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211.
Four triterpenoid saponins were isolated from Amaranthus hypochondriacus which are grain crops in the Nepal, Mexico and South America. Their structures were elucidated based on spectral evidence to be: (1) 3-O-alpha-L-rhamnopyranosyl(1----3)-beta-D-glucuronopyranosyl-2 beta,3 beta-dihydroxyolean-12-en-28-oic acid 28-O-beta-D-glucopyranosyl ester. (2) 3-O-alpha-L-rhamnopyranosyl(1----3)-beta-D-glucuronopyranosyl-2 beta,3 beta- dihydroxyolean-12-en-23-al-28-oic acid 28-O-beta-D-glucopyranosyl ester; (3) 3-O-alpha-L-rhamnopyranosyl(1----3)-beta-D-glucuronopyranosyl-2 beta, 3 beta-dihydroxy-30-norolean-12,20(29)-dien-28-oic acid 28-O-beta-D-glucopyranosyl ester. (4) 3-O-alpha-L-rhamnopyranosyl (1----3)-beta-D-glucuronopyranosyl-2 beta, 3 beta-dihydroxy-30-norolean-12, 20(29)-dien-23-al-28-oic acid 28-O-beta-D-glucopyranosyl ester. 相似文献
212.
Abstract Trapped electrons (et ?) were detected in irradiated PVA films at 77°K. Yield of et ? was decreased as evaporating water from the films, indicating that water molecules contribute to construct pre-existing traps in the polymer. The radical produced at 77°K was identified as a precursor of the radical produced at room temperature. 相似文献
213.
T. Takeuchi T. Detchprohm M. Iwaya N. Hayashi K. Isomura K. Kimura M. Yamaguchi S. Yamaguchi C. Wetzel H. Amano I. Akasaki Y. W. Kaneko R. Shioda S. Watanabe T. Hidaka Y. Yamaoka Y. S. Kaneko N. Yamada 《Journal of Electronic Materials》2000,29(3):302-305
We obtained 1 μm crack-free AlGaN layers up to an AlN molar fraction of 0.4 by growing directly on low-temperature-deposited
buffer layers. The buffer layer is effective for growing AlGaN layers without the stress caused by the lattice mismatch. We
also demonstrated nitride-based laser diodes with such a 1 μm crack-free n-AlGaN cladding layer/n-AlGaN contact layer/low-temperature-deposited
buffer layer/sapphire structure, which showed a clear single spot in a far field pattern. The AlGaN-based structure can suppress
optical leakage from the waveguide region to the underlying layer. The threshold current of the laser diode is about 230 mA,
which is comparable to or better than that of our laser diodes with the conventional GaN-based structure. 相似文献
214.
K Nishimura Y Noguchi T Matsumoto H Kitamura M Naito A Yamaoka 《Journal of electron microscopy》1991,40(3):162-166
The present study was undertaken to examine if our novel root treatment for human periodontally involved teeth can facilitate a new connective tissue attachment. The novel treatment was in two parts: 1) planning and surface decalcification with citric acid on the coronal quarter of the exposed root corresponding to pocket, and 2) curettage of superficial cementum of the apical three quarters of the exposed root. The interface of the root surface and regenerating connective tissue was observed 2 and 3 weeks after surgery by light and electron microscopy. The apical migration of junctional epithelium was effectively prevented. The fibroblasts synthesized new fibrillar materials and collagen fibrils towards the curetted cementum. The results suggested the possibility that this treatment for periodontally involved teeth would provide ideal root surface conditions for the formation of new fibrous attachment. 相似文献