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71.
The dispersion and damping of whistler waves has been measured in an essentially collisionless plasma at frequencies up to 0.92ωc, the electron cyclotron frequency. The experimental results agree to within ± 10% of the plane wave hot plasma dispersion relation. 相似文献
72.
A separation of selenium based on the extraction of different concentrations of Se(IV) from 12 M hydrochloric acid or 8 M hydrobromic acid into toluene is described. Recoveries of 92% and 97%, respectively, are achieved in 7 min. Oxidizing agents interfere. 相似文献
73.
74.
Cyclobutanone analogs of thienamycin, including N-acetyldeazathienamycin, have been synthesized and their chemical and biological properties studied. 相似文献
75.
MRI was performed in 54 patients with abnormalities of the inferior vena cava (IVC). These included 16 patients with extrinsic IVC compression, 32 patients with intrinsic IVC abnormalities, and 6 patients with IVC dilatation. All patients had spin-echo imaging, and 21 had MR angiography. While presaturated spin-echo images showed intrinsic lesions to advantage, collateral vessels were best appreciated with MR angiography. The IVC is well evaluated with MRI techniques. 相似文献
76.
P M Colletti A DeFrance T Tak W D Boswell P A Chandraratna 《Magnetic resonance imaging》1991,9(3):343-347
Cardiac cine field echo MRI and color Doppler were performed in 13 patients with aortic regurgitation (n = 4) or multiple valvular diseases (n = 9). The size, shape, and direction of regurgitation jets correlated well. Color Doppler was better able to follow flow jets in oblique planes. Cine MRI was better able to evaluate patients with marked cardiac dilatation. 相似文献
77.
78.
Electron microscope studies of small (111) triangularly shaped pseudomorphic silver-gold bi-crystals revealed a “spherical cap” type of elastic deformation. This deformation was found to be due to the perfect elastic accommodation of the misfit at interface between the silver and the gold. Good agreement between measured values of the radius of curvature at the centres of the bi-crystals and existing theory is found. 相似文献
79.
80.
G. Evan Boswell Robert W. Mcnutt Dulce G. Bubacz Ann O. Davis Kwen-Jen Chang 《Journal of heterocyclic chemistry》1995,32(6):1801-1818
The synthesis of a series of heterocyclic analogues of (±)-4-((αR*)-α-((2S*,5R*)-4-allyl-2,5-dimethyl-1-piperazmyl)-3-hydroxybenzyl)-N,N-diethylbenzarrude (BW373U86) for screening against opioid receptors is described. The intermediate α-heterocyclic benzyl alcohols 24 were synthesized either by low temperature reaction of lithioheterocycles with 3-((tert-butyldimethylsilyl)oxy)benzaldehyde ( 10 ) or by reaction of 3-((tert-butyldimethylsilyl)oxy)phenylmagnesium bromide ( 19 ) with heterocyclic carbaldehydes. The α-heterocyclic benzyl alcohols 24 were converted to chloromethines ( 25 ) with thionyl chloride and used to alkylate with trans-1-allyl-2,5-dimethylpiperazine ( 5 ) to give diastereomeric pairs of the target compounds. The bromoheterocycles were then derivatized to produce amides. Compounds that are potent and selective for the 5 or μ opioid receptors and some mixed δ/μ analogues are reported. 相似文献