787 resultados para 893
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The title complex, tris[2(eta5)-tert-butylcyclopentadi-enyl]-mu-chloro-1:2kappa2Cl-tris(tetrahydrofuran-1kappaO)lithiumneodymium, [Nd(C9H13)3(mu-Cl)Li(C4H8O)3], consists of the neutral moiety ((t)BuCp)3Nd linked to the cation [Li(thf)3]+ by a mu-Cl bridge
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Blends of poly(N-vinyl-2-pyrrolidone) (PVP) with a copolyamide (CoPA) randomly composed of 1:1:1 (wt) nylon 6, nylon 66 and nylon 610 structural units were prepared by casting from a common solvent. They were found to be miscible and show a single, composition-dependent glass transition temperature (T(g)). The addition of PVP to CoPA significantly lowers the crystallinity owing to an increasing T(g) of the system. The observed miscibility is proposed to be the result of specific interactions between the proton acceptor groups of PVP and the amide groups of CoPA.
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滤食性贝类以水体中的浮游植物和有机碎屑为主要食物,养殖海域的初级生产力水平、水动力学特性等生态环境因子的差异,不仅直接影响养殖贝类的产量,而且也与贝类养殖活动对生态环境的压力密切相关。由于养殖的种类、密度、方式及养殖海域的特性不同,关于贝类对生态环境的影响往往有不同的结果。本文以我国北方大连獐子岛扇贝底播海区和荣成桑沟湾贝类筏式养殖区为研究对象,采用现场调查、室内受控实验及生态数值模型模拟方法,分析研究了滤食性贝类对海域生态系统的影响,对这两个海域贝类养殖的生态容量进行了初步的评价。 主要结果: 1. 獐子岛海域底播贝类养殖活动对该海域生态系统的影响较小。非参数统计—符号检验的结果显示,养殖区与非养殖区之间的溶解性无机氮、磷酸盐浓度、氮磷摩尔比及浮游植物群落结构没有统计学上的差异(p>0.05)。但是从变化的趋势上来看,贝类养殖活动对水域环境的某些参数有一定程度的影响。例如,獐子岛底播贝类养殖海域的溶解性无机氮以氨氮为主,可能与贝类的代泄活动有关;不论是叶绿素浓度,还是网采浮游植物的生物量都是贝类高密度养殖区<贝类低密度养殖区<非养殖区(7月份除外),这种趋势可能与贝类的摄食压力有关。 桑沟湾各环境指标表现出明显的区域性。除春季外,非养殖区的DIN浓度高于各养殖区。在春季和冬季,贝类区的磷酸盐浓度显著降低;而硅酸盐浓度在夏季和秋季显著增大。综合分析DIN、PO4-P及SiO3-Si三个参数的四季变化,海带区、贝藻区及贝类区发生显著性变异的概率分别为25%,42%和50%,贝类区的变异较大。浮游植物、小型浮游动物的生物多样性指数都是以非养殖区为最高,贝类区的多样性指数最低。尤其是浮游动物的丰度,贝类区显著低于非养殖区。 2. 利用挪威的MOM (Modelling-Ongrowing fish farms-Monitoring)评价系统,评价了桑沟湾长期大规模的贝藻筏式养殖活动对底质环境的压力。在桑沟湾设10个取样站位,共获得66个底泥样品。比较了MOM-B评价系统的3组参数的季节变化特性。结果显示,底质条件属于1级,说明桑沟湾贝藻长期大规模的养殖活动对底质环境的压力较低。结合桑沟湾的环境及养殖特点,分析了压力较低的原因。 3. 经计算,2006年中国海水养殖的贝类和藻类使用浅海生态系统的碳可达396万吨,并通过收获从海中移出至少136.9万吨的碳。从1995年至2006年,养殖大型藻类和贝类累计移出的碳分别约为365万吨和893万吨,总计达1258万吨。证明了浅海的贝类和藻类养殖活动直接或间接地使用了大量的海洋碳,提高了浅海生态系统吸收大气CO2的能力。 4. 采用模拟现场生物沉积法测定了虾夷扇贝的滤水率、摄食率等生理指标及其与贝类个体大小、水温的关系。虾夷扇贝单位个体的滤水率与组织干重的关系符合幂函数方程CR=a×DWb,b值在0.45~0.65范围内;水温对虾夷扇贝滤水率的影响极其显著(p<0.01),温度(T)与滤水率(CR)呈抛物线的关系:CR=-0.0009T2+0.0188T-0.0306,水温为10℃时,虾夷扇贝的滤水率、摄食较大。 5. 采用模拟现场流水法测定了3种滤食性贝类的食物选择性。紫贻贝、长牡蛎及栉孔扇贝分别对直径4m, 6m 和 8m颗粒的保留效率达到最大值;对小颗粒(直径2m)的保留效率分别为17%, 19% 和 8%。栉孔扇贝对食物数量和质量浓度的变化相对敏感,随着数量浓度的增加,栉孔扇贝倾向于摄食较大的颗粒;随着颗粒食物质量浓度的增加,倾向于摄食较小的颗粒。 6. 獐子岛海域四个航次的调查结果显示,叶绿素浓度在1.23~2.85mg.m-3范围内,均值为1.78±0.57 mg.m-3;初级生产力的变化范围为30.4~117.0 mg C. m-2.d-1,平均值为76.6±41.9 mg C. m-2.d-1。通过虾夷扇贝生物量断面调查,获得了虾夷扇贝的壳高频率分布情况,7月份的众数值出现在100 mm,10月份壳高的众数值为80 mm。利用以上测定的虾夷扇贝的滤水率等基本生物学特性,结合虾夷扇贝的年产量、海域面积和有关的水文状况等数据,计算了滤水效率、摄食压力、调节比率3个食物限制性指标参数,全年的均值分别为0.048, 0.31和 0.16,都小于1,说明目前该海域虾夷扇贝的养殖量未达到养殖容量。 7. 利用STELLA软件,建立的桑沟湾贝藻养殖的数值模型,模拟了叶绿素a浓度及氮磷营养盐的周年变化情况,及其对贝类养殖生物量变化的响应。以叶绿素a浓度为指标,初步探讨了桑沟湾贝类的生态容量。
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海湾扇贝Argopecten irradian Lamarck于1982年从美国引种到中国,由于具有较快的生长速度和很高的经济效益,海湾扇贝成为中国最主要的养殖贝类之一。近年来海湾扇贝养殖遇到了死亡率高等问题,深入开展海湾扇贝功能基因的研究,尤其是免疫相关基因及其机制研究并在此基础上寻找扇贝疾病防治的有效方法对海湾扇贝的健康养殖十分重要。 对于贝类免疫系统来说,其血细胞在先天性免疫防御中起着重要的作用。当受到外界病原侵染时,贝类血细胞的一个重要免疫反应就是吞噬作用。在吞噬病原过程中,受到病原侵染的贝类还会产生其他多种免疫反应,这些免疫反应将消耗大量的能量(ATP),产能的呼吸链会加速运转,由此也会引发与呼吸链相耦联的活性氧(ROS)的大量产生。这些活性氧具有极强的反应特性,能破坏病原微生物的结构和功能分子,实现对入侵病原的杀灭。利用活性氧对被吞噬的病原进行杀灭,这是吞噬作用消除病原抵御侵染的重要机制。但由于活性氧分子反应的非特异性,它们也会破坏宿主机体细胞内的功能蛋白分子、不饱和脂肪酸分子和核酸等,对细胞造成严重的伤害,进而导致机体生理机能的损伤和免疫系统的破坏。所以,及时消除病原感染机体内过量产生的ROS,维持相关细胞的正常代谢,对提高机体抵抗力和免疫力具有重要的作用。O2-是生物体内产生的第一种活性氧分子,其他的活性氧分子也是由它衍生而来,消除过量O2-是消除过量活性氧危害的第一步也是关键一步。生物体内,超氧化物歧化酶(SOD)是催化O2-发生歧化反应,消除O2-的关键酶。 首先,本文通过RACE方法获得了海湾扇贝SOD家族全部三种基因的cDNA全长并对其进行了序列的生物信息学分析,海湾扇贝AiCuZnSOD全长cDNA为1047个碱基,其中开放阅读框为459个碱基,编码152个氨基酸,与栉孔扇贝Chlamys farreri的CuZnSOD相似度为77.5%,与长牡蛎Crassostrea gigas的相似度为75%,与人的相似度为74.7%。AiMnSOD全长cDNA为1207个碱基,其中开放阅读框为678个碱基,编码226个氨基酸,序列比对结果发现AiMnSOD的氨基酸序列与虾夷扇贝Mizuhopecten yessoensis和皱纹盘鲍Haliotis discus hannai的相似度分别为85%和78.4%,与哺乳动物相似度也在68%~72%之间。AiECSOD全长cDNA为893个碱基,其中开放阅读框为657个碱基,编码218个氨基酸。AiECSOD与其它物种ECSOD相似度比较低。与线虫Brugia pahangi的相似度为27.9%,与疟蚊Anopheles gambiae的相似度为31.4%,与斑马鱼Danio rerio的相似度为27.8%,与人的相似度也只有28.6%,与同是贝类的长牡蛎ECSOD也只有28.1%的相似性。主要原因是AiECSOD的信号肽和肝磷脂结合区域在各物种中无同源性。 其次,采用qRT-PCR(quantitative real time PCR)方法分析三种SOD基因在不同组织中的表达情况,结果表明三种SOD基因的组织表达有所差异。AiCuZnSOD基因在鳃中表达水平最高,其次是血细胞和性腺,在外套膜、闭壳肌和肝胰脏表达水平较低。AiMnSOD基因在鳃中表达水平最高,其次是外套膜,在血细胞、性腺,而在肝胰脏和闭壳肌表达较弱。AiECSOD基因在血细胞中表达水平最高,其次是肝胰脏,在鳃、闭壳肌表达水平较低,而性腺和外套膜没有检测到。同时,采用qRT-PCR对鳗弧菌Vibrio angullarum感染后海湾扇贝血细胞中三种SOD基因mRNA表达变化进行了检测。AiCuZnSOD表达量在各个时间段没有显著差异(P > 0.05)。AiMnSOD的表达量在1.5 h时略有下降,在3 h时达到最高表达量,是空白组(0h)的3倍(P < 0.01),从6 h到24 h表达量逐渐下降,24 h时表达量是空白组的1.6倍,24 h到48 h又稍有升高。AiECSOD的表达量在1.5 h时有所下降,是空白组的0.3倍(P < 0.05),随后逐渐升高,在12 h时达到最高表达量,是空白组(0h)的4.5倍(P < 0.01),从24 h到48 h表达量逐渐下降并恢复到空白组的水平。在对照组,各个时间点没有显著差异(P > 0.05)。在鳗弧菌感染后,海湾扇贝三种SOD的表达并不一致,且差异比较显著。AiCuZnSOD被认为是构成性表达基因,其受外界刺激的影响最小,AiMnSOD和AiECSOD受刺激后表达上调比较明显。 第三,采用Genome-walking的方法得到了海湾扇贝三种SOD基因的基因组全长和近端启动子序列并对其进行了相关分析。AiCuZnSOD的基因组序列全长为4279bp,包含有4个外显子和3个内含子。AiMnSOD的基因组序列全长为10692bp,包含有4个外显子和3个内含子。AiECSOD的基因组序列全长为5276bp,包含有5个外显子和4个内含子。三种基因外显子和内含子的结合处序列遵循-AT/GT-原则。我们把海湾扇贝SOD家族的三个基因的近端启动子进行了比较分析。发现三种SOD在靠近起始密码子的位置都有Oct-1结合位点。三种SOD共有的转录位点有:Oct-1、C/EBPalp、Oct2.1、Sp-1和GATA-1。AiCuZnSOD和AiMnSOD共有的转录位点有:ICSBP、Ftz、TATA-box、C/EBPbeta和Antp。AiCuZnSOD和AiECSOD共有的转录位点有:AP-1和NFκB。AiMnSOD和AiECSOD共有的转录位点有:GR和ER。AiCuZnSOD独有的位点有:SRF、YY-1和NF-1。AiMnSOD独有的位点有:HNF-1、Hb、MEB、NF-muE1、Pit-1a和Eve。AiECSOD独有的位点有:CREB、RATA-alph、Kruppel-like和AP-3。 此外,通过构建原核表达载体,本研究对AiCuZnSOD和AiECSOD基因进行了体外重组表达,并对纯化的重组蛋白进行了酶活分析。酶活分析表明,重组AiCuZnSOD蛋白有较高的酶活和稳定性。 最后,我们对海湾扇贝三种SOD基因的部分区域,包括启动子、编码区,部分内含子区域进行了SNP检测,并对SOD基因部分SNP位点多态性和鳗弧菌敏感性进行了相关分析。三种SOD基因中,我们共发现了59个SNP位点,其中AiECSOD的SNP位点最多,特别是在启动子区,AiCuZnSOD和AiMnSOD多态性较低。其中AiCuZnSOD启动子区的-1739 T-C 位点的基因型和等位基因,AiECSOD启动子区的-498 A-T和-267 G-A等位基因频率,AiECSOD的第一个外显子38 Thr-Lys的多态性在敏感和抗菌群体中存在显著差异(P < 0.05)。
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Extracellular superoxide dismutase (ECSOD) is a major extracellular antioxidant enzyme that protects organs from damage by reactive oxygen species (ROS). We cloned a novel ECSOD from the bay scallop Argopecten irradians (AiECSOD) by 3' and 5' RACE. The full-length cDNA of AiECSOD was 893 bp with a 657 bp open reading frame encoding 218 amino acids. The deduced amino acid sequence contained a putative signal peptide of 20 amino acids, and sequence comparison showed that AiECSOD had low degree of homology to ECSODs of other organisms. The genomic length of the AiECSOD gene was about 5276 bp containing five exons and six introns. The promoter region contained many putative transcription factor binding sites such as c-Myb, Oct-1, Sp1, Kruppel-like, c-ETS, NF kappa B, GATA-1, AP-1, and Ubx binding sites. Furthermore, tissue-specific expressions of AiECSOD and temporal expressions of AiECSOD in haemocytes of bay scallops challenged with bacteria Vibrio anguillarum were quantified using qRT-PCR. High levels of expression were detected in haemocytes, but not in gonad and mantle. The expression of AiECSOD reached the highest level at 12 h post-injection with V. anguillarum and then returned to normal between 24 h and 48 h post-injection. These results indicated that AiECSOD was an inducible protein and that it may play an important role in the immune responses against V anguillarum. Crown Copyright (C) 2008 Published by Elsevier Ltd. All rights reserved.
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西倾山地区位于青海省东南部 ,北纬 33°80′~ 35°50′ ,东经 10 0°10′~ 10 2°4 0′。本地区共有种子植物 56科、 257属、 711种。区系特征如下 :(1)温带成分占 96 88% ,以绝对优势确定了本区系明显的温带性质。 (2 )世界成分多为衍生 ,更兼所含的中国特有属亦多为衍生 ,表明本区系的年轻性和衍生的性质。 (3)主要植被均属典型的高寒类型 ,它们的建群种亦多为典型的高寒植被的特征种。所以 ,本区系高寒植被典型 ,特征种典型 ,高寒区系特色明显。(4 )生态环境对本区系特征的塑造表现为高寒生态因子的选择和高山特化的作用强烈 ,而在一定程度上湿冷生性质和寒旱生性质的高山特化作用更为明显。西倾山地区的植物区系是唐古特地区的代表区系之一。但在中国特有种的分析中,本区系却与横断山和甘肃南部区系的联系最为密切,三者间的共有种最为丰富,有363种,占本区中国特有种的66.73%。如此大的相似性,无疑且有力地支持了李锡文等(1993)关于横断山地区的“川西北、甘西南、青东南小区”划分的观点。
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A novel labeling reagent 1-(2-naphthyl)-3-methyl-5-pyrazolone (NMP) coupling to liquid chromatography with electrospray ionization mass spectrometry for the detection of carbohydrates from the derivatized rape bee pollen samples is reported. Carbohydrates are derivatized to their bis-NMP-labeled derivatives. Derivatives showed an intense protonated molecular ion at m/z [M+H](+) in positive-ion detection mode. The mass-to-charge ratios of characteristic fragment ions at m/z 473.0 could be used for the accurately qualitative analysis of carbohydrates. This characteristic fragment ion is from the cleavage of C2-C3 bond in carbohydrate chain giving the specific fragment ions at m/z [MH-CmH2m+1Om-H2O](+) for pentose, hexose and glyceraldehydes and at m/z [MH-CmH2m-1Om+1-H2O](+) for alduronic acids such as galacturonic acid and glucuronic acid (m = n - 2, n is carbon number of carbohydrate). No interferences for all aliphatic and aromatic aldehydes presented in natural environmental samples were observed due to the highly specific parent mass-to-charge ratio and the characteristic fragment ions. The method, in conjunction with a gradient elution, offered a baseline resolution of carbohydrate derivatives on a reversed-phase Hypersil ODS-2 column. The carbohydrates such as mannose, galacturonic acid, glucuronic acid, rhamnose, glucose, galactose, xylose, arabinose and fucose can successfully be detected.
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These are two parts included in this report. In the first part, the zonation of the complexes in its series, lithofacies, the depth of magma source and chambers is discussed in detailed for the first time based on the new data of petrol-chemistry, isotopes, tectono-magma activity of Mesozoic volcano-plutonic complexes in the southern Great Hinggan Mts. Then, the genetic model of the zonality, double overlapped layer system, is proposed. The main conclusions are presented as follows: The Mesozoic volcanic-plutonic complexes in the southern Great Hinggan were formed by four stages of magma activity on the base of the subduction system formed in late Paleozoic. The Mesozoic magmatic activity began in Meso-Jurassic Epoch, flourished in late Jurassic Epoch, and declined in early Cretaceous Epoch. The complexes consist dominantly of acidic rocks with substantial intermediate rocks and a few mefic ones include the series of calc alkaline, high potassium calc alkaline, shoshonite, and a few alkaline. Most of those rocks are characterized by high potassium. The volcano-plutonic complexes is characterized by zonality, and can be divided mainly into there zones. The west zone, located in northwestern side of gneiss zone in Great Xinggan mountains, are dominated of high potassium basalts and basaltic andesite. The middle zone lies on the southeast side of the Proterozoic gneiss zone, and its southeast margin is along Huangganliang, Wushijiazi, and Baitazi. It composed of dominatly calc-alkaline, high potassium calc-alkaline rocks, deep granite and extrusive rhyolite. The east zone, occurring along Kesheketong Qi-Balinyou Qi-Balinzuo Qi, is dominated of shoshonite. In generally, southeastward from the Proterozoic gneiss zone, the Mesozoic plutons show the zones-mica granitites zone, hornblende-mica granitite zone, mica-hornblende granitite zone; the volcanic rocks also display the zones of calc alkaline-high potassium calc alkaline and shoshonites. In the same space, the late Paleozoic plutons also display the same zonality, which zones are combined of binary granite, granodiorite, quartz diorite and diorite southeast wards from the gneiss. Meso-Jurassic Epoch granite plutons almost distribute in the middle zone on the whole. Whereas late Jurassic Epoch volcanic rocks distribute in the west and east zone. This distribution of the volcano-plutonic complexes reveals that the middle zone was uplifted more intensively then the other zones in Meso-Jurassic and late Jurassic Epoches. Whole rock Rb-Sr isochron ages of the high potassium calc-alkaline volcanic rocks in the west zone, the calc-alkaline and high potassium calc-alkaline granite the middle zone, shoshonite in the east zone are 136Ma, 175Ma and 154Ma, respectively. The alkaline rocks close to the shoshonite zone is 143Ma and 126Ma. The isochron ages are comparable well with the K-Ar ages of the rocks obtained previously by other researchers. The compositions of Sr ans Nd isotopes suggest that the source of Mesozoic volcanic-plutonic complexes in Great Hinggan Mts. is mostly Paleo-Asia oceanic volcanic-sedimentary rocks, which probably was mixed by antiquated gneiss. The tectonic setting for Mesozoic magmatism was subductive continental margin. But this it was not directly formed by present west Pacific subduction. It actully was the re-working of the Paleozoic subduction system( which was formed during the Paleo-Asia ocean shortening) controlled by west Pacific subduction. For this reason, Although Great Hinggan Mts. is far away from west Pacific subduction zone, its volcanic arc still occurred echoing to the volcanic activities of east China, it, but the variation trend of potassium content in volcano-plutonic complexes of Great Hinggan is just reverse to ones of west Pacific. The primitive magmas occurred in the southern Great Hinggan Mts. Include high-potassium calc-alkaline basalt, high potassium calc-alkaline rhyolite, high potassium rhyolite, non-Eu negative anomaly trachy-rhyolite et al. Therefore, all of primitive magmas are either mafic or acid, and most of intermediate rocks occurring in the area are the products of Mesozoic acid magma contaminated by the Paleozoic volcanic- sedimentary rocks. The depth of those primitive magma sources and chambers gradually increase from northwest to southeast. This suggests that Paleozoic subduction still controlled the Mesozoic magmatism. In summary, the lithosphere tectonic system of the southern Great Hinggan Mts. controlling Mesozoic magmatism is a double overlapped layer system developing from Paleozoic subduction system. For this reason, the depth of crust of the southern Great Hinggan Mts. is thicker than that of its two sides, and consequently it causes regional negative gravity abnormity. The second part of this report shows the prolongation of the research work carried on in my doctor's period. Author presents new data about Rb-Sr and Sm-Nd isotopic compositions and ages, geochamical features, genesis mineralogy and ore deposit geology of the volcanic rocks in Kunyang rift. On the base of the substantial work, author presents a prospect of copper bearing magnetite ore deposit. The most important conclusions are as follows: 1. It is proved that all of these carbonatites controlled by a ringing structure system in Wuding-Lufeng basin in the central Yunnan were formed in the Mesoproterozoic period. Two stages could be identified as follows: in the first stage, carbonatitic volcanic rocks, such as lavas(Sm-Nd, 1685Ma), basaltic porphyrite dykes(Sm-Nd, 1645Ma), pyroclastic rocks and volcaniclastic sedimentary rocks, formed in the outer ring; in the second stage, carbonatitic breccias and dykes(Rb-Sr, 1048 Ma) did in the middle ring. The metamorphic age of the carbonatitic lavas (Rb-Sr, 893 Ma) in the outer ring was determined. The magma of carbonatitic volcanic rocks derived mainly form enriched mantle whose basement is depleted mantle that had been metasomated by mantle fluid and contaminated by Archaean lower crust. Carbonatitic spheres were discovered in ore bearing layers in Lishi copper mining in Yimen recently, which formed in calcite carbonatitic magma extrusion. This discovery indicates that the formation of copper ore deposit genesis relates to carbonatitic volcanic activity. The iron and copper ore deposits occurring in carbonatitic volcanic- sedimentary rocks in Kunyang rift results from carbonatitic magmatism. Author calls this kind of ore deposits as subaqueous carbonatitic iron-copper deposit. The magnetic anomaly area in the north of Lishi copper mining in Yimen was a depression more lower than its circumference. Iron and copper ores occurrig on the margin of the magnetic anomaly are volcanic hydrothermal deposit. The magnetic body causing the magnetic anomaly must be magnetite ore. Because the anomaly area is wide, it can be sure that there is a large insidious ore deposit embedding there.
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在前人工作基础上,侧重研究石英脉型金矿床成矿的地质背景,建立了该类型金矿的成矿模式。进而开展三轴温压条件下的成岩成矿实验,构造形变特征及其与成矿物质活化、迁移、富集之间的相互关系的模拟实验。实验结果表明:(1)该区岩石、矿石在高温高压条件下,产生塑性变形(褶皱)和脆性变形(破裂);(2)在变形过程中使成矿物质活化、迁移和富集,形成顺层及穿层的含金石英脉,并在多期多次变形过程中使成矿物质叠加富集;(3)在褶皱(背斜)轴部形成富矿体。模拟实验结果与所建立的该类型金矿构造控矿和成矿模式非常相似。实验资料的力学分析表明,由轴压所产生的构造附加压力大大地提高了实际围压,从而促进了岩石流变、变形和物质的迁移,由此促进含矿流体向构造附加压力小的部位定向迁移、充填和成矿。构造附加压力是促进该区金成矿的重要动力条件.
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Novel mixed conducting oxides, B-site Bi-doped perovskites were exploited and synthesized. Cubic perovskite structures were formed for BaBi0.2COyFe0.8-yO3-delta (y less than or equal to 0.4) and BaBixCo0.2Fe0.8-xP3-delta (x=0.1-0.5) The materials exhibited considerable high oxygen permeability at high temperature. The oxygen permeation flux of BaBi0.2Co0.35Fe0.45O3-delta membrane reached about 0.77 x 10(-6) mol/cm(2) s under an air/helium oxygen partial pressure gradient at 900 degrees C, which was much higher than that of other bismuth-contained mixed conducting membranes. The permeation fluxes of the materials increased with the increase of cobalt content, but no apparent simple relationship was found with the bismuth content. The materials also demonstrated excellent reversibility of oxygen adsorption and desorption. Stable time-related oxygen permeation fluxes were found for BaBi0.2CO0.35Fe0.45O3-delta and BaBi0.3Co0.2Fe0.5O3-delta a membranes at 875 degrees C.
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The conversion of n-C4H10 was undertaken on MoO3/HZSM-5 catalyst at 773-973K and the phases of molybdenum species were detected by XRD. The XRD results show that bulk MoO3 on HZSM-5 can be readily reduced by n-C4H10 to MoO2 at 773 K and MoO2 can be gradually carburized to molybdenum carbide above 813 K. The molybdenum carbide formed from the carburization of MoO2 with n-C4H10 below 893 K is alpha-MoC1-x with fcc-structure, while hcp-molybdenum carbide formed above 933 K. During the evolution of MoO3 to MoO2 (>773 K) or the carburization of MoO2 to molybdenum carbide (>813 K), deep oxidation, cracking and coke deposition are serious, in particular at higher reaction temperatures, these lead to the poor selectivity to aromatics. Aromatization of n-C4H10 can proceed catalytically on both Mo2C/HZSM-5 and MoO2/HZSM-5, the distribution of the products for the two catalysts is similar below 813 K, but the, activity for Mo2C/HZSM-5 is much higher than that for MoO2/HZSM-5. (C) 2002 Elsevier Science B.V. All rights reserved.
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O Município de Machadinho d´Oeste, em Rondônia foi escolhido para um estudo de longo prazo. Já são 10 anos de acompanhamento de mais de 450 pequenas propriedades rurais e cerca de 250 variáveis biofísicas, sócio-econômicas e ambientais. A duração deste projeto é de 100 anos. Os estudos pedológicos da área do "Projeto de Assentamento Machadinho" teve como objetivos identificar os solos das Glebas e implementar uma base de dados do meio físico em escala municipal, através do uso de técnicas de geoprocessamento (SIG´s); bem com o caracterizar e avaliar química, física e morfologicamente os perfis de solos representativos das principais unidades identificadas, a fim de promover o desenvolvimento agrícola da região e fornecer subsídios para estudos em áreas semelhantes na Amazônia.
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Meyrick, Robert, 'Wealth Wise and Culture Kind', In: 'Things of Beauty: What Two Sisters did for Wales', (Cardiff: National Museum Wales Books), pp.96-111, 2007 RAE2008