樟子松人工固沙林稳定性的研究

提出了人工林稳定性的内涵及其评价标准．分析了影响沙地樟子松人工林稳定性的各种干扰因子，通过对沙地樟子松人工林造林成活、生长情况、对不良外界环境的抗御能力、林分寿命、林分结构和生产力的综合评价分析，认为沙地樟子松引种人工林基本上是稳定的；而生长在立地较好的丘间低地的林分，其稳定性大于沙丘顶部的林分；从抗枯梢病角度看，幼林的抗性大于中林；从林分密度和生产力角度来看．红花尔基沙地樟子松林稳定性高于章古台．

基于LandsatTM/ETM数据的锡林河流域土地覆盖变化

根据1987年、1991年、1997年和2000年4期LandsatTM/ETM影像的土地利用/土地覆盖分类结果,运用地理信息系统空间分析方法,分析了内蒙古锡林河流域1987~2000年间各土地利用类型及草甸草原、典型草原、荒漠草原的数量变化和空间变化特征。分析结果显示,锡林河流域土地利用/土地覆盖变化的主要特征为草甸草原、典型草原面积的大幅减少和荒漠草原、农田和沙漠化土地面积的大幅增加及城镇的扩张。其中面积增加最大的是荒漠草原,增加了2328km2;相当于1987年荒漠草原面积的56%。农田和城镇面积逐年增大,分别从1987年的114.3km2和25.2km2增加到2000年的332.1km2和43.6km2。面积减少最多的是羊草+丛生禾草、羊草+杂类草等优良高产温带典型草原类型,共减少2040km2。草甸草原面积亦呈逐年减少的趋势,从1987年的1103km2减少到2000年375km2,面积减少了65.9%。农田、沙化地及城镇等非草原土地利用类型面积增加了62.5%。

Effects of doping lanthanide ions in YAG : Ce system on the spectral properties of Ce3+

(Y0.95Ln(0.01)Ce(0.04))(3)Al5O12 phosphors were synthesized by high-temperature solid state reaction under reducing atmosphere and the doping effects of lanthanide ions (Ln(3+)) on the luminescence properties of phosphors were studied. YAG: Ce, Ln spectra of excitation and emission show that the influence between Ce3+ and Ln(3+) can be divided into the following three types

Microstructures and mechanical properties of as-cast Mg–5Al–0.4Mn–xNd (x=0, 1, 2 and 4) alloys

Mg-5Al-0.4Mn-xNd (x=0, 1, 2 and 4wt.%) alloys were prepared by metal mould casting method. The microstructures and mechanical properties were investigated. The results demonstrated that Al11Nd3 phase was formed and mainly aggregated along the grain boundaries with the addition of Nd. Meanwhile, the grain sizes were greatly reduced with the increasing Nd content.

One Pot, Facile Synthesis of Hierarchical Silver Nanostrip Assembling Architecture

Here we present a simple wet-chemical approach to synthesize flower-like silver nanostrip assembling architecture at room temperature. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images indicate that these microstructures with the diameter of similar to 500nm exhibit hietarchical characteristic. X-ray diffraction (XRD), energy-dispersed X-ray spectroscopy (EDX) and Raman spectroscopy indicate that poly (o-diaminobenzene) (PDB) also exists in the silver hierarchical microstructure.

马钱苷的电喷雾串联质谱及傅立叶变换离子回旋共振质谱研究

利用电喷雾串联质谱(ESI-MSn)技术研究马钱苷的质谱碎裂机理,探讨其碎裂方式,并利用傅立叶变换离子回旋共振质谱(FTICR-MS)及SORI-CID高分辨率、高质量准确度对其碎裂机理进行验证研究。采用H/D交换和串联质谱的方法,发现马钱苷羟基上的活泼氢在质谱中性碎片丢失过程中较易被转移,表现出较大的化学活性。通过加入特定的Na+和Li+等碱金属离子,极大地提高了马钱苷化合物质谱分析的灵敏度,获得了更多的结构信息,建立了马钱苷化合物质谱鉴定和分析的新方法。

Polyaniline as nonmetal catalyst for styrene synthesis by oxidative dehydrogenation of ethylbenzene

Polyaniline was used as a nonmetal catalyst in the oxidative dehydrogenation of ethylbenzene and yield of 22.9% at 573 K and similar to 40% at 673 K were obtained, respectively. An indirect oxidative dehydrogenation mechanism was proposed based on the results of pulse reactions.

Hollow DNA/PLL microcapsules with tunable degradation property as efficient dual drug delivery vehicles by alpha-chymotrypsin degradation

Hollow deoxyribonucleic acid (DNA)/poly-L-lysine (PLL) capsules were successfully fabricated through a layer-by-layer (LbL) self-assembly of DNA and PLL on porous CaCO3 microparticles, followed by removal of templates with ethylenediamine tetraacetic acid disodium salt (EDTA). The enzymatic degradation of the capsules in the presence of alpha-chymotrypsin was explored. The higher the enzyme concentration, the higher is the degradation rate of hollow capsules. in addition, glutaric dialdehyde (GA) cross-linking was found to be another way to manipulate degradation rate of hollow capsules.

Preparation and characterization of As-cast and hot-rolled Mg-3Al-0.5Mn-0.5Zn-1MM alloy

Mg-3Al-0.5Mn-0.5Zn-1MM alloy was prepared by metal mould casting method. The as-cast ingot was homogenized and then hot-rolled at 673 K with total thickness reduction of 65%. Microstructure and mechanical properties of the as-cast and hot-rolled samples were investigated. The results showed that the as-cast sample mainly consisted of alpha-Mg, beta-Mg17Al12, Al10Ce2Mn7, and Al11RE3 (RE = La and Ce) phases. The average grain size of the sample homogenized at 673 K was about 240 gm, and it was greatly refined to about 7 mu m by dynamic recrystallization for the hot-rolled sample.

Organic photovoltaic cells using hexadecafluorophthalocyaninatocopper (F16CuPc) as electron acceptor material

We fabricated organic photovoltaic cells by using hexadecafluorophthalocyaninatocopper (F16CuPc) as electron acceptor material and para-sexiphenyl (p-6P) as electron donor material. F16CuPc has wide absorption spectrum from 550 nm to 850 nm, which covers the maximum of solar photo flux. The measurement of their external quantum efficiency (EQE) demonstrated that the photocurrent comes from the excitons created in F16CuPc, which were separated into free electrons and holes at heterojunction interface of p-6P and F16CuPc. Moreover, F(16)FuPc with excellent air-stability improved the environmental stability of photovoltaic cells, and the unencapsulated cells exhibited the shelf lifetime of exceeding a week.

Synthesis, structural and electrical characterizations of Sr2Fe1-xMxNbO6 (M = Zn and Cu) with double perovskite structure

Sr2Fe1-xZnxNbO6-x/2 (0 <= x <= 0.5) and Sr2Fe1-xCuxNbO6-x/2 (0.01 <= x <= 0.05) with the double perovskite structure have been synthesized. The crystal structures at room temperature were determined from Rietveld refinements of X-ray powder diffraction data. The plots of the imaginary parts of the impedance spectrum, Z '', and the electric modulus, M '', versus log (frequency), possess maxima for both curves separated by less than a half decade in frequency with associated capacities of 2 nF. The enhancement of the overall conductivity Of Sr2Fe1-xMxNbO6-x/2 (M = Cu and Zn) is observed, as increases from 2.48 (3) x 10(-4) S/cm for Sr2FeNbO6 to 3.82 (5) x 10(-3) S/cm for Sr2Fe0.8Zn0.2NbO5.9 at 673 K. Sr2Fe0.8Zn0.2NbO5.9 is chemically stable under the oxygen partial pressure from 1 atm to 10(-22) atm at 873 K. The p and n-type electronic conductions are dominant under oxidizing and reducing conditions, respectively, suggesting a small-polaron hopping mechanism of electronic conduction.

Preparation, characterization and quantized capacitance of 3-mercapto-1,2-propanediol monolayer protected gold nanoparticles

Monolayer protected gold nanoparticles (MPCs) are the focus of recent research for their stability and are deemed as the building blocks of bottom-up strategies. In this Letter, 3-mercapto-1,2-propanediol monolayer protected gold nanoparticles (MPD-MPCs) were synthesized and characterized by transmission electron microscopy, UV/Vis spectroscopy, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The value of quantized double-layer capacitance (1.13 aF) of MPD-MPCs in aqueous media was obtained by differential pulse voltammograms.

Major, minor and trace-elemental contents analysis in northeast soybeans by ICP-AES

Major, minor and trace elemental contents in northeast China soybeans were determined by using inductively, coupled plasma atomic emission spectrometry (ICP-AES). Three different sample digestion methods including two wet digestions, HNO3-HClO4 and HNO3-H2SO4 and a dry ash method were compared. Owing to the high oil content in soybeans, long time is needed and access acid should be added, with mixed acid digestion methods, which may result in higher sample blank. Therefore, the dry ask method would be more proper for the pre-treatment of soybean samples. Potassium and phosphorus are major elements in soybeans, so the effect of potassium and phosphorus on the other elements was investigated. Results showed that the potassium and phosphorus did not affect the determination. of other trace elements. There are not significant differences in trace elemental contents for the eleven northeast China soybeans.

LaNi2和LaNi2.28储氢电极性能研究

在真空电弧炉内制备了LaNi<,2>和LaNi<,2.28>合金,在超高压下处理LaNi<,2>合金,得到了具有Laves相结构的AB<,2>型金属间化合物,采用机械合金化装置对上述铸造合金进行了球磨处理,制备了LaNi<,2.28>非晶合金粉末.利用这些合金制备储氢电极,与烧结镍阳极组成单电池,研究各种电极的充放电性能,得到如下结论:(1)LaNi<,2>和LaNi<,2.28>铸态合金电极的放电容量分别为199.4mAh/g和241.0mAh/g;(2)铸态AB<,2>合金的循环性能和放电容量高于Laves相结构的AB<,2>型合金;(3)非晶化的合金电极非常容易被活化,但循环性能和放电容量都远低于铸态合金电极.