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91.
S. L. Sorensen 《The European physical journal. Special topics》2009,169(1):79-84
Symmetry breaking is an important phenomenon connected to the excitation of core electrons in molecules. The fundamental question
of whether inner-shell electronic-state orbitals are delocalized, and what the underlying mechanism for breaking the symmetry
of a molecule upon dissociation are the subject of much debate, especially for the case of diatomic molecules. One method
for studying molecular fragmentation, which is based upon a symmetry picture, is multicoincidence ion spectroscopy. Here we
give a brief presentation of some of the applications of this technique, where symmetry, nuclear motion and the temporal signature
are of importance. 相似文献
92.
Alfredo?Macías Abel?Camacho Luis?F.?Barragán-Gil Claus?L?mmerzahl 《General Relativity and Gravitation》2010,42(3):489-508
The canonical quantization for N = 1 supergravity in the context of gravitational minisuperspace described by Gowdy T
3 and Bianchi class A cosmological models is analyzed in order to search for physical states. There are indeed physical states
in the minisuperspace sector of the theory. This fact entails that the non-physical states conjecture has a restricted validity,
and in consequence it cannot be considered a general result. 相似文献
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[formula: see text] WS9885B promotes the assembly of microtubules in vitro and displays cytotoxicity as potent as paclitaxel against several cancer cell lines. In this Letter, we propose a biogenesis for this architecturally complex bacterial metabolite from a much simpler, polyunsaturated precursor. We also present significant progress toward a convergent, enantioselective synthesis of WS9885B. Our work features a chemoselective palladium-catalyzed cross-coupling of two advanced building blocks and an uncommon Claisen-like cyclization. 相似文献
99.
Claus Scheiderer 《Proceedings of the American Mathematical Society》1999,127(3):695-700
We prove two conjectures on pro- groups made by Herfort, Ribes and Zalesskii. The first says that a finitely generated pro- group which has an open free pro- subgroup of index is a free pro- product , where the are free pro- of finite rank and the are cyclic of order . The second says that if is a free pro- group of finite rank and is a finite -group of automorphisms of , then is a free factor of . The proofs use cohomology, and in particular a ``Brown theorem' for profinite groups.
100.
Received: 11 March 1998/Revised version: 1 April 1998 相似文献