盐的合成温度降低近４００℃。用Ｘ射线粉未法分析此多晶粉未的结构。测定了室温下稀土离子的发光特性，Ｓｍ￣（３＋），Ｅｕ￣（３＋），Ｄｙ￣（３＋），Ｔｍ￣（３＋），Ｈｏ￣（３＋），和Ｅｒ￣（３＋）均具有很强的荧光发射。Ｙ＿（０．５－ｘ）Ｌｉ＿（１．５）ＶＯ＿４：（Ｄｙ￣（３＋），Ｅｕ￣（３＋））＿ｘ具有蓝（４７４．２～４８４．２ｎｍ）、黄（５６９～５７６．４ｎｍ）、橙（５８６～５９３．６ｎｍ）和红（６０８～６２６ｎｍ）多波段荧光。