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排序方式: 共有5401条查询结果,搜索用时 31 毫秒
31.
Abe F Amidei D Apollinari G Atac M Auchincloss P Baden AR Bamberger A Barbaro-Galtieri A Barnes VE Bedeschi F Behrends S Belforte S Bellettini G Bellinger J Bensinger J Beretvas A Berge JP Bertolucci S Bhadra S Binkley M Blair R Blocker C Booth AW Brandenburg G Brown D Buckley E Byon A Byrum KL Campagnari C Campbell M Carey R Carithers W Carlsmith D Carroll JT Cashmore R Cervelli F Chadwick K Chiarelli G Chinowsky W Cihangir S Clark AG Connor D Contreras M Cooper J Cordelli M Crane D Curatolo M 《Physical review letters》1990,65(18):2243-2246
32.
In this paper, we describe an algorithm to stably sort an array ofn elements using only a linear number of data movements and constant extra space, albeit in quadratic time. It was not known previously whether such an algorithm existed. When the input contains only a constant number of distinct values, we present a sequence ofin situ stable sorting algorithms makingO(n lg(k+1)
n+kn) comparisons (lg(K) means lg iteratedk times and lg* the number of times the logarithm must be taken to give a result 0) andO(kn) data movements for any fixed valuek, culminating in one that makesO(n lg*n) comparisons and data movements. Stable versions of quicksort follow from these algorithms.Research supported by Natural Sciences and Engineering Research Council of Canada grant No.A-8237 and the Information Technology Research Centre of Ontario.Supported in part by a Research Initiation Grant from the Virginia Engineering Foundation. 相似文献
33.
Abe F Amidei D Apollinari G Ascoli G Atac M Auchincloss P Baden AR Barbaro-Galtieri A Barnes VE Bedeschi F Behrends S Belforte S Bellettini G Bellinger J Bensinger J Beretvas A Berge P Bertolucci S Bhadra S Binkley M Blair R Blocker C Bofill J Booth AW Brandenburg G Brown D Byon A Byrum KL Campbell M Carey R Carithers W Carlsmith D Carroll JT Cashmore R Cervelli F Chadwick K Chapin T Chiarelli G Chinowsky W Cihangir S Cline D Connor D Contreras M Cooper J Cordelli M Curatolo M Day C DelFabbro R 《Physical review D: Particles and fields》1990,41(5):1722-1725
34.
Valence bond ground states in isotropic quantum antiferromagnets 总被引:5,自引:0,他引:5
Ian Affleck Tom Kennedy Elliott H. Lieb Hal Tasaki 《Communications in Mathematical Physics》1988,115(3):477-528
Haldane predicted that the isotropic quantum Heisenberg spin chain is in a massive phase if the spin is integral. The first rigorous example of an isotropic model in such a phase is presented. The Hamiltonian has an exactSO(3) symmetry and is translationally invariant, but we prove the model has a unique ground state, a gap in the spectrum of the Hamiltonian immediately above the ground state and exponential decay of the correlation functions in the ground state. Models in two and higher dimension which are expected to have the same properties are also presented. For these models we construct an exact ground state, and for some of them we prove that the two-point function decays exponentially in this ground state. In all these models exact ground states are constructed by using valence bonds.Supported in part by N.S.F. Grant PHY-80-19754. Fellow of the A.P. Sloan Foundation and the Canadian Institute for Advanced ResearchN.S.F. Post-doctoral FellowSupported in part by N.S.F. Grant PHY-85-15288-A01 相似文献
35.
Abe F Amidei D Apollinari G Ascoli G Atac M Auchincloss P Baden AR Barbaro-Galtieri A Barnes VE Bedeschi F Behrends S Belforte S Bellettini G Bellinger J Bensinger J Beretvas A Berge P Bertolucci S Bhadra S Binkley M Blair R Blocker C Bofill J Booth AW Brandenburg G Brown D Byon A Byrum KL Campbell M Carey R Carithers W Carlsmith D Carroll JT Cashmore R Cervelli F Chadwick K Chapin T Chiarelli G Chinowsky W Cihangir S Cline D Connor D Contreras M Cooper J Cordelli M Curatolo M Day C DelFabbro R 《Physical review letters》1989,62(26):3020-3023
36.
Abe F Amidei D Apollinari G Ascoli G Atac M Auchincloss P Baden AR Barbaro-Galtieri A Barnes VE Bedeschi F Behrends S Belforte S Bellettini G Bellinger J Bensinger J Beretvas A Berge P Bertolucci S Bhadra S Binkley M Blair R Blocker C Bofill J Booth AW Brandenburg G Brown D Byon A Byrum KL Campbell M Carey R Carithers W Carlsmith D Carroll JT Cashmore R Cervelli F Chadwick K Chapin T Chiarelli G Chinowsky W Cihangir S Cline D Connor D Contreras M Cooper J Cordelli M Curatolo M Day C DelFabbro R 《Physical review letters》1989,62(6):613-616
37.
Abe F Amidei D Apollinari G Atac M Auchincloss P Baden AR Bamberger A Barbaro-Galtieri A Barnes VE Bedeschi F Behrends S Belforte S Bellettini G Bellinger J Bensinger J Beretvas A Berge JP Bertolucci S Bhadra S Binkley M Blair R Blocker C Booth AW Brandenburg G Brown D Buckley E Byon A Byrum KL Campagnari C Campbell M Carey R Carithers W Carlsmith D Carroll JT Cashmore R Cervelli F Chadwick K Chiarelli G Chinowsky W Cihangir S Clark AG Connor D Contreras M Cooper J Cordelli M Crane D Curatolo M 《Physical review letters》1989,63(7):720-723
38.
Enthalpies of solution have been measured from 5 to 85°C for aqueous tetraethyl- and tetrapropylammonium bromides, and the integral heat method is employed to evaluate
for these electrolytes over a wide temperature range. Data taken from the literature have been used to evaluate
for aqueous Bu4NBr over a similar temperature range. These data, along with similar data for Me4NBr, previously reported, have been used to evaluate absolute ionic heat capacities. While the absolute values agree only qualitatively with two other methods of division, the temperature dependences of the three methods essentially agree up to 65°C. Heat capacities due to structural effects on the solvent, obtained by subtracting the inherent heat capacities of the ions, are extraordinarily positive for all four tetraalkylammonium ions and have negative temperature coefficients, indicating that all four ions, including the tetramethylammonium ion, are structure-making ions. 相似文献
39.
The use of allyl protecting group mediated intramolecular aglycon delivery (IAD) as a strategy for intramolecular glycosylation has been extended to allow the stereoselective synthesis of α-glucofuranosides and β-rhamnopyranosides, in a totally stereoselective fashion. The efficiency of intramolecular glycosylation is dependent on the protecting group pattern of the glycosyl donor, and on the steric bulk of the glycosyl acceptor. 相似文献
40.
Stephen G. Davies Ian A. Hunter Rebecca L. Nicholson Paul.M. Roberts Edward D. Savory Andrew D. Smith 《Tetrahedron》2004,60(35):7553-7577
α-Dibenzylamino- and α-benzyloxy- derivatives of N-acetyl-(S)-4-benzyl-5,5-dimethyloxazolidin-2-one readily undergo highly stereoselective boron mediated syn-aldol reactions with a range of aromatic and aliphatic aldehydes, generating the syn-aldol products in good to excellent yields as single diastereoisomers after purification. In the α-dibenzylamino series, deprotection of the functionalised aldol fragments to the corresponding α-amino-β-hydroxy methyl ester or α-amino-β-hydroxyaldehyde proved problematic, with a range of N- and O-protecting groups giving mixtures of products arising from endocyclic and exocyclic cleavage pathways. However, in the α-benzyloxy series, O-silyl protection of the aldol products, and subsequent DIBAL reduction gives stereoselectively the corresponding N-1′-hydroxyalkyloxazolidin-2-ones, which undergo base promoted fragmentation to the desired highly functionalised and differentially protected α,β-dihydroxyaldehydes in good yields and without loss of stereochemical integrity. 相似文献