On the basis of data on isotope and element abundance in meteorites and erustal rocks and in the light of nuclear physical experiments, it is suggested that the differentiation of crustal material (including magmatism...On the basis of data on isotope and element abundance in meteorites and erustal rocks and in the light of nuclear physical experiments, it is suggested that the differentiation of crustal material (including magmatism and ore-generation process) from the mantle is accompanied by high-energy nuclear reactions. This knowledge would provide important insights into the process of endogenic ore genesis. For example, the spallation reactions of antimony and high-energy fission of uranium may all result in large amount of lighter isotopes of tin. This among other things probably accounts for the enrichment of terrestrial eassiterite in light isotopes of tin. Under the conditions where spallation reactions is dominant, the oremetal association of Sn, W, Ta, Hf, ∑Y results; where high-energy fissions prevail,the association of Sn, Mo, Nb, Zr, ∑Ce takes place; and dominant low-energy fissions might give rise to the association of Mo, Nb, Zr, ∑Ce. If a combination of various nuclear reactions is involved, a more wide speetrum of ore-metal association may be brought about.展开更多
The discovery of the novel reactivity of conjugated enynes,mediated by readily available halogenation reagents,opens a broad range of mechanistically unique pathways for the synthesis of highly functionalized chiral a...The discovery of the novel reactivity of conjugated enynes,mediated by readily available halogenation reagents,opens a broad range of mechanistically unique pathways for the synthesis of highly functionalized chiral allene derivatives.Bromoallenyl pyrrolidines can be synthesized via 1,4-addition of sulfonamide nitrogen nucleophiles and halogens to conjugated enynes.This process can lead to simultaneous formation of a highly functionalized axially chiral allene and a stereogenic center under economical and environmentally friendly reaction conditions.展开更多
文摘On the basis of data on isotope and element abundance in meteorites and erustal rocks and in the light of nuclear physical experiments, it is suggested that the differentiation of crustal material (including magmatism and ore-generation process) from the mantle is accompanied by high-energy nuclear reactions. This knowledge would provide important insights into the process of endogenic ore genesis. For example, the spallation reactions of antimony and high-energy fission of uranium may all result in large amount of lighter isotopes of tin. This among other things probably accounts for the enrichment of terrestrial eassiterite in light isotopes of tin. Under the conditions where spallation reactions is dominant, the oremetal association of Sn, W, Ta, Hf, ∑Y results; where high-energy fissions prevail,the association of Sn, Mo, Nb, Zr, ∑Ce takes place; and dominant low-energy fissions might give rise to the association of Mo, Nb, Zr, ∑Ce. If a combination of various nuclear reactions is involved, a more wide speetrum of ore-metal association may be brought about.
基金the University of Wisconsin-Madison and the American Chemical Society Petroleum Research Fund (48092-G) for funding
文摘The discovery of the novel reactivity of conjugated enynes,mediated by readily available halogenation reagents,opens a broad range of mechanistically unique pathways for the synthesis of highly functionalized chiral allene derivatives.Bromoallenyl pyrrolidines can be synthesized via 1,4-addition of sulfonamide nitrogen nucleophiles and halogens to conjugated enynes.This process can lead to simultaneous formation of a highly functionalized axially chiral allene and a stereogenic center under economical and environmentally friendly reaction conditions.
