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排序方式: 共有167条查询结果,搜索用时 46 毫秒
1.
Diaper CM Sutherland A Pillai B James MN Semchuk P Blanchard JS Vederas JC 《Organic & biomolecular chemistry》2005,3(24):4402-4411
Aziridine analogues of diaminopimelic acid (DAP) have been prepared stereoselectively for the first time and evaluated as inhibitors of DAP epimerase. (2R,3S,3'S)-3-(3'-Aminopropane)aziridine-2,3'-dicarboxylate was synthesised and shown to be a reversible inhibitor of DAP epimerase with an IC(50) value of 2.88 mM. (2S,4S)- and (2S,4R)-2-(4-Amino-4-carboxybutyl)aziridine-2-carboxylic acid (ll-azi-DAP and dl-azi-DAP ) were made as pure diastereomers, and both were shown to be irreversible inhibitors of DAP epimerase. ll-Azi-DAP selectively binds to Cys-73 of the enzyme active site whereas dl-azi-DAP binds to Cys-217 via attack of sulfhydryl on the methylene of the inhibitor aziridine ring. These observations are consistent with the two base mechanism proposed for the epimerization of ll-DAP and meso-DAP by DAP epimerase. 相似文献
2.
Takimiya K Kunugi Y Konda Y Niihara N Otsubo T 《Journal of the American Chemical Society》2004,126(16):5084-5085
2,6-Diphenylbenzo[1,2-b:4,5-b']dichalcogenophenes including thiophene, selenophene, and tellurophene analogues as organic semiconductors for field-effect transistors were effectively synthesized in three steps from commercially available 1,4-dibromobenzene. All three benzodichalcogenophenes acted as good p-type semiconductors, and particularly the selenophene analogue, 2,6-diphenylbenzo[1,2-b:4,5-b']diselenophene, showed high FET mobility of 0.17 cm2 V-1 s-1. 相似文献
3.
Structural Chemistry - This work reports hydrogen uptake capacity and equilibrium isotope effect (EIE) for the Be, Li, and Ti-doped closoborate (B6H6) complexes using first-principles calculations... 相似文献
4.
N‐bromo‐hydantoin grafted polystyrene beads: Synthesis and nano‐micro beads characteristics for achieving controlled release of active oxidative bromine and extended microbial inactivation efficiency 下载免费PDF全文
Mahran Daif Konda Reddy Kunduru Natalia Laout Stanislav Ratner Nurit Beyth Abraham J. Domb 《Journal of polymer science. Part A, Polymer chemistry》2016,54(5):596-610
N‐bromo‐hydantoin and N‐bromo‐5,5′‐dimethylhydantoin conjugated polystyrene beads were synthesized from chloromethyl polystyrene beads which differ in their particles size, crosslinking, nano‐micro porosity, and tunnels size on the surface, in order to study the effect of these parameters on oxidative halogen release and resultant activity, for water purification applications. The synthesized beads were characterized using elemental analysis, FT‐IR, solid state 13C‐NMR, and scanning electron microscope (SEM). The conjugation yield and kinetics in different solvents and bromine loading capacity were studied. The N‐bromoamine polystyrene beads were tested for water decontamination according to NSF 231 protocol. The release of active bromine was analyzed by spectrophotometer using a DPD‐1 kit and also studied the antimicrobial activity against Escherichia coli and MS2 phages. Bead's nano‐micro characteristics were found critical for oxidative halogen release control: rate stabilization and modulation, extension and also influences antimicrobial activity. The synthesized beads exhibited extended and stable release of bromine, 6 and 4 log reduction for E. coli and MS2, respectively for 250 L of passing contaminated water. Thus, N‐halamine hydantoins conjugated polystyrenes, chemically or kinetically release modified should have applications as disinfectants in water purification systems as well as medical field. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 596–610 相似文献
5.
S. C. Tripathi K. K. Gupta M. Bindu P. M. Gandhi 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(1):657-661
Present investigation describes our study on photochemical generation of uranous ions and consequent degradation of solvent in the uranium loaded 30 % Tributyl phosphate-n-dodecane-nitric acid system. Samples of 30 % TBP-n-dodecane loaded with uranium were subjected to UV photolysis at 254, 300 and 350 nm respectively. Wavelength dependent formation of U(IV) has been determined spectrophotometrically by measuring absorbance at 656 nm. Additionally, photochemical yield of U(IV) has also been estimated semi quantitatively as a function of time of photolysis. The changes in the solvent composition under different photochemical conditions have been studied by examination of comparative gas chromatographic profiles of the solvent before and after photolysis. Among the wavelength of photo irradiation studied, the yield of U(IV) was found to be optimum at 300 nm with least degradation of PUREX solvent. 相似文献
6.
An efficient stereoselective three-component reaction for the synthesis of functionalized spiro[4H-pyran-3,3′-oxindole] derivatives was realized through an organocatalyzed domino Knoevenagel/Michael/cyclization reaction using a cinchonidine-derived thiourea as the catalyst. Using water as the additive was found to improve the product ee values significantly. Under the optimized conditions, the reactions between isatins, malononitrile, and 1,3-dicarbonyl compounds yield the desired spirooxindole products in good yields (71–92%) and moderate to high ee values (up to 87% ee). 相似文献
7.
ABSTRACTThis study was to investigate the piezotolerance and diversity indices of microflora of Indian white prawn (Fenneropenaeus indicus) after high pressure (HP)-treatment. Indian white prawns subjected to HP-treatments and its effect was studied up to species level and compared with unpressurized samples. The bacterium was identified by using bacterial identification schemes, biochemical tests and API kits (bioMérieux, Marcyl’Etoile, France). Diversity analysis was performed using PRIMER (Plymouth Routines in Multivariate Research) software v 5.2.2. The significant elimination of microflora was found to be proportional with the pressure level. In the case of spore formers, mere destruction was noticed after HP-treatment. Arthrobacter spp., Listeria grayi and Corynebacterium spp. were the most piezotolerant bacteria in HP-treated samples. Diversity indices revealed a significant reduction of microflora of Indian white prawn. The apparent reduction of microflora with pressure level was clearly evident from the diversity indices; moreover a diminished piezotolerance of Gram negative spoilage bacteria was also observed. 相似文献
8.
Litty Irimpan A. Deepthy Bindu Krishnan V.P.N. Nampoori P. Radhakrishnan 《Applied physics. B, Lasers and optics》2008,90(3-4):547-556
In the present work, we have investigated the nonlinear optical properties of self-assembled films formed from ZnO colloidal
spheres by z-scan technique. The sign of the nonlinear component of refractive index of the material remains the same; however,
a switching from reverse saturable absorption to saturable absorption has been observed as the material changes from colloid
to self-assembled film. These different nonlinear characteristics can be mainly attributed to ZnO defect states and electronic
effects when the colloidal solution is transformed into self-assembled monolayers. We investigated the intensity, wavelength
and size dependence of saturable and reverse saturable absorption of ZnO self-assembled films and colloids. Values of the
imaginary part of third-order susceptibility are calculated for particles of size in the range 20–300 nm at different intensity
levels ranging from 40 to 325 MW/cm2 within the wavelength range of 450–650 nm.
PACS 81.16.Dn; 42.65.-k; 42.65.An; 42.70.-a; 42.70.Nq; 78.20.Ci 相似文献
9.
10.
Adusumilli Srikrishna Vijendra H. Pardeshi Konda Mahesh 《Tetrahedron: Asymmetry》2010,21(20):2512-2516
The enantiospecific total synthesis of two epimers of the sesquiterpene isocalamusenone has been accomplished starting from the readily available monoterpene (R)-limonene, which of the natural product established the stereostructure and the absolute configuration. 相似文献