نتایج جستجو برای: ultraviolet spectra
تعداد نتایج: 145407 فیلتر نتایج به سال:
A new antitumor antibiotic, fredericamycin A (FCRC-A48, NSC-305263), has been isolated from a strain of Streptomyces griseus (FCRC-48). Based on its unique ultraviolet-visible spectrum, infrared spectrum, proton and carbon-13 nuclear magnetic resonance spectra and mass spectra, it is judged to be a novel acid-base indicator type of compound. Its production, isolation and physicochemical propert...
We used ultraviolet spectra from HST/STIS (R = 30, 000), together with optical spectra from Keck/HIRES (R = 45, 000), to study the three MgII-selected absorption systems at z = 0.9254, 0.9276, and 0.9342 toward the quasar PG 1206 + 459. A multi-phase gaseous structure, with low-ionization components produced in small condensations and high-ionization ones in diffuse clouds, is indicated in all ...
Infrared (IR) and ultraviolet (UV) spectroscopic analysis of eight structural isomers of C20 carbon nanostructures, i.e. ring, tadpole, bow-tie, dumb-bell, spiro, propellane, bowl and cage, were performed at different levels of theory including semi-empirical (AM1 and PM3), Hartree-Fock (HF/6-31++G, 6-31++G**) and density functional theory (B3LYP/6-31++G, 6-31++G**). A broad range of IR spectra...
The influence of geometry variations and solvent environment of N-methylacetamide on its energies and absorption intensities was systematically analyzed with the aid of the time-dependent density functional theory (TD DFT). Selective and often complicated reactions of individual electronic levels on the perturbations were found important for the resultant spectral profile. For example, the n-pi...
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