林下人参生长特征及其复合经营效益的研究

本文研究了林下人参地上部以及根部的生长特征和生长规律，分析了林下育参的整体效益。结果认为在林下发展具有野生人参特性的高档次、高价值的人参是可行的。林下育参将有效地减少毁林种参的面积，对于保护森林和濒危的野生人参资源有着重要的作用。同时，林下育参对于我国人参业的发展也有着战略上的意义。

石羊河下游民勤绿洲生态安全时空变化分析

以生态安全面临着严重威胁的干旱区民勤绿洲为例,应用GIS、RS技术,从绿洲耕地风蚀潜在危险性、水资源利用与空间分布、作物安全生长格局与绿洲防护体系变化四个方面,对该绿洲近14a间生态安全状况进行了系统分析。研究结果表明:绿洲土壤风蚀潜在危险性逐年增大。地下水埋深持续下降,5～20m的地下水埋深区域面积比例由1987年的39 6%上升到2001年的62 1%。地下水矿化度在绿洲的北部表现为上升的发展趋势。作物安全生长格局变化显示春小麦与棉花的安全生长面积由1987年占绿洲总面积的63 8%和91 5%下降到2001年的56 2%和71 3%。由林地与荒草地组成的绿洲防护体系逐年被破坏。地表水资源的逐年减少是绿洲生态安全状况不断下降的主导因素,而人类不断扩大耕地面积,以及毁林、毁草开荒等行为进一步加剧了生态环境的恶化,使绿洲生态安全水平逐年减低。

WETTABILITY OF EPOXY RESIN ON CARBON FIBER

The micrographs of epoxy resin on single carbon fiber at room temperature and the temperature dependent contact angle on single carbon fiber were investigated using field environmental scanning electron microscope (FESEM). The results showed that the contact angle decreases significantly with increasing temperature. The advantage of this experimental approach was that can directly reflected the wettability of epoxy resin to fiber. But the experimental process was complicated, and there were many influence factors. The reason is that the wettability of epoxy resin on parallel sheet can be improved at higher temperatures. The spreading procedures for the epoxy resin droplet on carbon fiber cluster were observed by means of drop shape analysis system ( DSA) in parallel and perpendicular directions of the aligned fibers.

Vertical structure permeable-base hybrid transistors based on multilayered metal base for stable electrical characteristics

In this work we present a permeable base transistor consisting of a 60 nm thick N,N'diphenyl-N,N'-bis(1-naphthylphenyl)-1,1'-biphenyl-4,4'-diamine layer or a 40 nm thick 2,6-diphenyl-indenofluorene layer as the emitter, a CalAl/Ca multilayer as the metal base, and p-Si as collector. In the base, the Ca layers are 5 nm thick and the Al layer was varied between 10 and 40 nm. the best results obtained with a 20 nm thick layer. The devices present common-base current gain with both organic layer and silicon acting as emitter, but there is only observable common-emitter current gain when the organic semiconductor acts as emitter. The obtained common-emitter current gain, similar to 2, is independent on collector-emitter voltage, base current and organic emitter in a reasonable wide interval. Air exposure or annealing of the base is necessary to achieve these characteristics, indicating that an oxide layer is beneficial to proper device operation.

Crystal structures and elastic properties of superhard IrN2 and IrN3 from first principles

First principles calculations were performed to investigate the structural, elastic, and electronic properties of IrN2 for various space groups: cubic Fm-3m and Pa-3, hexagonal P3(2)21, tetragonal P4(2)/mnm, orthorhombic Pmmn, Pnnm, and Pnn2, and monoclinic P2(1)/c. Our calculation indicates that the P2(1)/c phase with arsenopyrite-type structure is energetically more stable than the other phases. It is semiconducting (the remaining phases are metallic) and contains diatomic N-N with the bond distance of 1.414 A. These characters are consistent with the experimental facts that IrN2 is in lower symmetry and nonmetallic. Our conclusion is also in agreement with the recent theoretical studies that the most stable phase of IrN2 is monoclinic P2(1)/c. The calculated bulk modulus of 373 GPa is also the highest among the considered space groups. It matches the recent theoretical values of 357 GPa within 4.3% and of 402 GPa within 7.8%, but smaller than the experimental value of 428 GPa by 14.7%. Chemical bonding and potential displacive phase transitions are discussed for IrN2. For IrN3, cubic skutterudite structure (Im-3) was assumed.

Preparation and physical properties of enhanced radiation induced crosslinking of ethylene-vinyl alcohol copolymer (EVOH)

Preparation and physical properties of ethylene-vinyl alcohol copolymer (EVOH) crosslinked by enhanced radiation have been studied through various methods. It was found that the most effective agent for irradiation-crosslinking was triallyl isocyanurate (TAIC) among four kinds of polyfunctional monomers. Gel content (65.6%) was formed for EVOH-44 (content of ethylene is 44 mol%) at 200 kGy with 5% TAIC, but for EVOH-32 (content of ethylene is 32 mol%), only 37.4% gel content was formed under the same conditions. This result showed that the more the content of ethylene units comprised in EVOH, the easier the chemical bonds could be formed between different molecular chains. Tensile strength and elastic modulus increased after crosslinking at high test temperature and elongation at break decreased at the same time. Hygroscopicity of EVOH showed noticeable decrease after enhancement radiation-crosslinking.

蓝光萘酰亚胺发光材料的合成与表征

通过在4位引入不同芳香基团,采用Suzuki和Stille偶联反应,设计与合成了一系列新型1,8-萘酰亚胺类荧光染料,并研究了它们的紫外-可见吸收、荧光发射和电化学行为等光物理性质。这些化合物在甲苯中均发射蓝色荧光,最大吸收和荧光发射峰分别在357～378和423～451nm之间,且随着芳香基团供电性增强,吸收和荧光发射波长发生红移。芳香基团的结构对化合物的发光效率影响很大,其中,取代基为甲氧基苯的化合物具有最高的荧光量子效率,可达0.98,而取代基为噻吩的化合物荧光量子效率最低,只有0.17。电化学循环伏安研究表明该类化合物具有较高的电子亲合力,不同芳香基团的引入只影响化合物的被占分子轨道(HOMO)能级,而对化合物的最低空分子轨道(LUMO)能级没有影响,即LUMO能级由1,8-萘酰亚胺单元决定。

Investigation on acute biochemical effects of Ce(NO3)(3) on liver and kidney tissues by MAS H-1 NMR spectroscopic-based metabonontic approach

High resolution magic angle spinning (MAS)-H-1 nuclear magnetic resonance (NMR) spectroscopic-based metabonomic approach was applied to the investigation on the acute biochemical effects of Ce(No-3)(3). Male Wistar rats were administrated with various doses of Ce (NO3)(3)(2, 10, and 50 mg(.)kg(-1) body weight), and MAS H-1 NMR spectra of intact liver and kidney tissues were analyzed using principal component analysis to extract toxicity information. The biochemical effects of Ce (NO3)(3) were characterized by the increase of triglycerides and lactate and the decrease of glycogen in rat liver tissue, together with an elevation of the triglyceride level and a depletion of glycerophosphocholine and betaine in kidney tissues. The target lesions of Ce (NO3)(3) on liver and kidney were found by MAS NMR-based metabonomic method. This study demonstrates that the combination of MAS H-1 NMR and pattern recognition analysis can be an effective method for studies of biochemical effects of rare earths.

A novel terbium (III) beta-diketonate complex as thin film for optical device application

A novel terbium complex, Tb(acac)(3)AAP (acac: acetylacetone, AAP: 4-amino-antipyrine), was synthesized and its luminescent properties were studied. When it was used as an emitting center, triple-layer-type device with a structure of glass substrate/ITO (indium-tin oxide)/TPD (N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine)./Tb(acac)(3)AAP/PBD (2-(4-biphenyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole) or Alq(3) (tris(8-hydroxyquinolinato) aluminum)/Al (aluminum) exhibited bright characteristic emission of terbium ion upon applying d.c. voltage. The maximum luminance of the device is 56 cd/m(2) at 19 V and the maximum luminance efficiency is 0.357 lm/W.

层状复合氧化物La_4BaCu_(5-x)M_xO_(13)(M=Mn,Co)的物化性质和结构中活性氧的研究

合成了一系列结构为层状ＡＢＯ３的复合氧化物Ｌａ４ＢａＣｕ５－ｘＭｘＯ１３（Ｍ＝Ｍｎ，Ｃｏ），并利用ＸＲＤ、Ｘ射线能谱、氧程序升温脱附和化学分析方法对它们的结构和活性氧种进行了研究。ＸＲＤ分析结果表明：它们的结构为五层的ＡＢＯ３结构。活性氧种的研究表明Ｌａ４ＢａＣｕ５Ｏ１３中掺杂Ｍｎ或Ｃｏ之后，样品中明显存在的ＭＣｕ（Ｍ＝Ｍｎ，Ｃｏ）之间的协同作用，并且ＣｕＭｎ之间协同作用明显比ＣｕＣｏ的强。

Crystallization behaviour of poly(ether ether ketone)/poly(ether sulfone) block copolymer

The crystallization and melting behaviours of a multiblock copolymer comprising poly(ether ether ketone) (PEEK) and poly(ether sulfone) (PES) blocks whose number average molecular weights <((M)over bar (n)'s)> were 10 000 and 2900, respectively, were studied. The effect of thermal history on crystallization was investigated by wide-angle X-ray diffraction measurement. A differential scanning calorimeter was used to detect the thermal transitions and to monitor the energy evolved during the isothermal crystallization process from the melt. The results suggest that the crystallization of the copolymer becomes more difficult as compared with that of pure PEEK. The equilibrium melting point of the copolymer was found to be 357 degrees C, about 30 degrees C lower than that of pure PEEK. During the isothermal crystallization, relative crystallinity increased with crystallization time, following an Avrami equation with exponent n approximate to 2. The fold surface free energy for the copolymer crystallized from the melt was calculated to be 73 erg cm(-2), about 24 erg cm(-2) higher than that of pure PEEK. Copyright (C) 1996 Elsevier Science Ltd.

差分电化学质谱法（DEMS）的回顾Ⅱ：DEMS方法在某些电极反应中的应用

本文第一部分电化学，１９８６，２（３）回顾了ＤＥＭＳ方法原理和发展，这里继续介绍ＤＥＭＳ方法的一些应用结果，如ＣＨ３ＯＨ，ＨＣＯＯＨ，ＣＯ，ＣＯ２，ＮＯ２－，ＮＯ３－以及一些不饱和碳氢化合物的电化学氧化或还原研究．

聚乙烯醇双胺肟螯合纤维的合成及其吸附性能

利用预辐照接枝法合成了聚乙烯醇双胺肟螯合纤维。研究了影响接枝率和胺肟基团含量的因素，讨论了吸附酸度、吸附时间对Ｃｕ（Ⅱ）离子吸附容量的影响。合成的聚乙烯醇双胺肟螯合纤维对Ｃｕ（Ⅱ）离子的吸附容量达１．６２ｍｍｏｌ／ｇ干纤维，在５ｍｉｎ内达到吸附平衡。

SYNTHESIS AND CHARACTERIZATION OF HETEROPOLY BLUES OF BIS-2/17 MOLYBDOPHOSPHATE COMPLEXES WITH LANTHANIDE

Eight heteropoly blues of bis-2:17 molybdophosphate complexes with Lathanide, i.e., K17H2[Ln(P2Mo17O61)2] . nH2O and K17H4[Ln(P2Mo17O61)2] . nH2O were synthesized and characterized by elemental analyses potentiometric titration, IR, UV, polarography, cyclic voltammetry, X-ray photoelectron spectra X-ray powder diffraction, thermal analyses and ESR. Experimental results show that the properties of these series of heteropoly blues are different from those of their oxidized form, but no great changes in their structures were observed. The ligand P2Mo17O6110- remains alpha2-isomer's configuration.