نتایج جستجو برای: سن سنجی u pb
تعداد نتایج: 256148 فیلتر نتایج به سال:
This paper presents U, Pb isotopic data of synthetic EARTHTIME solutions and natural reference materials together with suggestions how to ensure long-term intra- inter-laboratory reproducibility high-precision TIMS U–Pb geochronology.
Introduction: The age significance of isotope chro-nometers in shocked, but not totally molten, extrater-restrial materials is still a matter of debate [1–3]. Numerous isotopic data from different isotopic systems have been obtained for meteorites, but most meteorites with apparent shock ages do not show petrographic evidence of strong shock metamorphic overprint. Deutsh and Schärer [4] carried...
The anti-neoplastic effects of histone deacetylase inhibitors (HDACi), Trichostatin A (TSA) and 4-phenylbutyrate (4-PB) on the human glioblastoma cell lines GBM-29, U-343 MG and U-343 MGa Cl. 2:6 were investigated. TSA and 4-PB induced apoptosis in the three cell lines in a dose- and time-dependent manner. Whereas caspase-3 activation was detected in all three cell lines, U-343 MG cells were mo...
Geochronology and thermochronology on detrital material provides unique constraints on sedimentary provenance, depositional ages, and orogenic evolution of source terrains. In this paper we describe a method and case-studies of measurement of both U/Pb and (U-Th)/He ages on single crystals of zircon that improves the robustness of constraints in each of these areas by establishing both formatio...
Multi-step chemical abrasion thermal ionization mass spectrometry (CA-TIMS) methods were developed for monazite using six samples that vary in composition and age—Amelia, Jefferson County, Burke, Elk Mountain, 554 and Madagascar. To evaluate whether the multi-step CA-TIMS approach reveals complexities in either age or composition that might be masked by single-step analysis, this study presents...
Department of Earth and Environmental Sciences, The Open University, Milton Keynes, MK7 6AA, U.K. 2 Department of Mineralogy, The Natural History Museum, London, SW7 5BD, U.K. 3 Department of Earth & Planetary Systems Science, Hiroshima University, 1-3-1 Kagamiyama, HigashiHiroshima 739-8526, Japan Department of Geology, Banaras Hindu University, Varanasi, 221005, India 5 Post Graduate Departme...
The past 15 years have produced numerous innovations in geochronology, including experimental methods, instrumentation, and software that are revolutionizing the acquisition and application of geochronological data. For example, exciting advances are being driven by Laser-Ablation ICP Mass Spectrometry (LA-ICPMS), which allows for rapid determination of U-Th-Pb ages with 10s of micrometer-scale...
هدف البحث الحالي إلى التعرف علي سمة التفاؤل وعلاقتها باضطراب الهلع المترتب على جائحة فيروس کورونا المستجد (Covied- 19) في ضوء علاقتها بمجموعة من المتغيرات (سن الأم ،مستواها التعليمي وعملها) لدى عينة أمهات الأطفال بمرحلة الرياض، ولتحقيق أهداف أعدت الباحثة مقياسين: أحدهما لقياس المرتبط بجائحة والآخر التفاؤل، وتکونت (250) أما المرحلة العمرية (30-40) سنة ، وقد توصل مجموعة النتائج أهمها: - تحقق صحة ...
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