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101.
Jií Davídek Miloslava Neméthová Josef Seifert 《Fresenius' Journal of Analytical Chemistry》1977,287(4-5):286-287
Summary An indirect polarographic method for the determination of phosmet was elaborated. It is based on the fact that N-hydroxymethylphthalimide formed by the reaction of phosmet with sulphuric acid is polarographically active and exhibits a behaviour during electrolysis at a Hg dropping-electrode similar to that of phthalimide. The method has been applied to the determination of phosmet in apples. The sensitivity is 0.1 ppm.
Indirekte polarographische Bestimmung von Phosmet O,O-Dimethyl-S-(phthalimidomethyl)dithiophosphat
Zusammenfassung Das Verfahren beruht darauf, daß N-Hydroxymethylphthalimid, das bei der Reaktion von Phosmet mit Schwefelsäure gebildet wird, polarographisch aktiv ist und sich bei der Elektrolyse mit der Quecksilber-Tropfelektrode ähnlich wie Phthalimid verhält. Die Methode wurde zur Bestimmung von Phosmet in Äpfeln angewandt. Die Empfindlichkeit beträgt 0,1 ppm.相似文献
102.
Leyla Bitiş Sevda Süzgeç Ulaş Sözer Hasan Özçelik Josef Zapp Alexandra K. Kiemer Filiz Meriçli Ali H. Meriçli 《Helvetica chimica acta》2007,90(11):2217-2221
From the aerial parts of Delphinium buschianum Grossh ., collected in Turkey, a new diterpenoid alkaloid 1 , named budelphine, was isolated along with the known diterpenoid alkaloids karakoline ( 2 ), 18‐hydroxy‐14‐O‐methylgadesine ( 3 ), delsoline ( 4 ), lapaconidine ( 5 ), columbianine ( 6 ), 14‐benzoylneoline ( 7 ), and hetisine ( 9 ). The structure of 1 was established on the basis of 1H‐, 13C‐, DEPT, 1H,1H‐COSY, NOESY, HSQC, and HMBC NMR studies. 相似文献
103.
104.
Markus Follmann Nils Griebenow Michael G. Hahn Ingo Hartung Franz‐Josef Mais Joachim Mittendorf Martina Schfer Hartmut Schirok Johannes‐Peter Stasch Friederike Stoll Alexander Straub Peter Jeschke Ralf Nauen Michael Edmund Beck Hans‐Wilhelm Engels Hans‐Georg Pirkl Reinhard Albers Rolf W. Albach Jens Krause Andreas Hoffmann Holger Casselmann Jeff Dormish 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2013,125(36):9503-9503
105.
Dr. George Serghiou Dr. Nicholas Odling Dr. Hans Josef Reichmann Dr. Gang Ji Prof. Dr. Monika Koch-Müller Prof. Dr. Daniel J. Frost Dr. Jonathan P. Wright Dr. Reinhard Boehler Dr. Wolfgang Morgenroth 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(57):14217-14224
Multi-anvil and laser-heated diamond anvil methods have been used to subject Ge and Si mixtures to pressures and temperatures of between 12 and 17 GPa and 1500–1800 K, respectively. Synchrotron angle dispersive X-ray diffraction, precession electron diffraction and chemical analysis using electron microscopy, reveal recovery at ambient pressure of hexagonal Ge−Si solid solutions (P63/mmc). Taken together, the multi-anvil and diamond anvil results reveal that hexagonal solid solutions can be prepared for all Ge−Si compositions. This hexagonal class of solid solutions constitutes a significant expansion of the bulk Ge−Si solid solution family, and is of interest for optoelectronic applications. 相似文献
106.
Christoph Kaiser Dr. Thomas Halbritter Dr. Alexander Heckel Dr. Josef Wachtveitl 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(35):9160-9173
Photoacids attract increasing scientific attention, as they are valuable tools to spatiotemporally control proton-release reactions and pH values of solutions. We present the first time-resolved spectroscopic study of the excited state and proton-release dynamics of prominent merocyanine representatives. Femtosecond transient absorption measurements of a pyridine merocyanine with two distinct protonation sites revealed dissimilar proton-release mechanisms: one site acts as a photoacid generator as its pKa value is modulated in the ground state after photoisomerization, while the other functions as an excited state photoacid which releases its proton within 1.1 ps. With a pKa drop of 8.7 units to −5.5 upon excitation, the latter phenolic site is regarded a super-photoacid. The 6-nitro derivative exhibits only a phenolic site with similar, yet slightly less photoacidic characteristics and both compounds transfer their proton to methanol and ethanol. In contrast, for the related 6,8-dinitro compound an intramolecular proton transfer to the ortho-nitro group is suggested that is involved in a rapid relaxation into the ground state. 相似文献
107.
Abstract The long range molecular dynamical behaviour of liquid-crystalline side chain polymers with the mesogenic groups linked laterally to the backbone have been studied by using dielectric relaxation spectroscopy over a broad temperature and frequency range. The samples were oriented homeotropically and homogenously by electric and magnetic fields and the relaxations were recorded during alignment and with the fully aligned samples. By fitting the data to theoretical relaxation curves, accurate relaxation parameters could be determined, allowing us to perform a comparison with end-fixed liquid-crystalline side chain polymers on the one hand and with low molecular weight liquid crystals on the other. The relaxation in homeotropic alignment for the laterally fixed compound has more analogies in some aspects, for example, the relaxation time distribution, with low molecular weight liquid crystals than with the corresponding end-fixed compounds, though the activation energy is very large (241 kJ/mol). We relate this to the length of the rigid mesogenic unit and the resulting stronger repulsion by the neighbouring side chains during reorientation. In homogeneous alignment the relaxation is very broad and also has a large activation energy. Different molecular processes are related to this relaxation regime. The relationship between the different relaxation processes and the molecular structure is discussed. 相似文献
108.
109.
Reactivity ratios for the copolymerization of styrene (r 1) meta-divinylben-zene (r 2–m) and with para-divinylbenzene (r 2–p) have been redetermined under different reaction conditions and with different radioactivity assay techniques. The copolymers were prepared at two conversion levels [0.55 to 3.7% and 2.7 to 7.5% and at 80° (rather than 100°)] with benzoyl peroxide (in place of τ-butylhydroperoxide) initiator. The ionization chamber-vibrating reed electrometer radioactivity assay technique developed for other copolymerization studies was used in place of the direct counting technique previously used for the styrene/divinylbenzene systems. The new values are r 1 = 0.605/r 2-m = 0.88: r 1 = 0.77/r 2-p = 2.08 at 0.55 to 3.7% conversion and r 1 = 1.27; r 2–m = 1.08 at 2.7 to 7.5% conversion. These are not in close agreement with previous values partly because of the difference in conditions of copolymerization (temperature, per cent conversion, initiator) and in the improved analytical precision. Also the high-DVB-content (80%) para copolymer data are not assumed to be invalid and are not omitted (as they were before) from selection of the r 2–p values. 相似文献
110.
Petr Kluson Stepan Kment Magdalena Morozova Pavel Dytrych Stanislav Hejda Morwenna Slater Zdenek Hubicka Josef Krysa 《Chemical Papers》2012,66(5):446-460
Chemistry and physics of thin semiconducting layers of various types are subjects of intense research. Especially when nanotechnology
methods such as self-assembly are involved, amazing structural and/or functional properties may appear. Also modern physical
methods using variously organized plasma arrangements are able to produce uniform structures with distinctive functionality.
In this review, based virtually on our own work, discussions on the preparation, structure, morphology, and function of titanium(IV)
oxide nanoscopic thin films are presented. It was shown that structurally and functionally similar titanium(IV) oxide films
can be prepared via completely different preparation techniques. Function tests were arranged as “primary”, covering the assessment
of the light induced charge separation efficiency, and “secondary”, based on photocatalytic surface oxidations. 相似文献