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排序方式: 共有278条查询结果,搜索用时 437 毫秒
21.
Vinay Girijavallabhan Ashok Arasappan Frank Bennett Yuhua Huang F. George Njoroge Malcolm MacCoss 《Tetrahedron letters》2010,51(21):2797-6881
Novel substituted thiazole[4,5-c]pyridines have been synthesized in good yields from unsubstituted thiazole[4,5-c]pyridine using direct C-H coupling reactions and N-oxide rearrangement chemistry. 相似文献
22.
23.
Pradeep Mathur Amrendra K. Singh Vinay K. Singh Shaikh M. Mobin 《Journal of organometallic chemistry》2010,695(7):950-141
Photolysis of a hexane solution of ferrocenylacetylene and sulfur powder in presence of Cr(CO)6 resulted in the formation of 2,6-diferrocenyldithiine and 2,5-diferrocenylthiophene. Similar reactions with Mo(CO)6 or W(CO)6 gave only the thiophene derivative. Formation of ferrocenyl-substituted thioketone complexes was observed in the reaction of ferrocenylacetylene with water and sulfur, in presence of W(CO)6. Use of D2O confirmed water as source of protons for the conversion of acetylenic CH to CH3. 相似文献
24.
25.
Pavagada Jagannathamurthy Ramesh Kanakapura Basavaiah Mysore Ranganath Divya Nagaraju Rajendraprasad Kanakapura Basavaiah Vinay Hosakere Doddarevanna Revanasiddappa 《Journal of Analytical Chemistry》2011,66(5):482-489
Doxycycline hyclate (DOX), a broad spectrum antibiotic with activity against a wide range of gram-positive and gram-negative bacteria, is widely used
as a pharmacological agent and as an effector molecule in inducible gene expression system. Three simple, selective, rapid,
accurate, precise and cost-effective spectrophotometric methods for the determination of DOX in bulk drug and in tablets have
been developed and validated. First method (method A) is based on the measurement of absorbance of DOX in 0.1 M HCl at 240
nm. The second method (method B) is based on the measurement of yellow chromogen at 375 nm which is formed in 0.1 M NaOH.
The third method is based on the measurement of 2: 1 complex formed between DOX and iron(III) in H2SO4 medium, the complex peaking at 420 nm (method C). The optimum conditions for all the three methods are optimized. Beer’s
law was obeyed over the ranges 2.5–50.0, 1.50–30.0 and 10–100 g/mL for method A, method B and method C, respectively. The
apparent molar absorptivity values are calculated to be 1.03 × 104, 1.73 × 104, and 5.21 × 103 L mol−1 cm−1 for method A, method B, and method C, respectively. The Sandell sensitivity, limit of detection (LOD) and limit quantification (LOQ) values are also reported. All the methods were validated in accordance with current ICH guidelines. The developed methods
were employed with high degree of precision and accuracy for the estimation of total drug content in commercial tablet formulations
of DOX. 相似文献
26.
Garbarine E DePasquale J Gadia V Polikar R Rosen G 《Computational Biology and Chemistry》2011,35(3):199-209
Analysis of DNA sequences isolated directly from the environment, known as metagenomics, produces a large quantity of genome fragments that need to be classified into specific taxa. Most composition-based classification methods use all features instead of a subset of features that may maximize classifier accuracy. We show that feature selection methods can boost performance of taxonomic classifiers. This work proposes three different filter-based feature selection methods that stem from information theory: (1) a technique that combines Kullback-Leibler, Mutual Information, and distance information, (2) a text mining technique, TF-IDF, and (3) minimum redundancy-maximum-relevance (mRMR). The feature selection methods are compared by how well they improve support vector machine classification of genomic reads. Overall, the 6mer mRMR method performs well, especially on the phyla-level. If the number of total features is very large, feature selection becomes difficult because a small subset of features that captures a majority of the data variance is less likely to exist. Therefore, we conclude that there is a trade-off between feature set size and feature selection method to optimize classification performance. For larger feature set sizes, TF-IDF works better for finer-resolutions while mRMR performs the best out of any method for N=6 for all taxonomic levels. 相似文献
27.
N. J. A. Sloane Vinay A. Vaishampayan Sueli I. R. Costa 《Discrete and Computational Geometry》2011,46(3):472-478
It is shown that, given any (n−1)-dimensional lattice Λ, there is a vector v∈ℤ
n
such that the orthogonal projection of ℤ
n
onto v
⊥ is, up to a similarity, arbitrarily close to Λ. The problem arises in attempting to find the largest cylinder anchored at
two points of ℤ
n
and containing no other points of ℤ
n
. 相似文献
28.
A novel method to synthesize tertiary alkyl/aryl sulfides in a mild and regioselective manner from unactivated alkenes using cobalt catalysis is described. The methodology is compatible with sensitive functionalities and is successful with several different types of alkenes and sulfides. 相似文献
29.
Vikram Singh Lalit Kumar Vinay Kumar A. K. Narula Gagan Deep 《Journal of Thermal Analysis and Calorimetry》2011,104(3):1185-1189
Curing behaviour of DGEBA was investigated in the presence of varying molar ratio of biuret and 4,4′-diaminodiphenylsulfone
(DDS) by means of Differential scanning calorimetery. The multiple heating rate method (5, 10, 15 and 20 °C min−1) was used to study the curing behaviour of epoxy resins. The peak exotherm temperature was found to be dependent on the heating
rates, structure of biuret as well as on the ratios of biuret:DDS used. Ozawa method was used for calculating the activation
energy of curing reaction. The thermal stability of the isothermally cured resins was evaluated by recording the thermogravimetric
traces in nitrogen atmosphere. All the samples were stable up to 330 °C. 相似文献
30.
Vinay Ambegaokar 《Journal of statistical physics》2006,125(5-6):1183-1192
The time development of the reduced density matrix for a quantum oscillator damped by coupling it to an ohmic environment
is calculated via an identity of the Debye-Waller form. Results obtained some years ago by Hakim and the author in the free-particle
limit(10) are thus recovered. The evolution of a free particle in a prepared initial state is examined, and a previously published
exchange(5,9) is illuminated with figures showing no decoherence without dissipation.
PACS number: 03.75.Ss 相似文献