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Chunming Shi Valerie Masson-Delmotte Valerie Daux Zongshan Li Qi-Bin Zhang 《Dendrochronologia》2010,28(4):225-237
Two new Juniper tree-ring-width (TRW) chronologies spanning more than 500 years were developed in the Yellow River source area, North Eastern Qinghai-Tibetan Plateau (NE-QTP). For the two studied sites, located approximately 50 km apart, split correlation and coherence analysis reveal unstable tree-growth responses to local moisture availability. While significant correlations are obtained with April–June local precipitation, Palmer Drought Severity Index (PDSI) and river flow from 1948/1954 to 1998 and from 1948/1954 to 1970s, these correlations vanish for the time period 1970s-1998. The local instrumental climate data (precipitation, PDSI and river flow) exhibit opposite correlations with large scale modes of variability (El Niño Southern Oscillation, ENSO, and Pacific Decadal Oscillation, PDO) before and after the 1977 PDO shift. One tree-ring chronology is coherent and anti-phased with instrumental ENSO/PDO indices at 5.2-year frequency. On the longer time span, this TRW chronology is compared with PDO reconstructed from historical Chinese data. This comparison also exhibits unstable multi-decadal relationships, notably in the mid 19th century. Altogether, the comparison between our two chronologies, local instrumental climate records, and ENSO/PDO indices suggest a cautious use of local TRW records for paleoclimate reconstructions. Further studies are needed to explore both the spatial coherency of tree-ring records and the temporal stability of their response to local and large scale climate variability. 相似文献
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The crystal and molecular structure of (20R)-20-phenyl-5-pregnene-3β, 20-diol hemihydrate has been determined by X-ray analysis in order to establish the configuration and conformation at C(20). Interest in this compound was stimulated by its high affinity inhibitory binding to cytochrome P-450SCC, the enzyme which catalyzes the biosynthesis of pregnenolone(3β-hydroxy-5-pregnen-20-one) from cholesterol. The results of the analysis suggest a possible conformation for the cholesterol side chain in the enzyme complex. 相似文献
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Daux V Lécuyer C Héran MA Amiot R Simon L Fourel F Martineau F Lynnerup N Reychler H Escarguel G 《Journal of human evolution》2008,55(6):1138-1147
The oxygen isotope composition of human phosphatic tissues (δ18OP) has great potential for reconstructing climate and population migration, but this technique has not been applied to early human evolution. To facilitate this application we analyzed δ18OP values of modern human teeth collected at 12 sites located at latitudes ranging from 4°N to 70°N together with the corresponding oxygen composition of tap waters (δ18OW) from these areas. In addition, the δ18O of some raw and boiled foods were determined and simple mass balance calculations were performed to investigate the impact of solid food consumption on the oxygen isotope composition of the total ingested water (drinking water + solid food water). The results, along with those from three, smaller published data sets, can be considered as random estimates of a unique δ18OW/δ18OP linear relationship: δ18OW = 1.54(±0.09) × δ18OP−33.72(±1.51) (R2 = 0.87: p [H0:R2 = 0] = 2 × 10−19). The δ18O of cooked food is higher than that of the drinking water. As a consequence, in a modern diet the δ18O of ingested water is +1.05 to 1.2‰ higher than that of drinking water in the area. In meat-dominated and cereal-free diets, which may have been the diets of some of our early ancestors, the shift is a little higher and the application of the regression equation would slightly overestimate δ18OW in these cases. 相似文献
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Pletnev V. Z. Goryacheva E. A. Tsygannik I. N. Nesmeyanov V. A. Pletnev S. V. Pangborn W. Daux W. 《Russian Journal of Bioorganic Chemistry》2004,30(5):417-420
The three-dimensional structure of the antigen-binding fragment of a monoclonal antibody to human interleukin-2 in a new crystal form (space group P212121; unit cell parameters: a = 42.82 Å, b = 90.68 Å, and c = 139.82 Å) was determined by the X-ray molecular replacement method at the resolution of 2.7 Å. The protein folding and the stereochemistry of its antigen-binding site were comparatively analyzed. 相似文献
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Pletnev VZ Goriacheva EA Tsygannik IN Nesmeianov VA Pletnev SV Pangborn W Daux W 《Bioorganicheskaia khimiia》2004,30(5):466-469
The three-dimensional structure of the antigen-binding fragment of a monoclonal antibody to human interleukin-2 in a new crystal form (space group P2(1)2(1)2(1); unit cell parameters: a = 42.82, b = 90.68, and c = 139.82 A) was determined by the X-ray molecular replacement method at the resolution of 2.7 A. The protein folding and the stereochemistry of its antigen-binding site were comparatively analyzed. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2004, vol. 30, no. 5; see also http: // www.maik.ru. 相似文献
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