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491.
Robert H. Heflich Eileen Mahoney-Leo Veronica M. Maher J. Justin McCormick 《Photochemistry and photobiology》1979,30(2):247-250
Abstract— S1 endonuclease was shown to remove thymine-containing pyrimidine dimers from UV-irradiated human DNA, although efficient removal could be demonstated only by using long digestion times, relatively high enzyme concentrations, and irradiation sufficient to yield dimer substitutions in DNA of 1 per 1W300 (dimers/base pair). Neutral and alkaline sucrose gradient analysis of strand break induction by S, of UV-irradiated DNA suggests that recognition of the dimer by S, is the limiting factor in its removal and dimer removal usually results from attack on the dimer containing DNA strand without the induction of a double-strand break. 相似文献
492.
Rudolf O. Duthaler Peter Mathies Walter Petter Christoph Heuberger Veronica Scherrer 《Helvetica chimica acta》1984,67(5):1217-1221
The substituted 1,2,3,4,4a,9,10,10a-octahydrophenanthrene-4,9-dione 2 , synthesized from the cyclohexanone 8 and quinone 11 (Scheme 2), was found by X-ray analysis adn 1H-NMR studies to be the isomer with cis-junction of the saturated rings. The cis-fusion could also be determined from the 1H-NMR data of the related compound 17 (Scheme 4), which was previously considered to be trans-fused. In contrary to previous argumentations, the interaction of the C(4)-carbonyl O-atom of trans-fused octahydrophenanthenes is more severe with a 5-methoxy than with a 5-methyl substituent. 相似文献
493.
494.
Cornel VM 《The Journal of organic chemistry》2007,72(1):303-312
Reviews are listed in order of appearance in the sources indicated. In multidisciplinary review journals, only those reviews which fall within the scope of this Journal are included. Sources are listed alphabetically in three categories: regularly issued review journals and series volumes, contributed volumes, and other monographs. Titles are numbered serially, and these numbers are used for reference in the index. Major English-language sources of critical reviews are covered. Encyclopedic treatises, annual surveys such as Specialist Periodical Reports, and compilations of symposia proceedings are omitted. This installment of Recent Reviews covers principally the middle part of the 2006 literature. Previous installment: J. Org. Chem. 2006, 71(20), 7923-30. 相似文献
495.
Solvent systems for countercurrent chromatography: an aqueous two phase liquid system based on a room temperature ionic liquid 总被引:1,自引:0,他引:1
A new aqueous two phase liquid system (ATPS) based on the ionic liquid 1-butyl-3-methyl imidazolium chloride (BMIM Cl), potassium dibasic phosphate (K(2)HPO(4)) and water was recently proposed in the literature. The full phase diagram of this ATPS was prepared and some tie lines were fully determined. It was compared to classical ATPSs based on polyethylene glycol with an average molecular mass of 1000 (PEG 1000) and 10,000 (PEG 10000) and K(2)HPO(4). Two countercurrent chromatography (CCC) columns, a hydrostatic Sanki and a J type hydrodynamic CCC columns were used to test the liquid phase retention of these ATPSs in all possible configurations. It was found that the BMIM Cl ATPS liquid phases were much easier to retain in the two CCC columns than the PEG 1000 ATPS phases. Using protein and alcohol solutes, it was established that the BMIM Cl ATPS has a polarity completely different from that of the PEG 1000 ATPS. For example, ovalbumin partitions equally between the two phases of the PEG 1000 ATPS (K(D)=1.4) when it is completely located in the BMIM Cl upper phase of the ionic liquid ATPS (K(D)=180). The discrimination factor of the ionic liquid system and its intrinsic hydrophobicity were respectively found three times higher and ten times lower than the respective values of the PEG 1000 ATPS. 相似文献
496.
X-Ray absorption spectra show that a CeO(2)-supported CO oxidation catalyst prepared from Au(III)(CH(3))(2)(C(5)H(7)O(2)) initially incorporated Au(III) complexes that were catalytically active at 353 K; during operation in a flow reactor, the gold aggregated into clusters and the catalytic activity increased. 相似文献
497.
Trufelli H Famiglini G Termopoli V Cappiello A 《Analytical and bioanalytical chemistry》2011,400(9):2933-2941
This paper focuses on the development of a novel approach to analyze underivatized fatty acids in human plasma. The method
is based on liquid–liquid extraction followed by reversed phase liquid chromatography coupled to direct-electron ionization
mass spectrometry (LC-Direct-EI-MS). The assay is validated. Calibrations show satisfactory linearity and precision in the
investigated range of linearity. Recoveries span from 75% to 104%. The method limits of detection, varying from 0.53 to 5.35 μM,
are satisfactory for the quantitation of non-esterified fatty acids (NEFAs) in plasma at physiological levels. The method
has been successfully applied to the NEFAs profiling of plasma samples from healthy adult volunteers and subjects affected
by diabetes mellitus. Compared with published protocols based on gas chromatography–mass spectrometry and liquid chromatography
coupled to electrospray ionization mass spectrometry, this method does not require derivatization and does not show matrix
effects, thus simplifying sample preparation procedure and reducing the total time of analysis to approximately 90 min. In
addition, Direct-EI-MS allows the acquisition of high-quality NIST library-matchable EI spectra, allowing an easy-to-obtain
identification of the target NEFAs. 相似文献
498.
Mirkhalaf F Mason TJ Morgan DJ Saez V 《Langmuir : the ACS journal of surfaces and colloids》2011,27(5):1853-1858
The covalent attachment of various organic molecules on conductive supports including indium tin oxide (ITO) using diazonium chemistry has been known for many years. A commonly used method to achieve this is the electrochemical reduction of diazonium compounds leading to radicals, followed by binding of the radicals to the support. In the present report, an alternative method using ultrasound at different frequencies (20, 582, 863, and 1142 kHz) to induce the surface grafting of nitrobenzene diazonium onto an ITO surface is described. It is shown that the grafting on ITO is more efficient in the lower ultrasonic frequency range that is ascribed to changes in the balance between the physical and chemical effects of cavitation with frequency. Both the physical and chemical effects of cavitation play important roles at all frequencies, but at high ultrasound frequencies, the physical effects are relatively small. At 20 kHz, the physical component, including mass transport, is larger than at higher frequencies, and mechanisms based on these observations have been proposed. Ultrasonic grafting has an advantage over electrografting in that it may provide more control over surface coverage, thus it is suggested that the ultrasonic method is used where the surface concentration of the organic layer must be controlled. 相似文献
499.
Mihaela Badea Ana-Maria Crasanda Mariana Carmen Chifiriuc Luminita Marutescu Veronica Lazar Dana Marinescu Rodica Olar 《Journal of Thermal Analysis and Calorimetry》2013,111(3):1743-1751
New complexes [FeO(DMBG)]2 and [Fe(DMBG)2]Cl·0.5H2O (HDMBG: N,N-dimethylbiguanide) have been synthesized and characterized by microanalytical, IR and UV–Vis data. Electronic spectra of the complexes are characteristic for a tetrahedral stereochemistry, whilst the modifications in the IR spectra indicate the presence of the DMBG anion as chelate. The thermal decomposition investigated in air by thermal analysis confirmed the proposed formulas for the complexes and provided information concerning the modifications during heating and also the thermodynamic effects accompanying them. The thermal transformations are complex, according to TG and DTG curves including dehydration, hydrochloric acid elimination, oxidative degradation and condensation of –C=N– unit. The final product of decomposition was iron (III) oxide as powder XRD indicates. Complexes were screened for their antimicrobial properties against Gram-positive, Gram-negative bacterial, as well as fungal pathogenic strains. The results indicate that Fe(III) complexes exhibit an improved antibacterial activity against S. aureus and E. coli strains in comparison with free biguanide. The Fe(III) complexes also inhibit the ability of S. aureus, B. subtilis, P. aeruginosa and E. coli strains to colonize the inert substratum, accounting for their possible use as anti-biofilm agents. 相似文献
500.
Ioana Dorina Vlaicu Rodica Olar Dana Marinescu Veronica Lazar Mihaela Badea 《Journal of Thermal Analysis and Calorimetry》2013,113(3):1337-1343
Four new complexes having general formula [CoL2(acr)2] (L: 1H-pyrazole (Hpz) (1); 3-methyl-1H-pyrazole (3-Me-Hpz) (2); 4-methyl-1H-pyrazole (4-Me-Hpz) (3); 3,5-dimethyl-1H-pyrazole (Hdmpz) (4); acr: acrylato ion) were synthesised and characterised. The infrared and UV–vis spectral data indicate that these pyrazole derivatives act as unidentate while acrylato ions act as bidentate chelate ligands generating Co(II) complexes with octahedral stereochemistry. TG experiments revealed the nature of complex species as anhydrous and confirmed those compositions. The biological assays revealed a good activity against Bacillus subtilis for all complexes. 相似文献