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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
701

The syntheses, NMR and photochromic properties of modified dimethyldihydropyrenes

Zhang, Rui 06 November 2007 (has links)
The cyclopentadienone-fused dihydropyrenes 46 and 47 were synthesized. The internal methyl resonances, the coupling constants, NICS calculations and X-ray results confirmed that the cyclopentadienone displays antiaromatic character resulting in bond localization in the annulene ring consistent with a 4n-pi fused system. The ring current of the dihydropyrene fragment is reduced by fusion of the antiaromatic system by about 80% of that caused by benzene. The syntheses of the methylfulvene fused dihydropyrene 56 and the phenylfulvene fused dihydropyrene 58 have been accomplished. The calculated and experimental NMR data and NICS calculations all demonstrated that the fulvenes had weak diatropic ring currents and caused bond localizations in the DHP rings, in which phenyl fulvene has a larger effect than that of methyl fulvene. A number of bis-dihydropyrene systems, bis-dihydropyrene ketone 117, bis-benzo[e]dihydropyrene ketone 119, benzo[e]dihydropyrene dihydropyrene ketone 122, bis-benzo[e]dihydropyrene methylene 124 and the benzo[e]dihydropyrene- dihydropyrene acetylene 130, have been synthesized, in which 117, 119 and 124 are homo-systems and 122 and 130 are hetero-systems. The multiple photoswitching properties study found that all of these systems except 130 showed multi-states during the photo opening and photo closing processes, which means that each end of the DHP units photo opens or closes separately rather than synchronously. In the homo switches 117, 119 and 124, the two DHP units act independently, but the relative differentiation is not very significant. On the other hand, the hetero-switch 122 showed fully differentiated photo opening process and almost a pure open-closed intermediate 122’ could be achieved. This is the first example which clearly showed four states in the UV closing process. The relative photo opening and closing rates compared to benzoDHP 36 have also been studied. It was found that while the carbonyl linker largely increased the relative photo opening rate (117, 119 and 122), the methylene linker only increased it slightly (124). The photo closing processes were always fast as usual. The studies of the thermal return reactions of these systems showed that while the carbonyl linker substantially slowed down the thermal return reactions of the DHP units (117, 119 and 122), the methylene linker speeded it up slightly (124). The mono-iron tricarbonyl benzo[e]dihydropyrene complex 152, the bis-iron tricarbonyl benzo[e]dihydropyrene complex 153 and the iron tetracarbonyl dihydropyrene complex 151 were synthesized. The structures of 152 and 153 were determined by X-ray crystallography. The coordinations of iron tricarbonyl moieties to the DHP rings caused a distortion of ca. 30 degree away from the central DHP plane. Coordination also increased bond alternation and reduced ring currents in the DHP rings. 1H-NMR and X-ray studies showed that 152 showed a weak paratropic ring current in the DHP ring. Iron coordination of the DHP completely stopped the photochromic properties of the dihydropyrenes.
702

Tectonique moléculaire : vers l'utilisation du dispirofluorène-indénofluorène comme unité de construction pour bâtir des réseaux cristallins poreux

Blair-Pereira, Joao-Nicolas 01 1900 (has links)
La chimie supramoléculaire est un domaine qui suscite depuis quelques années un intérêt grandissant. Le domaine s’appuie sur les interactions intermoléculaires de façon à contrôler l’organisation moléculaire et ainsi moduler les propriétés des matériaux. La sélection et le positionnement adéquat de groupes fonctionnels, utilisés en combinaison avec un squelette moléculaire particulier, permet d’anticiper la façon dont une molécule interagira avec les molécules avoisinantes. Cette stratégie de construction, nommé tectonique moléculaire, fait appel à la conception de molécules appelées tectons (du mot grec signifiant bâtisseur) pouvant s’orienter de façon prévisible par le biais d’interactions faibles et ainsi générer des architectures supramoléculaires inédites. Les tectons utilisent les forces intermoléculaires mises à leur disposition pour s’orienter de façon prédéterminée et ainsi contrecarrer la tendance à s’empiler de la manière la plus compacte possible. Pour ce faire, les tectons sont munies de diverses groupes fonctionnels, aussi appelés groupes de reconnaissance, qui agiront comme guide lors de l’assemblage moléculaire. Le choix du squelette moléculaire du tecton revêt une importance capitale puisqu’il doit permettre une orientation optimale des groupes de reconnaissance. La stratégie de la tectonique moléculaire, utilisée conjointement avec la cristallisation, ouvre la porte à un domaine de la chimie supramoléculaire appelé le génie cristallin. Le génie cristallin permet l’obtention de réseaux cristallins poreux soutenus par des interactions faibles, pouvant accueillir des molécules invitées. Bien que toutes les interactions faibles peuvent être mises à contribution, le pont hydrogène est l’interaction prédominante en ce qui a trait aux réseaux cristallins supramoléculaires. La force, la directionnalité ainsi que la versatilité font du pont hydrogène l’interaction qui, à ce jour, a eu le plus grand impact dans le domaine du génie cristallin. Un des groupements de reconnaissance particulièrement intéressants en génie cristallin, faisant appel aux ponts hydrogène et offrant plusieurs motifs d’interaction, est l’unité 2,4-diamino-1,3,5-triazinyle. L’utilisation de ce groupement de reconnaissance conjointement avec un cœur moléculaire en forme de croix d’Onsager, qui défavorise l’empilement compact, permet l’obtention de valeurs de porosités élevées, comme c’est le cas pour le 2,2’,7,7’-tétrakis(2,4-diamino-1,3,5-triazin-6-yl)-9,9’-spirobi[9H-fluorène]. Nous présentons ici une extension du travail effectué sur les cœurs spirobifluorényles en décrivant la synthèse et l’analyse structurale de molécules avec une unité dispirofluorène-indénofluorényle comme cœur moléculaire. Ce cœur moléculaire exhibe les mêmes caractéristiques structurales que le spirobifluorène, soit une topologie rigide en forme de croix d’Onsager défavorisant l’empilement compact. Nous avons combiné les cœurs dispirofluorène-indénofluorényles avec différents groupements de reconnaissance de façon à étudier l’influence de l’élongation du cœur moléculaire sur le réseau cristallin, en particulier sur le volume accessible aux molécules invitées. / Supramolecular chemistry is a field of rapidly increasing interest in recent years. The field uses weak intermolecular interactions to control molecular organisation and therefore modulate the properties of materials. Adequate selection and positioning of functional groups, combined with a carefully selected molecular core to which the groups are attached, allows for the creation of molecules with a high degree of predictability in the way they will interact with their neighbours. This approach to the design and construction of materials, called molecular tectonics, is based on subunits called tectons (derived from the Greek word for builder), which use weak interactions to organise themselves in a predictable manner and generate novel supramolecular architectures. In favorable cases, the interactions can counter the general tendency shown by molecules to pack together in a compact manner. Instead, specific functional groups direct molecular recognition and help guide the process of auto-assembly. At the same time, the molecular core of the tecton is also of capital importance as it must allow an optimal orientation of the recognition groups. The molecular tectonics approach, used jointly with crystallisation, opens the door to new opportunities in crystal engineering. For example, crystal engineering now allows the logical creation of porous crystalline networks that can accept guest molecules. Although any type of weak interaction can hold such networks together, the hydrogen bond is favored for constructing porous supramolecular networks. The strength, directionality and versatility of the hydrogen bond accounts for its special importance in the domain of crystal engineering. A recognition group of particular interest in crystal engineering is the 2,4-diamino-1,3,5-triazinyl unit. This unit forms hydrogen bonds according to various standard motifs. The use of this recognition group, joined to molecular cores specifically designed to inhibit close packing, such as Onsager crosses, allows for the construction of supramolecular networks with high porosity, as shown by the behaviour of 2,2’,7,7’-tetrakis(2,4-diamino-1,3,5-triazin-6-yl)-9,9’-spirobi[9H-fluorene]. We present here an extension of previous studies of spirobifluorenyl cores by describing the synthesis and structural analysis of molecules with related dispirofluorene-indenofluorenyl cores. This new core offers the same characteristics as the spirobifluorenyl core, namely rigid topology and an Onsager cross molecular shape which are known to inhibit close packing. We have combined this core with a variety of recognition groups to verify the influence of the molecular core on the crystalline networks generated, particularly on the volume accessible to guest molecules.
703

Technology-Scanning Capability and Market-Scanning Capability as Drivers of Product Innovation Performance

Alam, Md Shahedul 09 August 2011 (has links)
Changing trends in customer preference, competitors’ offerings, new technologies and development techniques may disrupt a firm from its current leading market position and may favor other firms that prioritize innovation. Once a market opportunity is identified (i.e., find an answer to the ‘what to do’ question), firms need to engage in a series of activities and information processing to determine an appropriate way to monetize that opportunity – that is, firms need to find an answer to the ‘how to do’ question. Alternately, a firm may first identify a technological opportunity (i.e. find an answer to the ‘how to do’) and then find a market opportunity (i.e. find an answer to the ‘what to do’ question) to make use of the technological opportunity. Two scales that measure the capabilities of firms to address the following two questions – ‘what to do’ and ‘how to do’ - were reported; these were labelled as market-scanning capability (MktScan) and technology-scanning capability (TechScan); and these two scales were also tested in a broader research model. In turbulent environments, marketing and R&D become more challenging, since they face an uncertain future. Firms need to learn systemic scanning and decoding of apparently random changes in their business environment and imagine a pattern that makes sense. One cannot plan for uncertainty. A better strategy is to be prepared for it. One way to prepare is to develop the capabilities that would help the firm to become more adaptive. Drucker (1992) also argued that instead of planning for the long term that is uncertain, firms needed to become adaptive to tackle uncertainty. The ability of a firm to adapt to the changes depends on its ability to sense the nature of the changes in its business environment and respond to those. Sense-and-respond framework (Haeckel 1999; Haeckel 2000; Day and Schoemaker 2006) was proposed to emphasize the identification of weak signals (Ansoff 1975) to tackle increased uncertainty in business environment. In current days, effectiveness of firm’s activities often depends on the richness of its sources of information and its capability to process the collected information to identify the patterns of change happening in its business environments. Information processing may happen in two dimensions: in market dimension and in technology dimension. Firms’ capabilities for information collecting and processing in these two dimensions were measured using two firm-level constructs. These are market-scanning capability and technology-scanning capability. Resource-based theory helped to understand how firms use their tangible and intangible resources to compete in the market. Specific problem-solving aspects of the processes, activities, and cultural norms enable firms to make decisions about engaging the available resources and capabilities in ways that maximize customer value, by realizing the identified opportunities into product and service offerings. This research identified the characteristic strength of this problem-solving approach of firms – collecting information both internally and externally about possible market opportunities and technological options, organization-wide processing of that information, and taking actions to respond using insights gained – as two latent constructs called ‘market-scanning capability’ and ‘technology-scanning capability’. The concepts of ‘market-scanning capability’ and ‘technology-scanning capability’ were first defined and then, scales were developed to enable researchers and managers to measure these firm-level constructs. Next, the predictive roles of these capabilities on firm performance were examined. Empirical analysis for scale development and validation of the research model were performed with data collected through a web-based survey of Canadian manufacturing firms. Firm performance was captured in two stages – first, by product innovation performance, and second, by overall firm performance. Product innovation performance was used as an intermediate performance measure to examine the direct influence on it of market-scanning capability and technology-scanning capability, and then, to relate product innovation performance to final business outcome measured using ‘overall firm performance’ scale. The study validated the notion of resource-based theory by supporting the belief that higher levels of market-scanning capability and technology-scanning capability would lead to improved product innovation performance. The role of environmental turbulence was also examined for its possible moderating effect. Two measures of environmental turbulence, namely, technology and market turbulence were used to test the moderation effect. The technology turbulence construct was found to have a moderating effect on the relationship between technology-scanning capability and product innovation performance, indicating that firms needed to focus more attention on the changes in the technology landscape when turbulence in the technological field was perceived to be higher, in order to keep the same level of product innovation performance. Insight gained from the study contributed to a knowledge-base that might be useful to both practitioners and researchers. The combination of TechScan and MktScan scales could be used as a benchmark tool by managers to assess firms’ readiness to take advantage of the opportunities that existed. On the theoretical side, the study contributed to the understanding by showing that both market-scanning capability and technology-scanning capability had direct and indirect influences on firm performance. Also, it was found that the indirect influence of a certain scanning capability became important when firms were pre-disposed to emphasize the other scanning capability.
704

On Evaluation Problem of the Quality of Educational Models

Testov, Vladimir A. 11 May 2012 (has links) (PDF)
The current approach to assessing the educational quality applicable to assessing objects and processes formed and realized in producing spheres is widely spread. However, as education is a much more complicated anthropological, social and cultural object in comparison to that of production, the above mentioned approach is least effective. In education both \"strong\" and \"weak\" models are used. There do not exist measurement instruments for accurate assessing mild results. Self control, expert assessing method and portfolio are being put forward.
705

Beyond the bamboo network : the internationalization process of Thai family business groups

Hemrit, Maetinee January 2010 (has links)
International Business research overwhelmingly tends to focus on firms that are perceived as rising international stars. This study, on the other hand, is motivated by the desire to examine other types of business organizations as they navigate the globalization process. In particular, a holistic view of family business groups (FBGs) and mainstream internationalization models governed by the concept of firm-specific advantages (FSAs) are con­fronted with the empirical findings of actual business expansion via personal connections. This serves as the conceptual framework of the study when investigating the nature of competitiveness of FBGs. Thailand is chosen as the research setting because of its both distinct and relevant economic and cultural background. The analysis begins by quantitatively exploring the population of the 139 largest Thai FBGs. Then, more fine­grained explanations are developed as a series of comparative case studies are carried out. Overall, the findings shed light on the study of emerging multinational corporations (EMNCs) in general by detailing and probing the evolution of Thai FBGs. Focus is on the internationalization process(es) and the subsequent need for organiza­tional adjustments; the latter involving imposing a measure of discipline on family affairs as well as modernizing business operations. This adds to the hitherto established notion of latecoming EMNCs simply scaling the techno­logical ladder. In essence, the tension between the "easy" path of relying on connections (i.e., what here is termed "the bamboo network") and the more "difficult" path of building competitiveness (i.e., going beyond the bamboo network) is exposed and explained. This study thus contributes to our understanding of the firm internationalization process. / Diss. Stockholm : Handelshögskolan i Stockholm, 2011
706

Study of 14O as a test of the unitarity of the CKM matrix and the CVC hypothesis

Burke, Jason Timothy January 2004 (has links)
Thesis (Ph.D.); Submitted to the University of California Berkeley, Berkeley, CA (US); 1 Jun 2004. / Published through the Information Bridge: DOE Scientific and Technical Information. "LBNL--56278" Burke, Jason Timothy. USDOE Director. Office of Science. Office of High Energy and Nuclear Physics. Division of Nuclear Physics (US) 06/01/2004. Report is also available in paper and microfiche from NTIS.
707

Le non-professionnel et le petit professionnel : la protection de deux contractants faibles par le droit privé / The non-professional and the small professional : the protection of two weak contractors by private law

Haba, Parfait 12 December 2017 (has links)
Pendant longtemps, le non-professionnel a été considéré comme un professionnel dont la situation de faiblesse était comparable à celle du consommateur et il était protégé comme tel. Or, le juge européen a défini le consommateur comme « visant exclusivement la personne physique ». Cela a conduit le juge français à nuancer sa position ; le non-professionnel est défini comme la personne morale n’exerçant pas d’activité professionnelle. De son côté, la notion de petit professionnel a été consacrée par les textes relatifs au droit de la consommation et au droit de la concurrence. Si ces contractants faibles sont protégés c’est avant tout parce qu’ils peuvent être marqués par une situation de faible économique, technique ou juridique. En tout état de cause la protection n’est accordée que par détermination de la loi et elle doit rester circonstanciée. Dans tous les cas, la protection de ces contractants est spécifiée par l’absence de standardisation car elle ne peut être calquée sur le modèle de protection du consommateur. Partant, la protection de ces contractants faibles est nécessaire contre les abus contractuels. Ainsi, le non-professionnel est essentiellement protégé contre les clauses abusives par l’appréciation du déséquilibre significatif dans les contrats de consommation. Alors que le petit professionnel est protégé par le contrôle du contenu du contrat et surtout contre toutes sortes d’abus dans les pratiques anticoncurrentielles. Aussi, les mécanismes de l’information prévus par le droit de la consommation, le Code civil ou ceux prévus au profit de l’acquéreur non-professionnel ou des non-avertis peuvent être étendus au profit du non-professionnel et du petit professionnel. / For a long time , the non-professional was considered as a professional whose weakness was comparable to that of the consumer and was protect as such. However, the European judge has defined the consumer as « exclusively targeting the natural person ». This led the french judge to qualify his position ; the non-professional is defined as the legal person not exercising a professional activity. For his part, the notion of small business has been enshrined in the text relating to consumer and competition low. If this weak contractors are protected it is primarily because they can be marked by a weak economic, technical or legal situation. In any case, protection is granted only by the determination of the law and must remain detailed. In all cases, the protection of this contractors is specified by the lack of standardization because it can not be modeled on the model of consumer protection. Therefore, the protection of these weak contractors is necessary against contractual abuses. Thus, the non-professional is essentially protected against unfair terms by appreciating the significant imbalance in consumer contracts. While the small business is protected by the control of the content of the contract and especially against all kinds of abuses in anti-competitive practices. Also, the information mechanisms provided by consumer law, the civil Code or those provided for the benefit of the non-professional purchaser or uninformed can be extended to the benefit of the non professional and the small business.
708

Moderní asymptotické perspektivy na modelování chyb v měřeních / Modern Asymptotic Perspectives on Errors-in-variables Modeling

Pešta, Michal January 2010 (has links)
A linear regression model, where covariates and a response are subject to errors, is considered in this thesis. For so-called errors-in-variables (EIV) model, suitable error structures are proposed, various unknown parameter estimation techniques are performed, and recent algebraic and statistical results are summarized. An extension of the total least squares (TLS) estimate in the EIV model-the EIV estimate-is invented. Its invariant (with respect to scale) and equivariant (with respect to the covariates' rotation, to the change of covariates direction, and to the interchange of covariates) properties are derived. Moreover, it is shown that the EIV estimate coincides with any unitarily invariant penalizing solution to the EIV problem. It is demonstrated that the asymptotic normality of the EIV estimate is computationally useless for a construction of confidence intervals or hypothesis testing. A proper bootstrap procedure is constructed to overcome such an issue. The validity of the bootstrap technique is proved. A simulation study and a real data example assure of its appropriateness. Strong and uniformly strong mixing errors are taken into account instead of the independent ones. For such a case, the strong consistency and the asymptotic normality of the EIV estimate are shown. Despite of that, their...
709

Proudění nestlačitelných tekutin s viskozitou závislou na tlaku (a jejich aplikace při modelování proudění v ložisku) / Flows of incompressible fluids with pressure-dependent viscosity (and their application to modelling the flow in journal bearing)

Lanzendörfer, Martin January 2011 (has links)
Title: Flows of incompressible fluids with pressure-dependent viscosity (and their application to modelling the flow in journal bearing) Author: Martin Lanzendörfer Department: Mathematical Institute of Charles University Supervisor: prof. RNDr. Josef Málek, DSc. Abstract: The viscosity of the fluids involved in hydrodynamic lubrication typically depends on pressure and shear rate. The thesis is concerned with steady isothermal flows of such fluds. Generalizing the recent results achieved in the case of homogeneous Dirichlet boundary conditions, the existence and uniqueness of weak solutions subject to the boundary conditions employed in practical applications will be established. The second part is concerned with numerical simulations of the lubrication flow. The experiments indicate that the presented finite element method is successful as long as certain restrictions on the constitutive model are met. Both the restrictions involved in the theoretical results and those indicated by the numerical experiments allow to accurately model real-world lubricants in certain ranges of pressures and shear rates. The last part quantifies those ranges for three representative lubricants. Keywords: existence and uniqueness of weak solutions, finite element method, pressure- thickening, shear-thinning, incompressible fluids,...
710

LA CESSIONE DI PRODOTTI AGROALIMENTARI: DALLA DISPARITA' DI POTERE CONTRATTUALE AL RIEQUILIBRIO DEL CONTRATTO. TUTELA DEL CONTRAENTE DEBOLE ED EFFICIENZA DEL MERCATO

ROSSI, ARIANNA 14 December 2018 (has links)
L’art. 62 del d.l. n. 1 del 2012, che riecheggia lo schema della Legge n. 192 del 1998, ma nello specifico settore agroalimentare, prevede non solo regole di forma, che hanno un obiettivo di protezione della parte debole del rapporto (neoformalismo contrattuale), ma anche regole di contenuto e di comportamento, che intendono prevenire la formazione di contratti iniqui. Lo scopo di questo studio non è soltanto quello di offrire un inquadramento sistematico ad una legislazione che, peraltro, si inserisce in un contesto sempre più frammentato, ma anche quello di analizzare i vari strumenti previsti e di valutare la loro capacità nel perseguimento dello scopo prefissato dalla legislazione, anche attraverso l'applicazione della disciplina generale prevista all'interno del codice civile, alla quale oggi, più che mai, si sente il bisogno di ridare spazio. Il lavoro si dipana lungo quattro capitoli, attraverso un percorso che inizia con l’analisi delle relazioni tra contratto e mercato, tramite un’indagine sistematica sulla nuova disciplina dei contratti, prosegue con l’approfondimento della disciplina dell’articolo 62, per poi analizzare gli strumenti introdotti in relazione all’impatto sull’efficienza del mercato, ed in particolare sul settore agroalimentare, in termini di food safety, food security e accesso al credito. / Article 62 of the d.l. n. 1 of 2012, which echoes the scheme of Law no. 192 of 1998, but in the agri-food sector, provides not only rules of form, which have the objective of protecting the weak part of the relationship (neoformalism), but also rules of content and behavior, which intend to prevent the formation of unfair contracts. The aim of this study is not only to offer a systematic framework for legislation that, moreover, is part of an increasingly fragmented context in italian legislation, but also to analyze the various instruments and to assess their ability to achieve the intended purpose, also through the application of the general principal of civil code which today, more than ever, feels the need to be applied. The work unfolds along four chapters, through a process that begins with the analysis of the relationship between contract and market, through a systematic survey on this new discipline of contracts, continues with the examination of the discipline of Article 62, and then analyze the tools introduced and their impact on the efficiency of the market, and in particular on the agri-food sector, in terms of food safety, food security and access to credit.

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