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61.
A benzoquinone and flavonoids from Cyperus alopecuroides 总被引:1,自引:0,他引:1
Nassar MI Abdel-Razik AF El-Khrisy Eel-D Dawidar AA Bystrom A Mabry TJ 《Phytochemistry》2002,60(4):385-387
A benzoquinone, named alopecuquinone, was isolated from the ethanol extract of the inflorescences of Cyperus alopecuroides. Its structure was primarily elucidated by spectroscopic analysis including 1H, 13C NMR, APT, HMQC, 1H-1H COSY and CIMS. The known flavonoids, vicenin 2, orientin, diosmetin, quercetin 3,3'-dimethyl ether and its 3,4'-dimethyl ether, were also isolated and characterized. The ethanol extract of the plant material showed moderate estrogenic activity using a strain of Saccharomyces cerevisiae. 相似文献
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Nassar R 《Genetics》1979,91(2):327-338
Results of fitness estimates for the Lap locus in Drosophila melanogaster revealed that under crowded media conditions gene frequency equilibrium was maintained by frequency-dependent selection. Evidence was obtained that indicated that mating and egg-to-adult viability were frequency dependent. 相似文献
64.
A. Y. Nassar S. E. Megalla H. M. Abd El-Fattah A. H. Hafez T. S. El-Deap 《Mycopathologia》1982,79(1):35-38
The aflatoxins B1, G1 and their metabolites exist in the systemic blood as protein conjugate. This conjugation is specific to plasma albumin and proceeds enzymatically by liver and kidney cells. The aflatoxin-albumin conjugate is permanent and the conjugation is an irreversible one. This may interpret the acute liver damage of animal ingested a single dose of aflatoxin (3, 4). The existence of bound aflatoxin-albumin in the systematic blood could be considered as one factor of low excretions of aflatoxins and their metabolites in urine (5, 6, 7). 相似文献
65.
Laurie Fajardo Valois Gonzlez Jafet M. Nassar Pablo Lacabana Carlos A. Portillo Q. Fabin Carrasquel Jon Paul Rodríguez 《Biotropica》2005,37(4):531-546
Tropical dry forests are located predominantly in the northern portion of Venezuela, above 6°N. Although their potential extent covers ca 400,000 km2 (44% of the land), they currently occupy about 10 percent of this area. The diversity and complexity of Venezuelan dry forests increases from north to south along a gradient of decreasing severity of the dry season. A typical dry forest in Venezuela presents ca 110–170 species of plants from ca 40 to 50 families within an area of approximately 10 ha. Species composition and forest structure, however, are dependent on local landscape conditions (e.g., soil type, topography), and nearby forest types can be very different. Our analysis of five dry forest variants showed a maximum family similarity of 67 percent, although most values fell in the 50–60 percent interval. They are currently considered as one of Venezuela's most threatened ecosystems, but only 5 percent of extant dry forests are included in protected areas; this represents 0.5 percent of their potential extent. It is fundamental to promote the creation of at least 3 or 4 more large protected areas (ca 5000 ha), with different climatic and orographic characteristics, in combination with the recovery of threatened species, the restoration of degraded systems, and the implementation of sustainable development projects. Their apparent high resilience suggests that with the proper management we can restore and maintain the integrity of Venezuelan dry forests. 相似文献
66.
A major unanswered question concerning "pain" circuitry is the extent to which different populations of primary afferent nociceptor engage the same or different ascending pathways. In the present study, we followed the transneuronal transport of a genetically expressed lectin tracer, wheat germ agglutinin, in Na(V)1.8-expressing nociceptors of the nonpeptide class. We found that interneurons of lamina II are at the origin of the major ascending circuits targeted by the nonpeptide nociceptors. These interneurons contact lamina V projection neurons, which in turn predominantly target fourth-order neurons in the amygdala, hypothalamus, bed nucleus of the stria terminalis, and to a remarkable extent, the globus pallidus. These circuits differ greatly from the lamina I-based projection that is targeted by the peptide class of nociceptors. Our results indicate that parallel, perhaps independent pain pathways arise from different nociceptor classes and that motor as well as limbic targets predominate in the circuits that originate from the nonpeptide population. 相似文献
67.
Re-examination of the chemical constituents of the leaves of Ferula sinaica afforded a new eudesmanolide and a new carotane. The structures were elucidated by spectroscopic methods. 相似文献
68.
M.A. El-Gendi S.H. Nassar M. Toppozada F. Abdel-Raheem 《Prostaglandins & other lipid mediators》1982,24(1):97-104
The pharmacotherapeutic effects of prostaglandin E2 (PGE2) and 15 (S) 15-methyl PGF2α given by different routes of administration, were studied in 20 normal persons and 100 patients with chronic schistosomal bladder ulcer in comparison to normal saline and antimony dimercaptosuccinate drug. Prostaglandins produced a rapid significant amelioration in the ulcer symptom complex with a good percentage of ulcer disappearance on cystoscopy, while the antimony dimercaptosuccinate treated group showed a less early response which improved with follow up. This was in contrast to prostaglandins which showed relapse in the symptom-complex in some cases after a follow up period of 2 months. The combined use of schistosomicidal drugs together with, or followed by, prostaglandins might give better results. 相似文献
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