黄土高原南部全新世黄土-古土壤序列若干元素分布特征及意义

IEECAS SKLLQG

半导体探测器及其在空间科学中的应用

阐述了空间辐射环境监测的意义 ,描述了由半导体探测器组成的望远镜系统在空间科学中的应用 ,并给出了已成功应用在卫星上进行地球辐射带的辐射环境监测的部分结果

图像采集及处理技术在粒子加速器束流剖面测量中的应用

介绍了 HIRFL (兰州重离子研究装置 )上利用荧光靶对束团截面形状和流强大小的实时测量方法和对光斑图像进行动态分析的硬件结构以及软件的设计方法 ,并定量地给出一些测量结果。该系统具有可靠性好、精度高、测量直观、应用软件的界面友好等优点

Interference Effects in Hyperfine Induced 2s2p P-3(0), P-3(2) -> 2s(2) S-1(0) Transitions of Be-like Ions

In this paper, we explored the characteristics of the interference effects between perturbative states in hyperfine induced 2s2p P-3(0), P-3(2) -> 2s(2) S-1(0) transitions of Be-like ions. It was found that the interference effects non-monotonically change with increasing atomic number Z in these two transitions. The strongest interference effect is near Z = 9 for 2s2p P-3(0), -> 2s(2) (1)S(0)transition and near Z = 7 for the other.

Heat capacity and enthalpy of fusion of penconazole (C13H15C12N3)

Low-temperature heat capacities of penconazole (C13H15Cl2N3) were precisely measured with an automated adiabatic calorimeter over the temperature rang from 78 to 364 K. The sample was observed to melt at 332.38 +/- 0.06 K. The molar enthalpy and entropy of fusion of the compound were determined to be 33580 +/- 11 J mol(-1), 101.03 +/- 0.02 J mol(-1) K-1, respectively. Further research of the melting process for this compound was carried out by means of differential scanning calorimetry (DSC) technique. The result was in agreement with that obtained from the measurements of heat capacities. (C) 2003 Elsevier B.V. All rights reserved.

长期重金属胁迫对农田土壤微生物生物量、活性和种群的影响

调查了沈阳张士灌区长期污水灌溉造成的原位农田土壤重金属污染状况,从土壤微生物生物量、微生物活性和微生物种群数量的角度评价了长期重金属污染对农田土壤生态系统的影响.结果表明,张士灌区土壤存在严重的Cd污染,土壤Cd含量达1.75~3.89mg.kg-1,部分区域还伴有Cu、Zn复合污染.在目前污染程度下,土壤微生物生物量碳(Cmic)、微生物商(qM)、土壤脱氢酶活性以及自生固氮菌数量随土壤重金属含量增加呈下降趋势,代谢商(qCO2)随土壤重金属含量增加显著升高,而底物诱导呼吸强度(SIR)、纤维素酶活性以及细菌、放线菌和真菌数量无明显变化.相关性分析表明,土壤Cd含量变化是影响微生物参数变化的主要因素,在微生物参数中微生物商和代谢商对重金属污染最敏感.

A velocity map ion-imaging study on C2H5SH and C3H7SH photodissociation at 243 nm

Photodissociation dynamics Of C2H5SH, i-C-3-H7SH and n-C3H7SH at 243.1 nm were investigated using velocity map ion-imaging method. H-atom photolysis products were detected by a (2 + 1) resonance enhanced ionization scheme. Both the angular distribution and translational energy distribution of the H-atom elimination processes were determined from the ion images of the H-atom products. The experimental results indicate that the H-atom eliminations from these molecules are mainly direct and fast dissociation processes from a repulsive potential energy state. And a more statistical dissociation process that likely occurs oil the ground state via internal conversion has also been observed. Dissociation energies of the S-H bonds are also derived from the H-atom product translational energy distributions. (C) 2002 Elsevier Science B.V. All rights reserved.

科尔沁沙地沙丘演替过程的土壤种子库特征

该文研究了科尔沁沙地沙丘演替阶段(流动沙丘-半流动沙丘-半固定沙丘-固定沙丘)的土壤种子库特征.土壤种子库物种组成和种子密度均以一年生植物为主.流动和半流动沙丘土壤种子库密度约为90和364粒/m2,半固定和固定沙丘种子密度显著增加到723和8 880粒/m2.沙丘演替阶段种子密度的时间动态和土壤种子垂直分布特征分析结果表明:流动半流动沙丘无显著差异(P>0.05),固定半固定沙丘则有显著差异(P≤0.002);固定半固定沙丘的植物种子表现为持久土壤种子库类型Ⅲa,并且随土壤深度增加,土壤种子密度显著下降.沙丘演替阶段土壤种子库的种子密度与植物在地上植被中出现的频度具有显著相关性,二者相关系数为0.568.

辽河三角洲湿地区域生态风险评价

生态风险评价区别于生态影响评价的重要特征在于其强调不确定性因素的作用 ,区域生态风险评价相对于一般生态风险评价而言 ,其所涉及的风险源以及评价受体等都在区域内具有空间异质性 ,即具有区域分异现象 ,因而更具复杂性。以辽河三角洲湿地 (盘锦市 )为研究范围进行区域生态风险评价理论和方法的探讨。针对辽河三角洲主要生态风险源洪涝、干旱、风暴潮灾害和油田污染事故的概率进行了分级评价 ;并提出度量生态环境重要性和脆弱性的指标 ,分析了风险源的危害作用 ;运用遥感资料和地理信息系统 ( GIS)技术 ,完成了区域生态风险综合评价。

近30年来青海三江源地区草地退化的时空特征

在20世纪70年代中后期MSS图像、90年代初期TM图像和2004年TM/ETM图像支持下,通过三期遥感影像的直接对比分析,获得了三江源地区草地退化空间数据集,并在此基础上分析了70年代以来青海三江源地区草地退化的主要时空特征。结果表明:三江源地区草地退化是一个在空间格局上影响范围大,在时间过程上持续时间长的连续变化过程。研究发现,三江源草地退化的格局在70年代中后期已基本形成,70年代中后期至今,草地的退化过程一直在继续发生,总体上不存在90年代至今的草地退化急剧加强现象。草地退化的过程在不同区域和地带有明显不同的表现,如在湿润半湿润地带的草甸类草地上,发生着草地破碎化先导,随后发生覆盖度持续降低,最后形成黑土滩的退化过程;在干旱、半干旱地带的草原类草地上,发生着覆盖度持续降低,最后形成沙地和荒漠化草地的退化过程。三江源地区草地退化具有明显的区域差异,草地退化可以分为7个区,各区草地退化在类型、程度、范围与时间过程方面具有明显不同的特点。

Fabrication, thermal stability and mechanical properties of novel composite hardmetals obtained by solid-state reaction and hot-pressing sintering

A novel cemented carbides (W0.7Al0.3)C-0.65-Co with different cobalt contents were prepared by solid-state reaction and hot-pressing technique. Hot-pressing technique as a novel technique was performed to fabricate the bulk bodies of the hard alloys. The novel cemented carbides have superior mechanical properties compared with WC-Co. The density, operate cost of the novel material were lower than WC-Co system. The novel materials were easy to process nanoscale sintering and get the rounded particles in the bulk materials. There is almost no eta-phase in the (W0.7Al0.3)C-0.65-Co cemented carbides system although the carbon deficient get the astonished 35% value.