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排序方式: 共有118条查询结果,搜索用时 15 毫秒
111.
Kattamuri Chandra Mohan Krishnan Ravikumar Meera M. Shetty 《Journal of chemical crystallography》2003,33(2):97-103
The key intermediates, in the synthesis of phenothiazines, 5-hydroxy-5-methyl 3(phenyl) 2,4-N-dimethylcarbamoyl cyclohexanone, C17H22O4N2 (I), and 5-hydroxy-5-methyl 3(2-methylphenyl) 2,4-N-dimethylcarbamoyl cyclohexanone, C18H24O4N2 (II), contain essentially substituted cyclohexanone rings in chair conformation with approximately perpendicular oriented phenyl rings. The carbamoyl groups are aligned in opposite directions to facilitate the formation of intramolecular C–HO interaction and O–HO hydrogen bonding. The molecules are linked in helical fashion by an N–HO type intermolecular hydrogen bonding framework. Crystal data: [I], orthorhombic, space group Pbca, a = 9.278(1), b = 19.094(2), c = 19.802(2) Å, V = 3508.0(6) Å3, Z = 8 and d = 1.206 Mg m–3, R = 0.074 (wR = 0.137) for 208 parameters and 1190 observed reflections with I 2 (I); [II], monoclinic, space group P21/n, a = 10.523(1), b = 9.005(1), c = 19.771(2) Å, = 94.96(6)°, V = 1866.5(3) Å3, Z = 4 and d = 1.183 Mg m–3, R = 0.062 (wR = 0.131) for 217 parameters and 2276 observed reflections with I 2 (I). 相似文献
112.
K. Chandra Mohan K. Ravikumar Meera M. Shetty S. Thiyagarajan S.S. Rajan 《Journal of chemical crystallography》2003,33(2):113-121
The crystal structure of 1,4-dihydro-6-methyl-5-N,N-diethylcarbamoyl-4-phenyl-2(3H)-pyrimidinethione, C16
H
21
N
3OS (1), is monoclinic, space group P21/n, a = 6.818(1), b = 13.211(2), c = 18.807(3) Å, = 99.53(1)°, V = 1670.6(4) Å3, Z = 4 and d
cal = 1.206 Mg/m3, R = 0.042 (wR = 0.119) for 190 parameters and 2560 observations with I 2(I) and 1,4-dihydro-6-methyl-5-N-methyl carbamoyl-4-(2-nitrophenyl)-2(3H)-pyrimidinethione hemihydrate, C13
H
14N4O3S 0.5H2O, (2), is triclinic, space group P1, a = 7.513(1), b = 14.381(2), c = 15.506(2)Å, = 114.95(2), = 98.11(1), = 93.55(1)°, V = 1490.0(3) Å3, Z = 4 and d
cal = 1.406 Mg/m3, R = 0.062 (wR = 0.165) for 388 parameters and 3094 observations with I 2(I).The compound 2 crystallized having two molecules in the asymmetric unit, which can be regarded as monohydrated dimers, and forming a hydrate. The conformation of the central heterocyclic ring (1,4-dihydropyrimidine) in both compounds was found to be close to a half-chair conformation. The 2-nitrophenyl substituent in 2 is in the axial synperiplanar orientation. In both compounds, the conformation of the 3-substituted carbamoyl group appears to be influenced by hydrogen bonding with anticlinal orientation observed for carbonyl groups serving as hydrogen bonding acceptors. 相似文献
113.
K. Meera R. Muralidharan A. K. Tripathi R. Dhanasekaran P. Ramasamy 《Journal of Crystal Growth》2004,260(3-4):414-421
Thiourea-doped Triglycine sulphate (ThTGS) crystal with three different concentrations of thiourea was grown from aqueous solution by slow cooling technique. The cell parameters were determined from powder X-ray diffraction analysis. A qualitative analysis of the presence of thiourea in doped crystals was estimated by FTIR analysis. Microhardness studies were carried out using Leitz Weitzler hardness tester at room temperature. Dielectric properties of the crystals were studied which showed a shift in the Tc when compared to pure TGS crystal. Pyroelectric studies were carried out and the pyroelectric coefficient was found. Piezoelectric studies (d33 coefficient) has also been carried out. 相似文献
114.
Unequal spaced channel allocation (USCA) is a technique to reduce Four wave mixing (FWM). In this paper, system performance of 8 channel WDM system considering different optical transmitter formats (RZ, NRZ, Raised cosine and Gaussian) using USCA has been evaluated in terms of Q-factor. The simulation results reveal that four wave mixing is minimum for NRZ format. Also the effect of changing the laser power and increasing the bit rate has been observed. 相似文献
115.
Pharmacological chaperones (PCs) represent a promising therapeutic strategy for treatment of lysosomal storage disorders based
on enhanced stabilization and trafficking of mutant protein upon orthosteric and/or allosteric binding. Herein, we introduce
a simple yet reliable enzyme assay using capillary electrophoresis (CE) for inhibitor screening of PCs that target the lysosomal
enzyme, β-glucocerebrosidase (GCase). The rate of GCase-catalyzed hydrolysis of the synthetic substrate, 4-methylumbelliferyl-β-d-glucopyranoside was performed using different classes of PCs by CE with UV detection under standardized conditions. The pH
and surfactant dependence of inhibitor binding on recombinant GCase activity was also examined. Enzyme inhibition studies
were investigated for five putative PCs including isofagomine (IFG), ambroxol, bromhexine, diltiazem, and fluphenazine. IFG
was confirmed as a potent competitive inhibitor of recombinant GCase with half-maximal inhibitory concentration (IC
50
) of 47.5 ± 0.1 and 4.6 ± 1.4 nM at pH 5.2 and pH 7.2, respectively. In contrast, the four other non-carbohydrate amines were
demonstrated to function as mixed-type inhibitors with high micromolar activity at neutral pH relative to acidic pH conditions
reflective of the lysosome. CE offers a convenient platform for characterization of PCs as a way to accelerate the clinical
translation of previously approved drugs for oral treatment of rare genetic disorders, such as Gaucher disease. 相似文献
116.
Rubel Chakravarty Meera Venkatesh Ashutosh Dash 《Journal of Radioanalytical and Nuclear Chemistry》2011,290(1):45-51
A novel electrochemical process to avail clinical grade 99mTc from (n,γ)99Mo has been demonstrated. The electrochemical parameters were optimized to maximize the 99mTc yield with minimal 99Mo contamination. 99Mo/99mTc generators containing up to 29.6 GBq (800 mCi) 99Mo were developed and their performance were extensively evaluated for 10 days without changing the operating conditions.
Very high radioactive concentration of 99mTcO4
− of acceptable quality, commensurate with hospital radiopharmacy requirements could be availed from the system with >90% yield.
The compatibility of the product for the formulation of 99mTc labeled radiopharmaceuticals such as 99mTc-DMSA and 99mTc-EC was found to be satisfactory in terms of high labeling yields. The proposed route represents an important step for enhancing
the scope of accessing clinical grade 99mTc from low specific activity (n, γ)99Mo. 相似文献
117.
K. V. Vimalnath A. Rajeswari Viju Chirayil P. L. Sharad K. C. Jagadeesan P. V. Joshi Meera Venkatesh 《Journal of Radioanalytical and Nuclear Chemistry》2011,290(1):221-225
64Cu (t1/2 12.7 h) is a versatile radionuclide owing to its unique decay scheme and exhibits three types of decay electron capture (41%),
β− (40%), β+ (19%) that is useful in nuclear medicine applications. Different batches of natural copper oxide (CuO) and 99.9% enriched
63CuO targets were irradiated in research reactors at a neutron flux of 6.6 × 1012 n cm−2 s−1 for duration of 3 days. Irradiated samples dissolved in hydrochloric acid solution were measured in HPGe-MCA system, the
activity of 64Cu, co-produced radionuclide impurities and radionuclide purity was determined. Average specific activity of 254 GBq 64Cu per g Cu and ~348 GBq 64Cu per g Cu was recorded at the end of irradiation from natural and enriched CuO targets, respectively. 相似文献
118.
Hazaana S. Aafrin Joseph Ancemma Selvasekarapandian S. Naachiyar R. Meera Vignesh N. Muniraj 《Journal of Solid State Electrochemistry》2023,27(2):539-557
Journal of Solid State Electrochemistry - In the present work, biopolymer electrolytes based on agar–agar (AA) and lithium chloride (LiCl) have been prepared using solution casting technique... 相似文献