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21.
Highlights? A highly modified nucleotide as substrate for polymerases ? The reversibility of the polymerase reaction at the template level ? Synthesis of a nucleoside with two anomeric centers  相似文献   
22.
Quantum interference corrections in ballistic conductors require a minimal time: the Ehrenfest time. In this Letter, we investigate the fate of the interference corrections to quantum transport in bulk ballistic conductors if the Ehrenfest time and the dephasing time are comparable.  相似文献   
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The study of the acidic sites in zeolites is important to understand the nature of the acidic catalytic function.  相似文献   
25.
Based on our analysis of the hopcount of the shortest path between two arbitrary nodes in the class G p (N) of random graphs, the corresponding flooding time is investigated. The flooding time T N (p) is the minimum time needed to reach all other nodes from one node. We show that, after scaling, the flooding time T N (p) converges in distribution to the two-fold convolution (2*) of the Gumbel distribution function (z)=exp (–e z ), when the link density p N satisfies Np N /(log N)3 if N .  相似文献   
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We develop the general nonequilibrium theory of transport through a quantum dot, including Coulomb blockade effects via a 1/N expansion, where N is the number of scattering channels. At lowest order we recover the Landauer formula for the current plus a self-consistent equation for the dot potential. We obtain the leading corrections and compare with earlier approaches. Finally, we show that to leading and to next leading order in 1/N there is no interaction correction to the weak localization, in contrast to previous theories, but consistent with experiments by Huibers et al. [Phys. Rev. Lett. 81, 1917 (1998)], where N=4.  相似文献   
28.
It has been suggested that chaotic motion inside the nucleus may significantly limit the accuracy with which nuclear masses can be calculated. Using a power spectrum analysis we show that the inclusion of additional physical contributions in mass calculations, through many-body interactions or local information, removes the chaotic signal in the discrepancies between calculated and measured masses. Furthermore, a systematic application of global mass formulas and of a set of relationships among neighboring nuclei to more than 2000 nuclear masses allows one to set an unambiguous upper bound for the average errors in calculated masses, which turn out to be almost an order of magnitude smaller than estimated chaotic components.  相似文献   
29.
In this article a new method for the photolithographical deposition of temperature-sensitive hydrogels is presented. The method can be used in conjunction with standard 365 nm UV-photolithography to accurately dimension and position temperature-sensitive hydrogel microactuators in a highly parallel fashion. A number of characteristics of the hydrogels were investigated. These include: the photolithographical reproduction quality, the effect of the crosslinking density in the hydrogels on their swelling behavior, the swelling hysteresis behavior, the effect of dimensional constraints on the swelling of the hydrogels and the effect of copolymerization with an ionizable comonomer on the temperature behavior of the hydrogels. The method presents a considerable improvement in the microfabrication of temperature-sensitive hydrogel microactuators and has potential for the mass-fabrication of these interesting microactuators.  相似文献   
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The synthesis of fully [13C/15N] labeled pyrimidine nucleosides has been achieved from 13C-glucose and labeled nucleobases. The reaction scheme leads directly to the protected nucleosides without the need for the inversion of configuration of C-3 of 13C-glucose. This was achieved by an oxitative ring-opening reaction removing the carbon with the wrong configuration.  相似文献   
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