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排序方式: 共有171条查询结果,搜索用时 93 毫秒
31.
Pralay Maiti Ganga Radhakrishnan Palanisamy Aruna Goutam Ghosh 《Macromolecular Symposia》2006,241(1):51-59
Novel polyurethane gels have been reported in common solvent like dimethyl formamide (DMF). Polyurethanes have been synthesized from diisocyanates, diols and rigid chain extenders. We have illustrated the influence of chemical structure of the chain extenders on gelation rate, thermal property and morphology of the gels in DMF. Gelation rate increases significantly with the rigidity of the chain extender. Introduction of more rigid chain extender molecules in polyurethane prepolymer enhanced the thermal stability of the pure polymer. On the contrary, the solvent retention power of the gels gradually decreases with increasing rigidity of chain extender presumably because of the poor dispersion/greater aggregation of the hard segments in the soft segment matrix. Morphology and formation of gelation have been discussed. 相似文献
32.
E. D. V. Nagesh G. Santosh Babu V. Subramanian V. Sivasubramanian V. R. K. Murthy 《Pramana》2005,65(6):1115-1120
We report the use of low dielectric constant materials to form two-dimensional microwave band-gap structures for achieving
high gap-to-midgap ratio. The variable parameters chosen are the lattice spacing and the geometric structure. The selected
geometries are square and triangular and the materials chosen are PTFE (ε = 2.1), PVC (ε = 2.38) and glass (ε = 5.5). Using the plane-wave expansion method, proper lattice spacing is selected for each structure and material. The observed
experimental results are analyzed with the help of the theoretical prediction 相似文献
33.
Thomas Balasingh Sudha Palanisamy Thanikaivelan Meiyazhagan Ashokkumar Bangaru Chandrasekaran 《Applied biochemistry and biotechnology》2011,163(2):247-257
A hybrid protein fiber from different protein sources such as casein and soybean using wet-spinning technique was prepared.
The casein/soybean hybrid fibers were synthesized at different weight ratios such as 100/0 (casein), 75/25, 50/50, 25/75,
and 0/100 (soy) and characterized. Electron microscopic analysis confirmed the growth of pure and hybrid fibers and shows
an increased surface roughness as the soy concentration increases in the hybrid fibers. Infrared spectra did not exhibit any
significant changes in the functional groups between pure and hybrid fibers. X-ray diffraction pattern indicates slight increase
in the diffraction peak values of hybrid fibers compared with the neat fibers. Thermal analyses show a moderate increase in
the thermal stability of hybrid fibers when compared with the pure fibers. These results implicitly indicate that the casein
and soy proteins are homogeneous in the hybrid fiber form. It has been demonstrated that the hybrid fiber with ≥50 wt.% casein
content exhibits better morphology and increased thermal stability, which has scope for application in technical and medical
industries. 相似文献
34.
Chockalingam Venkatachalapathy Muniappan Thirumalaikumar Shanmugam Muthusubramanian Kasi Pitchumani Shunmugaperumal Sivasubramanian 《合成通讯》2013,43(23):4041-4047
Abstract: The first clean and the facile clay catalysed synthesis of á,N-diarylnitrones in good yield is reported. 相似文献
35.
36.
M. Sivasubramanian 《Applied Mathematics Letters》2010,23(9):1137-1139
37.
On 3H-Methyl-1H-pyrazole-1-carboxamide (3MPC), Single crystal XRD, Fourier Transform Infrared Spectroscopy, Fourier Transform Raman Spectroscopy, Molecular Electrostatic Potential, Density function theoretical analysis and Molecular docking analysis are conducted. The target protein docking experiments revealed that the small molecule (MET) is a good molecule that docks well with several Nav channel 1 targets. Molecular Electrostatic Potential (MEP) aids in the optimization of protein-ligand electrostatic interactions. The molecular surface and hydrogen bonding interactions in the 3MPC crystal structure were located and analyzed using a fingerprint plot and Hirshfeld Surfaces. DFT–B3LYP calculations with the 6-31G (d,p) basis set are used to establish the optimised structure of the MET molecule, and the measured vibrational frequencies are compared to experimental values. The parameters of absorption, distribution, metabolism, excretion (ADME) and toxic (Tox) were assessed using the online server preADMET. 相似文献
38.
Sivasubramanian Muthusaravanan Subbu Perumal Perumal Yogeeswari Dharmarajan Sriram 《Tetrahedron letters》2010,51(49):6439-6443
The domino reactions of pyridine/isoquinoline, bromoacetonitrile/ethyl bromoacetate and a series of β-nitrostyrenes in the presence of triethylamine afforded novel tri-/disubstituted indolizines and pyrrolo[2,1-a]isoquinolines regioselectively, presumably via substitution-dipole generation-1,3-dipolar cycloaddition-elimination and/or aromatisation sequence. In vitro screening of all the seventeen compounds synthesized against Mycobacterium tuberculosis H37Rv discloses that ethyl 2-(4-fluorophenyl)pyrrolo[2,1-a]isoquinoline-3-carboxylate displays maximum potency with minimum inhibitory concentration (MIC) of 1.0 μM, being 7.6 and 4.7 times more potent than the standard first line TB drugs, ethambutol and ciprofloxacin, respectively. 相似文献
39.
High-quality single-wall carbon nanotubes (SWNTs) with narrow diameter distribution have been grown on Fe/Co-loaded MCM41 by using acetylene as the carbon source within a short reaction period, typically 10 min or less. The optimum temperature for SWNTs synthesis is 850 degrees C. Longer reaction time (i.e., 30 min) favors the formation of multiwall carbon nanotubes (MWNTs) and graphitic carbon. When the reaction time is reduced to less than 10 min, formation of MWNTs and graphitic carbon is greatly suppressed, and high-quality SWNTs dominates the yield. The surface of the as-grown SWNTs is found to be free from amorphous carbon, as observed from high-resolution transmission electron microscope (HRTEM) analysis. Raman spectral data show a G/D ratio above 10, indicating that the as-grown SWNTs have very few defects. Furthermore, radial breathing mode (RBM) analysis reveals that the diameter distribution of the current SWNTs is narrow and ranges from 0.64 to 1.36 nm. 相似文献
40.
Satheesh Kumar Palanisamy Velusamy Arumugam Samyutha Rajendran Anandhan Ramadoss Subash Nachimuthu Magesh Peter D. 《Natural product research》2019,33(14):2120-2124
The chemical diversity of three macroalgae (Ulva reticulata, Sargassum wightii, Gracilaria sp) were determined using the GC-MS method with principal component analysis (PCA) and their potential efficacy against human pathogens and cervical carcinoma cells evaluated using MTT bioassay method. Our results showed that >30 metabolites were detected in three seaweeds, among these, steroids and fatty acids are the most dominant chemical group that highly contributes to discriminate this species. The PCA of GC-MS mass spectral variables showed a clear discrimination between three different species based on the phytochemical diversity of seaweeds. The extracts of U. reticulata exhibited anti-microbial activity with Pseudomonas aeruginosa (6.00?mm) and showed potential anti-proliferative activity against the HeLa cells (IC50 37?µmol/L) at concentration 1–50?µM treatment. Results of this study concluded that PCA analysis of mass spectral variables could be utilized as a reliable tool for species discrimination and chemotaxonomic classification of seaweeds. 相似文献