نتایج جستجو برای: bond stretching
تعداد نتایج: 85676 فیلتر نتایج به سال:
The MD simulations have been performed using the OPLS force-field [1]. The toluene and phosphine molecules have been treated as fully rigid bodies, whereas the borane molecule has been also parametrized for pyramidalization and aryl torsions. The functional form of the force-field consists of harmonic terms for bond stretching and angle bending, Fourier series for torsional energetics, and Coul...
A remarkable nickelacycle has been synthesised via olefin metathesis of the α,ω-diene complex [Ni(η5-C5H4R)(Br)(NHC)] (R = C(CH3)2CH2CH[double bond, length as m-dash]CH2, NHC = 1-(6-hexenyl)-3-(2,4,6-trimethylphenyl)-imidazol-2-ylidene). Single-crystal X-ray analysis reveals a helical shape of the molecule and stretching of some interatomic distances in the Ni(ii) coordination sphere. The Cp-NH...
The vibrational wavenumbers of sulphaguanidine were calculated using Gaussian03 software at different levels and compared with experimentally observed data. The predicted infrared intensities, Raman activities and first hyperpolarizability are reported. The calculated geometrical parameters (DFT) are in agreement with that of similar derivatives. The potential energy scan studies for different ...
To assess the potential use of O-H stretching modes of aromatic alcohols as ultrafast local probes of transient structures and photoacidity, we analyze the response of the O-H stretching mode in the 2-naphthol-acetonitrile (2N-CH3CN) 1:1 complex after UV photoexcitation. We combine femtosecond UV-infrared pump-probe spectroscopy and a theoretical treatment of vibrational solvatochromic effects ...
The ir-spectra in the N-H stretching region of Piv-Pro-NHMe and Boc-Pro-NHMe have been studied in carbon tetrachloride and chloroform solutions over a wide range of concentrations. Based on the concentration dependence of the N-H stretching bands, i t has been shown that the characteristic N-H stretching band due to the C7 intramolecular hydrogen bond is around 3335 cm-'. Intermolecular hydroge...
The present study reports an unusual diffuse reflection Fourier transform (DRIFT) spectrum of ethane adsorbed by gallium oxide. One of the stretching C-H bands in this spectrum with a maximum at 2753 cm(-1) is more than by 100 cm(-1) shifted toward lower frequencies in comparison with gaseous ethane. In addition, the relative intensity of this band is unusually high. This indicates a very stron...
مقدمه : اپی کندیلیت خارجی یا آرنج تنیس بازان ( tennis elbow ) یکی از بیماریهای شایع خارج مفصلی است که با درد و حساسیت حاد در محل اتصال عضلات اکستانسور ساعد همراه می باشد. یکی از روشهایی که در سالهای اخیر جهت درمان مبتلایان به اپی کندیلیت خارجی مورد توجه متخصصان علم ارتوپدی قرار گرفته است، استفاده از طب سوزنی و needling می باشد که میزان کارایی آن در بهبود علائم بیماران هنوز بطور دقیق مشخص نیست. ...
این مطالعه در نظر دارد تا استحکام برشی 4 نوع سیستم چسبنده عاجی موجود در بازار را مقایسه کند. چهار نوع چسب عاجی شامل: 1-cleafil-se bond(kuraray) 2-etch&prime 3.03-excite single component(vivadent) 4-single bond(3m) است.
Compared with other molecular liquids, water is highly structured because of its ability to form up to four hydrogen bonds, resulting in a tetrahedral network of molecules. However, this underlying intermolecular structure is constantly in motion, exhibiting large fluctuations and reorganizations on time scales from femtoseconds to picoseconds. These motions allow water to play a key role in a ...
We investigate the viscoelastic properties of an associating rigid rod network: aqueous suspensions of surfactant stabilized single wall carbon nanotubes (SWNTs). The SWNT suspensions exhibit a rigidity percolation transition with an onset of solidlike elasticity at a volume fraction of 0.0026; the percolation exponent is 2.3+/-0.1. At large strain, the solidlike samples show volume fraction de...
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