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31.
32.
Ferdinand Bohlmann Elena Tsankova Jasmin Jakupovic Robert M. King Harold Robinson 《Phytochemistry》1983,22(2):557-560
The investigation of Encelia canescens afforded, in addition to several known compounds, four new dimeric p-hydroxyacetophenone derivatives, two epimeric chromene dimers and two epimeric mixed dimers of euparin and encecalin. Furthermore, derivatives of tremetone and of encecalin were present. The structures were elucidated hy high field 1H NMR spectroscopy. 相似文献
33.
Surface sediment diatoms from the east coast of Lake Tanganyika were analysed using ordination and classification techniques, and compared with assemblages previously described from the northern part of the lake. Grain-size analyses were performed on subsamples. Four groups of diatom assemblages were recognised. The first group clusters samples taken in the north, far from the Rusizi river mouth. The second group comprises samples taken on silty sediment along the Tanzanian coast, including one sample taken near the mouth of the Malagarazi river and those from the northernmost part of the lake. The third group comprises surface sediments along the Burundian coast (near Ramba and Magara), and the fourth is characterised by epipsammic taxa. A sample taken near the central arm of the Malagarazi river is included in the latter group. The impact of small rivers on the diatom assemblages in the surface sediments is restricted to the mouth area. 相似文献
34.
Jonathan Porter Joan Robinson Roger Pickup Clive Edwards 《FEMS microbiology letters》1995,133(1-2):195-199
Abstract The effectiveness of immunofluorescence flow cytometry and cell sorting to detect, quantify and separate indigenous bacterial populations present in low concentrations in sewage outflow was investigated. Preparatory experiments for targeted recovery revealed indigenous, immunoglobulin-G-binding particles present at low levels in sewage outflow samples taken from Coniston Water. Fluorescence-activated cell sorting of this population was employed to enrich for these particles, which were confirmed as bacterial cells. This cell population comprised approximately 23% of the total plate count on MacConkey agar before cell sorting, rising to approximately 95% after sorting. These results corresponded to cell densities of less than 5% of the total plate count on R2A agar. Taxonomic tests suggested the bacterium to be Ochrobactrum anthropi . 相似文献
35.
The blue and the black wildebeest, Connochaetes taurinus and C. gnou, are currently classified as congeneric, but previous reports have placed C. taurinus in its own genus, Gorgon. To further clarify the evolutionary relationship between these two species, we examined and compared their mitotic chromosomes and mitochondrial DNA (mtDNA). No species-specific G-banded or C-banded chromosomal markers were found, and we conclude that the karyotypes are invariant at the level of resolution obtained. An evolutionary divergence time of approximately 1 million years was calculated from mtDNA restriction fragment data, indicating a close phylogenetic relationship for the two wildebeest species. The low nucleotide diversity detected within the black wildebeest (0.09%) is thought to reflect the recent population bottleneck to which the species has been subjected. In contrast, the limited heterogeneity (0.02%) within the South African blue wildebeest herds sampled in this study was surprising, and we argue that for many populations, especially those on smaller reserves, this may reflect common descent from a small number of animals through management-controlled translocations. 相似文献
36.
Joong Kyu Kim Mark Klinger Jonathan Benjamin Yuanyuan Xiao David J. Erle Dan R. Littman Nigel Killeen 《PloS one》2009,4(8)
Signaling through the T cell antigen receptor (TCR) is important for the homeostasis of naïve and memory CD4+ T cells. The significance of TCR signaling in regulatory T (Treg) cells has not been systematically addressed. Using an Ox40-cre allele that is prominently expressed in Treg cells, and a conditional null allele of the gene encoding p56Lck, we have examined the importance of TCR signaling in Treg cells. Inactivation of p56Lck resulted in abnormal Treg homeostasis characterized by impaired turnover, preferential redistribution to the lymph nodes, loss of suppressive function, and striking changes in gene expression. Abnormal Treg cell homeostasis and function did not reflect the involvement of p56Lck in CD4 function because these effects were not observed when CD4 expression was inactivated by Ox40-cre.The results make clear multiple aspects of Treg cell homeostasis and phenotype that are dependent on a sustained capacity to signal through the TCR. 相似文献
37.
Jan Suchá?ek Petr Sed’a Václav Friedrich Renata Wachowiak-Smolíková Mark P. Wachowiak 《PloS one》2016,11(11)
Media, and particularly TV media, have a great impact on the general public. In recent years, spatial patterns of information and the relevance of intangible geographies have become increasingly important. Gatekeeping plays a critical role in the selection of information that is transformed into media. Therefore, gatekeeping, through national media, also co-forms the generation of mental maps. In this paper, correspondence analysis (a statistical method) combined with cloud lines (a new visual analytics technique) is used to analyze how individual major regional events in one of the post-communist countries, the Czech Republic, penetrate into the media on a national scale. Although national news should minimize distortions about regions, this assumption has not been verified by our research. Impressions presented by the media of selected regions that were markedly influenced by one or several events in those regions demonstrate that gatekeepers, especially news reporters, functioned as a filter by selecting only a few specific, and in many cases, unusual events for dissemination. 相似文献
38.
Household‐level correlates of children's physical activity levels in and across 12 countries
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Deirdre M. Harrington Fiona Gillison Stephanie T. Broyles Jean‐Philippe Chaput Mikael Fogelholm Gang Hu Rebecca Kuriyan Anura Kurpad Allana G. LeBlanc Carol Maher Jose Maia Victor Matsudo Timothy Olds Vincent Onywera Olga L. Sarmiento Martyn Standage Mark S. Tremblay Catrine Tudor‐Locke Pei Zhao Peter T. Katzmarzyk for the ISCOLE Research Group 《Obesity (Silver Spring, Md.)》2016,24(10):2150-2157
39.
Hydroacoustic data indicate that the benthic red crab Pleuroncodesplanipes(Stimpson, 1860) rises from the bottom towards the surfaceat dusk from very compacted patches settled on the continentalshelf. The behaviour is fast and abrupt, lasting >60 min. 相似文献
40.