نتایج جستجو برای: carbonates
تعداد نتایج: 9055 فیلتر نتایج به سال:
Paleoelevation reconstruction using stable isotopes, although a relatively new science, is making a signifi cant contribution to our understanding of the recent growth of the world’s major orogens. In this review we examine the use of both light stable isotopes of oxygen and the new “clumped-isotope” (Δ47) carbonate thermometer in carbonates from soils. Globally, the oxygen isotopic composition...
The hydration of propargylic alcohols is a green route to synthesize a-hydroxy ketones. Herein a CO2reactive ionic liquid (IL), [Bu4P][Im], was found to display high performance for catalyzing the hydration of propargylic alcohols in the presence of atmospheric CO2, and a series of propargylic alcohols could be converted into the corresponding a-hydroxy ketones in good to excellent yields. In t...
An efficient coupling reaction of epoxides with CO2 affording cyclic carbonates with the use of 2,2',2''-terpyridine as catalyst under solvent-free conditions has been developed.
RATIONALE The isotopic composition and elemental abundance of boron (B) in marine carbonates provide a powerful tool for tracking changes in seawater pH and carbonate chemistry. Progress in this field has, however, been hampered by the volatile nature of B, its persistent memory, and other uncertainties associated with conventional chemical extraction and mass spectrometric measurements. Here w...
Conjugated dienes were produced with complete regio- and stereoselectivity by the titanocene(ii)-promoted alkylation of propargyl carbonates via the formation of 2,3,4-trisubstituted titanacyclobutenes.
Complex conductivity measurements of carbonate rocks are scarce despite the occurrence these at surface Earth. The complex spectra 57 samples were measured in a broad frequency range and four salinities (NaCl). A simple model induced polarization is developed to be applied field. in-phase (related conduction) reported as function pore water determine (intrinsic) formation factor conductivity. n...
Article history: Carbonates capping Neop Received 22 May 2008 Received in revised form 10 October 2008 Accepted 10 November 2008 Available online xxxx Editor: P. DeMenocal
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