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排序方式: 共有73条查询结果,搜索用时 562 毫秒
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KL Britton HF Rogers Y Asano T Dairi Y Kato TJ Stillman DW Rice 《Acta crystallographica. Section D, Biological crystallography》1998,53(4):124-126
The novel NAD+-linked opine dehydrogenase from a soil isolate Arthrobacter sp. strain 1C belongs to an enzyme superfamily whose members exhibit quite diverse substrate specificites. Crystals of this opine dehydrogenase, obtained in the presence or absence of co-factor and substrates, have been shown to diffract to beyond 1.8 ? resolution. X-ray precession photographs have established that the crystals belong to space group P21212, with cell parameters a = 104.9, b = 80.0, c = 45.5 ? and a single subunit in the asymmetric unit. The elucidation of the three-dimensional structure of this enzyme will provide a structural framework for this novel class of dehydrogenases to enable a comparison to be made with other enzyme families and also as the basis for mutagenesis experiments directed towards the production of natural and synthetic opine-type compounds containing two chiral centres. 相似文献
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A new, green, regioselective, one-step, tandem reaction of an aldehyde possessing a non-enolizable carbonyl function with a highly substituted cyclohex-2-enone, under amine catalysis afforded highly substituted phenols or 2-arylidenecyclohexanones, respectively. The yields and regioselectivities were good. Evidence for a pathway involving formation of novel push-pull dienamines is presented along with examples demonstrating the amenability of the process to combinatorial chemistry. 相似文献
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A novel and green approach for the two-carbon homologation of aldehydes using amino acid catalysis has been developed and further extended to the generation of pharmaceutically active cyano-esters via four-component reactions in one-pot. 相似文献
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Determination of isotopic composition of boron 总被引:4,自引:0,他引:4
K. L. Ramakumar A. R. Parab P. S. Khodade A. I. Almaula S. A. Chitambar H. C. Jain 《Journal of Radioanalytical and Nuclear Chemistry》1985,94(1):53-61
Investigations were carried out on the determination of isotopic composition of boron using Cs2BO
2
+
ion and thermal ionisation mass spectrometry. The results show distinct advantage over the normally used Na2BO
2
+
ion. 相似文献
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Y. Sesha Sayi K. L. Ramakumar Rajendra Prasad C. S. Yadav P. S. Shankaran G. C. Chhapru H. C. Jain 《Journal of Radioanalytical and Nuclear Chemistry》1998,230(1-2):5-9
A hot vacuum extraction technique for the determination of hydrogen in metal and alloy samples has been standardised. After measuring the total pressure of the evolved gases, individual hydrogen and deuterium intensities are measured using an on-line quadrupole mass spectrometer. Synthetic mixtures of H2 and D2, in known concentrations, have been analysed by QMS and an analytical expression correlating the measured [D2]/[HD] intensity ratio with the mole fraction of deuterium in the synthetic mixture has been arrived at. The precision and accuracy in the measurement of hydrogen is about 10% at 50 ppmw level. 相似文献
10.
Dhevalapally B. Ramachary Vidadala V. Narayana Kinthada Ramakumar 《Tetrahedron letters》2008,49(17):2704-2709
A practical and novel ionic liquid promoted organocatalytic selective diazo-transfer process for the synthesis of highly substituted diazo-compounds in high yields is reported. The ionic liquid can be reused without affecting the reaction rates or yields over five runs. 相似文献