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排序方式: 共有103条查询结果,搜索用时 31 毫秒
21.
Ramu Rajasekaran Prakasarao Aruna Dornadula Koteeswaran Munusamy Baludavid Singaravelu Ganesan 《Journal of fluorescence》2014,24(4):1199-1205
Urine is one of the diagnostically potential bio fluids, as it contains many metabolites and some of them are native fluorophores. These fluorophores distribution and the physiochemical properties may vary during any metabolic change or at different pathologic conditions. Since urine is a multicomponent fluid, synchronous luminescence technique, a powerful tool has been adopted to analyse multicomponents in single spectrum and to resolve emission spectrum without much of photobleaching of fluorophores. In this study, urine samples of both normal subjects and cancer patients were characterised using synchronous luminescence spectroscopy with a Stokes shift of 20 nm. Different ratio parameters were calculated from the intensity values of the synchronous luminescence spectra and they were used as input variables for a multiple linear discriminant analysis across normal and cancer groups. The stepwise linear discriminant analysis classifies 90.3 % of the original grouped cases and 88.6 % of the cross-validated grouped cases correctly. 相似文献
22.
An efficient and facile chemoenzymatic synthesis of duloxetine by lipase mediated resolution of 3-hydroxy-3-(2-thienyl)propanenitrile has been achieved. This process also describes an enantioconvergent synthesis of duloxetine via a Mitsunobu reaction. 相似文献
23.
Rajendiran Thekkel M. Kannappan Ramu Mahalakshmy Rajaram Rajeswari Janarthanam Venkatesan Rangarajan Rao Pillutla 《Transition Metal Chemistry》2003,28(4):447-454
A series of binuclear CuII complexes [Cu2XL]
n+ having two copper(II) ions bridged by different motifs (X = OH–, MeCO2
–, or Cl–) have been prepared using the ligands: H2L1 = 4-methyl-2-[N-(2-{dimethylamino}ethyl-N-methyl)aminomethyl]-6-[(prolin-1-yl)methyl]phenol, H2L2 = 4-nitro-2-[N-(2-{dimethylamino}ethyl-N-methyl)aminomethyl]-6-[(prolin-1-yl)methyl]phenol, H2L3 = 4-methyl-2-[N-(2-{diethylamino}ethyl-N-ethyl)aminomethyl]-6-[(prolin-1-yl)methyl]phenol and H2L4 = 4-nitro-2-[N-(2-{diethylamino}ethyl-N-ethyl)aminomethyl]-6-[(prolin-1-yl)methyl]phenol. The complexes have been characterized by spectroscopic, analytical, magnetic and electrochemical measurements. Cryomagnetic investigations (80–300 K) revealed anti-ferromagnetic exchange between the CuII ions (–2J in the range –50 to –182 cm–1). The strength of anti-ferromagnetic coupling lies in the order: OAc > OH > Cl. Cyclic voltammetry revealed the presence of two redox couples, assigned to CuII/CuII/CuII/CuI/CuI/CuI. The first reduction potential is sensitive to electronic effects from the aromatic ring substituents and steric effect on the donor nitrogens (side arm) of the ligand systems. 相似文献
24.
Rajendiran Thekkel M. Mahalakshmy Rajaram Kannappan Ramu Rajeswari Janarthanam Venkatesan Rangarajan Rao Pillutla 《Transition Metal Chemistry》2003,28(3):280-287
Binuclear CuII complexes having new flexible heptadentate ligands 2,6-bis{[bis(3,3-N,N-dimethylaminopropyl)amino]methyl}-4-bromophenol [HL1], 2,6-bis(3,3-N,N-dimethylaminopropyl)amino]methyl}-4-methylphenol [HL2], and 2,6-bis{[bis(3,3-N,N-dimethylaminopropyl)amino]methyl}-4-methoxyphenol [HL3], capable of assembling two copper ions in close proximity have been synthesized. Comparisons of the charge-transfer (CT) features, observed in electronic spectra of these complexes, are correlated with the electronic effect on the aromatic ring of the ligand systems. Cyclic voltammetry has revealed the existence of two reduction couples,
The first is sensitive to the electronic effects of aromatic ring substituents of the ligand system, shifting to more positive potentials when more electrophilic groups replace the existing substituents. The conproportionation constants (k
con) for the mixed valent CuICuII complexes have been determined electrochemically. The magnetic susceptibilities of the complexes have been measured over the 70–300 K range and the exchange coupling parameter (–2J) determined by a least squares fit of the data which indicates an antiferromagnetic spin exchange (–2J = 94–172 cm–1) between the CuII ions with bridging units in the order: N3 NO2 > OAc > OH. 相似文献
25.
An unexpected reduction of indolic double bond of mitragynine was described by using n-butyl silane and tris(pentafluorophenyl)triborane. 相似文献
26.
Sanjay Kumar Saxena Archana Mukherjee Yogendra Kumar Ramu Ram A. S. Tapase Vivek J. Anand Ashutosh Dash 《Journal of Radioanalytical and Nuclear Chemistry》2014,302(3):1237-1243
‘Permanent seed implantation’ using 125I- seeds has emerged as an effective treatment modality for management of prostate cancer. An indigenous technology for the production of 125I brachytherapy sources (‘BARC 125I Ocu-Prosta seed’) has been developed. In this current work, we describe an overview of our experience on large scale production of 125I brachytherapy sources, their quality assessment, in vivo bio-evaluation and initial experience on their journey from bench to bed-side for the treatment of prostate cancer. 相似文献
27.
The pressure dependences of 35Cl nuclear quadrupole resonance (NQR) frequency, temperature and pressure variation of spin lattice relaxation time (T1) were investigated in 3,4‐dichlorophenol. T1 was measured in the temperature range 77–300 K. Furthermore, the NQR frequency and T1 for these compounds were measured as a function of pressure up to 5 kbar at 300 K. The temperature dependence of the average torsional lifetimes of the molecules and the transition probabilities W1 and W2 for the Δm = ±1 and Δm = ±2 transitions were also obtained. A nonlinear variation of NQR frequency with pressure has been observed and the pressure coefficients were observed to be positive. A thermodynamic analysis of the data was carried out to determine the constant volume temperature coefficients of the NQR frequency. An attempt is made to compare the torsional frequencies evaluated from NQR data with those obtained by IR spectra. On selecting the appropriate mode from IR spectra, a good agreement with torsional frequency obtained from NQR data is observed. The previously mentioned approach is a good illustration of the supplementary nature of the data from IR studies, in relation to NQR studies of compounds in solid state. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
28.
Gem-difluoroalkenes are an easily accessed fluorinated functional group, and a useful intermediate for elaborating into more complex fluorinated compounds. Currently, most functionalization reactions of gem-difluoroalkenes, with or without a transition metal-based catalyst system, involve the addition or removal of a fluorine atom to generate trifluorinated or monofluorinated products, respectively. In contrast, we present a complementary “fluorine-retentive” reaction that exploits an organocatalytic strategy to add phenols across gem-difluoroalkenes to deliver β,β-difluorophenethyl arylethers. The products are produced in good to moderate yields and selectivities, thus providing a range of compounds that are underrepresented in the synthetic and medicinal chemistry literature. 相似文献
29.
A short asymmetric approach for the synthesis of bis-tetrahydrofuran units of various annonaceous acetogenins is described. The key steps of the synthesis are self-cross metathesis and Sharpless asymmetric dihydroxylation. 相似文献
30.
Loganathan Ramu Narendra Kuppan Keralapura Parthasarathy Ramesh Rattihalli Chandramani Daivagna Ramananda 《Magnetic resonance in chemistry : MRC》2019,57(8):499-505
35Cl NQR frequency and spin lattice relaxation time in 3,4-dichloronitrobenzene have been measured as a function of temperature and pressure. Two NQR signals were observed in the temperature range 77 to 300 K and pressure up to 5.1 kbar at 300 K. The contributions to the relaxation from the torsional motion of the molecule and reorientational motion of the nitro group have been analyzed on the basis of the Woessner and Gutowsky model. The temperature dependence of the average torsional lifetimes of the molecules, transition probabilities, and the activation energy for the reorientation of the nitro group was estimated. The pressure dependence of the NQR frequency in 3,4-Dichloronitrobenzene shows a nonlinear increase in NQR frequency with increase in pressure, indicating increased contribution from the static effects at higher pressures. A thermodynamic analysis of the data was carried out to determine the constant-volume temperature coefficients of the NQR frequency. The spin–lattice relaxation was found to be weakly dependent on pressure. 相似文献