分子束外延生长的n型Al掺杂ZnS_(1-x)Te_x深中心研究

应用电容-电压、光致荧光和深能级瞬态谱技术研究了分子束外延生长的n型Al掺杂ZnS_(1-x)Te_x外延层深中心。Al掺杂ZnS_(0.977)Te_(0.023)的光致荧光强度明显低于不掺杂的ZnS_(0.977)Te_(0.023),这表明一部分Al原子形成非辐射深中心。Al掺杂ZnS_(1-x)Te_x(x=0,0.017,0.04和0.046)的深能级瞬态傅里叶谱表明，Al引进导带下的0.21和0.39eV电子陷阱，Te除了作为材料合金的成分和等电子中心外，还涉及到一个电子陷阱的形成，其相对导带的能级位置随Te组分增加而减小。实验结果还表明仅有少量掺杂的Al原子形成非辐射中心，这说明Al对于Te组分范围内(x≤0.046)的ZnS_(1-x)Te_x外延层的确是一种非常好的施主杂质。

Observation of deep electron states in n-type Al-doped ZnS1-xTex grown by molecular beam epitaxy

Deep level transient spectroscopy (DLTS) technique was used to investigate deep electron states in n-type Al-doped ZnS1-xTex epilayers grown by molecular fiction epitaxy (MBE), Deep level transient Fourier spectroscopy (DLTFS) spectra of the Al-doped ZnS1-xTex (x = 0. 0.017, 0.04 and 0.046. respectively) epilayers reveal that At doping leads to the formation of two electron traps at 0.21 and 0.39 eV below the conduction hand. 1)DLTFS results suggest that in addition to the rules of Te as a component of [lie alloy as well as isoelectronic centers, Te is also involved in the formation of all electron trip, whose energy level relative to the conduction hand decreases a, Te composition increases.

杉木人工林凋落物分解的研究

杉木是我国特有的速生针叶树种，栽培面积广泛（北纬21°41'－33°41'；东经102°-122°）。我国商品材的近1/4出自杉木人工林。杉木连栽地力衰退，生产力降低，是当前困扰杉木人工林发展的重大生产问题。在水热条件优越的亚热带山地，土壤肥力是影响林木持续保持高生产力的重要因素。因此，加速杉木人工林系统内养分循环是维持系统生产力稳定的关键，而凋落物分解又是养分循环的核心，于是对分解过程的调控便成为关键之关键。本研究的目的在于，探索促进杉木凋落物分解的途径，以增强林木自我培肥土壤的能力，为杉木人工林的可持续发展提供理论依据。研究所采用的实验材料全部来源于湖南省会同县广坪林区的中国科学院会同森林生态实验站。室内缩微模拟实验在英国陆地生态所完成，其它试验均在会同森林生态实验站进行。1. 杉木叶凋落物属难分解的凋落物，其原因是凋落物养分含量较低，尤其是N的含量偏低，为6.0mg.g~(-1)，仅为分解较快的桤木叶凋落物的41.6％；C/N比较高，为134.0，相当于桤木叶凋落物的2.38倍。杉木叶凋落物到第420天时的分解速率为43.3％，而桤木叶凋落物为67.2％。2. 根系凋落物也是杉木人工林生态系统凋落物的重要组分。杉木纯林细根年死亡量为497 kg.hm~(-2).a~(-1)，而火力楠人工纯林为595 kg.hm~(-2).a~(-1)。当火力楠与杉木混交后，细根年死亡量大幅度提高，达1149kg.hm~(-2).a~(-1)。杉木林死细根生物量年动态变化与地上部分生长规律基本一致。杉木细根象地上部分凋落物一样养分贫乏，除Ca以外，N、P、K、Mg分别比火力楠细根低53.0％、131％、595.9％、447.5％，而C/N比值高51.9％。杉木细根的年分解为32.78％，而火力楠为57.70％。因此，杉木纯林中通过细根归还的养分量相对较少，N、P、Ca、K、Mg归还量分别为0.32、0.007、0.58、0.52和0.83kg.hm~(-2)，而混交林中依次为2.59、0.046、1.87、6.06、7.86kg.hm~(-2)，大幅度增加。3. 杉木叶凋落物与阔叶树叶凋落物混合分解时表现出不同的相互作用形式。野外网袋法分解试验的结果表明，桤木与杉木叶凋落物混合分解，失重速率明显加快；火力楠与杉木叶凋落物分别以不同比例混合分解时，失重速率或强或弱得到促进；其它阔叶树并没有促进失重速率。除木荷外，其它阔叶树凋落物都不同程度地促进了Ca的释放。对于P，桤木和红栲，对于K，桤木和刺楸，明显促进了其释放，而其它阔叶树没有对这2种元素的释放产生任何作用。除木荷和樟树外，其它树种叶凋落物明显促进Mg的释放。实验中还发现，促进作用的强弱与阔叶树叶凋落物初始N含量高低有关。室内模拟实验中观察到的木荷叶凋落物明显抑制杉木叶凋落物分解的现象并没有在野外实验中发现。如果仅以凋落物分解过程中促进作用的强弱为标准选择杉木的混交林树种的话，选择这6种阔叶树的优先顺序为桤木、刺楸、红栲、火力楠、樟树、木荷。4. 本研究还用微型渗滤器进行模拟实验发现，投加NO_3-N促进了杉木叶凋落物的分解，在15周的时间分解速率提高2.38个百分点，而投加NH_4-N则未产生任何影响。投加NH_3－N和NH_4－N的负面效应是促进土壤养分的淋失。除Na~+以外，投加NH_4-N使NO_3-N、K~+、Ca~(2+)、Mg~(2+)的淋失明显增多。投加NO_3－N未明显合任何养分元素淋失增多。

长白山阔叶红松林太阳辐射分光谱特征

根据对林冠上方和林下太阳辐射的观测及气象站资料,分析了长白山阔叶红松林太阳辐射分光谱特征.结果表明,长白山阔叶红松林区太阳总辐射、直接辐射、散射辐射的光合有效辐射系数有一定的日变化和年变化,年平均值分别为046、043、056.阔叶红松林中不同树种的单叶对于太阳总辐射的反射率、透射率、吸收率的平均值分别为270%、234%、496%.单叶的分光谱反射、透射和吸收的特点是,单叶对紫外辐射几乎全部吸收;对光合有效辐射的吸收也很大(718%),透射很小(96%),有一定的反射(186%);对近红外辐射、反射率和透射率接近吸收率小些(269%).林冠分光谱辐射特点是,可见光和紫外辐射主要被林冠吸收(939%、941%),有少量反射和透过;林冠对近红外辐射的吸收较大(592%),有一定的反射(263%),透过较少(144%).

Hydrothermal synthesis and crystal structure of a novel layered compound [Ni(C10H8N2)(2)V3O8.5]

A novel layered compound, [Ni(C10H8N2)(2)V3O8.5], was hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction. The compound crystallizes in monoclinic system, space group P21/c with a = 1.551 8(3) nm, b = 1.476 1(3) nm, c = 1.048 3(2) nm, beta = 92.02(3), V = 2.399 8(8) nm(3), Z = 4, R = 0. 046 7, wR(2) = 0. 085 9.

K-2[MoO3(C2O4)].H2O

In the title compound, catena-poly[dipotassium [[(oxalato-O,O')dioxomolybdate]-mu-oxo]monohydrate], oxalate acts as a bidentate ligand coordinating to each Mo atom through the two deprotonated carboxylate groups. The coordination polyhedron of molybdenum is distorted octahedral and there are infinite chains in the structure. Principal dimensions are: Mo-O(terminal) 1.560 (3) and 1.739 (3) Angstrom, Mo-O(bridging) 2.046 (4) and 2.410 (4) Angstrom, and Mo-O(carboxylate) 1.949 (3) and 2.113 (3) Angstrom.

Synthesis and molecular structures of di- and trinuclear molybdenum complexes containing pyridine-2-thiolato (pyS) ligand

Dinuclear complexes [Mo-2(mu-pyS)(2)(CO)(4)(PPh(3))(2)] (1), [Mo-2(mu-pyS)(2)(CO)(5)(PPh(3))] (2) and a trace quality of trinuclear complex [Mo-3(mu-pyS)(2)(mu(3)-pyS)(2)(CO)(6)] (3) were obtained from the reaction of [Mo(CO)(3)(MeCN)(3)] with pyridine-2-thione (pySH) and PPh(3) in THF. The crystal structures of 1.2C(7)H(8) and 3.7 C7H8 have been determined by X-ray diffraction studies. Crystals of 1.2C(7)H(8) are monoclinic, space group C2/c and Z = 4, with a = 18.797(3), b = 11.143(4), c = 28.157(7) Angstrom, beta = 101.23(2)degrees. The structure was refined to R = 0.050 and Rw = 0.057 for 3146 observed reflections, Crystals of 3.7 C7H8 are monoclinic, space group P2(1)/a and Z = 4, with a = 13.912(2), b = 17.161(2), c = 15.577(3) Angstrom, beta = 101.17(1)degrees. The structure was refined to R = 0.046 and Rw = 0.051 for 4357 observed reflections. The molecule of 1 consists of two Mo(CO)(2)(PPh(3)) fragments linked by an Mo-Mo bond (2.974(2)Angstrom) and by two doubly-bridging pyS ligands. The compound 3 contains a bent open geometry of three molybdenum atoms (Mo(1)-Mo(2)-Mo(3) angle 122.99(3)degrees) linked by two Mo-Mo bonds (2.943(1) and 2.950(1) Angstrom) and by two doubly- and two triply-bridging pyS ligands.

(C_8H_8)Sm(C_8H_8)Na(THF)_3的晶体结构

(C_8H_8)Sm(C_8H_8)Na(THF)_3的晶体属单斜晶系,P2_1空间群.晶胞参数为α=12.140(3),b=13.794(3),c=8.944(3)(?),β=111.68(3)°,V=1391.8(7)(?)~3,Z=2,μ=21.93cm~(-1),D_c=1.43g/cm~3,F(000)=610,Mr=598.0。结构经Patterson函数和Fourier技术解出并经最小二乘修正,最终的偏离因子R为0.046.配合物具有双层夹心结构.其中Sm~(3+)和Na~+通过η~8-环辛四烯基连接。

PrP_5O_(14)的晶体结构与铁弹畴

本文用X射线衍射方法研究了PrP_5O_(14)的晶体结构和铁弹相变。晶体空间群为P2_1/c,晶胞参数a=8.777(1)A,b=9.029(2)A,c=13.068(2)A,β=90.35°(1),z=4,最终R值为0.046。在130±5℃转变成正交晶系,空间群为P_(ncm),a=8.813(7)A,b=9.075(2)A,c=13.119(10)A。高温相变使晶体产生了铁弹性孪晶,室温下晶体属mmmF2/m类铁弹体。

Identification of factors affecting the growth and survival of the settling Japanese flounder larvae, Paralichthys olivaceus

A series of experiments were conducted to identify the factors that affected the growth and survival of the settling flounder larvae Paralichthys olivaceus. Settling larvae 24 days after hatching (DAH) were reared in 10-l experimental tanks up to 40 DAH, and two of the following factors were changed as controlled factors in each experiment: light regime (24L:0D or 12L:12D), prey density (1500, 3000, or 5000 Artemia l(-1)), shelter (sand or no sand) and stocking density (5, 10, or 15 fish l(-1)). Early settling larvae (24-35 DAH) experienced little mortality (less than 10% of the overall mortality) that was not significantly affected by above factors. In contrast, late settling larvae (36-40 DAH) suffered high cannibalistic mortality which was significantly influenced by each of the above factors. Larvae experienced significantly lower mortality at 10 fish l(-1) level than at other densities. Larvae at 15 fish l(-1) level had higher mortality than at 5 fish l(-1) when all other factors were identical. Larvae at 3000 and 5000 Artemia l(-1) treatments survived significantly better than at 1500 Artemia l(-1), but no significant differences in larval mortality were found between the two higher densities. Larvae suffered higher mortality at low prey density or at the absence of sand when they were exposed to longer photoperiod. Low stocking density significantly improved the growth of the settling larvae. The average daily instantaneous growth rate (G) at 5 and 15 fish l(-1) treatments were 0.050 and 0.034, with the coefficient of variation (CV) in final length at 16.4 and 23.5, respectively. Daily instantaneous growth rate increased significantly from 0.033 in the 1500 Artemia l(-1) to 0.041 and 0.045 in the 3000 and 5000 Artennia l(-1), respectively, but no significant difference in larval growth existed between the two higher prey densities. These findings suggested that the optimal prey density for growth and survival of the settling flounder larvae at a stocking density of 5 - 15 fish l(-1) was around 3000 Artemia l(-1) . Larvae that were exposed to 24L showed 20% increase in growth ( G = 0.046, CV = 18.7) than those exposed to 12L ( G = 0.037, CV = 20.5). Longer exposure to light significantly improved larval growth, provided sufficient food was available. Sand substrate did not show significant effects on larval growth, possibly because the larvae spent most of the time swimming or feeding in the water column during this stage. (C) 2003 Elsevier Science B.V. All rights reserved.

贵阳市表层土壤中镍的基线及污染研究

以贵州省贵阳市8 046 km2 为研究区域, 将土壤中镍的空间分布规律与环境地球化学机理研究相结合, 建立镍的区域土壤环境地球化学基线, 并进行污染分析. 通过对332 个样品的分析, 得到以下结论: 贵阳市表层土壤中镍的基线值为1710 mg/ kg , 大于5710 mg/ kg 的样品可能遭受人为污染. 地质累积指数分析结果显示贵阳市1912 %的表层土壤未受镍的污染, 6317 %的表层土壤在无污染到中度污染之间, 1618 % 的中度污染, 只有013 %的表层土壤介于中度污染到强污染之间. 污染程度指数分析则显示贵阳市64 %的表层土壤未受到镍的污染, 镍的污染程度最大为1156 , 总污染程度小于0 , 即总体未受到污染.

贵阳市表层土壤中汞的环境地球化学基线及污染研究

以土壤环境地球化学研究为主线,在贵州省贵阳市8 046 km2研究区域中,将土壤重金属元素汞的空间分布规律与环境地球化学机理研究相结合,建立区域土壤环境地球化学基线,选用合适的判别指标判识自然作用过程与人类活动过程对土壤环境的影响,对487个样品的汞含量进行了统计分析.结果表明,贵阳市表层土壤中重金属元素汞的基线值为0.045 mg·kg^-1,样品中汞元素含量大于0.530 mg·kg^-1的样品可能遭受人为污染的影响.地质累积指数分析结果显示,贵阳市12%的表层土壤未受汞的污染,37%的表层土壤在无污染到中度污染之间,36%的中度污染,11%的表层土壤介于中度污染到强污染之间,2%的强污染,1%的介于强污染到极强污染之间.污染程度指数分析显示,贵阳市56.1%的表层土壤未受到汞的污染,汞的污染程度最大为45.87,总污染程度大于0（即受到污染）.

贵阳市表层土壤中镉的环境地球化学基线研究

以土壤环境地球化学研究为主线,以贵州省贵阳市8 046 km^2为研究区域,将土壤重金属污染元素镉的空间分布规律与环境地球化学机理研究相结合,建立区域土壤环境地球化学基线,选用合适的判别指标判识自然作用过程与人类活动过程对土壤环境的影响.通过对487个样品的镉含量的统计分析,结果表明,贵阳市表层土壤中镉的基线值为0.068 mg/kg,镉元素含量大于1.010 mg/kg的样品可能遭受人为污染的影响.地质累积指数分析结果显示,贵阳市40%的表层土壤未受镉污染,19%的表层土壤在无污染与中度污染之间,14%受中度污染,19%的表层土壤介于中度污染到强污染之间,7%受强污染,1%的表层土壤介于强污染到极强污染之间.污染程度指数分析则显示,贵阳市57.9%的表层土壤未受到镉污染,镉的污染程度最大为12.1,96%的表层土壤污染程度小于4,总污染程度大于0,即总体受到污染.[

Neural Pattern Recognition With Multi-Scale Pyramidal Coding and Selective Attention

A new neural network architecture for spatial patttern recognition using multi-scale pyramida1 coding is here described. The network has an ARTMAP structure with a new class of ART-module, called Hybrid ART-module, as its front-end processor. Hybrid ART-module, which has processing modules corresponding to each scale channel of multi-scale pyramid, employs channels of finer scales only if it is necesssary to discriminate a pattern from others. This process is effected by serial match tracking. Also the parallel match tracking is used to select the spatial location having most salient feature and limit its attention to that part.