302 resultados para Laço homoclínico


Relevância:

10.00% 10.00%

Publicador:

Resumo:

An L-amino acid oxidase (TM-LAO) from the venom of Hunan Trimeresurus mucrosquamatus was purified to homogenicity by three steps including DEAE Sephadex A-50 ion-exchange chromatography, Sephadex G-75 gel filtration and Resourse Q ion-exchange chromatography. TM-LAO is composed of two identical subunits with a molecular weight of 55 kD by SDS-polyacrylamide gel electrophoresis. The molecular weight was different with that of LAO purified from the same species distributed in Taiwan that was 70 kD. The 24 N-terminal ammo acid sequence of TM-LAO is ADNKNPLEECFRETNYEEFLEIAR, which shares high similarity with other Viperid snake venom LAOs and has moderate similarity with Elapid snake venom LAOs. Further studies found that TM-LAO inhibited the growth of E. colt, S. aurues and B. dysenteriae. TM-LAO also showed cytotoxicity and platelet aggregation activity. All the biological activities were eliminated by catalase, a H2O2 scavenger. It shows that these biological effects are possibly due to the formation of H2O2 produced by TM-LAO.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The black-crested gibbon, Hylobates concolor, is one of the few species of gibbons that has not yet been the subject of a long term field study. Field observations in the Ai Lao and Wu Liang Mountains of Yunnan Province, China indicate that in this area the habitat and ecology of this species differ markedly from those of other gibbons that have been studied to date. These differences are correlated with some behavioral differences. In particular, these gibbons apparently have greater day ranges than other gibbons. It has also been suggested that this species lives in polygynous groups. To demonstrate this requires observation of groups with two or more females with young. Our own observations and those from other recent studies suggest that there are alternative explanations consistent with available data.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

苯多酸作为配体,因有多个可参与配位的羧基,因此,可以和稀土离子生成不同配比而结构特殊的化合物,同时这类化合物具有一系列有趣的性质。本论文选择1,2,4,5-苯四酸(H_4L),1,3,5-苯三酸(H_3L_I),1,2,4-苯三酸(H_3L_(II))和1,2,3-苯三酸(H_3L_(III))作为配体,合成了除P_m以外的十四个镧系元素和Y的络合物。对于稀土和均苯四酸的络合物,除得到了文献曾报导过的4:3组成外,还合成了一个新的系列,其组成为1:1的络合物:Ln·HL·nH_2O(Ln = La-Gd,Er,Y)和Ln·L·NH_4·nH_2O(Ln=Eu,Tb-Lu)。培养出了未见文献报导的稀土Er与均苯四酸络合物的单晶,晶体结构分析指出其组成为[ Er·L·3H_2O]·NH_4·4H_2O,中心离子和配体形成八配位络阴离子,呈畸变的四方反棱柱结构。对所合成的稀土苯多酸络合物(除稀土和1,2,3-苯三酸络合物外),进行了热分析研究,结果表明这类络合物具有很高的热稳定性,空气中,除Ce外,其分解温度均大于420 ℃。指出了络合物热分解机理,对于绝大部分稀土苯多酸络合物。分解分两步进行,第一步络合物脱水,第二步分解为氧化物。镧的苯多酸络合物其分解过程经碱式碳酸盐(LaO)_2 CO_3,最后分解为La_2O_3。络合物DTA分解峰温随稀土原子序有规律地变化,且不同的苯多酸系列络合物呈类似的变化规律,变价元素处于曲线峰谷的位置。测定Ln_4L_3·nH_2O系列络合物的脱水热及脱水和分解表观活化能。系统地研究了络合物在4000-100cm~(-1)范围内的FT-IR光谱,通过对羧基反对称和对称伸缩振动的分析,指出了络合物中羧基的可能配位形式。对组成为Ln·HL·nH_2O(Ln=La-Gd,Y),Ln·L·NH_4·nH_2O (Ln=Tb-Lu),LnL_I·nH_2O (Ln = La-Ho)和LnL_(II)·nH_2O (Ln=Pr-Tm)的络合物,指认了Ln-O链伸缩振动,其振动频率随稀土离子总角动量量子数呈类似“斜W”效应的变化。对于Ln_4L_3·nH_2O,LnL_I·nH_2O和LnL_(II)·nH_2O络合物,随着配体的不同,羧基反对称和对称伸缩振动频率差ΔV以ΔV_(1,3,5)BTA > ΔV_(PMA) > ΔV_(1,2,4)BTA的规律变化。研究了Eu和Tb苯多酸铬合物的萤光相对亮度及其萤光光谱,对Tb络合物,其萤光相对亮度随配体结构的变化有如下变化规律:PMA > 1,2,4 BTA≥1,2,3 BTA > 1,3,5 BTA。Tb的PMA络合物由于其发光强度较大,有可能在实际中得到应用。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Fe is still the commonly used dopant to fabricate semi-insulating(SI) InP, a key material for high-speed electronic and optoelectronic devices. High resolved absorption spectra of the internal d-d shell transitions at Fe2+ in InP and the related phonon sidebands and a series of iron related absorption Lines are presented. Detailed infrared absorption study of the characteristic spectra of four zero-phonon lines(ZPLs), which are attributed to transitions within the 5D ground state of Fe2+ (3d(6)) on the indium site in a tetrahedral crystal field of phosphorus atoms and their temperature effects are given.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

在前人对热带亚热带季风型气候条件下云南个旧砂矿、老挝Xaymomboun特区Ban Nameung铜多金属矿和Champasak省Boloven高原玄武岩等研究成果基础上,采用典型表生矿床实证解剖思路,选择个旧白云岩风化剖面、锡铅砂矿、锰结核、砂矿重选流程、Ban Nameung硫化氧化矿和Boloven玄武岩风化壳等对象,通过岩矿鉴定、主量微量元素地球化学、稀土元素地球化学、人工重砂、化学物相和微区分析等研究手段,研究这些矿床表生成矿物质来源、成矿机理、矿床地球化学特征和矿物工业可利用性等内容,并探索热带亚热带季风型气候条件下典型矿床表生成矿三个问题:(1)Sn、Pb、Mn、Ag、REE、Nb、Ta、Ga和Cd等元素表生富集成矿(矿化)规律;(2)上述元素成矿机理和工业利用可能性;(3)典型矿床其他20几种元素表生贫化与富集规律。研究获得如下主要认识: 1. 个旧地区燕山期以来持续抬升和亚热带季雨林的表生环境,使个旧地区大面积出露的碳酸盐岩风化形成强烈岩溶地貌,碳酸盐岩风化过程中CaO和MgO大量淋失,为砂矿提供了巨大容矿空间,同时碳酸盐地区碱性环境有利于原生硫化矿分解。含矿或不含矿白云岩、花岗岩、玄武岩、夕卡岩和原生硫化矿石等风化形成粘土矿物和铁锰氧化物,释放出Sn、Pb、Mn、Ga、Cd、Ag、In、Cu和Zn等元素,难风化重矿物如锡石表生残留富集,而粘土矿物和铁锰氧化物对成矿元素吸附是砂矿表生成因机理之一。 2. 个旧地区岩溶型砂矿形成机理为:(1)原生重矿物残留富集成矿,如锡石、磁铁矿。(2)金属硫化物残留成矿,如砂矿中残存大量方铅矿、黄铜矿、黄铁矿,是原生硫化物残留结果。(3)表生矿物富集成矿,如白铅矿、孔雀石、自然铅和自然铜等富集。(4)铁锰氧化物吸附和包裹成矿,如铁锰氧化物吸附Pb和Ga等元素,包裹含Pb和Zn微粒矿物。(5)锰结核吸附包裹成矿,锰结核吸附和包裹Sn、Pb和Cu等元素和微粒矿物。(6)类质同象成矿,如Ga和Al类质同象,Cd和Zn等类质同象成矿。(7)岩溶作用成矿,岩溶落水洞或溶洞内水流冲刷使锡石等重矿物富集成矿。元素表生成矿不仅是单一成矿作用结果,而是综合作用结果,如Pb有表生矿物富集成矿,也有铁锰氧化物吸附成矿。 3. 砂矿中锰结核是锰铁结核,主要成分为Fe2O3 、Al2O3、SiO2和MnO等,包裹了赤铁矿、方解石、云母、石英、蒙脱石、高岭石、白云石、钾长石等和锡石、白铅矿等矿物。锰结核中Mn、Sn、Pb、Ag、Ga、Cd和In富集成矿,Cu和Zn富集矿化,锰结核比砂矿更富集Mn、Pb和REE,其成矿机理应是吸附和包裹成矿元素或矿物使其富集成矿。 4. 个旧表生砂矿共生伴生组分复杂,有用矿物有锡石、方铅矿、白铅矿、黄铜矿、自然铅、自然铜、孔雀石、软锰矿、白钨矿、磁铁矿和褐铁矿等。模拟岩溶作用自然过程中砂矿矿物流向的源兴采选车间砂矿重选流程结果表明,锡铅精矿中Pb、Ga、Mo、Cd、In、Cu和Zn等金属总实收率仅为3.03%~6.44%,绝大部分金属留在了尾矿中。一段床和矿泥床分析中,Ag和Mn回收率低于0.66%~0.29%,Ag富集在硫化物态中,没有富集在铁锰氧化物态中;Mn富集在碳酸盐态中,没有铁锰氧化物态中。整个流程中Pb、Mn、Cu和Zn等富集在碳酸盐态矿物中,没有富集在硫化物态中。选矿流程没有利用具有潜在利用价值矿物如磁铁矿。重选流程解释了岩溶过程能富集Pb、Mn、Cu和Zn的碳酸盐矿物,不能富集这些元素的硫化矿物。 5. 老挝Ban Nameung硫化矿氧化初期,风化产物中Ag、Pb、Zn和Cu淋失,SiO2、K2O和CaO富集,风化后期Ag、Fe和Mn富集。硫化矿风化过程中,Au硫化物态部分变为有机态和铁锰氧化物态;Ag硫化物态部分变为铁锰氧化物态和有机态;Cu硫化物态部分变为铁锰氧化物态和碳酸盐态;Pb硫化物态、吸附态、碳酸盐态和铁锰氧化物态部分变为铁锰氧化物态、碳酸盐态和有机态;Zn硫化物态变为部分铁锰氧化物态、有机态、碳酸盐态和吸附态矿物。随着风化作用加强,上述几种相态比例还会改变。 6. 老挝Boloven新生代亚碱性玄武岩富Nb、Ta和Ga等微量元素,风化壳中REE、Nb、Ta和Ga已富集成矿,∑REE最高775×10-6~1003×10-6,(Nb2O5+Ta2O5)最高642×10-6~656×10-6,Ga最高81.6 ×10-6。风化壳中达到边界品位的(Nb2O5+Ta2O5)厚度有2m以上。REE可能存在于含P和Ti矿物中,也可能形成REE独立矿物。Nb、Ta和Ga应赋存在Ti、U、Zr和Th矿物中,其成矿应是重矿物表生残留富集结果,与粘土矿物吸附和三水铝石关系不紧密。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

http://www.archive.org/details/anorientallandof00freeuoft

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The research project takes place within the technology acceptability framework which tries to understand the use made of new technologies, and concentrates more specifically on the factors that influence multi-touch devices’ (MTD) acceptance and intention to use. Why be interested in MTD? Nowadays, this technology is used in all kinds of human activities, e.g. leisure, study or work activities (Rogowski and Saeed, 2012). However, the handling or the data entry by means of gestures on multi-touch-sensitive screen imposes a number of constraints and consequences which remain mostly unknown (Park and Han, 2013). Currently, few researches in ergonomic psychology wonder about the implications of these new human-computer interactions on task fulfillment.This research project aims to investigate the cognitive, sensori-motor and motivational processes taking place during the use of those devices. The project will analyze the influences of the use of gestures and the type of gesture used: simple or complex gestures (Lao, Heng, Zhang, Ling, and Wang, 2009), as well as the personal self-efficacy feeling in the use of MTD on task engagement, attention mechanisms and perceived disorientation (Chen, Linen, Yen, and Linn, 2011) when confronted to the use of MTD. For that purpose, the various above-mentioned concepts will be measured within a usability laboratory (U-Lab) with self-reported methods (questionnaires) and objective indicators (physiological indicators, eye tracking). Globally, the whole research aims to understand the processes at stakes, as well as advantages and inconveniences of this new technology, to favor a better compatibility and adequacy between gestures, executed tasks and MTD. The conclusions will allow some recommendations for the use of the DMT in specific contexts (e.g. learning context).

Relevância:

10.00% 10.00%

Publicador:

Resumo:

BACKGROUND & AIMS: The risk of progression of Barrett's esophagus (BE) to esophageal adenocarcinoma (EAC) is low and difficult to calculate. Accurate tools to determine risk are needed to optimize surveillance and intervention. We assessed the ability of candidate biomarkers to predict which cases of BE will progress to EAC or high-grade dysplasia and identified those that can be measured in formalin-fixed tissues. METHODS: We analyzed data from a nested case-control study performed using the population-based Northern Ireland BE Register (1993-2005). Cases who progressed to EAC (n = 89) or high-grade dysplasia =6 months after diagnosis with BE were matched to controls (nonprogressors, n = 291), for age, sex, and year of BE diagnosis. Established biomarkers (abnormal DNA content, p53, and cyclin A expression) and new biomarkers (levels of sialyl Lewis(a), Lewis(x), and Aspergillus oryzae lectin [AOL] and binding of wheat germ agglutinin) were assessed in paraffin-embedded tissue samples from patients with a first diagnosis of BE. Conditional logistic regression analysis was applied to assess odds of progression for patients with dysplastic and nondysplastic BE, based on biomarker status. RESULTS: Low-grade dysplasia and all biomarkers tested, other than Lewis(x), were associated with risk of EAC or high-grade dysplasia. In backward selection, a panel comprising low-grade dysplasia, abnormal DNA ploidy, and AOL most accurately identified progressors and nonprogressors. The adjusted odds ratio for progression of patients with BE with low-grade dysplasia was 3.74 (95% confidence interval, 2.43-5.79) for each additional biomarker and the risk increased by 2.99 for each additional factor (95% confidence interval, 1.72-5.20) in patients without dysplasia. CONCLUSIONS: Low-grade dysplasia, abnormal DNA ploidy, and AOL can be used to identify patients with BE most likely to develop EAC or high-grade dysplasia.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Demonstration of a tunable conductivity of the LaAlO3/SrTiO3 interfaces drew significant attention to the development of oxide electronic structures where electronic confinement can be reduced to the nanometer range. While the mechanisms for the conductivity modulation are quite different and include metal insulator phase transition and surface charge writing, generally it is implied that this effect is a result of electrical modification of the LaAlO3 surface (either due to electrochemical dissociation of surface adsorbates or free charge deposition) leading to the change in the two-dimensional electron. gas (2DEG) density at the LaAlO3/SrTiO3 (LAO/STO) interface. In this paper, using piezoresponse force microscopy we demonstrate a switchable electromechanical response of the LAO overlayer, which we attribute to the motion of oxygen vacancies through the LAO layer thickness. These electrically induced reversible changes in bulk stoichiometry of the LAO layer are a signature of a possible additional mechanism for nanoscale oxide 2DEG control on LAO/STO interfaces.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Esophageal adenocarcinoma is a cancer with rising incidence and poor survival. Most such cancers arise in a specialized intestinal metaplastic epithelium, which is diagnostic of Barrett's esophagus. In a genome-wide association study, we compared esophageal adenocarcinoma cases (n = 2,390) and individuals with precancerous Barrett's esophagus (n = 3,175) with 10,120 controls in 2 phases. For the combined case group, we identified three new associations. The first is at 19p13 (rs10419226: P = 3.6 × 10(-10)) in CRTC1 (encoding CREB-regulated transcription coactivator), whose aberrant activation has been associated with oncogenic activity. A second is at 9q22 (rs11789015: P = 1.0 × 10(-9)) in BARX1, which encodes a transcription factor important in esophageal specification. A third is at 3p14 (rs2687201: P = 5.5 × 10(-9)) near the transcription factor FOXP1, which regulates esophageal development. We also refine a previously reported association with Barrett's esophagus near the putative tumor suppressor gene FOXF1 at 16q24 and extend our findings to now include esophageal adenocarcinoma.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A Suão - Associação para o Desenvolvimento Comunitário, fundada em dezoito de Abril de 1998, localizada em São Miguel de Machede, freguesia do concelho de Évora, desenvolve a sua actividade focada na educação e aprendizagens comunitárias, desde o seu início. A Associação tem, neste momento, duzentos e cinquenta associados, membros ligados à comunidade (quer por serem pessoas com origem em São Miguel de Machede, quer por serem agentes participativos ou por estabelecerem, ainda, um laço profissional com a Instituição).

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A crescente evolução do conceito de RS conduziu as organizações a uma nova perspetiva. Atualmente, as organizações assumem um papel mais ativo e dinâmico perante os seus colaboradores e a sociedade. As práticas de RS implementadas promovem a maximização de lucro das empresas, mas também funcionam como um factor crucial de desenvolvimento das relações humanas e de diferenciação competitiva, que permitem o alcance de benefícios sociais e ambientais. A presente investigação teve como objetivo geral, analisar o impacto que a RS tem no processo de Identificação dos colaboradores com a organização e no seu EO, numa amostra constituída por 182 colaboradores. Os dados foram recolhidos através de um instrumento constituído por três escalas: a escala de Responsabilidade Social – Model of Corporate Social Responsibility (Quazi & O’Brien, 2000), a escala de Identificação Organizacional (Oliveira, 2008) e a escala de Empenhamento Organizacional (Rego, Cunha & Souto, 2006). Foram também registados alguns dados da organização e algumas variáveis demográficas dos inquiridos. Os resultados obtidos sugerem que a RS contribuiu positivamente para a IDO dos indivíduos, bem como no tipo de empenhamento e laço que os colaboradores estabelecem para com a organização. Verifica-se que a RS e a IDO têm um poder preditor sobre qualquer das dimensões do EO. De um modo geral, a adoção de políticas e práticas de RS constituem uma vantagem para as organizações, na medida em que os indivíduos fortalecem a sua Identificação com a organização, o que consequentemente irá refletir-se no seu empenhamento. Desta forma, as organizações que adotam políticas de RS estimulam o desenvolvimento de sentimentos identificativos e afiliativos.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Relatório da prática de ensino supervisionada, Mestrado em Ensino da Informática, Universidade de Lisboa, Instituto de Educação, 2011

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Double mariage, édition illustrée.Par le maître du pavillon Bu yue ; préface de Mo zhuang lao ren. Édition sans illustrations, gravée à la salle Zhen song.4 livres (18 hui).