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排序方式: 共有155条查询结果,搜索用时 15 毫秒
91.
92.
93.
94.
An EtOAc extract from the roots of Sophora flavescens (Kushen) potentiated γ-aminobutyric acid (GABA)-induced chloride influx in Xenopus oocytes transiently expressing GABAA receptors with subunit composition, α
1
β
2
γ
2S. HPLC-based activity profiling of the extract led to the identification of 8-lavandulyl flavonoids, kushenol I, sophoraflavanone
G, (−)-kurarinone, and kuraridine as GABAA receptor modulators. In addition, a series of inactive structurally related flavonoids were characterized. Among these, kushenol
Y (4) was identified as a new natural product. The 8-lavandulyl flavonoids are first representatives of a novel scaffold for the
target. 相似文献
95.
96.
M.M. Ivanenko H. Handreck J. Göthel W. Fuss K.-L. Kompa P. Hering 《Applied physics. B, Lasers and optics》1997,65(4-5):577-582
2 to the CHClF2/He mixture irradiated by a Q-switched CO2 laser leads to oxidation of the dissociation product according to the reaction: CF2+NO2→COF2+NO. The resulting COF2 with a 13C content near 50% is easy to convert to CO2 or CO for further enrichment by a nonlaser process. We measured the dependence of the fraction of dimerised CF2 on NO2 pressure pNO2 and the amount of NO2 required to suppress dimerisation on the dissociation yield. Both agree with a kinetic model using known rate constants.
For the range of the dissociation parameters (13CF2 yield of 10% per pulse, isotope selectivity of 130) of practical interest, 95% of the CF2 produced is oxidized at pNO2≈1/2pCHClF2. In the absence of NO2, major (20%–35%) losses of CF2 at the metal walls of the irradiation system were observed. Addition of NO2 suppresses them. For comparison, we also used O2 as a scavenger in CHClF2 dissociation. NO2 is by orders of magnitude more efficient.
Received: 21 January 1997/Revised version: 23 March 1997 相似文献
97.
2 laser using a miniature water spray is demonstrated. An ablation threshold of 1.4 J/cm2, an optimal energy density of 9–10 J/cm2, and a corresponding specific ablation energy of 25–30 J/mm3 are found for pig thighbone compacta at λ=9.57 μm and a beam waist diameter of 0.5 mm. The water spray alleviates tissue
carbonization even at high laser pulse repetition rates and increases ablation efficiency.
Received: 9 March 1998/Revised version: 6 July 1998 相似文献
98.
99.
Karl Hering 《Fresenius' Journal of Analytical Chemistry》1929,78(1-2):91-94
Ohne Zusammenfassung 相似文献
100.
D. Kleine J. Lauterbach K. Kleinermanns P. Hering 《Applied physics. B, Lasers and optics》2001,72(2):249-252
Cavity ring-down spectroscopy (CRDS) has so far mostly been used for measurements in the gas phase. Only in 1999 was a first
spectrum of condensed phase published. This spectrum was measured by using a coated plate between the cavity mirrors. Rather
than using this method, our measurements were made using the cavity mirrors as a substrate. This way, the scattering losses
could be reduced by approximately a factor of 100. In our measurements we investigated molecularly thin layers of iodine.
The iodine spectra were taken in the frequency range from 16200 to 17200 cm-1 using pulsed CRDS.
Received: 14 April 2000 / Revised version: 26 July 2000 / Published online: 22 November 2000 相似文献