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901.
Pitx2 regulates lung asymmetry, cardiac positioning and pituitary and tooth morphogenesis. 总被引:27,自引:0,他引:27
C R Lin C Kioussi S O'Connell P Briata D Szeto F Liu J C Izpisúa-Belmonte M G Rosenfeld 《Nature》1999,401(6750):279-282
902.
Aerodynamics. Insects can halve wind-turbine power. 总被引:1,自引:0,他引:1
903.
Metamorphic core complexes are domal uplifts of metamorphic and plutonic rocks bounded by shear zones that separate them from unmetamorphosed cover rocks. Interpretations of how these features form are varied and controversial, and include models involving extension on low-angle normal faults, plutonic intrusions and flexural rotation of initially high-angle normal faults. The D'Entrecasteaux islands of Papua New Guinea are actively forming metamorphic core complexes located within a continental rift that laterally evolves to sea-floor spreading. The continental rifting is recent (since approximately 6 Myr ago), seismogenic and occurring at a rapid rate ( approximately 25 mm yr-1). Here we present evidence-based on isostatic modelling, geological data and heat-flow measurements-that the D'Entrecasteaux core complexes accommodate extension through the vertical extrusion of ductile lower-crust material, driven by a crustal density inversion. Although buoyant extrusion is accentuated in this region by the geological structure present-which consists of dense ophiolite overlaying less-dense continental crust-this mechanism may be generally applicable to regions where thermal expansion lowers crustal density with depth. 相似文献
904.
Ageing, fitness and neurocognitive function. 总被引:18,自引:0,他引:18
A F Kramer S Hahn N J Cohen M T Banich E McAuley C R Harrison J Chason E Vakil L Bardell R A Boileau A Colcombe 《Nature》1999,400(6743):418-419
905.
D E Humphries G W Wong D S Friend M F Gurish W T Qiu C Huang A H Sharpe R L Stevens 《Nature》1999,400(6746):769-772
906.
Plasmid-related anaerobic autotrophy of the novel archaebacterium Sulfolobus ambivalens 总被引:1,自引:0,他引:1
Three different species of the genus Sulfolobus, S. acidocaldarius, S. solfataricus (= Caldariella) and S. brierleyi, have been distinguished by the conditions required for optimal growth, by the component patterns of their DNA-dependent RNA polymerases and by DNA sequence data. Many isolates of these species are able to grow chemolithoautotrophically using CO2 as the sole carbon source and the oxidation of S(0) with O2 yielding sulphuric acid, as the energy source, though a few others grow only heterotrophically. We show here that a strain of a novel Sulfolobus species, S. ambivalens, is alternatively able to live by an anaerobic mode of chemolithoautotrophy, also using CO2 as the sole carbon source, but using reduction of S(0) with H2, yielding H2S as the energy source. This mode of growth is correlated with the amplification of a plasmid, pSL10. 相似文献
907.
Inositol phosphates and cell signalling 总被引:189,自引:0,他引:189
Inositol 1,4,5-trisphosphate is a second messenger which regulates intracellular calcium both by mobilizing calcium from internal stores and, perhaps indirectly, by stimulating calcium entry. In these actions it may function with its phosphorylated metabolite, inositol 1,3,4,5-tetrakisphosphate. The subtlety of calcium regulation by inositol phosphates is emphasized by recent studies that have revealed oscillations in calcium concentration which are perhaps part of a frequency-encoded second-messenger system. 相似文献
908.
909.
T. Garland Jr A. F. Bennett C. B. Daniels 《Cellular and molecular life sciences : CMLS》1990,46(5):530-533
Summary Locomotor capacities and their physiological bases are thought to be of considerable selective importance in natural populations. Within this functional complex, organismal performance traits (e.g., speed, stamina) are expected to be of more direct selective importance than their suborganismal determinants (e.g., heart size). Quantitative genetics theory predicts that traits of greater selective importance should generally have lower heritabilities at equilibrium. Contrary to these expectations, we report that organismal performance traits had the highest heritabilities in a natural population of garter snakes. 相似文献
910.
F. Carlei J. M. Allen A. E. Bishop S. R. Bloom J. M. Polak 《Cellular and molecular life sciences : CMLS》1985,41(12):1554-1557
Summary Significant quantities of a newly discovered peptide, neuropeptide Y, were found in the rat pancreas, where they were localized to nerves in the exocrine parenchyma and around arterial and ductal structures. Although unaffected by surgical parasympathectomy, the periarterial and periductal nerves were abolished by chemical sympathectomy, suggesting that NPY is partially costored with sympathetic transmitters in nerve fibers. 相似文献