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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.
71

Výzkum reakcí katalyzovaných zlatem / Research of gold catalyzed reactions

Jašíková, Lucie January 2016 (has links)
The main focus of the current dissertation thesis is research of gold catalyzed reactions. I was using mass spectrometry as the primary research technique. I complemented the results with infrared multiphoton dissociation spectroscopy, nuclear magnetic resonance spectroscopy and quantum chemical calculations. I have investigated the interaction of the gold(I) cation with unsaturated hydrocarbons in the first part of my thesis. Secondly, I have studied gold(I) or silver(I) affinity to gold acetylides. In the last part, I have investigated the reaction mechanism of a gold mediated addition of methanol to alkynes. I found out that the gold(I) cation interacts stronger with gold acetylides than with nonactivated triple CC bonds. I showed that the complexes containing two gold atoms represent the key intermediates in the mechanism of addition of methanol to alkynes and that the ligand on the gold catalyst plays a fundamental role in the determination of the mechanism. Powered by TCPDF (www.tcpdf.org)
72

Datování vývěrů radioaktivních minerálních vod v krkonošsko-jizerském krystaliniku metodou 230Th/234U / Dating of radioactive mineral springs of the Krkonoše-Jizera crystalline by 230Th/234U method

Fanta, Martin January 2016 (has links)
The isotopes 238 U, 234 U and 230 Th, as members of the uranium-radium decay chain, are fractionated in the environment by changes of geochemical conditions, and they can be used for dating of recent or past geochemical processes in the Quaternary. Samples of water with uranium and of water-activated solids were taken of radioactive mineral water springs at two study sites in the area of Krkonoše-Jizera crystalline complex: Svatý Vojtěch (St. Adalbert) in Horní Malá Úpa, and Bukový Pramen in the Těsný důl valley in Janské Lázně. Uranium was co-precipitated in field conditions with hydroxides of FeIII+ in 50-liter water samples of the radioactive springs. In the lab, uranium and thorium were separated from water precipitates, as well as from solid samples after their chemical decomposition, using chromatographic extraction agent UTEVA. All the three isotopes of interest emit alpha particles, and so their activities were measured by alpha spectrometry and expressed as 234 U/238 U and 230 Th/234 U ratios. As an internal standard, 232 U/228 Th was used. The resulting 234 U/238 U activity ratios of four water samples measured ranged from 1.0747 to 1.423. In twelve samples of solid phases activity ratios 234 U/238 U from 0.861 to 1.129 were determined. The 230 Th/234 U activity ratios form two distinct...
73

Analýza historických léčivých přípravků s obsahem alkaloidů, sulfonamidu, derivátů barbiturové kyseliny a derivátu pyrazolu / Analysis of Historical Pharmaceutical Preparations Containing Alkaloids, Sulphonamide, Derivatives of Barbituric Acid, and Derivative of Pyrazolone

Kudláček, Karel January 2016 (has links)
Pharmaceutical preparations of quinine (injection solutions), sulfanilamide, aminophenazone, barbital (tablets), caffeine, phenobarbital (dragee), and theophylline (suppositories) about seventy years old were analyzed using RP-HPLC. Samples were quantified by HPLC-UV and UV-spectrophotometry. Products of degradation were identified using HPLC-UV and HPLC-MS. Conditions of separation were optimized. The samples of quinine injection solutions consist of 92% or 87% of declared quinine content. Quinotoxine has been identified as the product of quinine degradation. The quantification of theophylline in suppositories and caffeine in dragee did not show any degradation after more than 67 years from their manufacturing. Decrase of potent amount (decrase about 8-22 %) were found in drugs containing sulfanilamide, barbital, phenobarbital and aminophenazone. Products of degradation of these pharmaceuticals were not found.
74

Vývoj technik pulsního značení pro studium dynamiky proteinových komplexů. / Development of pulse labelling technology for studying the dynamics of protein complexes.

Fiala, Jan January 2021 (has links)
(IN ENGLISH) Structural mass spectrometry (MS) is an evolving field of structural biology introducing novel techniques for the characterization of biomolecules. Although MS-based techniques only can provide "low-resolution" information compared to standard high-resolution techniques representing by X-ray crystallography, cryo-electron microscopy or nuclear magnetic resonance, its uniqueness lies in the ability to easily obtain structural information about various biomolecules in their native or native-like environment. By employing various approaches, from protein covalent labelling through chemical cross- linking to ion mobility, structural MS provides insight into the structure and dynamics of proteins and their complexes over a broad timescale. This thesis is dedicated to the development of novel structural MS approaches based on pulse covalent labelling and chemical cross-linking. Employing the developed quench-flow microfluidics apparatus, we performed footprinting experiments on proteins and protein complexes in timescale from a few microseconds to single seconds. Specifically, fast photochemical oxidation of proteins (FPOP) and novel fast fluoro alkylation of proteins (FFAP) techniques were utilized to track structural changes of myoglobin upon release of the prosthetic heme group....
75

Monitoring obsahu rtuti a methylrtuti v rybím mase a zhodnocení rizik spojených s konzumací tohoto masa / Monitoring of mercury and methylmercury content in fish meat and evaluation of risks associated with the consumption of this meat

Křížová, Lucie January 2021 (has links)
Mercury and its compounds are one of the most toxic global pollutants in the environment. It occurs in all segments of the environment, and it attains the food chain ang human body by people consuming fish. The theoretical part of this thesis examines the characteristics of mercury, its occurrence, the roots of its pollution, and the toxicity of various forms of mercury. Consequently, the thesis delineates analytical methodologies applied to determine the overall level of mercury and chemical forms of mercury. The practical part focuses on monitoring the level of mercury and methylmercury in 12 extracts of fish meat. The analyzer AMA 254 has been used to determine the level of mercury and methylmercury in these extracts. Based on the level that resulted from the measurements, the thesis concludes a risk that correlates with consuming this type of meat.
76

Detekce vsakování vody do zemin injektovaných jíly metodou EIS / Detection of water infiltration into soils injected by clays using EIS method

Marek, Ondřej January 2020 (has links)
The diploma thesis deals with the study of water infiltration into soil samples with various types of clay. The soil matrix was represented by homogeneous sand; clay samples were supplied by LB Minerals, Ltd. Soil analysis with injected clays was focused on sealing ability of examined clays for possible use in construction practice for the construction of sealing objects. Electric impedance spectrometry (EIS) measuring system was used to monitor the infiltration process. The measurement was carried out by a measuring apparatus made by the solution of the international project E! 7614 of applied research in the EUREKA program within its sustainability.
77

Ramanova spektroskopie pro výuku / Raman spectroscopy teaching equipment

Indra, Zdeněk January 2021 (has links)
This thesis examines the principle of the Raman phenomenon and the function of the Raman spectrometer in order to build a low-cost Raman spectrometer assembly for school laboratory teaching. The thesis lists the important parts of the device and describes their key features. Subsequently, the selection of each component is discussed and a basic experiment is performed to verify the principle of this spectrometer. In the final part, a low-cost Raman spectrometer is constructed and tested thanks to the knowledge gained.
78

Studium reakcí kyslíku a ozónu na povrchu konstrukčních materiálů / Study of oxygen and ozone reactions on the surface of construction materials

Krzyžanková, Anežka January 2021 (has links)
This master's thesis deals with the study of the reactions of the ozone and oxygen with various construction materials. Ozone as an unstable gas tends to decompose spontaneously and this process can be accelerated by reaction with other substances. The aim of this work is to determine the course of ozone's formation and its depletion in after the contact with various substances. Ozone is widely used mainly due to its disinfecting effects. Therefore, the monitoring of these reactions is beneficial for the choosing of ozonizer's material or its accessories. The theoretical part of this work describes the important properties of the ozone, the possibilities of using this gas, various methods of its generation, the influence of gas admixtures and a temperature on its generation and decomposition, the methods of determining the concentration and surface reaction. The dependence of ozone's formation on the size of the reaction space was monitored for either the silicone and Teflon material in the experimental part of the thesis. The length of the hoses was 20-50 cm and the diameter of the inner space was 6 mm for Teflon and 7,99 mm for a silicone. Furthermore, other experiments were performed for the silicone material, where the formation of the ozone was monitored while the oxygen and argon were being used as working gases. The formation and the depletion of the ozone depending on the changes of reaction time were investigated in the third series of experiments. We worked with a ceramic material with two different inner diameters and also with a brass and a stainless steel material in this experiment. The materials were constructed as the tubes of the same length of 54 cm. The ozone generated from the oxygen was enclosed into the reaction tube and the depletion was monitored. The last experiment was focused on the monitoring of the course of ozone's formation in a quartz cuvette influenced by the reaction time and the composition of the working gas. The amount of generated ozone was determined by absorption spectrometry in the all studied cases. The ozone flowing through the system was adsorbed by the surface of the material during the discharge. A mixture of gases (the adsorbed ozone, the oxygen and the argon in various ratios) was present in the sealed reaction space. The Ozone was formed on the surface of the material. The adsorbed ozone decomposed into a molecular and an atomic oxygen. The atomic oxygen reacted with the oxygen molecule occurring in the reaction space. The reaction time leading to the biggest obtained concentration of generated ozone was determined by the experimental data. For most of the materials, the reaction time was about 6 minutes.
79

Využití metody LC/MS k analýze vybraných přírodních fyziologicky aktivních látek / Use of LC/MS technique to analysis of some physiologically active natural compounds

Trčková, Marie January 2008 (has links)
Presented work is focused on application of combined instrumental method RP-HPLC/ESI-MS in analysis of several groups of natural compounds with positive physiological activities. Especially some antioxidants were studied in commonly and abundantly consumed food. Moreover some other substances than standard compounds were observed in complex dies. In conclusion the HPLC/ESI-MS method is comparatively advantageous in phenolic analysis, while another type of ionisation would be used in case of carotenoid compound.
80

Miniaturizované techniky pro analýzu průmyslových kvasinek / Miniaturized techniques for analysis of industrial yeasts

Obalil, Jiří January 2008 (has links)
Carotenoids are natural pigments that have antioxidation and antimutagenic abilities. They are produced with the help of new technological methods. For example, carotenoid yeast Rhodotorula glutinis produces -carotene with the yield of up to 6 – 10 mg/g of the dry substance. The method of the mass spectrometry with the nanoelectrospray in the positive mode was optimized for the determination of -carotene, lycopene and astaxanthin in this project. Ionizing voltage of 4 kV and the sample flow rate of 15 – 80 nl/min through the spray silica fused capillary with the internal diameter of 25 µm were found to be the optimum parameters of the analysis. A mixture of chloroform with the addition of ammonia was used as a spray solvent for both standard and cellular samples. During the process of ionization by nanoelectrospray, -carotene and lycopene form cation radical [M] • + with the molecular mass to charge ratio (m/z) of 536, while asthaxanthin forms the protonated molecule [M + H]+ with the m/z of 597. The partial lysis of individual Rhodotorula glutinis cells was demonstrated under microscope in the organic solvents tetrahydrofuran and dimethylsulfoxide. Chloroform, acetone, acetonitrille, methanol and isopropanol did not affect the cells after a 15 min treatment.

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