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71.
Marcelo Samuel Berman 《Astrophysics and Space Science》2007,311(4):359-361
Pathria (1972) has shown, for a pressureless closed Universe, that it is inside a black (or white) hole. We show now, that the Universe
with a cosmic pressure obeying Einstein’s field equations, can be inside a white-hole. In the closed case, a positive cosmological
constant does the job; for the flat and open cases, the condition we find is not verified for the very early Universe, but
with the growth of the scale-factor, the condition will be certainly fulfilled for a positive cosmological constant, after
some time. We associate the absolute temperature of the Universe, with the temperature of the corresponding white-hole. 相似文献
72.
73.
D. O'Donoghue 《Astrophysics and Space Science》1995,230(1-2):63-74
An overview of the observational and theoretical study of white dwarf pulsators is given. Particular attention is drawn to the contributions of South African-based workers. 相似文献
74.
本文主要论述了覆盖区进行125万多目标区域地球化学调查的特点及其基本工作方法技术,并从我省覆盖区区域地球化学调查工作的现状出发,提出下步工作的设想. 相似文献
75.
A. C. Moore 《Australian Journal of Earth Sciences》2013,60(3):243-258
The orthopyroxenes of Gosse Pile, a layered ultramafic sequence within the Giles Complex of central Australia, show unusual exsolution features such as the development of ‘hour‐glass’ shapes by clinopyroxene lamellae, and also the exsolution of spinel and rutile. Both orthopyroxene and clinopyroxene have high R2O3 contents and their distribution coefficients for Mg and Fe are high (average KD = 0.88). Some, if not all, of these features are considered to indicate that the Gosse Pile rocks crystallized under high pressure. This interpretation also explains the predominance of orthopyroxene over olivine as an early cumulus phase. Estimated conditions during crystallization are 10–14 kilobars and between 1,200‐l,400°C. 相似文献
76.
Do Young Oh 《Urban geography》2013,34(7):1066-1068
In this study, we use a Geographic Information System-based index to measure spatial accessibility of public high schools. The index is applied to the Baton Rouge Metropolitan Statistical Area in 1990, 2000, and 2010. Overall, urban areas had consistently worse accessibility scores compared with suburban and rural areas. High schools with more African American students tended to have poorer accessibility levels. Schools with lower accessibility tended to be associated with poorer average student performance, and the effect strengthened between 2000 and 2010. In developing a better understanding of the accessibility of public high schools, this paper reaffirms the significance of space, place, and race, and challenges the notion of declining relevance of accessibility in Louisiana public education policymaking. 相似文献
77.
The results of modeling for M2 surface and internal tides in the White Sea are discussed. These results are obtained for the case when shore-fast and drifting ice covers are present concurrently. It is assumed that the interface between ice covers is of non-tidal origin (i.e., it is pre-assigned) and that ice rheology is viscous-elastic, representative of the low temperatures typical of winter conditions. Emphasis is placed on tidal energetics and, in particular, on the averaged (over a tidal cycle) values of the density and the dissipation rate of barotropic/baroclinic tidal energy. It is shown that in the White Sea, unlike in other marginal seas, the averaged (over a tidal cycle) and depth-integrated density of baroclinic tidal energy for the combined ice cover is much less than the same defined density of barotropic tidal energy. Similarly, the averaged and integrated (over the volume of the White Sea) rate of baroclinic tidal energy dissipation is much less than the same defined rate of barotropic tidal energy dissipation. The latter, in turn, is greater than for the shore-fast ice cover, but is smaller than for the drifting ice cover. 相似文献
78.
79.
综合考虑酶混合液处理时间和初始细胞密度两个因素,选取终浓度为4%半纤维素酶和2%崩溃酶的酶混合液对一株海洋经济微藻——微拟球藻(Nannochloropsis oculata)进行原生质体的制备与再生,Calcofluor White染料染色可在荧光显微镜下观察到完整的原生质体细胞。实验结果表明:同一初始密度藻细胞酶处理1~3 h制备率较高;酶处理相同时间较高初始密度(2×107~3×107cells/mL)的藻细胞制备率较高,并且原生质体在再生培养基上可再生,生长趋势与野生型细胞一致。考虑到酶处理时间过长或者密度过大会对原生质体的再生产生影响,本实验选择最适酶处理时间为1h,初始细胞密度为2×107cells/mL。 相似文献
80.
In this work the potential of live and active Phanerochaete chryosporium, a white rot fungi, to remove lower Cr(VI) concentration from aqueous solutions was reported for the first time. A medium pH had significant effect on the growth of the fungus and bioremoval of Cr(VI). Substrate inhibition on the growth of Phanerochaete chrysosporium was evident beyond 20 g L?1 of dextrose concentration. A maximum biomass concentration of 15.64 g L?1 was obtained for an initial dextrose concentration of 20 g L?1 in metal free medium at pH 6.0. An increase in Cr(VI) concentration beyond 10 mg L?1 inhibited the growth of the fungi, thereby, reducing the chromium bioremoval efficiency. A maximum reduction efficiency of 98.92% was reported for an initial metal concentration of 10 mg L?1. A mathematical expression for the bioreduction of Cr(VI) considering the organic compounds in the cells was proposed. 相似文献