26 resultados para Mier y Terán, Luis, d. 1894
em Chinese Academy of Sciences Institutional Repositories Grid Portal
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Strain energy density expressions are obtained from a field model that can qualitatively exhibit how the electrical and mechanical disturbances would affect the crack growth behavior in ferroelectric ceramics. Simplification is achieved by considering only three material constants to account for elastic, piezoelectric and dielectric effects. Cross interaction of electric field (or displacement) with mechanical stress (or strain) is identified with the piezoelectric effect; it occurs only when the pole is aligned normal to the crack. Switching of the pole axis by 90degrees and 180degrees is examined for possible connection with domain switching. Opposing crack growth behavior can be obtained when the specification of mechanical stress sigma(infinity) and electric field E-infinity or (sigma(infinity), E-infinity) is replaced by strain e and electric displacement D-infinity or (epsilon(infinity), D-infinity). Mixed conditions (sigma(infinity),D-infinity) and (epsilon(infinity),E-infinity) are also considered. In general, crack growth is found to be larger when compared to that without the application of electric disturbances. This includes both the electric field and displacement. For the eight possible boundary conditions, crack growth retardation is identified only with (E-y(infinity),sigma(y)(infinity)) for negative E-y(infinity) and (D-y(infinity), epsilon(y)(infinity)) for positive D-y(infinity) while the mechanical conditions sigma(y)(infinity) or epsilon(y)infinity are not changed. Suitable combinations of the elastic, piezoelectric and dielectric material constants could also be made to suppress crack growth. (C) 2002 Published by Elsevier Science Ltd.
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1 13;(Ephedra likiangensis)(E. fedtschenkoae);(E. regeliana)(E. glauca)(E. sinica)(E. distachya)Ephedra rituensis Y. Yang, D. Z. Fu et G. Zhu 2 3 4I(Ephedra intermedia);II(E. equisetina);III(E. rhytidosperma);IV3(E. minuta)(E. gerardiana)(E. saxatilis) 4 (Ephedra przewalskii)54 5 6 7 2 Ephedra archaeorhytidosperma Y. Yang, B. Y. Geng et D. L. Dilcher et Z. D. Chen212morphological stasis Alloephedra xingxueii J. R. Tao et Y. Yang22 8 87
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Tulipa L.401501644/5 1)18328Tulipa sect. Amanasect. Orithyiasect. Eriostemonessect. Leiostemonessect. TulipanumLloydiasect. Amana2-3-4sect. AmanaAmana Honda 2)Amana kuocangshanica D.Y. Tan et D. Y. HongA. erythronioides A. anhuiensis2/30.640.08 cm 3164 419Amana4 15 516Amana;12 6166Fritillaria typeDrusa typeTulipa iliensis typeTulipa tetraphylla type Adoxa typeEriostemones typeTulipa iliensis typeTulipa iliensisT. heterophyllaT. heteropetala3 7212nrDNA ITScpDNA trnL-F sect. Orithyiasect. Tulipanumsect. Eriostemonessect. Leiostemones
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Phylogeographical analyses on Sinocyclocheilus grahami samples from seven localities within the Lake Dianchi Basin in China were conducted to explore the main factors shaping population structure within this species. Phylogenetic and network analyses reve
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It has been demonstrated that growth hormone (GH) transgenic fish often posses a trait for fast growth. Here, we investigated the growth of F-4 'all-fish' GH transgenic carp Cyprinus carpio and their serum GH levels for a year. The results showed that F-4 all-fish GH transgenic carp were significantly larger in body mass (c. two-fold, P < 0 center dot 001) and body length (c. 1 center dot 3 fold, P < 0 center dot 001), compared with the non-transgenic group. The discrepancy of serum GH levels between the transgenic carp group and control group is 54 fold, when the water temperature was 12-34 degrees C. When the water temperature decreased to 3 center dot 5 degrees C in January, the discrepancy was 256 fold. The serum GH level of the transgenic group was relatively constant, while that of control varied greatly based on month and water temperature. The changes of growth rates between the transgenic group and the control group were similar for a year. Taken together, the results indicated that F-4 all-fish GH transgenic carp had not only higher and constant serum GH levels but also a significant fast-growing effect, compared with the control. To our knowledge, this is the first report on a one-year investigation of growth trait and serum growth hormone level in F-4 all-fish GH transgenic carp.
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An incubation experiment was performed on Potamogeton crispus (P. crispus) using sediment collected from Lake Tangxunhu in the center of China, in order to determine the effects of plant growth on Fe, Si, Cu, Zn, Mn, Mg, P, and Ca concentrations in the sediments and overlying waters. After 3 months of incubation, Ca, Mg, and Si concentrations in the water column were significantly lower, and P and Cu concentrations were significantly higher than in unplanted controls. The effect of P. crispus growth on sediment pore waters and water-extractable elements varied. Concentrations of Ca, Mg, Si, Fe, Cu, and Zn were significantly higher, and P was significantly lower, than in pore waters of the control. Water-extracted concentrations of Fe, Mg, and Si in the sediments were lower, and P was higher, than in the control. Presence of P. crispus generally enhanced concentration gradients of elements between pore waters and overlying waters but not for P. The growth of P. crispus was associated with an increase in water pH and formation of root plaques, resulting in complex effects on the sediment nutritional status.
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IEECAS SKLLQG
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