排序方式: 共有40条查询结果,搜索用时 15 毫秒
1.
The processing of oil sands materials and upgrading of bitumens present a variety of problems for conventional technologies. This article describes a preliminary study of the concept of using microwave induced catalytic techniques to decompose the complex and viscous hydrocarbon compounds contained in these materials to allow efficient extraction of volatile and economically useful organic products such as C2 and C3 hydrocarbons. Addition of water to the tar sand material prior to reaction facilitated separation from the sand component as well as promoting the formation of economically very useful, liquid, oxygenated hydrocarbon products. 相似文献
2.
Tallarico JA Depew KM Pelish HE Westwood NJ Lindsley CW Shair MD Schreiber SL Foley MA 《Journal of combinatorial chemistry》2001,3(3):312-318
The synthesis and use of an alkylsilyl-tethered large (500-600 microm) polystyrene resin (1) are disclosed. An optimized Suzuki coupling of bromine-functionalized polystyrene and a silicon-functionalized alkylborane generates the silicon-substituted polystyrene 1 in large scale (>100 g). Resin loading is accomplished by activation as the silyl triflate, which can accommodate even sterically encumbered secondary alcohols and phenols. Treatment with HF/pyridine for linker cleavage is mild, efficient, and amenable to an automated, large-scale distribution system. This platform delivers, minimally, 50 nmol of each small molecule derived from a diversity-oriented, split-pool synthesis on a per bead basis for use in both forward and reverse chemical genetic assays. This technology satisfies many requirements of a one bead-one stock solution approach to chemical genetics. 相似文献
3.
Free radical reactions induced by the photolysis of the lignin model compound α-guaiacoxylacetoveratrone have been studied by conventional and time-resolved ESR spectroscopy. In the presence of efficient hydrogen donors such as aqueous and hydroxylic solvents the primary reaction involves photoreduction of the triplet phenacyl ether to form the ketyl radical followed by rapid cleavage to the phenacyl radical and guaiacol. Subsequent formation of polarized guaiacoxyl radicals is due to secondary photo-oxidation. The cleavage of the ketyl radical is retarded in basic media and accelerated in acetic acid. Minor reaction pathways involving excited singlets cannot be ruled out by the current CIDEP observations. 相似文献
4.
Tahira Foyzun Abdullah Al Mahmud Md. Salim Ahammed Md. Imran Nur Manik Md. Kamrul Hasan KM Monirul Islam Simin Sobnom Lopa Md. Yusuf Al-Amin Kushal Biswas Mst. Rejina Afrin AHM Khurshid Alam Golam Sadik 《Molecules (Basel, Switzerland)》2022,27(3)
Neurotoxicity is a serious health problem of patients chronically exposed to arsenic. There is no specific treatment of this problem. Oxidative stress has been implicated in the pathological process of neurotoxicity. Polyphenolics have proven antioxidant activity, thereby offering protection against oxidative stress. In this study, we have isolated the polyphenolics from Acacia nilotica and investigated its effect against arsenic-induced neurotoxicity and oxidative stress in mice. Acacia nilotica polyphenolics prepared from column chromatography of the crude methanol extract using diaion resin contained a phenolic content of 452.185 ± 7.879 mg gallic acid equivalent/gm of sample and flavonoid content of 200.075 ± 0.755 mg catechin equivalent/gm of sample. The polyphenolics exhibited potent antioxidant activity with respect to free radical scavenging ability, total antioxidant activity and inhibition of lipid peroxidation. Administration of arsenic in mice showed a reduction of acetylcholinesterase activity in the brain which was counteracted by Acacia nilotica polyphenolics. Similarly, elevation of lipid peroxidation and depletion of glutathione in the brain of mice was effectively restored to normal level by Acacia nilotica polyphenolics. Gallic acid methyl ester, catechin and catechin-7-gallate were identified in the polyphenolics as the major active compounds. These results suggest that Acacia nilotica polyphenolics due to its strong antioxidant potential might be effective in the management of arsenic induced neurotoxicity. 相似文献
5.
A novel and efficient process for the cracking of benzene to acetylene with over 90% selectivity is described. The reactions are induced by a pulsed microwave technology over alumina and silica supported Nickel catalysts. 相似文献
6.
7.
KM Varier AM Vinodkumar NVSV Prasad PV Madhusudhana Rao DL Sastry Lagy T Baby MC Radhakrishna NG Puttaswamy JJ Das P Sugathan N Madhavan AK Sinha DO Kataria 《Pramana》1999,53(3):529-533
Large enhancements have been observed in the sub-barrier fusion cross sections for Ti+Ni systems in our previous studies.
Coupled channel calculations incorporating couplings to 2+ and 3− states failed to explain these enhancements completely. A possibilty of transfer channels contributing to the residual enhancements
had been suggested. In order to investigate the role of relevant transfer channels, measurements of one- and two-nucleon transfer
were carried out for 46,48Ti+61Ni systems. The present paper gives the results of these studies. 相似文献
8.
J. K. S. Wan Y. G. Chen Y. J. Lee M. C. Depew 《Research on Chemical Intermediates》2000,26(6):599-619
Conversion of methane to higher hydrocarbon products, in particular, aromatic hydrocarbons has been achieved with good methane
conversion and selectivity to aromatic products over heterogeneous catalysts using both high power pulsed microwave and rf
energy. For example, under microwave irradiation > 85% conversion of methane and 60% selectivity to aromatics could be achieved.
Cu, Ni, Fe and Al metallic materials are highly effective catalysts for the aromatization of methane via microwave heating;
however, with a variety of supported catalysts the major products were C2 hydrocarbons and the conversion of methane was low. The use of sponge, wire and net forms of these metal catalysts was found
advantageous in effective methane conversion. The reactions are considered to be free radical in nature and to proceed through
an intermediate stage involving formation of acetylene. The influence of catalyst nature and configuration, as well as the
microwave and rf irradiation parameters on the reaction efficiency and product selectivity has been examined in both batch
and continuous flow conditions. 相似文献
9.
10.
A CIDEP study of the radical adducts formed by addition of phosphonyl radicals to several unsaturated organic compounds is described. The complicated time-resolved ESR spectra obtained for these adducts were interpreted on the basis of competing chemical and physical processes involved in polarization transfer to the secondary radicals produced. This is a novel example illustrating for the first time radical pair polarization transfer in solution. 相似文献