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91.
92.
A lifting is a map from the state of a system to that of a compound system, which was introduced in Accardi and Ohya (Appl.
Math. Optim. 39:33–59, 1999). The lifting can be applied to various physical processes. 相似文献
93.
Masanori Hino 《Potential Analysis》2002,16(3):249-264
For conservative symmetric diffusions on a general state space (X,m), the short time asymptotic behavior of tlog
X
1
A
T
t
1
B
dm is investigated, where T
t
is the associated semigroup and A and B are measurable subsets of X. It is proved that the superior limit is dominated by the inferior limit up to some absolute constant. When 2 of the associated Dirichlet form is lower bounded, it is shown that the limit exists for any A and B, and is described by the intrinsic metric between them. Applications to infinite-dimensional spaces and fractals are given. 相似文献
94.
5-[4-(1-Hydroxyethyl)phenyl]-10,15,20-triphenylporphyrin (1a) and zinc porphyrin 1b were designed and synthesized to experimentally examine the validity of the transition-state model previously proposed for the lipase-catalyzed kinetic resolution of secondary alcohols. The lipases from Pseudomonas cepacia (lipase PS), Candida antarctica (CHIRAZYME L-2), Rhizomucor miehei (CHIRAZYME L-9), and Pseudomonas aeruginosa (lipase LIP) exhibited excellent enantioselectivity (E >100 at 30 degrees C). Subtilisin Carlsberg from Bacillus licheniformis (ChiroCLEC-BL) also showed high enantioselectivity for 1a (E = 140 at 30 degrees C), and the thermodynamic parameters were determined: DeltaDeltaH = -6.8 +/- 0.8 kcal mol(-1), DeltaDeltaS = -13 +/- 3 cal mol(-1) K(-1). Lipases and subtilisin showed R- and S-preference for 1, respectively. The mechanisms underlying the experimental observations are explained in terms of the transition-state models. The large secondary alcohol 1 is a powerful tool for investigating the conformation of the transition state of the enzyme-catalyzed reactions. The fact that 1 was resolved with high enantioselectivity strongly suggests that the gauche conformation, but not the anti conformation, is taken in the transition state, in agreement with the transition-state models involving the stereoelectronic effect. 相似文献
95.
[structure: see text] 8,11-Dideoxytetrodotoxin, an unnatural tetrodotoxin analogue, was synthesized in a highly stereoselective manner from a common intermediate in our synthetic studies on tetrodotoxin. The synthesis features neighboring group participation of trichloroacetamide for stereoselective hydroxylation, protection of ortho ester, and guanidine installation with Boc-protected isothiourea. 相似文献
96.
[reaction: see text] The stereoselectivity of nucleophilic addition of 2-trimethylsilyloxyfuran to N-gulosyl-C-alkoxymethylnitrones was investigated. It was found that the selectivity was highly dependent on the bulkiness of the C-substituent of the nitrone. The major adducts were elaborated into the key intermediate of polyoxin C. 相似文献
97.
Widmann E Eades J Ishikawa T Sakaguchi J Tasaki T Yamaguchi H Hayano RS Hori M Torii HA Juhász B Horváth D Yamazaki T 《Physical review letters》2002,89(24):243402
Using a newly developed laser-microwave-laser resonance method, we observed a pair of microwave transitions between hyperfine levels of the (n,L)=(37,35) state of antiprotonic helium. This experiment confirms the quadruplet hyperfine structure arising from the interaction of the antiproton orbital angular momentum, the electron spin and the antiproton spin as predicted by Bakalov and Korobov. The measured frequencies of nu(+)(HF)=12.895 96+/-0.000 34 GHz and nu(-)(HF)=12.924 67+/-0.000 29 GHz agree with recent theoretical calculations on a level of 6x10(-5). 相似文献
98.
Hori M Eades J Hayano RS Ishikawa T Sakaguchi J Tasaki T Widmann E Yamaguchi H Torii HA Juhász B Horváth D Yamazaki T 《Physical review letters》2002,89(9):093401
Initial distributions of metastable antiprotonic (4)He and (3)He atoms over principal (n) and angular momentum (l) quantum numbers have been deduced using laser spectroscopy experiments. The regions n = 37-40 and n = 35-38 in the two atoms account for almost all of the observed fractions [(3.0 +/- 0.1)% and (2.4 +/- 0.1)%] of antiprotons captured into metastable states. 相似文献
99.
Armed crown ethers (1-4) bonding through an amine, amide, ether, or ester linkage to naphthyl group were found to display unique photophysical properties in the presence of guest salts. Complexation of PET fluoroionophores (1a and 1b) with Zn(2+) increased the fluorescence intensities of the host by a factor of 2.4 and 2.7, respectively. (1)H and (13)C NMR analyses of this complexation behavior of 1a revealed that Zn(2+) strongly coordinates with the armed crown nitrogen to cause a dramatic decrease in an intramolecular charge-transfer character. The armed crowns (2 and 3), bonding through an ether or ester linkage to a naphthalene, gave fluorescence quenching with guest thiocyanates. While the amide derivative (4) exhibited high Ba(2+) fluorescence selectivity and in the presence of this cation the host fluorescence intensity was by a factor of 3.69. 相似文献
100.