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141.
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143.
S Jayakumar 《Tetrahedron》2004,60(19):4315-4324
The reactions of 1,3-diazabuta-1,3-dienes 1 with 2-aminothiophenol have been shown to result in excellent yields of N-benzothiazol-2-yl-N′-aryl benzamidines 2. Their regioselective [4+2] cycloadditions with various ketenes are shown to yield novel benzothiazolo pyrimidinones 4. A similar and convenient protocol for the synthesis of bisthiosubstituted 1,3-diazabuta-1,3-dienes 8 and 9 and interesting rearrangements accompanying their [4+2] cycloadditions with a number of ketenes are described. 相似文献
144.
Titanium-catalyzed hydroamination of 1,4- and 1,5-diynes by primary amines leads to imino-alkynes that undergo in situ 5-endo dig and 5-exo dig cyclization reactions, respectively. The products are 1,2,5-trisubsituted pyrroles accessed directly from readily available diyne starting materials. 相似文献
145.
Bowtell R Gutteridge S Ramanathan C 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2001,150(2):147-155
We describe imaging experiments in which the pattern of the dipolar field generated by spatially modulated nuclear magnetization is directly visualized in simply structured phantoms. Two types of experiment have been carried out at 11.7 T using (1)H NMR signals. In the first, the field from a single spin species is imaged via its own NMR signal. In the second, the NMR signal from one spin species is used to image the field generated by a second species. The field patterns measured in these experiments correspond well with those calculated using simple theoretical expressions for the dipolar field. The results also directly demonstrate the spatial sensitivity of the signal generated using dipolar field effects, indicating that the range of the field depends upon the inverse of the spatial frequency with which the magnetization is modulated. 相似文献
146.
Journal of Solid State Electrochemistry - The kinetics of dissolution of Co in alkaline glycine solution under anodic conditions was investigated. Potentiodynamic polarization and electrochemical... 相似文献
147.
Gradient echo single scan inversion recovery: application to proton and fluorine relaxation studies 下载免费PDF全文
Single scan longitudinal relaxation measurement experiments enable rapid estimation of the spin‐lattice relaxation time (T1) as the time series of spin relaxation is encoded spatially in the sample at different slices resulting in an order of magnitude saving in time. We consider here a single scan inversion recovery pulse sequence that incorporates a gradient echo sequence. The proposed pulse sequence provides spectra with significantly enhanced signal to noise ratio leading to an accurate estimation of T1 values. The method is applicable for measuring a range of T1 values, thus indicating the possibility of routine use of the method for several systems. A comparative study of different single scan methods currently available is presented, and the advantage of the proposed sequence is highlighted. The possibility of the use of the method for the study of cross‐correlation effects for the case of fluorine in a single shot is also demonstrated. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
148.
Mubarak N. M. Sahu J. N. Abdullah E. C. Jayakumar N. S. Ganesan P. 《Research on Chemical Intermediates》2016,42(4):3257-3281
Research on Chemical Intermediates - Removal of toxic metals is one of the biggest challenges in ensuring safe water for all as well as protecting the environment. Novel multi-walled carbon... 相似文献
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150.
Mohandas Annapoorna Sun Wook Nimal T. R. Shankarappa Sahadev A. Hwang Nathaniel S. Jayakumar Rangasamy 《Research on Chemical Intermediates》2018,44(8):4873-4887
Research on Chemical Intermediates - The work focuses on the development of an injectable chitosan-fibrin (CF) based nanocomposite hydrogel for angiogenic response. The hydrogel base is made of... 相似文献