观察了7 种牧草种子在8 个NaCl浓度:0(0 Mpa),21(-0.1 Mpa),66(-0.3 Mpa),110(-0.5 Mpa),150(-0.70 Mpa),200(-0.9 Mpa),267(-1.2 Mpa),334(-1.95 Mpa),445(-2.603Mpa) m m ol/L下的发芽率及胚根和胚芽的生长,将盐胁迫下未萌发种子移入...观察了7 种牧草种子在8 个NaCl浓度:0(0 Mpa),21(-0.1 Mpa),66(-0.3 Mpa),110(-0.5 Mpa),150(-0.70 Mpa),200(-0.9 Mpa),267(-1.2 Mpa),334(-1.95 Mpa),445(-2.603Mpa) m m ol/L下的发芽率及胚根和胚芽的生长,将盐胁迫下未萌发种子移入营养液中,观测它们在解除盐胁迫后发芽率、胚根和胚芽生长的恢复情况。结果表明,盐胁迫下,随盐浓度的增加,种子的发芽率呈下降趋势,但长穗偃麦草的发芽率几乎不受盐胁迫的影响,总体上它的胚芽和胚根长度随渗透势的降低而减少。21 m m ol/L的盐浓度对不同种的胚芽和胚根有不同的刺激作用。解除盐胁迫后,种子发芽率随原浓度的增加而增加,445 m m ol/L的高浓度对所有种的胚芽和胚根恢复生长最有利。因此,短时间,尤其是高浓度下的盐分锻炼,对种子的发芽及胚根和胚芽的生长有促进作用,但促进的幅度因种而异。生产实践中可用盐锻炼促进种子的发芽率,提高建植效果。展开更多
Dynamic recovery and dynamic recrystallizatin behaviors of AA7005 aluminium alloy (Al - Zn - Mg) during hot compression are investigated by isothermal compression testing.The interdependence of flow stress,stress, s...Dynamic recovery and dynamic recrystallizatin behaviors of AA7005 aluminium alloy (Al - Zn - Mg) during hot compression are investigated by isothermal compression testing.The interdependence of flow stress,stress, strain rate,true strain and deformation temperature for the alloy is analyzed by introduc- ing Zener-Hollomon parameter. A steady - state flow of the 7005 alloy is confirmed to be a thermal- ly activated process.which is governed by rate-controlling mechanisms of dislocations.A hyperbolic sine relationship can satisfactorily correlate temperature, strain rate with flow stress through an Arrhe- nius term that involves thermal activation parameters. The dynamic recovery mechanisms of the alloy are discussed.Cross- slip of jogged screw dislocations is the main dynamic recovery mechanism over the deformation temperatures and strain rates.Subgrains are highly developed in the originally elongat- ed grains.The size of the subgrain increases with decrease of the natural logarithm of Zener- Hol - lomon parameter.Local dynamic recrystallization is operative when the alloy is deformed at temperature of 500℃ and strain rate of 0. 001s - 1.展开更多
文摘观察了7 种牧草种子在8 个NaCl浓度:0(0 Mpa),21(-0.1 Mpa),66(-0.3 Mpa),110(-0.5 Mpa),150(-0.70 Mpa),200(-0.9 Mpa),267(-1.2 Mpa),334(-1.95 Mpa),445(-2.603Mpa) m m ol/L下的发芽率及胚根和胚芽的生长,将盐胁迫下未萌发种子移入营养液中,观测它们在解除盐胁迫后发芽率、胚根和胚芽生长的恢复情况。结果表明,盐胁迫下,随盐浓度的增加,种子的发芽率呈下降趋势,但长穗偃麦草的发芽率几乎不受盐胁迫的影响,总体上它的胚芽和胚根长度随渗透势的降低而减少。21 m m ol/L的盐浓度对不同种的胚芽和胚根有不同的刺激作用。解除盐胁迫后,种子发芽率随原浓度的增加而增加,445 m m ol/L的高浓度对所有种的胚芽和胚根恢复生长最有利。因此,短时间,尤其是高浓度下的盐分锻炼,对种子的发芽及胚根和胚芽的生长有促进作用,但促进的幅度因种而异。生产实践中可用盐锻炼促进种子的发芽率,提高建植效果。
文摘Dynamic recovery and dynamic recrystallizatin behaviors of AA7005 aluminium alloy (Al - Zn - Mg) during hot compression are investigated by isothermal compression testing.The interdependence of flow stress,stress, strain rate,true strain and deformation temperature for the alloy is analyzed by introduc- ing Zener-Hollomon parameter. A steady - state flow of the 7005 alloy is confirmed to be a thermal- ly activated process.which is governed by rate-controlling mechanisms of dislocations.A hyperbolic sine relationship can satisfactorily correlate temperature, strain rate with flow stress through an Arrhe- nius term that involves thermal activation parameters. The dynamic recovery mechanisms of the alloy are discussed.Cross- slip of jogged screw dislocations is the main dynamic recovery mechanism over the deformation temperatures and strain rates.Subgrains are highly developed in the originally elongat- ed grains.The size of the subgrain increases with decrease of the natural logarithm of Zener- Hol - lomon parameter.Local dynamic recrystallization is operative when the alloy is deformed at temperature of 500℃ and strain rate of 0. 001s - 1.
