نتایج جستجو برای: mechanisms of cis and trans beta lactam ring formation

تعداد نتایج: 24118100  

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه گیلان - دانشکده علوم انسانی 1392

this study investigated how group formation method, namely student-selected vs. teacher-assigned, influences the results of the community model of teaching creative writing; i.e., group dynamics and group outcome (the quality of performance). the study adopted an experimental comparison group and microgenetic research design to observe the change process over a relatively short period of time. ...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه صنعتی اصفهان 1371

the effect of the presence of perforations on he stresses of a plate is a problem which is of great interest in structural design and in the mathemattical theory of elasticity. among the many hole patterns that are likely to require consideration is the ring of equally spaced circular holes. the present worke investigates stress & strain analysis of a thin isotropic circular plate containing a ...

Journal: :Chembiochem : a European journal of chemical biology 2009
Mary L Raber Alvaro Castillo Alexander Greer Craig A Townsend

beta-Lactam synthetase (beta-LS) is the paradigm of a growing class of enzymes that form the critical beta-lactam ring in the clavam and carbapenem antibiotics. beta-LS catalyzes a two-stage reaction in which N(2)-(2-carboxyethyl)-L-arginine is first adenylated, and then undergoes intramolecular ring closure. It was previously shown that the forward kinetic commitment to beta-lactam formation i...

The mechanism of the self-reaction of HCO radicals is investigated by using high-level quantum-chemical methods including M05-2X, CCSD, CCSD(T) and CRCC(2,3). Next, the rate coefficients for several product channels as a function of pressure and temperature are computed by employing statistical rate theories. Four important product channels are predicted to be CO + CO + H2, HCOH + OH, cis-(HCO)...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه رازی - دانشکده علوم 1387

boron nitride semiconducting zigzag swcnt, $b_{cb}$$n_{cn}$$c_{1-cb-cn}$, as a potential candidate for making nanoelectronic devices was examined. in contrast to the previous dft calculations, wherein just one boron and nitrogen doping configuration have been considered, here for the average over all possible configurations, density of states (dos) was calculated in terms of boron and nitrogen ...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه صنعتی اصفهان - دانشکده فیزیک 1390

in this thesis, barium ferrite nano particles were prepared by sol-gel method. their structural and magnetic properties of samples have been investigated using thermo gravimetric analysis (tg-dta), x-ray powder diffractometer (xrd), fourier transform infrared (ftir), scanning electron microscopy (sem), field emission scanning electron microscopy (fesem), ac susceptometer, vibrating sample magne...

آهنجان, محمد, سلیمانی, آریا, نادری, فاطمه,

Background and purpose: : Klebsiella pneumoniae has emerged as a significant opportunistic pathogen responsible for nosocomial infections. This bacteria is frequently resistant to multiple classes of antibiotics such as family of beta-lactam antibiotics. β-lactamases enzyme represent the main mechanism of bacterial resistance to β-lactam antibiotics. This study was conducted to determi...

Journal: :Biochemistry 2008
Marcus Lundberg Per E M Siegbahn Keiji Morokuma

Isopenicillin N synthase (IPNS) catalyzes a key step in the biosynthesis of the important beta-lactam antibiotics penicillins and cephalosporins. Density-functional calculations with the B3LYP functional are used to propose a detailed mechanism for this reaction. The results support the general scheme outlined from experimental observations, with formation of a four-membered beta-lactam ring fo...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه سیستان و بلوچستان 1390

during natural gas processing, water in natural gas may cause to hydrates formation in pipelines which may lead to serious damages to process equipments. given the problems raised by present of water in natural gas, glycol solvent uses to remove water.in contact of glycol with gas always an amount of btex and voc absorb along with water, which on glycol recovery process, these substances separa...

نخعی, محمودرضا , پالیزوان, محمدرضا, خزاعی, محمودرضا , غزنوی‌راد, احسان‌اله,

    Background & Aim: Impressive research demonstrates the importance of essential fatty acids for many physiological and behavioral mechanisms in both humans and animals. Experimental research showed that deficit in learning and memory is induced after kindling. The objective of this study was to investigate whether dietary cis and trans fatty acids, pre and during pentylenetetraxol(PTZ) kindl...

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