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11.
In vitro produced bovine embryos were frozen by pellet freezing or vitrification method. In the pellet freezing method, the embryos were cooled on the dry ice and then frozen as pellets. At warming, the pellets were immersed directly into 0.5 M sucrose. The survival rates of blastocysts frozen by the pellet freezing method were higher (P<0.01) in 40% ethylene glycol (EG) than those in the lower concentrations (20 and 30% EG). Higher survival rates of blastocysts frozen by the pellet freezing method were obtained but the development rates did not differ, as compared with those by the vitrification method. There were no significant differences between the pellet freezing and vitrification method in the frequencies of post-thaw survival of hatched blastocysts. These results demonstrate that the pellet freezing method using dry ice can be used successfully for the cryopreservation of blastocysts. 相似文献
12.
Rednikov AY; Zhao Hong; Sadhal SS; Trinh EH 《The Quarterly Journal of Mechanics and Applied Mathematics》2006,59(3):377-397
The steady (acoustic) streaming associated with a sphericaldrop displaced from the velocity antinode of a standing waveis studied. The ratio of the particle size to the acoustic wavelengthis treated as small but non-zero, and the solution is developedin the form of a two-term expansion in terms of the correspondingsmallness parameter. The drop viscosity is assumed to be muchhigher than that of the surrounding fluid, which is the casefor a drop in a gas medium. There are essentially three distinctregions where the steady streaming flow is analysed: insidethe drop (internal circulation), in the Stokes shear-wave layerat the surface on the gas side, and the gas outside the Stokeslayer (the outer streaming region). Solutions for the internalcirculation and the outer streaming are obtained in the limitof small Reynolds number. Despite the gas-to-liquid viscosity ratio being small, the outerstreaming may be dramatically affected by the fact that thesphere is liquid as opposed to solid. The parameter that measuresthe effect of liquidity is essentially the viscosity ratio dividedby the relative (to the particle size) thickness of the Stokeslayer. The case of a solid sphere is recovered by letting thisparameter go to zero. 相似文献
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In this talk we present an overview of accelerator-driven sub-critical reactor systems (ADS), and bring out their attractive
features for the elimination of troublesome long-lived components of the spent fuel, as well as for nuclear energy generation
utilizing thorium as fuel. In India, there is an interest in the programmes of development of high-energy and high-current
accelerators due to the potential of ADS in utilizing the vast resources of thorium in the country for nuclear power generation.
The accelerator related activities planned in this direction will be outlined. 相似文献
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Polarization effects on population transfer by stimulated Raman transition using overlapping time dependent pump and Stokes
laser pulses from the ground X
1Σ
g
/+
(v
g=0, J
g=1) level of H2 to the final X
1Σ
g
/+
(v
f=1, J
f=1) level via the intermediate B
1Σ
u
/+
(v
i=14, J
i=0,2), C
1Π
u
/+
(v
i=3, J
i=2) and C
1Π
u
/−
(v
i=3, J
i=1) levels have been theoretically investigated by applying the density matrix formalism. We have studied in detail the dependence
of the population transfer on time delay between two pulses for the cases of on-resonance excitations considering linear parallel
and same-sense circular polarizations of the fields. The pump and Stokes fields are taken as having Gaussian pulse shapes
with peak intensities I
P
/0
(I
S
/0
)=2 × 106 and 1 × 107 W/cm2. Density matrix equations have been solved for each value of the magnetic quantum number M
g(0, ±1) of the initial ground level taking into account the M
g dependence of the Rabi frequencies. M
g — averaged population transfer to the final level has also been calculated. For resonance excitations to the B(14, 0) or C(3, 1) levels, appreciable population transfer is achieved for intuitive pulse order for some particular values of M
g and M
i (magnetic quantum number of the resonant intermediate level) depending on the nature of polarizations. The calculated values
of M
g — averaged population transfer for the two cases of polarizations show that for on-resonance excitation to the B(14, 0) or the C(3, 1) level, linear parallel polarization of the laser fields yield more transfer efficiency whereas for resonance excitation
to the B(14, 2) level, larger population transfer results from the same-sense circular polarizations. For resonance excitation to
the C(3, 2) level, M
g — averaged population is found to be almost polarization independent. The calculations for the six-level H2 system reveal some interesting features of polarization effects on the population transfer efficiency. 相似文献
19.
20.
We have investigated the superconducting properties of the Bi1.7 Pb0.3Sr2Ca2−xCe
x
Cu3O10+δ system with x=0.00, 0.02, 0.04, 0.08 and 0.1 by X-ray diffraction and magnetic susceptibility. The substitution of Ce for Ca has been found
to drastically change the superconducting properties of the system. X-ray diffraction studies on these compounds indicate
decrease in the c-parameter with increased substitution of Ce at Ca site and volume fraction of high T
c (2 : 2 : 2 : 3) phase decreases and low T
c phase increases. The magnetic susceptibility of this compound shows that the diamagnetic on set superconducting transition
temperature (onset) varies from 109 K to 51 K for x=0.00, 0.02, 0.04, 0.08 and 0.1. These results suggest the possible existence of Ce in a tetravalent state rather than a trivalent
state in this system; that is, Ca2+ → Ce4+ replacement changes the hole carrier concentration. Hole filling is the cause of lowering T
c of the system. 相似文献