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排序方式: 共有116条查询结果,搜索用时 156 毫秒
111.
Shravani Basu Sean Mayes Michael Davey Jeremy A. Roberts Sayed N. Azam-Ali Richard Mithen Remy S. Pasquet 《Euphytica》2007,157(1-2):59-68
Controlled crosses in bambara groundnut were attempted between a range of thirty-six bambara groundnut landraces (thirty domesticated
(V. subterranea var. subterranea) and six wild (V. subterranea var. spontanea)). Ten F1 seed were produced. Of these, eight germinated producing F2 populations. On seed set, four populations could be unambiguously confirmed as true crosses by F3 seed coat colour. A single F2 population, derived from a domesticated landrace from Botswana (DipC; female parent) crossed with a wild accession collected
in Cameroon (VSSP11; male parent) was used to study a range of agronomic and domestication traits. These included; days to
emergence, days to flowering, internode (fourth) length at harvest, number of stems per plant, leaf area, Specific Leaf Area
(SLA), Carbon Isotope Discrimination (CID), 100 seed weight, testa colour and eye pattern around the hilum. On the basis of variation for internode length and stems
per plant, 14 small F3 families were selected and grown under field conditions to further investigate the genetic basis of the ‘spreading’ versus
‘bunched’ plant character, a major difference between wild and cultivated bambara groundnut. Results presented suggest that
traits including leaf area, SLA, CID and 100 seed weight are controlled by several genes. In contrast, the variation for traits
such as internode length, stems per plant, days to emergence and seed eye pattern around the hilum are likely to be under
largely monogenic control. The results of this work are discussed in relation to the domestication of bambara groundnut. 相似文献
112.
The initial ratios of neodymium-143 to neodymium-144 in kimberlites ranging in age between 90 x 10(6) to 1300 x 10(6) years from South Africa, India, and the United States are different from the corresponding ratios in the minerals of peridotite inclusions in the kimberlites but are identical to the ratios in the basaltic achondrite Juvinas at the times of emplacement of the respective kimberlite pipes. This correlation between the kimberlites and Juvinas, which represents the bulk chondritic earth in rare-earth elements, strongly indicates that the kimberlite's source in the mantle is chondritic in rare-earth elements and relatively primeval in composition. 相似文献
113.
Multiple chondritic meteorite fragments have been found in two sedimentary rock samples from an end-Permian bed at Graphite Peak in Antarctica. The Ni/Fe, Co/Ni, and P/Fe ratios in metal grains; the Fe/Mg and Mn/Fe ratios in olivine and pyroxene; and the chemistry of Fe-, Ni-, P-, and S-bearing oxide in the meteorite fragments are typical of CM-type chondritic meteorites. In one sample, the meteoritic fragments are accompanied by more abundant discrete metal grains, which are also found in an end-Permian bed at Meishan, southern China. We discuss the implications of this finding for a suggested global impact event at the Permian-Triassic boundary. 相似文献
114.
Basu AR Poreda RJ Renne PR Teichmann F Vasiliev YR Sobolev NV Turrin BD 《Science (New York, N.Y.)》1995,269(5225):822-825
An olivine nephelinite from the lower part of a thick alkalic ultrabasic and mafic sequence of volcanic rocks of the northeastern part of the Siberian flood basalt province (SFBP) yielded a (40)Ar/(39)Ar plateau age of 253.3 +/- 2.6 million years, distinctly older than the main tholeiitic pulse of the SFBP at 250.0 million years. Olivine phenocrysts of this rock showed (3)He/(4)He ratios up to 12.7 times the atmospheric ratio; these values suggest a lower mantle plume origin. The neodymium and strontium isotopes, rare earth element concentration patterns, and cerium/lead ratios of the associated rocks were also consistent with their derivation from a near-chondritic, primitive plume. Geochemical data from the 250-million-year-old volcanic rocks higher up in the sequence indicate interaction of this high-(3)He SFBP plume with a suboceanic-type upper mantle beneath Siberia. 相似文献
115.
A Mukhopadhyay G Chaudhuri S K Arora S Sehgal S K Basu 《Science (New York, N.Y.)》1989,244(4905):705-707
Methotrexate coupled to maleylated bovine serum albumin was taken up efficiently through the "scavenger" receptors present on macrophages and led to selective killing of intracellular Leishmania mexicana amazonensis amastigotes in cultured hamster peritoneal macrophages. The drug conjugate was nearly 100 times as effective as free methotrexate in eliminating the intracellular parasites. Furthermore, in a model of experimental cutaneous leishmaniasis in hamsters, the drug conjugate brought about more than 90% reduction in the size of footpad lesions within 11 days. In contrast, the free drug at a similar concentration did not significantly affect lesion size. These studies demonstrate the potential of receptor-mediated drug delivery in the therapy of macrophage-associated diseases. 相似文献
116.
This study was exclusively conducted to evaluate healing of surgically created defects on the radius of adult Black Bengal goat after implantation of porous bioglass blocks and compare the process kinetics with normal healing. Twelve Black Bengal goats were divided randomly into two groups: control and experimental group implanted with bioglass blocks. Unicortical bone defects in radius were generated in all animals under aseptic condition. Local inflammatory reaction and healing of wound, radiological investigations, histological studies, oxytetracycline leveling and angiographic studies were performed up to 90th day post-operatively and compared with normal healing. It has been found that extensive new bone formation originating from host bone towards the implant whereas in control, the process was active from both the ends; the defect site appeared as homogenous nonfluorescent area. Thus, porous bioglass promoted bone formation over the entire extension of the defect independent of size of block in comparison to control group. 相似文献