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941.
Claudia Mureşanu Lucian Copolovici Florina Pogącean 《Central European Journal of Chemistry》2005,3(4):592-604
The inhibitory effect of para-nitrophenol on the catalytic reaction of catalase was investigated. Michaelis-Menten kinetic parameters were determined from
Lineweaver-Burk plots obtained in the absence or in the presence of the inhibitor. The inhibitor pattern, revealed by the
Lineweaver-Burk plots, suggested a fully mixed inhibition mechanism. Spectrophotometric monitoring of the indicator reaction:
in conjunction with initial rate measurements was employed for the kinetic determination of the inhibitor. Calibration plots
of initial rate vs. para-nitrophenol concentration were linear in the concentration range 0.9·10−5–2.5·10−5 mol/L and the detection limit was 3·10−6 mol/L (417 μg/L) para-nitrophenol. Interferences from other phenolic compounds like orto-cresole, meta-and orto-nitrophenol were observed. 相似文献
942.
IntroductionConsiderableattelltionisno\vbeillgpaidtotheCO7refonningof.etha..llto]forseveralreasonst(l)withthedevelopmentofindustrics.moreandnlorcCOZIsabettedintotheatmosphere,leadingto"greenhouseeffect",whichhasbroughtaboutgreatilltcreslallovertheworld.Th… 相似文献
943.
Renata Ga<parová Daniel Zbojek Margita Lácová Katarína Král'ová Anton Gatial Branislav Horváth Alžbeta Krutošíková 《Central European Journal of Chemistry》2005,3(4):622-646
The reactions of substituted furo[3,2-b]pyrrole-5-carboxhydrazides 1 with 5-arylfuran-2-carboxaldehydes 2, 4,5-disubstituted furan-2-carboxaldehydes 3 and thiophene-2-carboxaldehyde 4 has been studied. The advantage of microwave irradiation on some of these reactions was reflected in the reduced reaction
time and increased yields. Reactions of 1 with 4-substituted 1,3-oxazol-5(4H)-ones 11 led to diacylhydrazines 13 or to imidazole derivatives 14 depending on the temperature. 1,2,4-Triazole-3-thione 17 was synthesized by two-step reaction of 1 with phenylisothiocyanate and subsequent base-catalyzed cyclization of thiosemicarbazide 16. The effects of hydrazones 5–10 on inhibition of photosynthetic electron transport in spinach chloroplasts and chlorophyll content in the antialgal suspensions
of Chlorella vulgaris were investigated. 相似文献
944.
Ming-Liang Zhang Yu-Peng Tian Xuan-Jun Zhang Jie-Ying Wu Sheng-Yi Zhang Dong Wang Min-Hua Jiang Suchada Chantrapromm Hoong-Kun Fun 《Transition Metal Chemistry》2004,29(6):596-602
A new Schiff base ligand derived from S-benzyldithiocarbazate and 4-[N-hydroxy ethyl-N-(methyl)amino]benzaldehyde (HL, where H is a dissociable proton) and its NiII, CuII, ZnII and PdII complexes were prepared and fully characterized. The structures of HL and Ni(L)2 were determined by X-ray diffraction analysis, which revealed that the geometry of the NiII ion is square-planar with two equivalent Ni=N and Ni=S bonds, and that the two neighboring molecules in two layers have weak contact. The electronic spectra and solution fluorescence of the ligand and the complexes were studied, and the quantum yields of single-photon fluorescence for the compounds were determined. The compounds possess two-photon absorption (t.p.a.) character and the t.p.a. coefficient and t.p.a. cross-section were determined by the Z-scan technique. Especially, the Zn(L)2complex and the HL ligand exhibit intensive two-photon fluorescence (t.p.f.) at 800 nm laser pulses in the femtosecond regime. 相似文献
945.
Yinghong Sheng Jerzy Leszczynski Thuc-Quyen Nguyen Anu Bamgbelu 《Structural chemistry》2007,18(6):827-832
A theoretical study using density functional theory was performed to understand the structure/property relationship of the
cationic conjugated polyelectrolytes, poly[9,9-bis-(6′-N,N,N-trimethylammonium) hexyl] fluorene-alt-4,7-(2,1,3-benzothiadiazole)] (PFBT-X, where X = Br). The torsion angle between the fluorene and benzothiadiazole units in the PFBT monomer was found to substantially affect
the structural and electronic properties of the cationic PFBT monomer. The changes of geometrical parameter, HOMO and LUMO energy levels, and band gap, as well as the absorption maximum
are discussed in terms of the torsion in the PFBT monomer structure. For comparison, its neutral analogue, the monomer of
poly(9,9-di-n-octylfluorene-alt-benzothiadiazole) (F8BT) was also studied. The length of conjugation backbone was also examined. 相似文献
946.
Electrodeposition of nanocrystalline zinc from acidic sulfate solutions containing thiourea and benzalacetone as additives 总被引:1,自引:0,他引:1
Mou Cheng Li Li Li Jiang Wen Qi Zhang Yu Hai Qian Su Zhen Luo Jia Nian Shen 《Journal of Solid State Electrochemistry》2007,11(4):549-553
Nanocrystalline zinc coatings were produced by pulse electrodeposition in acid sulfate bath containing thiourea and benzalacetone
additives and characterized by X-ray diffraction and scanning electron microscopy techniques. The influence of benzalacetone
concentration and pulse peak current density on the grain size and crystallographic orientation of zinc deposits was investigated.
Zinc electrodeposited from additive-free solutions or with one of the two additives is not composed of nanosized crystals.
The mixture additives of thiourea and benzalacetone give rise to the formation of particle-like nanocrystalline zinc with
a (10ī1) random orientation. A change in peak current density from 2 to 1 A/cm2 only increases the grain size from 60 to 62 nm. 相似文献
947.
Su-Hong Ge Xin-Lu Cheng Xin-Xing Wang Guang-xing Dong Gui-hua Sun 《Structural chemistry》2007,18(6):985-991
Some explosives are stable molecules with large energy barriers to chemical reaction, and in shock or impact initiation, a
sizable amount of phonon energy must be converted to the molecular internal higher vibrations by multiphonon up pumping. To
investigate the relationship between impact sensitivities and energy transfer rates, the number of doorway modes of explosive
molecules is estimated by a simple theory in which the rate is proportional to the number of normal mode vibrations. We evaluated
frequencies of normal mode vibrations of 13 explosive molecules which are CHNO nitramine-contained and have not been analyzed
previously. The number of doorway modes in the regions of 200–700 cm−1 was evaluated by the direct counting method. For more clear investigation of the relationship we have classified these 13
nitramine explosive molecules, by the number of nitramine group they contained, into two groups. There are eight molecules
that contained one nitramine group and five molecules that contained poly-nitramine groups. It is found that the number of
doorway modes shows a linearly correlation to the impact sensitivities derived from drop hammer tests. This result is in agreement
with that of several previous works. Besides, it is also noted in our study that in those nitramine explosives molecules with
similar molecular structure (similar number nitramine group they contained) and similar molecular weight, the correlation
between the sensitivity and the number of doorway modes is higher. We found that the vibrational frequency of ω corresponds
to nitro group motions of every molecule is contributed to the number of doorway modes in the regions of 200–700 cm−1. 相似文献
948.
The guaianolide ester is a potent inhibitor of cancer cells. Lactucopicrin, a guaianolide, shows analgesic, antitussic, and sedative activities. In order to investigate its structure, 1H and 13C NMR and 2D NMR have been carried out at a proton field strength of 400 MHz and a carbon field strength of 100 Mhz in DMSO-d
6 at 20°C. Resonances for all protons and carbons have been assigned. The results of HMQC and HMBC experiments suggest that the structure of lactucopicrin is as shown in Fig. 1. Its stereostructure is verified by the X-ray experiment. 1H and 13C NMR of lactucopicrin are reported. Its 2D NMR and X-ray are reported for the first time. 相似文献
949.
The inducing method for preparing Ag-micelle solution with the use of mixed solvent/nonsolvent, and the morphological characterization of the generated metal–micelles were investigated and reported in this paper. In this method, an Ag containing metal chelate polymer (MCP) raw solution was preprepared by dissolving poly(vinyl acetate) (PVAc)–silver nitrate (AgNO3) MCP in conc. formic acid, and a mixed solvent of HCOOH/H2O with specific water composition was then added to induce the micellization of the MCP chain. The critical water concentration (CWC) that was needed for inducing the formation of the Ag-micelles, and the water concentration at which the flocculation of the Ag-micelles occurred in micellar solution, were studied by measuring the transmittance of the dilute MCP solution; the results showed that a long-lasting MCP solution with stable micelles might be prepared by using a H2O/HCOOH solvent of specific weight ratio 1:1.2. The effect of the AgNO3 concentration on the morphology of the Ag-micelles was also investigated by transmission electron microscopy (TEM). At AgNO3 concentration below 0.5 wt%, the Ag-micelles displayed a variety of core-shell structure; but as the AgNO3 concentration was increased to 1.0–2.0 wt%, micelles that had Ag-solid embedded in the micellar core were observed. 相似文献
950.
Anna Worobiec Lucyna Samek Zoya Spolnik Velichka Kontozova Elzbieta Stefaniak René Van Grieken 《Mikrochimica acta》2006,156(3-4):253-261
The St. Michael Archangel’s Church in Szalowa, Poland, was selected for closer investigation with respect to the indoor/outdoor
air exchange and its influence on the air quality and work arts preservation. Chemical composition, size and abundance of
particulate matter and concentration of gases NO2, SO2, O3 inside and outside the church were determined. To study seasonal variation of the weather condition (temperature, inversion
level, wind direction) and the influence of seasonal sources of the air pollution (like heating of the nearby houses), samples
were collected in winter and summer time. It was stated that suspended particulate matter inside the wooden church has in
general an outdoor source. Several groups of particles were distinguished such as the organic ones, soil dust, nitrates and
sulphates. In case of organic and soil dust particles, the concentration inside was higher than outside. From the results,
in comparison to literature data, one can conclude that accumulation of particulate suspended matter in the church is more
intense than in other types of buildings. Gaseous pollutants were detected but their concentration was negligible. 相似文献