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排序方式: 共有867条查询结果,搜索用时 15 毫秒
1.
Benedict Ita P. Murugavel V. Ponnambalam A. R. Raju 《Journal of Chemical Sciences》2003,115(5-6):519-524
Fine powders of lanthanum iron oxide, LaFeO3, have been prepared by solid state reaction as well as sol-gel synthesis and nebulized spray pyrolysis. Structures, morphologies
and magnetic susceptibility measurements of these powders have been examined. The powders prepared by all the three low-temperature
routes contain nearly spherical particles with an average diameter of 40 nm. These samples show a lower Neel temperature than
the powder prepared by solid state reaction besides showing much lower magnetic susceptibility at low temperatures.
Dedicated to Professor C N R Rao on his 70th birthday 相似文献
2.
Chandra Raju 《Czechoslovak Journal of Physics》1986,36(12):1350-1357
In this paper, we show that 2m
e
m
/(m
e
2
+m
2
= (g
V/g
A)
e
2
. From this expression, the Weinberg mixing parameter is shown to be 0·2254 or 0·2746. Assuming that the electron and muon neutrino masses are degenerate, we find thatm
v = (g
V/g
A)
e
2
. (m
e
m
)/M
WL, where MWL is the mass of the standard W± boson. The neutrino mass turns out to be 6·5 eV. The -neutrino mass is found to be about 81 MeV. The masses of c, t, s and b quarks are found to be respectively 1·7 GeV, 21·2 GeV, 0·57 GeV and 2·18 GeV by assumingm
d=m
u= 0·3 GeV. All these masses agree with other estimates except the b quark which has about half of its expected value. 相似文献
3.
A highly effective synthesis of (±)-12-HETE (1) from the components 2, 3 and 6 is described which employs a new class of cuprate reagents. 相似文献
4.
L. H. Johnston S. R. Raju G. R. Sudhakaran R. M. Lees 《International Journal of Infrared and Millimeter Waves》1982,3(4):517-527
Laser-Stark spectra have been observed for methyl alcohol using the 311 m line of the HCN laser. Partial assignments are presented for the three most distinctive structures in the spectra. The low field structure is clearly associated with a member of the J=2019qRa-type multiplet, and is tentatively identified as the k=13 A vt=0 transition. The other two structures originate from the 9382 E vt=0 transition, and from a member of the k= 65 A vt=1 Q branch, tentatively assigned as the J=32 member. 相似文献
5.
A convenient method has been developed for the conversion of indoles and indigos into anthranilic acids in good to excellent yields using a bromamine-B/PdCl2 system. The general process utilizes our efficient method for the oxidation of indoles and indigos in alkaline (pH 12) acetonitrile/water (1:1) at 60 °C. 相似文献
6.
1‐[(Substituted carbamoyl)amino]‐1H,3H‐1λ5‐[1,3,2]oxazaphospholo[3,4‐a]benzimidazol‐1‐ones were synthesized by reacting benzimidazole 2‐methanol (4) with different chlorides of carbamidophosphoric acids (3) in the presence of triethylamine at 40–45°C. Their 1H, 13C, and 31P NMR spectral data were discussed. The title compounds were tested for their activity against the fungi Aspergillus niger and Fusarium solani and bacteria Staphylococcus aureus and Escherichia coli. These compounds showed moderate antibacterial activity when compared with antifungal activity. 相似文献
7.
8.
R. Karthikraj L. Sridhar M. R. V. S. Murty N. P. Raju M. Vairamani S. Prabhakar 《Analytical and bioanalytical chemistry》2014,406(21):5093-5102
Most of the precursors and/or degradation products related to the Chemical Weapons Convention (CWC) are polar. Identification of these molecules in environmental samples provides clues regarding the alleged usage and/or synthesis of the parent toxic chemicals. Such polar compounds need to be derivatized in order to analyze them by gas chromatography–mass spectrometry (GC–MS). In this study, we developed a new derivatizing reagent, para-tolyl isocyanate (PTI), for derivatization of polar CWC-related compounds. The PTI reagent selectively derivatizes the –OH and/or?SH functional groups with high efficiency, but does not react with carboxylic acid (?COOH) or phosphonic acid (?(O)P(OH)2) groups. The PTI derivatives of dialkyl aminoethanols, dialkyl aminoethanol-N-oxides, and 3-quinuclidinol were successfully eluted through GC, and their electron ionization (EI) mass spectra were distinct and provided the structure information by which the isomeric compounds can be easily distinguished. We also calculated the GC-retention index values that can be used for further confirmation of the target compounds. All the studied PTI derivatives can be analyzed by EI-MS with direct insertion probe and/or by direct electrospray ionization mass spectrometry (ESI-MS) together with the MS–MS data; both sets of data provide full structure information. The PTI reagent was found to be better in some respects than the conventional bistrimethylsilyl trifluoroacetamide (BSTFA), a trimethyl silylating reagent. The PTI reagent is commercially available, and the PTI derivatives are highly stable for months and are not sensitive to moisture. The applicability of the PTI derivatization for trace-level determination of the target CWC-related polar compounds in environmental matrices and in human plasma samples is also evaluated. Fig. a
? 相似文献
9.
The (110) twins of normal octacosane crystals with hexagonal shape are observed. Various factors that may lead to a shape change are considered. Effect of growth rate anisotropy on the reentrent faces is studied with the help of growth patterns which are derived from a lattice net. 相似文献
10.
K. S. Raju 《Crystal Research and Technology》1983,18(10):1277-1281
Sparingly water soluble Calcium Sulphate dihydrate (Gypsum) single crystals are grown by gel method, derived from the highly soluble reactants, Calcium Chloride and ammonium sulphate. By the diffusion of 1M Calcium Chloride solution into Sodium metasilicate gel (Sp.gr: 1.06 gm Cm–3, pH ∼ 7.5), imbedded before setting, with varied amounts of weak acid (acetic acid) and 20 ml of 1M ammonium sulphate solution, dendritic structures are commonly observed in the gel at the interface, at a particular concentration of the acid. The needle shaped tabular crystals are also observed to grow at the greater depths in the gel. Dendrites are studied by optical, X-ray diffraction and Infra-red studies. It has been established that the dendrites are Calcium Sulphate dihydrate crystals formed probably due to the influence of soluble impurities (like calcium acetate, in the present case), when the rate of diffusion is fairly high and the twinning mechanism favoured. The implications are discussed. 相似文献