995 resultados para 708
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讲故事作为学校和家庭教育儿童的有效手段,一直是国内外各研究机构的研究热点。目前的很多儿童讲故事软件以各种形式为儿童提供了故事创作工具,但是它们大多不能让儿童相互协作,也没有提供讲故事中的智能辅助。多用户输入技术具有节约设备成本和提高合作效率的优点,故事中的智能体具有动态地生成故事的功能,但是这两者在儿童软件方面的应用并不多,在儿童讲故事中引入这两个技术,可以提高讲故事的益智性与娱乐性。 在此研究背景下,本文研究多用户输入技术与故事中的智能体技术,结合笔式用户界面的优势,以儿童用户为中心,开发基于智能体的儿童协作讲故事系统。让多个儿童既能协同进行故事创作,也能与故事智能体一起交互地创作非线性的故事,享受合作与创作的乐趣。 本文的主要工作如下: 1、多用户输入研究 分离了各用户的输入数据,设计多用户输入下的事件处理机制,研究了多用户输入下的界面支持,并结合笔式用户界面,设计了常用命令的输入手势,使得系统接入多个指点输入设备后,就能支持多个用户共同进行操作,并给予用户各自的响应。 2、故事中智能体的研究 归纳了讲故事中使用的知识库,设计了情节智能体来保持故事的连贯性与管理用户的参与,设计了角色智能体来指导角色完成任务并管理情绪,使得在用户的参与下,智能体能根据故事目标,动态地生成故事。 3、故事显示的设计 研究了已有的适合儿童的角色设计工具,并在此基础上设计了故事显示的方法,在三维的故事世界中,采用角色设计工具的作品作为故事素材,加入角色与动作的渲染,将儿童讲故事的结果可视化。 4、系统的设计与实现 在以上研究的基础上,设计了多用户输入的识别方法、数据分析过程和事件处理机制,设计了知识库、情节智能体、角色智能体及它们三者之间的交互接口,结合儿童讲故事的应用,实现基于智能体的儿童协作讲故事系统。
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Ce3+ and/or Tb3+ doped LaPO4 nanofibers and microbelts have been prepared by a combination method of sol-gel process and electrospinning. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL), low voltage cathodoluminescence (CL) and time-resolved emission spectra as well as kinetic decays were used to characterize the resulting samples. SEM and TEM results indicate the as-formed precursor fibers and belts are smooth. and the as-prepared nanofibers and microbelts consist of nanoparticles. The doped rare-earth ions show their characteristic emission under ultraviolet excitation, i.e. Ce3+ 5d-4f and Tb3+ D-5(4)-F-7(j) (J = 6-3) transitions, respectively. The energy transfer process from Ce3+ to Tb3+ in LaPO4:Ce3+, Tb3+ nanofibers was further studied by the time-resolved emission spectra.
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列举若干实例,从习惯用法、具体含义和特殊用法讨论数字“两”、“二”和“2”的使用方法。
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Rabies virus was used as the antigen to immunize laying chickens. Anti-rabies virus immunoglobulin Y(IgY) was isolated from yolks of the eggs laid by these chickens using a two-step salt precipitation and one-step gel filtration protocol. The purified IgY was reduced with dithiothreitol, and heavy chains (HC) and light chains (LC) were obtained. In addition, the purified IgY was digested with pepsin and the fragment with specific antigen binding properties (Fab) was produced. Using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOFMS), the average molecular weights of IgY, HC, LC, and Fab were determined as 167 250, 65 105, 18 660, and 45,359 Da, respectively. IgY has two structural differences compared with mammalian IgGs. First, the molecular weight of the heavy chain of IgY is larger than that of its mammalian counterpart, while the molecular weight of the light chain of IgY is smaller. Second, upon pepsin digestion, anti-rabies virus IgY is degraded into Feb, in contrast to mammalian IgG, which has been reported to be degraded into F(ab')(2) under the same conditions. Copyright (C) 2001 John Wiley & Sons, Ltd.
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The toughening effect of the shell content of a core-shell latex polymer poly(butyl acrylate) (PBA)-cs-poly(methyl methacrylate) (PMMA) on its blends with polycarbonate (PC) was studied. The changes of mechanical properties, morphology, and compatibility of the blends of PC/PBA-cs-PMMA with the change of the shell thickness of PBA-cs-PMMA were investigated. It is interesting to notice that mechanical properties of the blends are very sensitive to the shell thickness (i.e., shell content), and that there is a possibility to adjust the impact and tensile properties of the blend by selecting a PBA-cs-PMMA with a proper core/shell ratio. Hence, a modified PC material with balanced mechanical properties may be prepared.
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The positive- and negative-ion electrospray ionization mass spectra of beta-cyclodextrin-amino acids complexes in NH4Ac buffer have been reported in this paper. Compared with positive-ion ESI mass spectra of beta-cyclodextrin-amino acids complexes under the same condition, negative-ion mass spectra obtained for inclusion complexes of beta-cyclodextrin (CD) with tyrosine, phenylalanine and tryptophan, respectively, were completely dominated by deprotonated complex ions and [CD-H](-) ion which is the only daughter ion in collision-induced dissociation (CID) experiment of deprotonated complexes, The results indicated that the charged position for protonated and deprotonated complexes is different from each other. In addition, two complex ions for the same complex have similarly relative dissociation energies, which are higher than that of [CD+NH4](+), indicating that complexes observed in gasphase are not electrostatic adducts at all but complexes formed by hydrogen bonds.
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近年来,电喷雾质谱作为“软电离”质谱新技术广泛应用于生命科学领域[1,2],1991年Ganem等[3]首次利用电喷雾质谱(ESI-MS)对溶液中特异性免疫蛋白质-药物复合物进行了研究.目前生物酶-底物/抑制剂、DNA-药物、蛋白质-配体及生物大分子…
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Lectins are a family of carbohydrate-recognition proteins which play crucial roles in innate immunity. In this study, a new lectin (CfLec-2) gene was cloned from Chlamys farreri by EST and RACE approaches. The full-length cDNA of CfLec-2 was composed of 708 bp, encoding a typical Long form carbohydrate-recognition domain of 130 residues. The deduced amino acid sequence showed high similarity to Brevican in Homo sapiens, C-type lectin-1 and lectin-2 in Anguilla japonica. The cDNA fragment encoding the mature peptide of CfLec-2 was recombined into plasmid pET-32a (+) and expressed in Escherichia coli Rosseta-Gami (DE3). The recombinant CfLec-2 (rCfLec-2) protein exhibited aggregative activity toward Staphylococcus haemolyticus, and the agglutination could be inhibited by D-mannose but not EDTA or D-galactose, indicating that CfLec-2 was a Ca2+ independent lectin. Moreover, rCfLec-2 could suppress the growth of E. coli TOP10F'. These results suggested that CfLec-2 was perhaps involved in the recognition and clearance of bacterial. pathogens in scallop. (C) 2007 Elsevier Ltd. All rights reserved.
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坛紫菜(Porphyra haitanensis),属红藻门(Rhodophyta),红毛菜科(Bangiacease)紫菜属(Porphyra),是我国大规模养殖的重要经济海藻之一,主要产于我国南方沿海如福建、广东、浙江等地。紫菜作为中药,具有“补肾养心,利水消肿”的功效,实验室前期所作的工作表明,坛紫菜多糖具有良好的抗衰老作用。分子量对多糖生物活性有重大影响,本文以福建沿海的坛紫菜为原料,对坛紫菜多糖(P)的降解方法和该紫菜多糖的抗衰老活性与分子量的关系展开了研究。 本论文首次将植物生长发育过程中发生的抗坏血酸和过氧化氢反应体系应用于坛紫菜多糖的降解。抗坏血酸和过氧化氢的浓度及两者的比例是该降解方法的主要影响因素。采用该法制备了分子量分别为50、30、13、8.2和2.7 kD 的P1、P2、 P3、P4和P5五种产品。其中P1、P2和P3产品的红外图谱与原料多糖的红外图谱一致,表明这两种多糖的化学结构在降解过程中并未发生改变,而P4和P5样品的红外图谱显示该样品中出现了少量的羧基。 本论文还首次对各产物进行了抗氧化、免疫调节、抗疲劳、延长寿命、抗老年痴呆等活性的筛选与研究,具体结果如下: 采用化学法对五种降解多糖和原料多糖的抗氧化活性进行研究。结果表明分子量对坛紫菜多糖清除各种自由基能力的影响是不同的。降解之后,坛紫菜多糖清除超氧阴离子的能力有所下降,与金属离子的螯合能力几乎全部丧失,但是多糖清除羟基自由基的能力变化甚微。降解之后,坛紫菜多糖清除有机自由基的能力和还原能力显著提高,随分子量的降低这两种能力明显加强,其中P4样品清除有机自由基能力最强,而分子量最小的P5样品还原能力最突出。 通过测定T、B淋巴细胞增殖率考察了五种降解多糖和原料多糖的免疫调节作用。研究表明:不同分子量坛紫菜多糖均具有免疫调节作用,可显著促进小鼠脾脏T淋巴细胞增殖,显著抑制小鼠脾脏B淋巴细胞增殖。P2和P4样品效果强于其它降解产品和原料。 通过测定小鼠游泳和爬杆时间考察了三种降解多糖P1、P2、P4和原料多糖的耐疲劳作用。研究表明:坛紫菜多糖降解产品耐疲劳作用要优于原料多糖P。P1、P2和P4通过提高小鼠肝糖原储备从而达到显著延长小鼠爬杆时间和负重游泳时间的功效。 通过测定D. melanogaster果蝇寿命、热耐受时间和性活力考察了三种降解多糖P1、P2、P4和原料多糖对寿命及生命活力的影响。研究表明:分子量对坛紫菜多糖对果蝇的寿命和生命活力有很大影响。降解使坛紫菜原料多糖P对果蝇的延长寿命和提高生命活力作用得到加强。在果蝇正常代谢状态下,降解产品中分子量较大的P1和P2作用更显著,而在热应激状态下,降解产品中分子量较小的P4作用更突出。 采用小鼠侧脑室注射Aβ1-40致痴呆模型考察了样品P1改善认知功能的作用。研究表明:P1通过降低皮层和海马组织乙酰胆碱酯酶活性,显著提高乙酰胆碱转移酶的活性,有效改善痴呆小鼠的认知能力,使之水迷宫游泳时间缩短,使避暗潜伏期延长。 为探讨P1样品改善小鼠认知功能的作用机制,本文采用Aβ25-35损伤神经母细胞瘤株SH-SY5Y模型对P1样品的神经细胞的保护作用进行了研究。结果显示低浓度下P1对该损伤模型具有显著保护作用,高浓度下表现出显著的抑制作用。 本文的研究表明坛紫菜多糖在降解之后生物活性得到显著改善。分子量对坛紫菜多糖活性影响很大。总的看来,在体外实验中,分子量越低其体外抗氧化活性和免疫调节作用越显著,但是,在体内实验中,降解产品中分子量最大的P1样品能更有效地改善小鼠疲劳程度、延长果蝇的寿命及热耐受时间,P1样品还能显著改善痴呆小鼠记忆功能。不同分子量坛紫菜多糖体内和体外生物活性的这种差异还需要进行深入研究。
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The objective was to identify an appropriate cryoprotectant and protocol for vitrification of red sea bream (Pagrus major) embryos. The toxicity of five single-agent cryoprotectants, dimethyl sulfoxide (DMSO), propylene glycol (PG), ethylene glycol (EG), glycerol (GLY), and methyl alcohol (MeOH), as well as nine cryoprotectant mixtures, were investigated by comparing post-thaw hatching rates. Two vitrifying protocols, a straw method and a solid surface vitrification method (copper floating over liquid nitrogen), were evaluated on the basis of post-thaw embryo morphology. Exposure to single-agent cryoprotectants (10% concentration for 15 min) was not toxic to embryos, whereas for higher concentrations (20 and 30%) and a longer duration of exposure (30 min), DMSO and PG were better tolerated than the other cryoprotectants. Among nine cryoprotectant mixtures, the combination of 20% DMSO + 10% PG + 10% MeOH had the lowest toxicity after exposure for 10 min or 15 min. High percentages of morphologically intact embryos, 50.6 +/- 16.7% (mean +/- S.D.) and 77.8 +/- 15.5%, were achieved by the straw vitrifying method (20.5% DMSO + 15.5% acetamide + 10% PG, thawing at 43 degrees C and washing in 0.5 M sucrose solution for 5 min) and by the solid surface vitrification method (40% GLY, thawing at 22 degrees C and washing in 0.5 M sucrose solution for 5 min). After thawing, morphological changes in the degenerated embryos included shrunken yolks and ruptured chorions. Furthermore, thawed embryos that were morphologically intact did not consistently survive incubation. (C) 2007 Elsevier Inc. All rights reserved.
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高原584是中国科学院西北高原生物研究所生态农业研究中心郜和臣研究员等培育的节水型春小麦新品种,原代号91D58-4,1999年11月25日经青海省农作物品种审定委员会审定通过,定名为"高原584",2003年2月26日又通过甘肃省农作物品种审定委员会第十九次会议审定。
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赣杭构造带中西段发育的基性脉岩以辉绿岩为主,SiO2质量分数为46.88%-53.69%,从西段至中段总体显示亚碱性至碱性的变化规律。微量元素相对富集大离子亲石元素(LILE)和轻稀土元素(LREE),亏损高场强元素(HFSE)和重稀土元素(HREE)。稀土元素总量具有明显的规律性分布,即呈中段(广丰)-中西段交接部(余江、东乡)-西段(永丰、峡江)的递减趋势。西段永丰地区有明显的负Eu异常。Sr、Nd同位素变化比较大((^87Sr/^86Sr)i为0.704 635-0.708 769,(^143Nd/^144Nd)i为0.512 173-0.512 758,εNd(t)为-6.8-+5.6),暗示其源区具有明显的不均一性。具体表现为中西段结合部(东乡、余江)及西段(峡江)为亏损地幔,而西段(永丰)和中段(广丰)为偏向EMⅡ型富集地幔来源。基性脉岩总体表现为地幔部分熔融的产物,西段(永丰)受到较明显的分离结晶作用影响。在古太平洋板块俯冲影响下产生的弧后拉张作用以及造成的构造带重新活化作用对基性脉岩的形成产生了重要影响,地区间岩石地球化学特征上的差异主要与流体对岩浆源区交代程度的不同有关.
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RESUMO: O presente trabalho teve como objetivo avaliar a influência de densidades de semeadura de genótipos de girassol em suas características agronômicas. O experimento foi realizado no campo experimental do IFMT, Campus Campo Novo do Parecis - MT, entre os meses de fevereiro e junho de 2015. O delineamento experimental utilizado foi de blocos casualizados, em esquema fatorial 5 x 5, sendo cinco genótipos de girassol AGUARÁ 04, GNZ NEON, HÉLIO 251, SYN 045 e SYN 3950HO) e cinco populações de plantas (30.000, 37.500, 45.000, 52.500 e 60.000 plantas ha-1), com 3 repetições. Foram analisadas as características altura de planta, diâmetro da haste, tamanho do capítulo, massa de mil aquênios e produtividade de aquênios. Os dados obtidos foram submetidos à análise de variância, seguido de teste Tukey para cultivares e análise de regressão para as diferentes populações de plantas (p<0,05). O genótipo SYN 045 apresentou a maior produtividade de aquênios, 1.708,90 kg ha-1 enquanto que a população de 60.150 plantas ha-1 foi a que possibilitou a maior produtividade de aquênios, 2.391,92 kg ha-1. ABSTRACT: This study aimed to evaluate the influence of sowing density of sunflower genotypes on their agronomic characteristics. The experiment was conducted in the experimental field of IFMT, Campus Campo Novo do Parecis - MT, between February and June 2015. The experimental design was randomized blocks in a factorial 5 x 5, five sunflower genotypes (AGUARÁ 04, GNZ NEON, HÉLIO 251, SYN 045 and SYN 3950HO) and five plant populations (30,000, 37,500, 45,000, 52,500 and 60,000 plants ha-1) with 3 repetitions. Plant height, stem diameter, chapter length, mass thousand achenes and achenes productivity were analyzed. The data were submitted to analysis of variance followed by Tukey test for cultivars and regres. -