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排序方式: 共有68条查询结果,搜索用时 15 毫秒
41.
42.
The influence of microwave irradiation on the mass transfer kinetics of an insulin variant in reversed-phase liquid chromatography (RPLC) was investigated. The elution band profiles of insulin were obtained by the pulse-response method, under linear conditions. The RPLC column was placed in a microwave oven and the incremental change in the temperature of the column effluent stream at various microwave energies and mobile phase flow rates were measured. The microwave energy dissipated in the column was set at 15 and 30 W and the mobile phase flow rate was varied from 1.0 to 2.5 mL/min at a mobile phase composition of acetonitrile, water, and trifloroacetic acid (31:69:0.1, v/v/v). The experimental data were analyzed using the conventional method of moment analysis and the lumped pore diffusion model. Regardless of mobile flow rates, the effluent temperatures measured at 15 and 30 W microwave power input were 25+/-1 and 30+/-1 degrees C, respectively. The effect of microwave irradiation on the mass transfer of the variant insulin was determined by comparing the band profiles obtained under the same experimental conditions, at the same column temperature, with and without irradiation. The calculated intraparticle diffusion coefficient, D(e), at 30 W (30+/-1 degrees C) microwave irradiation was ca. 20% higher than without irradiation at 30+/-1 degrees C. These preliminary results suggest that microwave irradiation may have a significant influence on the intraparticle diffusion of insulin in RPLC. 相似文献
43.
González-Ferrer S Pineda-Bernal L Delgado-Luengo W Villalobos-Cabrera H 《Community genetics》2004,7(2-3):153-156
Zulia is a state located in the northwest of Venezuela. Congenital malformations, deformities and chromosomal anomalies are the second cause of infant and neonatal mortality. There are seven public and private groups providing genetic services, the most important of which, the Medical Genetic Unit at the Zulia University was created in 1973. So far, this unit has provided genetic services to 12,000 families, and has been responsible for undergraduate and postgraduate education in human and medical genetics. Prenatal diagnosis is performed at the Unit and a private practice group, the most frequent referral reason being advanced maternal age. The most frequent genetic diseases in the state are Huntington's disease, sickle cell anemia, neural tube defects and Down's syndrome. Research in genetics includes the clinical, epidemiological and molecular characterization of hereditary diseases, cancer, reproductive problems and genetic diversity. Other public groups are conducting research on dementias, including Alzheimer's disease, and on the genotoxic effects of environmental pollutants. 相似文献
44.
The relative rates of H-transfer between partners in ion-neutral complexes were compared with those in intramolecular rearrangements using results of first differential photoionization mass spectrometry measurements. Complex-mediated H-transfers are inferred to have rates of the same order as those for intramolecular hydrogen rearrangements, suggesting a similar range of motion of the reactive sites in both types of reactions. It is also concluded that at their fastest H-transfers take place between the partners in ion-neutral complexes within at most the time of several rotations of the partners in the complexes. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
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46.
Lev Z. Vilenchik S. Rubinsztajn Martel Zeldin Wilmer K. Fife 《Journal of Polymer Science.Polymer Physics》1991,29(9):1137-1140
The relationship between viscosity constants, k', a and Kη from the equations of Huggins and Mark-Kuhn-Houwink has been considered. It is shown, theoretically, that the sum of k' and a must be constant for all flexible-chain macromolecules irrespective of the solvent used. On this basis, a combination of chromatography and viscometry measurements can be used to characterize a new species. The method has been applied to the new polymer, poly[methyl(pyridin-3-yl) siloxane] ( 1 ) where no suitable calibration standards are available. The value of a, k', and Kη for 1 has been calculated. The calculated constants enabled an estimation of different average molecular weights (MnMwMz) and polydispersity (Mw/Mn) from a minimum of experimental data. The new method is general and can be applied to any homogeneous linear flexible-chain nondraining macromolecule. 相似文献
47.
Christopher G. Eckel Randy R. Sibbitt Wilmer L. Sibbitt Jr. John D. Newell Jr. Andrew Narva Roderick Fields William Orrison 《Magnetic resonance imaging》1988,6(6):713-715
We describe a case of polyarteritis nodosa with diffuse abnormalities in subcutaneous fat by magnetic resonance imaging. These abnormalities returned to normal following treatment. Magnetic resonance imaging may have a role in the identification and diagnosis of systemic vasculitis. 相似文献
48.
Wilmer J. Colmená rez Rodriguez 《Transactions of the American Mathematical Society》2005,357(10):4131-4140
In this paper we show nonuniform hyperbolicity for a class of attractors of flows in dimension three. These attractors are partially hyperbolic with central direction being volume expanding, contain dense periodic orbits and hyperbolic singularities of the associated vector field. Classical expanding Lorenz attractors are the main examples in this class.
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Wilmer H. Perera Alexander M. Scherbakov Galina I. Buravchenko Ekaterina I. Mikhaevich Suzana Guimares Leito Paul Cos Andrey E. Shchekotikhin Lianet Monzote William N. Setzer 《Molecules (Basel, Switzerland)》2022,27(6)
In this study, the in vitro antimicrobial, antiparasitic, antiproliferative and cytotoxic activities of essential oil from Baccharis parvidentata Malag. (EO-Bp) and Lippia origanoides Kunth (EO-Lo) were explored. The relevant effects were observed against the parasitic protozoans Plasmodium falciparum, Trypanosoma cruzi, Trypanosoma brucei and Leishmania amazonensis (ranging 0.6 to 39.7 µg/mL) and malignant MCF-7, MCF-7/HT, 22Rv1, and A431 cell lines (ranging 6.1 to 31.5 µg/mL). In parallel, EO-Bp showed better selective indexes in comparison with EO-Lo against peritoneal macrophages from BALB/c mice and MRC-5 cell line. In conclusion, EO-Lo is known to show a wide range of health benefits that could be added as another potential use of this oil with the current study. In the case of EO-Bp, the wide spectrum of its activities against protozoal parasites and malignant cells, as well as its selectivity in comparison with non-malignant cells, could suggest an interesting candidate for further tests as a new therapeutic alternative. 相似文献