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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.
91

Příprava a katalytické vlastnosti fosfinoferrocenového guanidinu / Synthesis and catalytic properties of phosphinoferrocene guanidine

Bárta, Ondřej January 2016 (has links)
Title: Synthesis and catalytic properties of phosphinoferrocene guanidine Author: Ondřej Bárta Institution: Faculty of Science, Charles University in Prague, Department of Inorganic Chemistry Supervisor: prof. RNDr. Petr Štěpnička, Ph.D. Polar phosphine ligands proved to be useful in homogeneous and biphasic catalysis. Most of these phosphines bears anionic functional groups. On the other hand, functionalization of phosphines by cationic substituents is still quite uncommon, although these functional groups possess properties that could improve catalytic performance of the catalyst. In this regard, nitrogenous bases are particularly attractive due to their inherent basicity and the ability to enter into hydrogen bonding interactions. This thesis describes the synthesis of a novel ferrocene-based phosphine functionalized with guanidine moiety, viz. N-[1′-(diphenylphosphino)ferrocenylmethyl]guanidine (3). This compound was obtained by direct guanylation of 1′-(diphenylphosphino)- 1-(aminomethyl)ferrocene (2) (see scheme). Compound 3 was further used to prepare palladium complexes including the unusual zwitterionic complex [PdCl3(3H)]. The molecular structures of the prepared complexes were determined by X-ray diffraction analysis. Catalytic properties of phosphine 3 and complex [PdCl3(3H)] were...
92

Syntéza C15-C20 fragmentu tiakumicinu / Synthesis of the C15-C20 tiacumicin fragment

Havlíček, Vojtěch January 2017 (has links)
In the diploma thesis, a method for preparation of the unsaturated C15-C20 tiacumicin fragment was developed. Tiacumicin is classified as a macrolidone antibiotic. Although three syntheses of tiacumicin have been recently published, this study has aimed to develop a novel pathway for its preparation utilizing catalytic reactions instead of stoichiometric ones. In the second part, an enantioselective allylation of (E)-3-jod-2-methylpropenal has been developed applying catalysis by a series of N,N'-dioxide catalysts. The asymmetric induction achieved in the allylation was up to 99% ee. This procedure allows relatively simple, straightforward and efficient preparation of wide range of natural products. Keywords tiacumicin, asymmetric synthesis, allylation, catalysis, chiral Lewis bases, organocatalysis
93

Využití organokatalýzy pro přípravu sloučenin obsahujících kvarterní uhlíkové centrum / Organocatalytic preparation of compounds containing chiral quaternary stereocenter

Patlevičová, Michaela January 2017 (has links)
In this thesis, I was paid to the preparation of enantiomerically and diastereomerically pure spiro compounds using asymmetric organocatalysis.
94

Syntéza nového typu acyklických nukleosid fosfonátů a příprava proléčiv a systémů doručení léčiva / Synthesis of novel types of acyclic nucleoside phosphonates and preparation of prodrugs and drug delivery systems

Kalčic, Filip January 2021 (has links)
First part of this thesis was focused on the previously overlooked field of C1'-branched acyclic nucleoside phosphonates (ANPs). Five diverse synthetic approaches were developed/optimized affording key 6-chloropurine intermediates bearing N9 -phosphonomethoxyethyl (PME) branched at C1' position in 2-4 steps. It was demonstrated that these intermediates can be further vastly diversified into ANPs bearing both natural and unnatural nucleobases. Single enantiomers as well as racemates of final C1'-branched ANPs (overall 48 final compounds) were prepared and selected compounds were evaluated with respect to their biological properties. The aforementioned ANPs showed no antiviral potency against studied viruses and only weak to moderate cytostatic activity. Adenine C1'-branched ANPs proved to be the most potent currently known inhibitors of Trypanosoma brucei adenine phosphoribosyl transferase (TbrAPRT), an enzyme involved in purine salvage pathway (PSP) of T. brucei. Further biological evaluation of prepared compounds is in progress. Second part of this thesis was focused on development of novel prodrug moieties with higher selectivity index (i.e. toxicity/potency ratio - SI) based on so-called ProTide prodrugs where phenol (present in ProTides) was replaced by tyrosine derivatives. Tenofovir was...
95

Enantioselektivní syntéza chirálních cyklohexenonů za použití NHC katalýzy / Enantioselective Synthesis of Chiral Cyclohexenones Using NHC Catalysis

Lóška, Ladislav January 2021 (has links)
This work deals with the enantioselective synthesis of chiral cyclohexenones from substituted 4-nitroisoxazoles and α-bromo-α,β-unsaturated aldehydes using of N-heterocyclic carbenes (NHC) as organocatalysts. The work includes the preparation of commercially unavailable NHC-precursors and the synthesis of starting materials, substituted 4-nitroisoxazoles and α-bromo-α,β-unsaturated aldehydes. The second part of the work deals with the optimization of reaction conditions of the enantioselective synthesis of chiral cyclohexenones, proceeding via an azolium dienolate intermediate, and the detailed substrate scope screening.
96

Automatizovaná syntéza stromových struktur z reálných dat / Automated Synthesis of Tree Structures from Real Data

Želiar, Dušan January 2019 (has links)
This masters thesis deals with analysis of tree structure data. The aim of this thesis is to design and implement a tool for automated detection of relation among samples of read data considering their three structure and node values. Output of the tool is a prescription for automated synthesis of data for testing purposes. The tool is a part of Testos platform developed at FIT BUT.
97

Dynamická prezentace fotografií s využitím hloubkové mapy / Dynamic Image Presentations Using Depth Maps

Hanzlíček, Jiří January 2019 (has links)
This master's thesis focuses on the dynamic presentation of still photography using a depth map. This text presents an algorithm that describes the process of creating a spatial model which is used to render input photography so that the movement of virtual camera creates parallax effect due to depth in image. The thesis also presents an approach how to infill the missing data in the model. It is suggested that a guided texture synthesis is used for this problem by using rendering outputs of the model themselves as guides. Additional information in model allows the virtual camera to move more freely. The final result of the camera movement can be saved to simple video sequence which can be used for presenting the input photography.
98

Vliv chemické struktury změkčovadla na vlastnosti bioplastu na bázi polyhydroxybutyrátu / Effect of chemical structure of plasticizer on material properties based on polyhydroxybutyrate

Stehnová, Ivana January 2018 (has links)
This master’s thesis deals with plasticization of poly(3-hydroxybutyrate), polylactid acid and their blend. It explores effect of chemical structure of plasticizer on mechanical properties of this polymer blend and on its diffusion from the polymer blend. Syntheses of plasticizers based on oligomeric polyadipates, citrates, lactate and esters of 2 ethylhexanoic acid with poly(ethyleneglycol) were carried out. Molecular weight distribution of synthesized plasticizers was determined using gel permeation chromatography. Poly(3-hydroxybutyrate), polylactid acid and their blend were plasticized with synthesized and commercial plasticizers. From commercial, chosed plasticizers were based on citrates and ester of 2-ethylhexanoic acid with poly(ethyleneglycol). Thermal stability of selected commercial plasticizers in polylactid acid was studied using thermogravimetry. Diffusion of plasticizers from poly(3-hydroxybutyrate), polylactid acid and their blend during exposure to 110 °C was also investigated. Mechanical properties of prepared blends were tested by tensile test. Almost all used plasticizers showed positive softening effect in blend. The highest elongation at break was detected for the blend with commercial acetyltributylcitrate, where elongation at break reached 328 % relative to 21 % for neat non-plasticized blend.
99

Syntéza a optimalizace polymorfních obvodů / Polymorphic circuits synthesis and optimization

Crha, Adam January 2021 (has links)
Tato práce se zabývá metodami logické syntézy a optimalizací pro polymorfní obvody. V práci jsou jak diskutovány existující metody pro konvenční obvody, tak i představeny nové metody, aplikovatelné na polymorfní elektroniku. Hlavním přínosem práce je představení nových metod optimalizace a logické syntézy pro polymorfní obvody. Přesto, že v minulých letech byly představeny metody pro návrh polymorfních obvodů, jsou tyto metody založené na evolučních technikách nebo nejsou dobře škálovatelné. Z toho vyplývá, že stále neexistuje stabilní metodika pro návrh složitějších polymorfních obvodů. Tato práce představuje zejména reprezentaci polymorgních obvodů a metodiku pro jejich návrh založenou na And-Inverter grafech. Na polymorfní obvody reprezentované pomocí AIG je možné aplikovat známé techniky jako například přepisování [rewriting]. Nasazením techniky přepisování na polymorfní AIG získáme obvod, obsahující polymorfní prvky uvnitř obvodu, a je možné dosáhnout značných úspor prostředků, které mohou být sdíleny mezi dvěma funkcemi současně. Ověření návrhové metodiky pro polymorfní obvody bylo provedeno nad sadou veřejně dostupných obvodů, čímž je demonstrována efektivita metodiky.
100

Hodnocení finanční situace podniku a návrhy na její zlepšení / Financial Situation in the Firm and Proposals to its Improvement

Doláková, Hana January 2008 (has links)
The objective of this master´s thesis is an appreciation of financial stability of the company Sladovny Soufflet ČR, a.s. in terms of elementary methods of financial analysis. In connection with incorporation of outputs of financial analysis the proposals for improvements in problematic areas of company´s financial stability are formulated.

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