920 resultados para differentiate


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Mass spectrometry is not able to differentiate NOx and N2 from other interferences (e.g. CO and C2H4) in the deNOx reactions. In the present study, a quantitative method for analysis of NOx and N2 simultaneously in these reactions with an assisted converter operated at higher temperature under O2-rich condition, which eliminates the interferences, is developed. The NOx conversion from this method is comparable to the one from an Automotive Emission Analyser equipped with NOx electrochemical sensor. Two types of deNOx reactions are tested in terms of selectivity of N2 production. The application of this method is discussed.

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Over expression of cyclin A in human tumors has been linked to cancer by various experimental lines of evidence. However, physical and spectral characterization of the human cyclin A gene and its interactions with anticancer drugs have not been reported. Our gene sequence analysis, singular value decomposition method and melting studies in the presence of antitumor agents, daunomycin, doxorubicin and Hoechst 33258 showed that cyclin A gene had both AT-rich and GC-rich domains. For a ligand with unknown DNA binding specificity, this gene sequence can be used to differentiate its DNA binding preference.

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Seven structure analogical flavonoid aglycones have been analyzed using electrospray ionization tandem mass spectrometry (ESI-MSn) in the negative-ion mode. The spectra obtained ESI-MSn allowed us to propose plausible schemes for their fragmentation mechanism. By analyzing the product ions spectra of deprotonated molecule ions [M-H](-), some neutral diagnostic losses and specific retro Diels-Alder fragments were obtained. By using all of these characteristic fragment ions we can specially differentiate the flavone isomer.

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To improve the mechanics properties of polyurethane materials at a high or low temperature, a hydroxy compound N-100 of HDI was synthesized, The structure analysis and characterization were made by NMR (H-1, C-13, H-1-H-1 COSY, C-13-H-1 COSY), In addition, quantitative description of the network was made on the basis of some ideal assumptions, 1D and 2D NMR can differentiate four sorts of carbonyl groups and establish the connections of all carbon and hydrogen atoms of mixed structures that originated from five different substitutions, Besides, the alkene and isocyanate, urea, biuret and trimerized isocyanuric groups were also detected, Therefore, the structure of N-100 was suggested be a polyisocyanate with complicated network which contained nitrogen atom as cross-linkage, isocyanate and alkene as end groups, The consistence of calculated values with tested values of isocyanate content, mean function degree and mean molecular weight demonstrated the correct of structure characterization and the validity of network description.

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Polysiphonia urceolata is one type of potential commercial red seaweeds used for breeding and cultivation, because of its significant biochemical and biomedical application. However, the information of breeding and seedling incubation for cultivation is limited, especially the early development. In this study, tetrasporohyte and gametophyte of P. urceolata were taken as the study materials in Huiquan Bay, Qingdao, China. The cleaned and sterilized tetrasporophytes and gametophytes were pre-cultured in sterilized seawater, then nurtured at 18A degrees C, 25 mu mol photons m(-2) s(-1) in 12:12 h (light:dark) photoperiod. Continuous observation under microscope showed that the early development consists of bipolar division stage and seedling stage. In the division stage, tetraspores germinate into bipolar sporelings that further differentiate into a colorless rhizoidal portion and a lightly pigmented upright shoot. The lightly pigmented rhizoidal cell develops to a rhizoid and the larger pigmented cell transforms to an erect axis. In the seedling stage, several quasi-protuberances appear on the erect axis and form juvenile seedlings. The results demonstrate the culture of P. urceolata from tetraspores under laboratory conditions.

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Porphyra katadae Miura var. hemiphylla Tseng et T. J. Chang, a species distributed around the Liaodong and Shandong Peninsulas of China, produces gametophytes from late winter to early spring. These are monoecious with male and female reproductive tissues in distinct halves or sectors. Vegetative tissues from sectors expected to differentiate into sexual tissue were cultured in the laboratory. Male and female reproductive organs, as well as conchocelis and blades, were differentiated from these tissues. The male and female reproductive tissues were in patches and mixed on the cultured tissue pieces. This was quite different from the wild-type sectored individuals. The F-1 conchospore germlings also produced monospores, carposporangia, spermatangia and conchocelis. These carposporangia and spermatangia were in patches and were mixed on the F-1 fronds. The results imply that P. katadae var. hemiphylla is possibly sex-differentiated rather than sex-determined. This is the first report of such a dimorphic life history in the genus Porphyra.

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数值模式是潮波研究的一种有利手段,但在研究中会面临各种具体问题,包括开边界条件的确定、底摩擦系数和耗散系数的选取等。数据同化是解决这些问题的一种途径,即利用有限数量的潮汐观测资料对潮波进行最优估计,其根本目的是迫使模型预报值逼近观测值,使模式不要偏离实际情况太远。本文采用了一种优化开边界方法,沿着数值模型的开边界优化潮汐水位信息,目的是设法使数值解在动力约束的意义下接近观测值,获得研究区域的潮汐结果。边界值由指定优化问题的解来定,以提高模拟区域的潮汐精度,最优问题的解是基于通过开边界的能量通量的变化,处理开边界处的观测值与计算值之差的最小化。这里提供了辐射型边界条件,由Reid 和Bodine(本文简称为RB)推导,我们将采用的优化后的RB方法(称为ORB)是优化开边界的特殊情况。 本文对理想矩形海域( E- E, N- N, 分辨率 )进行了潮波模拟,有东部开边界,模式采用ECOM3D模式。对数据结果的误差分析采用,振幅平均偏差,平均绝对偏差,平均相对误差和均方根偏差四个值来衡量模拟结果的好坏程度。 需要优化入开边界的解析潮汐值本文采用的解析解由方国洪《海湾的潮汐与潮流》(1966年)方法提供,为验证本文所做的解析解和方文的一致,本文做了其第一个例子的关键值a,b,z,结果与其结果吻合的相当好。但略有差别,分析的可能原因是两法在具体迭代方案和计算机保留小数上有区别造成微小误差。另外,我们取m=20,得到更精确的数值,我们发现对前十项的各项参数值,取m=10,m=20各项参数略有改进。当然我们可以获得m更大的各项参数值。 同时为了检验解析解的正确性讨论m和l变化对边界值的影响,结果指出,增大m,m=20时,u的模最大在本身u1或u2的模的6%;m=100时,u的模最大在本身u1或u2的模的4%;m再增大,m=1000时,u的模最大在本身u1或u2的模的4%,改变不大。当l<1时, =0处u的模最大为2。当l=1时, =0处u的模最大为0.1,当l>1时,l越大,u的模越小,当l=10时,u的模最大为0.001,可以认为为0。 为检验该优化方法的应用情况,我们对理想矩形区域进行模拟,首先将本文所采用的优化开边界方法应用于30m的情况,在开边界优化入开边界得出模式解,所得模拟结果与解析解吻合得相当好,该模式解和解析解在整个区域上,振幅平均绝对偏差为9.9cm,相位平均绝对偏差只有4.0 ,均方根偏差只有13.3cm,说明该优化方法在潮波模型中有效。 为验证该优化方法在各种条件下的模拟结果情况,在下面我们做了三类敏感性试验: 第一类试验:为证明在开边界上使用优化方法相比于没有采用优化方法的模拟解更接近于解析解,我们来比较ORB条件与RB条件的优劣,我们模拟用了两个不同的摩擦系数,k分别为:0,0.00006。 结果显示,针对不同摩擦系数,显示在开边界上使用ORB条件的解比使用RB条件的解无论是振幅还是相位都有显著改善,两个试验均方根偏差优化程度分别为84.3%,83.7%。说明在开边界上使用优化方法相比于没有采用优化方法的模拟解更接近于解析解,大大提高了模拟水平。上述的两个试验得出, k=0.00006优化结果比k=0的好。 第二类试验,使用ORB条件确定优化开边界情况下,在东西边界加入出入流的情况,流考虑线性和非线性情况,结果显示,加入流的情况,潮汐模拟的效果降低不少,流为1Sv的情况要比5Sv的情况均方根偏差相差20cm,而不加流的情况只有0.2cm。线性流和非线性流情况两者模式解相差不大,振幅,相位各项指数都相近, 说明流的线性与否对结果影响不大。 第三类试验,不仅在开边界使用ORB条件,在模式内部也使用ORB条件,比较了内部优化和不优化情况与解析解的偏差。结果显示,选用不同的k,振幅都能得到很好的模拟,而相位相对较差。另外,在内部优化的情况下,考虑不同的k的模式解, 我们选用了与解析解相近的6个模式解的k,结果显示,不同的k,振幅都能得到很好的模拟,而相位较差。 总之,在开边界使用ORB条件比使用RB条件好,振幅相位都有大幅度改进,在加入出入流情况下,流的大小对模拟结果有影响,但线形流和非线性流差别不大。内部优化的结果显示,模式采用不同的k都能很好模拟解析解的振幅。

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红毛菜(Bangia Lyngb.)属于红藻门,与紫菜属同属红毛菜科,其味道和营养都优于紫菜。目前红毛菜栽培产业已在我国福建莆田展开,但栽培技术还有待提高。海藻栽培技术的发展和成熟依赖于对其生长发育过程的认识。本研究针对红毛菜发育过程及相关光合生理展开,并初步探讨了一采自山西娘子关泉淡水红毛菜群体(FWB)的系统地位。 色素突变标记的壳孢子萌发特征表明最初两次分裂产生的4细胞决定了完整植株的形态建成。成熟植株,为雌雄异体。雌性生殖器果胞的标志性分化结构为原始受精丝,环境因子是促发原始受精丝发展的外部因素,其膨大程度随受精的延迟而增大。原孢子是主要的无性生殖孢子类型,在不良环境中,藻体也会形成内生孢子或休眠包囊,或者藻体断裂后重新形成完整的植株。 红毛菜的生长发育很大程度上受环境因子的控制。高温不利于配子体的发育,15-20 ºC比较适宜。红毛菜无性繁殖的最适温度-光照组合为20 ºC-8 h,有性繁殖为15 ºC-12h。 不同发育阶段,PSII实际光合效率(Y(II))与细胞的健康状况以及光合器官完整性及其在细胞内的分布有关,而与细胞的类型关系不大。健康的假根细胞、已分化未成熟的精子以及果孢子细胞均具有很高的Y(II)。色素体由中间位变为围周位,中央大液泡(营养藻丝)和大小纤维囊泡(成熟孢子与精子)的产生,使得细胞Y(II)降低。刚放散的壳孢子Y(II)很低,说明在壳孢子由贝壳基质释放到自由水体过程,光合作用受到一定程度抑制;而2h后,Y(II)开始恢复,rbcL的转录水平非常高,为孢子的萌发储备物质和能量需求。 在失水和低盐胁迫下,藻体均维持较高的Y(II)。干出处理至藻体重量不再变化,复水后Y(II)可回复初始水平。海生红毛菜在100%淡水培养基中(约20ºC)培养7天后,部分雄性藻体依然活着。从而体现了红毛菜位居高潮带的生理优势。 FWB终生行无性繁殖,藻体形态与发生以及染色体数目(4条)与海生群体没有区别。而rbcL-rbcS Spacer序列显示,红毛菜海生群体(无性和有性)具有完全相同的序列,而FWB与它们有5bp差异,但是与欧洲、北美地区的淡水群体仅1bp不同,初步说明所有淡水红毛菜群体具有共同的原始起源。

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Vision plays an important role in the living habits of animals, especially in feeding. We investigated the postnatal development of retina in root vole Microtus oeconornus. The result shows that the retina of the M. oeconornus is very primitive before postnatal day (PD) 3. The neuroblastic layer does not differentiate and makes up more than half of the retina layer. The outer plexiform layer (OPL) first comes into existence at PDS. At PD6, as the presence of the OPL becomes obvious, the outer nuclear layer (ONL) and inner nuclear layer (INL) are much clearer. At PD18, the retina is similar to an adult retina and each layer becomes distinct. The thickness and cell density of the ganglion cell layer (GCL) and ONL during different postnatal days were also examined. These results show that the thickness and density of ONL increase during ontogeny, while the thickness and density of GCL decrease. Compared with Rattus norvegicus, Apodemus agrarius , Cricetulus triton, Microtus mandarinus , Myospalax cansus , Spermophilus dauricus and Sciurotamias davidianus, the histological structure of the retina of M. oeconornus is between that of nocturnal and diurnal rodents.

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The loess-paleosols in the Chinese loess plateau and Europe are the main eolian sediment sequences in mid-latitude area of north hemisphere. They record not only the paleoclimatic and paleoenvironmental processes since the last interglacial, but also the configuration of magnetic field during polarity transition. Comparisons of environmental magnetism, paleomagnetism and climate proxy analysis has been made for the loess/paleosol sequences in Datong and Czech Republic. The Datong loess/paleosol sequence is composed of the Holocene soil SO, the last glacial loess LI, the last interglacial soil SI and the upper penultimate loess L2. A basalt layer occurs in L2. The main magnetic minerals in LI and SI are magnetite, maghemite and ilmenite. The presence of local volcanic elastics in the loess and the characteristics of the magnetic minerals indicate that there are local materials in Datong loess, which differentiate the Datong loess from the central and eastern loess of the Chinese Loess Plateau. In addition, there are four polarity events in Datong loess, which are generally consistent with Gothenburg> Mono Lake, Laschamp and Blake events. Some signals of the East Asia monsoon were recorded in the Datong loess/paleosol sequences. Magnetic susceptibility, the content of >63um grains and the organic matter are used as climate proxies, which are similar to those of the typical eolian sediments in the loess plateau. In addition, it is possible that the Datong loess also recorded the Younger Dryas and the climatic fluctuations during the Holocene. The main magnetic minerals in the loess/paleosol at Znojmo section are magnetite, maghemite, hematite, pyrite, pyrrhotite and goethite. The morphology of these grains reveals that the iron sulfides originated from the eluvium loam above hypothetical ore deposits in the vicinity of the section or glaciofluvial sediments from nearby glacial margins. The pattern of the susceptibility variation at Dolni Vestonice section is coincident with that of the organic matter content. The grain size variation along the section recorded the climate instability since the last interglacial. The climate events in the Dolni Vestonice section may be correlated with the Heinrich events recorded in North Atlantic sediments, suggesting they controlled by the same marine-continent climate system.

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Population research is a front area concerned by domestic and overseas, especially its researches on its spatial visualization and its geo-visualization system design, which provides a sound base for understanding and analysis of the regional difference in population distribution and its spatial rules. With the development of GIS, the theory of geo-visualization more and more plays an important role in many research fields, especially in population information visualization, and has been made the big achievements recently. Nevertheless, the current research is less attention paid to the system design for statistical-geo visualization for population information. This paper tries to explore the design theories and methodologies for statistical-geo-visualization system for population information. The researches are mainly focused on the framework, the methodologies and techniques for the system design and construction. The purpose of the research is developed a platform for population atlas by the integration of the former owned copy software of the research group in statistical mapping system. As a modern tool, the system will provide a spatial visual environment for user to analyze the characteristics of population distribution and differentiate the interrelations of the population components. Firstly, the paper discusses the essentiality of geo-visualization for population information and brings forward the key issue in statistical-geo visualization system design based on the analysis of inland and international trends. Secondly, the geo-visualization system for population design, including its structure, functionality, module, user interface design, is studied based on the concepts of theory and technology of geo-visualization. The system design is proposed and further divided into three parts: support layer, technical layer, user layer. The support layer is a basic operation module and main part of the system. The technical layer is a core part of the system, supported by database and function modules. The database module mainly include the integrated population database (comprises spatial data, attribute data and geographical features information), the cartographic symbol library, the color library, the statistical analysis model. The function module of the system consists of thematic map maker component, statistical graph maker component, database management component and statistical analysis component. The user layer is an integrated platform, which provides the functions to design and implement a visual interface for user to query, analysis and management the statistic data and the electronic map. Based on the above, China's E-atlas for population was designed and developed by the integration of the national fifth census data with 1:400 million scaled spatial data. The atlas illustrates the actual development level of the population nowadays in China by about 200 thematic maps relating with 10 map categories(environment, population distribution, sex and age, immigration, nation, family and marriage, birth, education, employment, house). As a scientific reference tool, China's E-atlas for population has already received the high evaluation after published in early 2005. Finally, the paper makes the deep analysis of the sex ratio in China, to show how to use the functions of the system to analyze the specific population problem and how to make the data mining. The analysis results showed that: 1. The sex ratio has been increased in many regions after fourth census in 1990 except the cities in the east region, and the high sex ratio is highly located in hilly and low mountain areas where with the high illiteracy rate and the high poor rate; 2. The statistical-geo visualization system is a powerful tool to handle population information, which can be used to reflect the regional differences and the regional variations of population in China and indicate the interrelations of the population with other environment factors. Although the author tries to bring up a integrate design frame of the statistical-geo visualization system, there are still many problems needed to be resolved with the development of geo-visualization studies.

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Theories of Visual search generally differentiate between bottom-up control and top-down control. Bottom-up control occurs when visual selection is determined by the stimulus properties in the search field. Top-down control takes place when observers are able to select those stimuli that are in line with their attentional sets. Pure stimulus-driven capture and contingent capture are two main theories on attentional capture by now, in which, theory of pure capture more emphasize bottom-up control, while theory of contingent capture more emphasize top-down control. Besides those two theories, Perceptual load theory of attention provides completely new perspective to explain attentional capture. The aim of this study is to investigate the mechanism of attentional capture in visual search on the basis of the existing theory of attentional capture and Perceptual load theory of attention. Three aspects of questions were explored in this study, which includes: the modulation role of perceptual load on attentional capture; the influence of search mode on attentional capture; and the influence of stimuli’s spatial and temporal characteristics on attentional capture. The results showed that: (1) Attentional capture was modulated by perceptual load in both conditions in which perceptual load manipulated either by amount of stimuli or similarity of stimuli. (2) Search mode did influence attentional capture, but more important, which was also modulated by perceptual load. (3) The spatial characteristics of congruent and incongruent distractor did influence attentional capture, specifically, the further the distractor from the target, the more interference effect the distractor had on visual search. (4) The temporal characteristics of distractor did influence attentional capture, specifically, the pattern of results from the study in which distractor were presented after the search display, were similar to those from the study in which distractors were presented before the search display. In sum, the results indicated that attentional capture are controlled not only by bottom-up factors, top-down factors but also modulated by available attention resources. These findings contribute to resolve the controversy for mechanism of attentional capture. And the potential application of this research was discussed.

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In current days, many companies have carried out their branding strategies, because strong brand usually provides confidence and reduce risks to its consumers. No matter what a brand is based on tangible products or services, it will possess the common attributes of this category, and it also has its unique attributes. Brand attribute is defined as descriptive features, which are intrinsic characteristics, values or benefits endowed by users of the product or service (Keller, 1993; Romaniuk, 2003). The researches on models of brand multi-attributes are one of the most studied areas of consumer psychology (Werbel, 1978), and attribute weight is one of its key pursuits. Marketing practitioners also paid much attention to evaluations of attributes. Because those evaluations are relevant to the competitiveness and the strategies of promotion and new product development of the company (Green & Krieger, 1995). Then, how brand attributes correlate with weight judgments? And what features the attribute judgment reaction? Especially, what will feature the attribute weight judgment process of consumer who is facing the homogeneity of brands? Enlightened by the lexical hypothesis of researches on personality traits of psychology, this study choose search engine brands as the subject and adopt reaction time, which has been introduced into multi-attributes decision making by many researchers. Researches on independence of affect and cognition and on primacy of affect have cued us that we can categorize brand attributes into informative and affective ones. Meanwhile, Park has gone further to differentiate representative and experiential with functional attributes. This classification reflects the trend of emotion-branding and brand-consumer relationship. Three parts compose the research: the survey to collect attribute words, experiment one on affective primacy and experiment two on correlation between weight judgment and reaction. The results are as follow: In experiment one, we found: (1) affect words are not rated significantly from cognitive attributes, but affect words are responded faster than cognitive ones; (2) subjects comprehend and respond in different ways to functional attribute words and to representative and experiential words. In experiment two, we fund: (1) a significant negative correlation between attributes weight judgment and reaction time; (2) affective attributes will cause faster reaction than cognitive ones; (3) the reaction time difference between functional and representative or experiential attribute is significant, but there is no different between representative and experiential. In sum, we conclude that: (1): In word comprehension and weight judgment, we observed the affective primacy, even when the affect stimulus is presented as meaningful words. (2): The negative correlation between weight judgment and reaction time suggest us that the more important of attribute, the quicker of the reaction. (3): The difference on reaction time of functional, representative and experiential reflects the trend of emotional branding.

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A computer may gather a lot of information from its environment in an optical or graphical manner. A scene, as seen for instance from a TV camera or a picture, can be transformed into a symbolic description of points and lines or surfaces. This thesis describes several programs, written in the language CONVERT, for the analysis of such descriptions in order to recognize, differentiate and identify desired objects or classes of objects in the scene. Examples are given in each case. Although the recognition might be in terms of projections of 2-dim and 3-dim objects, we do not deal with stereoscopic information. One of our programs (Polybrick) identifies parallelepipeds in a scene which may contain partially hidden bodies and non-parallelepipedic objects. The program TD works mainly with 2-dimensional figures, although under certain conditions successfully identifies 3-dim objects. Overlapping objects are identified when they are transparent. A third program, DT, works with 3-dim and 2-dim objects, and does not identify objects which are not completely seen. Important restrictions and suppositions are: (a) the input is assumed perfect (noiseless), and in a symbolic format; (b) no perspective deformation is considered. A portion of this thesis is devoted to the study of models (symbolic representations) of the objects we want to identify; different schemes, some of them already in use, are discussed. Focusing our attention on the more general problem of identification of general objects when they substantially overlap, we propose some schemes for their recognition, and also analyze some problems that are met.

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Bonthron, Karen; Urquhart, Christine; Thomas, Rhian; Armstrong, Chris; Ellis, David; Everitt, Jean; Fenton, Roger; Lonsdale, Ray; McDermott, Elizabeth; Morris, Helen; Phillips, Rebecca; Spink, Sian, and Yeoman, Alison. (2003, June). Trends in use of electronic journals in higher education in the UK - views of academic staff and students. D-Lib Magazine, 9(6). Retrieved September 8, 2006 from http://www.dlib.org/dlib/june03/urquhart/06urquhart.html This item is freely available online at http://www.dlib.org/dlib/june03/urquhart/06urquhart.html Sponsorship: JISC