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251.
The nature and ion-exchange capacity of clay minerals obtained from a number of deposits of Irkutsk region was studied. The effect exerted by acidity of the medium on the ion-exchange process and the dependence of the cation exchange capacity of clay on the ionic strength of electrolytes were determined. 相似文献
252.
A total synthesis of (R,S)S-glucoraphanin (GRP) has been completed by a novel, simple and convenient method in high overall yield (17% over seven steps). The study describes a method for the synthesis of natural and unnatural (methylsulfinyl)alkyl glucosinolates (GLs) and also opens useful pathways to synthesize GRP as well as other sulfinyl GLs. 相似文献
253.
Preautopsy magnetic resonance imaging: initial experience 总被引:4,自引:0,他引:4
To our knowledge, there are no prospective data in the literature investigating the role of magnetic resonance imaging (MRI) in detecting abnormalities in cadavers to determine the feasibility of this concept. We prospectively studied six cadavers (three stillborn infants, one infant, and two adults) with a 0.15 T resistive magnet. The images obtained allowed detection of abnormalities in multiple organs. Although autopsy was superior to MRI in detecting very small abnormalities, MRI was equal to autopsy in detecting gross cranial, pulmonary, abdominal, and vascular pathology in this small series. In addition, MRI was superior to autopsy in detecting air and fluid in potential body spaces. Preautopsy MRI may be an alternate method in restricted or denied autopsies and may provide an additional MRI research and educational tool. 相似文献
254.
255.
Michel Langlois Claude Guilloneau Tri Vo Van Raymond Jolly Jacques Maillard 《Journal of heterocyclic chemistry》1983,20(2):393-398
The synthesis of pyrrolo[1,2-α] pyrimidines is described. Several homologous compounds contain pyridine or azepine instead of pyrrole ring. They are obtained by cyclization of iminolactams with β-ketoesters, αβ-unsaturated esters, aldehydes or ketones, or diketene. The possibility of obtaining isomers is discussed. 相似文献
256.
The influence of different chemical treatments on the electrical behaviour of n- and p-type Al/Si Schottky junctions was studied. A Schottky barrier height of 0.91 eV was achieved on p-type Si probably due to the unpinning of the Fermi-level at the Al/Si interface. This is one of the highest barrier height values reported so far for a solid-state Schottky junction prepared to p-Si. A doping level reduction was observed in the vicinity of the Si surface for wafers with native oxide and for those boiled in acetone or annealed in forming gas. It was observed unexpectedly that the reactive plasma etch used for the formation of mesa structures decreases the apparent Schottky barrier height. The relation between the sum of n- and p-type Schottky barrier heights and forbidden gap is discussed. 相似文献
257.
258.
Pant R Vo TD Xiong C Pelusi MD Madden SJ Luther-Davies B Eggleton BJ 《Optics letters》2011,36(2):298-300
We demonstrate on-chip all-optical pulse erasure based on four-wave mixing and cross-phase modulation in a dispersion engineered chalcogenide (As(2)S(3)) rib waveguide. We achieve an erasure efficiency of ~15 dB for picosecond pulses in good agreement with numerical simulations using the nonlinear Schr?dinger equation. The combined effect of the high instantaneous optical nonlinearity (γ = 9900 (W km)(-1)) and small group-velocity dispersion (D = 29 ps/nm km), which reduces pulse walk-off, will enable all-optical pulse erasure for ultrafast signal processing. 相似文献
259.
N. V. Astrakhantsev V. M. Bardakov Vo Nhu Dan G. N. Kichigin N. V. Lebedev N. A. Strokin 《Technical Physics》2011,56(9):1325-1332
We report on the results of theoretical analysis and numerical calculation of two new mass analyzers: a hybrid analyzer, which
is a contiguous combination of the Hughes-Rozhansky energy analyzer and the Wien velocity filter with superimposed sector
uniform magnetic and radial electric fields, and a device formed by a combination of a cylindrical deflector and a sector
Wien filter with uniform electric and radial magnetic field. 相似文献
260.
TN Vo PL Nguyen LT Tuong LM Pratt PN Vo KP Nguyen NS Nguyen 《Chemical & pharmaceutical bulletin》2012,60(9):1125-1133
Two new lignans, pseuderesinol (1), pseuderanoside (2) and a new triterpene, pseuderanic acid (3) were isolated from the dried root of Pseuderanthemum carruthersii (SEEM.) GUILL. var. atropurpureum (BULL.) FOSB. (Acanthaceae), together with ten known compounds, including five lignans, (+)-eudesmin (4), (+)-magnolin (5), (+)-syringaresinol (6), (+)-episyringaresinol (7), (+)-1-hydroxysyringaresinol (8) and five triterpenes, squalene (9), oleanolic acid (10), lupeol (11), betulin (12), betulinic acid (13). Their chemical structures were elucidated by 1D- and 2D-NMR, computational quantum chemistry, as well as high resolution-electrospray ionization (HR-ESI)-MS spectroscopic analysis. The acetylcholinesterase inhibition and cytotoxic activities against HeLa and MCF-7 cancer cell lines were evaluated on some purified compounds at the concentration of 100?μg/mL. Pseuderesinol (1) and magnolin (5) exhibited moderate cytotoxic activities against the MCF-7 cancer cell line. 相似文献