排序方式: 共有4条查询结果,搜索用时 0 毫秒
1
1.
V. L. Afanasiev S. N. Dodonov A. V. Moiseev V. Chavushyan R. Mujica Y. Juarez A. G. Gorshkov V. K. Konnikova M. G. Mingaliev 《Astronomy Letters》2003,29(9):579-586
We present the classification of optical identifications and radio spectra of six radio sources from a complete (in flux density) sample in the declination range 10° to 12°30′ (J2000.0). The observations were carried out with the 6-m Special Astrophysical Observatory telescope (Russia) in the wavelength range 3600–10000 Å, the 2.1-m GHAO telescope (Mexico) in the range 4200–9000 Å, and the RATAN-600 radio telescope in the frequency range 0.97–21.7 GHz. Three of the six objects under study are classified as quasars, one is a BL Lac object, one is an absorption-line radio galaxy, and one is an emission-line radio galaxy. Five objects have flat radio spectra, and one object has a power-law radio spectrum. All of the radio sources identified as quasars or BL Lac objects show variable radio flux densities. The spectra of three objects were separated into extended and compact components. 相似文献
2.
T. Martinez J. Lartigue F. Juarez P. Avila-Perez G. Zarazua C. Marquez M. P. Orta V. Alvarez 《Journal of Atmospheric Chemistry》2004,49(1-3):415-424
Lead isotopic studies of airborne particulate matter, gasoline and other environmental samples have been carried out to determine possible sources of lead pollution in the Metropolitan Zone of the Valley of Mexico. 206Pb/207Pb ratio in gasoline was 1.1395 ± 0.0165 and 1.071 ± 0.008 for industrially-derived lead as a mean. Natural lead is more radiogenic with values from 1.2082 ± 0.022 to 1.211 ± 0.108. The measured Pb isotopic signature of airborne particulate matter reflects the relative importance of each of these sources. The 206Pb/207Pb ratio was 1.179 ± 0.105 as a mean. The relative importance of gasoline has decreased, and, therefore, other sources (natural and industrial) can be identified by means of isotopic studies. This is a consequence of the introduction of unleaded gasoline as mandaped by strictest environmental regulation. 相似文献
3.
Light stable isotopes have been used for many years to characterize the source and transport of materials. More recently heavy isotope systems such as Sr, Nd and Pb have been added to this list in order to aid source identification. With the advent of multiple collector ICP-MS, the range of isotopic tools now available has increased considerably, however, until the isotope systematics of these new non-traditional isotope systems have become better understood, they will not be as useful in characterizing material source and transportation. Applications using heavy metal stable isotopes (mostly traditional heavy isotopes) have reached most avenues in science, including earth sciences, archaeology, anthropology, animal physiology, ecology and toxicology. This field will continue to grow as new applications are developed and techniques become simpler and quicker. This paper provides a review of how this field has grown and presents two new applications using Pb and Sr isotopes in glazes to determine the source of ore used in glazes, and using Sr isotopes to determine the origin of undocumented deceased Mexican border crossers. 相似文献
4.
Prol-Ledesma Rosa Maria M. Gerardo Juarez 《Journal of Volcanology and Geothermal Research》1986,28(3-4)
Silica temperatures were calculated for 326 water samples from hot and warm springs located throughout Mexico as an attempt to estimate heat flow. Available heat flow data (Smith, 1974; Smith et al., 1979) for northern Mexico were related to silica temperature data to obtain the appropriate constants for the regional conditions according to Swanberg and Morgan's equation (1979, 1980). The constants obtained are similar to those obtained for the United States, therefore heat flow can be estimated on the basis of silica temperature data. By contouring calculated temperatures a map is obtained where the main geothermal provinces are shown. 相似文献
1