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1.
Jeffrey Kovac 《Foundations of Chemistry》2002,4(2):163-171
Traditional philosophy of science regards theoretical reasoning, based on the example of Euclidian geometry, as the hallmark
of a mature science. There is, however, a parallel tradition of practical reasoning based on specific cases that goes back
to Aristotle. In this paper I argue that practical reasoning is an essential part of the practice of chemistry and should
be understood and appreciated on its own merits rather than regarded as a symbol of the immaturity and inferiority of chemistry
as a science.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
2.
The electronic structure of all isomeric dihalobenzenes C6H4XY (X, Y = Cl, Br, I) has been investigated by HeI/HeII photoelectron spectroscopy, Green's functions calculations, and comparison with the spectra of related dihalobenzenes C6H4X2 (X = Cl, Br, I). The careful analysis of measured pi orbital and halogen lone pair ionization energies enabled us to describe substituent effects in terms of resonance, inductive, steric, and spin-orbit coupling interactions. 相似文献
3.
The H-bonding between the phenol and a series of alkylisothiocyanates has been studied over a range of temperatures. Association constants for the systems phenol-isothiocyanates were determined from IR spectre. Enthalpies and entropies of association were estimated from the tempperature-dependencies of the association constants. The -ΔH values of the systems studied in the range of 1·7–2·8 Kcal/mole indicate weaker H-bonding than those reported for the systems phenolalkylthiocyanates. 相似文献
4.
Jeffrey Kovac 《Foundations of Chemistry》2000,2(3):207-219
This essay offers a preliminary philosophy ofchemistry as a profession focusing on professionalethics. First, I look at how
well chemistry fits themodel of a liberal profession. I then explore therelationship between epistemology and ethics. Therelationship
between chemistry and society isdiscussed in the context of the two-dimensionalclassification of research developed by Donald
Stokesin his book Pasteur's Quadrant. Finally, Iraise the questions of an appropriate moral ideal forchemistry and the ethical conflicts that can occurwhen chemists
simultaneously fulfill more than one role.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
5.
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7.
Novak I Kovac B 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(11-12):2771-2774
HeI and HeII photoelectron spectra of 6-chloro-1,3-dimethyluracil have been measured. The assignment of the spectrum was made by comparison with photoelectron spectra of related compounds and by high-level OVGF calculations. The electronic structure changes in substituted nucleobases are discussed on the basis of photoelectron spectroscopic data. The electronic structure data are compared with structure-activity relationships regarding enzyme inhibition and complex formation. The electronic structure data give some insight into the nature of binding between nucleobases' derivatives and different enzymes whose activity they inhibit. 相似文献
8.
Juraj Piestansky Jaroslav Galba Branislav Kovacech Vojtech Parrak Andrej Kovac Peter Mikuš 《Biomedical chromatography : BMC》2020,34(10):e4907
Creatinine is an important diagnostic marker and is also used as a standardization tool for the quantitative evaluation of exogenous/endogenous substances in urine. This study aimed at evaluating and comparing three analytical approaches, based on hyphenations of different separation [two-dimensional capillary isotachophoresis (CITP–CITP), capillary zone electrophoresis (CZE), ultra-high-performance liquid chromatography (UHPLC)] and detection [conductivity (CD), ultraviolet (UV), tandem mass spectrometry (MS/MS)] techniques, for their ability to provide reliable clinical data along with their suitability for the routine clinical use (cost, simplicity, sample throughput). The developed UHPLC–MS/MS, CITP–CITP–CD, and CZE–UV methods were characterized by favorable performance parameters, such as linearity (r ˃ 0.99), precision (relative standard deviation, 0.22–2.97% for the creatinine position in analytical profiles), and recovery (87.1–115.1%). Clinical data, obtained from the analysis of 24 human urine samples by a reference enzymatic method, were comparable with those obtained by the tested methods (Passing–Bablok regression and Bland–Altman analysis), approving their usefulness for the routine clinical use. In this context, the UHPLC–MS/MS method provides benefits of enhanced orthogonality/accuracy and high sample throughput (threefold shorter total analysis times than the CE methods), whereas advantages of the CE methods for routine labs are simplicity and low cost of both the instrumentation and measurements. 相似文献
9.
The electronic structures of several halogen substituted bezoquinones and benzoquinoneimines have been studied by HeI/HeII photoelectron spectroscopy and Green's function calculations. The information on the electronic structure is discussed in the context of their electron-transfer properties and biological activity. 相似文献
10.
Andrej Vincze Ján Jakabovi? Rudolf Srnánek Alexander ?atka Jaroslav Kovac Jr. 《Central European Journal of Physics》2009,7(2):270-278
To improve Organic Thin Film Transistor (OTFT) properties we study OTFT semiconductor/dielectric interfacial properties via
examination of the gate dielectric using thin Parylene C layer. Structural and morphology properties of pentacene layers deposited
on parylene layer and SiO2/Si substrate structure were compared. The surface morphology was investigated using atomic force microscopy (AFM) and scanning
electron microscopy (SEM). AFM topography of pentacene layer in non-contact mode confirmed the preferable pentacene grain
formation on parylene surface in dependence on layer thickness. The distribution of chemical species on the surfaces and composition
depth profiles were measured by secondary ion mass spectroscopy (SIMS) and surface imaging. The depth profiles of the analyzed
structures show a homogenous pentacene layer, characterized with C or C2 ions. Relatively sharp interface between pentacene and parylene layers was estimated by characteristic increased intensity
of CCl ions peak. For revealing the pentacene phases in the structures the Micro-Raman spectroscopy was utilized. Conformal
coatings of parylene and pentacene layers without pinholes resulted from the deposition process as was confirmed by SIMS surface
imaging. For the pentacene layers thicker than 20 nm, both thin and bulk pentacene phases were detected by Micro-Raman spectroscopy,
while for the pentacene layer thickness of 5 and 10 nm the preferable thin phase was detected. The complete characterisation
of pentacene layers deposited on SiO2 and parylene surface revealed that the formation of large grains suggests 3D pentacene growth at parylene layer with small
voids between grains and more than one monolayer step growth. The results will be utilized for optimization of the deposition
process.
相似文献