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52.
We measured the sputtering yield, surface roughness and surface damage of thin leucine films bombarded with Ar cluster ions and examined the usefulness of large gas cluster ions for the depth profiling of organic compounds. Ar cluster ion beams with a mean size of 2000 atoms/cluster and energies from 5 to 30 keV were used. Sputtering yields increased linearly with incident ion energy and were extremely high compared to inorganic materials. Surface damage was investigated by measuring positive secondary ions emitted from the leucine film before and after cluster ion irradiation. After irradiation the leucine surface became smoother. The yield ratio of protonated leucine ions to other fragment ions kept constant before and after Ar cluster ion irradiation. These results indicate that large gas cluster ions are useful for depth profiling of organic compounds. 相似文献
53.
Toshio Morikawa Xuezheng Li Eriko Nishida Seikou Nakamura Kiyofumi Ninomiya Hisashi Matsuda Yoshimi Oda Osamu Muraoka Masayuki Yoshikawa 《Helvetica chimica acta》2010,93(3):573-586
The MeOH extract from the flowers of Bellis perennis was found to show pancreatic‐lipase inhibitory activity (IC50 455 μg/ml). From the extract, seven new triterpene saponins named perennisaponins G ( 1 ; IC50 163 μM ), H ( 2 ; 137 μM ), I ( 3 ; 147 μM ), J ( 4 ; 148 μM ), K ( 5 ; 223 μM ), L ( 6 ; 81.4 μM ), and M ( 7 ; 195 μM ) were isolated as pancreatic lipase inhibitors. The stereostructures of 1 – 7 were elucidated on the basis of chemical and spectroscopic evidence. 相似文献
54.
Ninomiya K Kurita T Hohsaka T Sisido M 《Chemical communications (Cambridge, England)》2003,(17):2242-2243
A simple and versatile method for aminoacylation of a dinucleotide (pdCpA) in aqueous micellar solution was developed by using a hydrophobic amino acid derivative, N-pentenoyl-L-2-naphthylalanine cyanomethyl ester (Pen-napAla-OCM), and a CTACl micelle. 相似文献
55.
This paper is concerned with a change-point problem in random fields. Tests for detecting a change-structure in a two-way table are constructed. Solutions to this problem require calculations of multiple integrals, but the calculations become difficult as the table gets large. To overcome this difficulty, the tube method is developed in differential geometry. It is shown by simulations that the proposed method is superior to other available methods. 相似文献
56.
57.
We show that the large distance behavior of gauge theories is stable, within certain limits, with respect to addition of gauge noninvariant interactions at small distances. 相似文献
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59.
Luminescence with decay time of about 10 nsec or shorter was found in a?As2S3 at 4.2 K on the high energy side of the luminescence observed by Kolomiets et al. From the dependence of the emission spectra on the excitation energy, it is interpreted as being due to the recombination of localized excitons. 相似文献
60.