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81.
Benzynes were generated from o-(trimethylsilyl)phenols using nonafluorobutanesulfonyl fluoride (NfF) by a domino process, i.e., the nonaflation of the phenolic hydroxyl group of o-(trimethylsilyl)phenols by NfF followed by the attack of the produced fluoride ion on the trimethylsilyl group. The generated benzyne immediately underwent various reactions to give polysubstituted benzenes. 相似文献
82.
Yamamoto Y Yamashita K Nishiyama H 《Chemical communications (Cambridge, England)》2011,47(5):1556-1558
A ruthenium cyclic biscarbene complex reacted with a H(2)O molecule under mild conditions to produce η(5)-oxapentadienyl complex, that proved to be the intermediate in the catalytic hydrative cyclization of a diyne. 相似文献
83.
H. Sukumar J. A. Stone T. Nishiyama C. Yuan G. A. Eiceman 《International Journal for Ion Mobility Spectrometry》2011,14(2-3):51-59
A paper spray ion source was combined with a drift tube operating at ambient pressure for mobility measurements of ions derived from pharmaceutical solutions. Paper spray ionization with solvent alone resulted in a mixture of ions convolved to a single peak with a reduced mobility of 2.19 cm2/Vs in the mobility spectrum. These were mass-identified principally as m/z 157, (MeOH)2(HCOOH)2H+ and m/z 129, (MeOH)4(H2O)H+ while pharmaceuticals with nitrogen bases formed MH+ product ions. The duration of response was governed by the volume of liquid added to the paper source and was limited by evaporation of solvent in gas at 58 °C venting the drift tube. Quantitative variation was attributed in part to morphologic changes in the tip of the paper spray source. This was associated with mass flow in the electrical discharge and not due alone to cycles of wetting and drying of the paper. Mobility spectra of chlorpromazine in urine, exhibited a single product ion peak and linear response was 30 to 500 ng with an estimated limit of detection of 1.5 ng. Ion flux could be prolonged by continuous addition of liquid and findings portend a combination of paper spray ionization IMS with paper chromatography. 相似文献
84.
85.
Muonium spin relaxation measurements of the \alpha‐, \beta‐, and \gamma‐tridymite phases of quartz have been carried out over
a temperature range from 300 to 1250 K. Anomalous relaxation rate increases are observed which may result either from resonance
coupling between the other impurity ions and defects in the lattice and the diffusing muonium, or may result from phonon interactions
with the muonium quadrupole moment.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
86.
Y. Nishiyama 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,6(3):335-340
Ground-state phase diagram of the one-dimensional bond-random S=1 Heisenberg antiferromagnet is investigated by means of the loop-cluster-update quantum Monte-Carlo method. The random couplings
are drawn from a rectangular uniform distribution. We found that even in the case of extremely broad bond distribution, the
magnetic correlation decays exponentially, and the correlation length is hardly changed; namely, the Haldane phase continues
to be realized. This result is accordant with that of the exact-diagonalization study, whereas it might contradict the conclusion
of an analytic theory founded in a power-law bond distribution instead. The latter theory predicts that a second-order phase
transition occurs at a certain critical randomness, and the correlation length diverges for sufficiently strong randomness.
Received: 31 March 1998 / Revised and Accepted: 7 July 1998 相似文献
87.
E. Torikai K. Nishiyama K. Kojima K. Nagamine H. Kitazawa I. Tanaka H. Kojima 《Hyperfine Interactions》1993,79(1-4):879-883
In order to investigate the electronic structure around oxygen in superconducting La2–x
Sr
x
CuO4 (x=0.10 and 0.14), precise measurements were carried out on the paramagnetic Knight shifts in the spin rotation frequency of the negative muon bound to the oxygen with reference to antiferromagnetic La2–x
Sr
x
CuO4 (x=0.05). Remarkable temperature as well as crystalline-axis dependence was observed for the highT
c case with a divergence character towardsT
c. Possible mechanisms to explain the observed results are given. 相似文献
88.
F. Dimmling N. Bräuer B. Focke T. Kornrumpf K. Nishiyama D. Riegel 《Zeitschrift für Physik A Hadrons and Nuclei》1974,271(2):103-105
The isomeric 731 keV, 11/2? state in113Sn was populated by the reaction113In(p, n). The halflife of the state was measured to be T1/2=89(3) ns and the magnetic moment was determined by means of the pulsed beam PAD method as μ=?1.293(22) n.m. 相似文献
89.
90.
Shigeru Nishiyama Yoshikazu Shizuri Daizo Imai Shosuke Yamamura Yukimasa Terada Masatake Niwa Kazuaki Kawai Hideyuki Furukawa 《Tetrahedron letters》1985,26(27):3243-3246
Isocitreoviridinol has been newly isolated from the mycelium of B. (IFO 6050) together with citreoviridinol, and their stereostructures have also been elucidated by means of chemical method: the 2,6-dioxabicyclo[3.2.1]octanes have been made, one of which is regarded as a promising synthetic intermediate of citreoviridinol. In addition, isocitreoviridinol diacetate has been derived from citreoviridin in 3 steps. 相似文献