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排序方式: 共有937条查询结果,搜索用时 31 毫秒
1.
Hiroshi Noguchi Masanori Ueda Yoshinobu Baba Masako Takasu 《Journal of Polymer Science.Polymer Physics》2003,41(12):1316-1322
The electrophoresis of DNA chains in uncrosslinked polymer solutions with a Brownian dynamics simulation with an anisotropic friction tensor was analyzed. According to the degree of anisotropy, three types of migration behavior are obtained: fluctuation without or with periodicity between U‐shaped and compact conformations, or migration with linear conformation. We found good agreement between our simulation results and the direct observations of DNA by fluorescence microscopy. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1316–1322, 2003 相似文献
2.
We theoretically investigated the mass dependence of the sympathetic cooling rate of gas-phase ions trapped in a linear radio-frequency-quadrupole
ion trap. Using an a priori molecular dynamical calculation, tracing numerically with Newtonian equations of motion, we found
that ions with a mass greater than 0.54±0.04 times that of the laser-cooled ions are sympathetically cooled; otherwise, they
are heated. To understand the mass dependence obtained using the molecular-dynamical calculation, we made a heat-exchange
model of sympathetic cooling, which shows that the factor of 0.54±0.04 is a consequence of absence of micro-motion along the
axis of the linear ion trap.
Received: 10 December 2001 / Revised version: 28 January 2002 / Published online: 14 March 2002 相似文献
3.
4.
Tatsushi Baba 《Tetrahedron letters》2004,45(31):5973-5975
New water-soluble porphycenes having sulfonic acid groups at the β-pyrrolic positions were synthesized and characterized by UV-vis, NMR, IR, and mass spectroscopy as well as elemental analyses. The series of mono- to tri-sulfonato derivatives were simply separated by the extraction method. 相似文献
5.
Toshihide Baba Satoru Hikita Haruhisa Handa Yoshio Ono 《Research on Chemical Intermediates》1998,24(5):495-505
Europium supported on alumina (Eu/Al2O3) was prepared by impregnation from an ammoniacal solution of the metal. The catalytic activity of Eu/Al2O3 for the isomerization of 2,3-dimethylbut-1-ene to 2,3-dimethylbut-2-ene was examined. Eu/Al2O3 showed the highest catalytic activity for the isomerization when heated under a vacuum at 523 K, the yield of 2,3-dimethylbut-2-ene
in 20 min being 81.6% at 314 K. IR spectrum shows the presence of two kinds of Eu amides. The change of the IR spectra and
the catalytic activities with evacuation temperature suggest that only one of the two Eu amides is catalytically active for
this base-catalyzed isomerization. 相似文献
6.
7.
Akio Nara Nobuko Kobayashi Kazuko Hasegawa Katsuko Honba Shigeo Baba 《Microchemical Journal》1975,20(4):440-448
For the conductometric titration of fluoride with calcium acetate, solvent system in sample solution and titrant, concentration, and acidity of sample solution were examined to establish the titration conditions. Results of these examinations were transferred to the microdetermination of fluorine in organic compounds using oxygen flask combustion method.Comparative examination between quartz and Pyrex flasks for the combustion of fluorine samples indicated that good results were obtained by the use of the former flask, whereas the use of the latter one gave negative values of 1.0–1.6% due to the formation of boron fluoride during the combustion. 相似文献
8.
Shinichi Kikkawa Kazuteru Nagasaka Mark Bailey Yoshinari Miyamoto 《Journal of solid state chemistry》2007,180(7):1984-1989
Gallium oxynitride, isostructural to hexagonal gallium nitride (h-GaN), was obtained by ammonia nitridation of a precursor prepared from the addition of citric acid to an aqueous solution of gallium nitrate. Gallium oxynitride produced at 750 °C had a small amount of gallium vacancies, and was formulated as (Ga0.89□0.11) (N0.66O0.34) where the symbol □ stands for gallium vacancy. Both the gallium vacancies and oxygen substituted for nitrogen were randomly distributed within the structure. The amount of vacancies decreased with nitridation temperatures in the range of 750-850 °C. Approximately, 10 at% Li+ was doped into the gallium oxynitride, using a similar preparation with the additional presence of lithium nitrate, resulted in the random substitution of Ga3+ in an atomic ratio of Li/Ga<1 at 750 °C. Oxygen was codoped with lithium and substituted nitrogen in the wurtzite-type crystal lattice. These substitutions reduced the electrical conductivity in the gallium oxynitride semiconductor. A new oxynitride, Li2Ga3NO4, was also obtained with Li2CN2 impurity using similar preparations from a mixture of Li/Ga?1. The crystal structure was isostructural with h-GaN, and was refined as P63mc with a=0.31674(1) nm, and c=0.50854(2) nm. The Ga and Li occupancies at the 2b site were refined to be 0.6085 and 0.3915, respectively, assuming that the other 2b site was randomly occupied with 1/5O and 4/5N. When the new compound was washed for over 1 min for the removal of Li2CN2 impurities, it was decomposed to a mixture of α-GaOOH and α-LiGaO2. The as-prepared product with Li/Ga=1 showed the highest intensity in yellow luminescence among the products under excitation at 254 nm. 相似文献
9.
The relative gamma-ray intensities in the energy region between 122 and 411 keV in the decay of152Eu were measured by using a Ge(Li) detector. Its efficiency calibration was carried out with the radioactive sources of241Am,57Co,203Hg,137Cs,133Ba,75Se,169Yb and192Ir. 相似文献
10.
Miyashita T Baba M Shigeta S Mori K Shinozuka K 《Chemical & pharmaceutical bulletin》2003,51(6):630-634
A series of novel 10-thiaisoalloxazine derivatives bearing an alkoxymethyl or benzyloxymethyl moiety at the N-1 position has been synthesized through the bromination of 1-substituted-5-hydroxyuracils and subsequent condensation with aminobenzenethiol in a one-pot reaction. Contrary to the previous report, the formation of intermediary 5,6-diethoxy-5-hydroxy-5,6-dihydrouracil seems to be not the necessary factor for the formation of the thiaisoalloxazines, since the reaction proceeds in tetrahydrofuran (THF) or acetonitrile far more smoothly than in ethanol. The anti-human immunodeficiency virus (HIV)-1 activity of the resulted thiaisoalloxazine derivatives was evaluated in lymphocyte cells based on the inhibitory activity against the viral-induced cytopathic activity. Among the derivatives, compounds 6, 7, and 8 bearing an alkoxymethyl moiety at the N-1 position exhibited modest inhibitory activity towards the cytotopathic effect of HIV-1. 相似文献