排序方式： 共有11条查询结果，搜索用时 15 毫秒
1.
The reproduction characteristics of 343 sows in six different breeding groups were analyzed to estimate the crossbreeding parameters. The results indicated that the ovulation rate and the weights of uterus and ovary are mainly determined by the additive genetic effects while the nonadditive genetic effects play an important role in embryonal traits and litter performance. The heterosis effects in the first litter are larger than those in the second litter because of heterosis x environment interaction. The results also showed the existence of a highly significant maternal heterosis effect on the fertility traits of sows. 相似文献
2.
The production of elastase by Bacillus sp. EL31410 at various temperatures was investigated. In order to study the effect of temperature on elastase fermentation, different cultivation temperatures, ranging from 39 ℃ to 28 ℃, were evaluated in shake flask. The result indicated that 37 ℃ was best for cell growth at earlier stage; while maximum elastase activity was obtained when the cells were cultivated at 30 ℃. This result was verified by batch fermentation in 5-L bio-reactor under 37 ℃ and 30 ℃ temperature, respectively. The specific cell growth rate at 37 ℃ was higher than that at 30 ℃ during earlier stage of cultivation. The maximum value [5.5 U/(h-g DCW)] of elastase formation rate occurred at 24 h at 30 ℃ compared to 4.6 U/(h-g DCW) at 30 h at 37 ℃. Based on these results, two-stage temperature shift strategy and oscillatory temperature cultivation mode were evaluated in the next study. When compared to single temperature of 37 ℃ or 30 ℃, both two-stage temperature shift strategy and os 相似文献
3.
嗜热酶的稳定机制和稳定策略的研究进展 总被引：1，自引：0，他引：1
来源于嗜热菌的嗜热酶具有热稳定性和嗜热性。嗜热酶与对应的中温酶序列具有高度的序列同源性、高度相似的三级结构和催化机制。在简单总结了嗜热酶的生化和分子特性后,本文重点讨论了嗜热酶稳定的分子机制和提高蛋白质稳定性的策略。嗜热酶稳定的分子机制包括:氨基酸组成特性、蛋白质分子内的作用力、蛋白质构型的影响、锚定N末端和C末端、环的缩短和固定、翻译后修饰。提高蛋白质热稳定性的策略包括:蛋白质工程策略(序列一致概念、理性设计、定向进化、多肽链延伸和计算模型)、化学修饰法、添加保护剂提高酶的稳定性。 相似文献
5.
6.
ＩＮＴＲＯＤＵＣＴＩＯＮＤＮＡｆｉｎｇｅｒｐｒｉｎｔｉｎｇｉｓａｍｅｔｈｏｄｆｏｒｐｒｏｄｕｃｉｎｇｔｈｅＤＮＡｆｒａｇｍｅｎｔｂａｎｄｐａｔｔｅｒｎ ,ｓｐｅｃｉｆｉｃｆｏｒｔｈｅｇｅｎｏｍｅｏｆａｃｅｒｔａｉｎｉｎｄｉｖｉｄｕａｌ.Ｔｈｅｐｒｏｄｕｃｔｉｏｎｏｆｔｈｅｉｎｄｉｖｉｄｕａｌｓｐｅｃｉｆｉｃｂａｎｄｐａｔｔｅｒｎｉｓｂａｓｅｄｏｎｔｈｅｓｉｍｕｌｔａｎｅｏｕｓｄｅｔｅｃｔｉｏｎｏｆｓｅｖｅｒａｌｈｉｇｈｌｙｐｏｌｙｍｏｒｐｈｉｃ,ｒｅｐｅｔｉｔｉｖｅｇｅｎｏｍｉｃｒｅｇｉｏｎｓ,ｗｈ… 相似文献
7.
INTRODUCTION Butyric acid has several potential applications in industry. Its applications in the foodstuffs and beverage industries are widespread. It may be used as the pure acid in the dairy industry, or in the form of esters as a food additive to increase fruit fragrance. Furthermore, butyric acid could also have some important physiological functions. For example, butyric acid esters are the character-impact flavors in tropic fruits and dairy products (Centeno et al., 2002; Watson e… 相似文献
8.
阮晖 《全国优秀作文选(高中)》1997,(3)
生活也许是最富有敏感性的,岁月的流逝犹如梦,时光决不会再倒流,人生中的某一瞬间也永远不会再现,一切都显得匆匆忙忙。我们应该怎样做呢?追随时代的脚步,挑起历史的重负,去开创新的生活。曾经听人说过:“一切都是建立在人自强不息的本身的基础上的。”只要我们不丧失进取心和自信心,努力进取,便能不丧失永恒性的一瞬间。 相似文献
9.
The production of elastase by Bacillus sp. EL31410 at various temperatures was investigated. In order to study the effect of temperature on elastase fermentation, different cultivation temperatures, ranging from 39 ℃ to 28 ℃, were evaluated in shake flask. The result indicated that 37 ℃ was best for cell growth at earlier stage; while maximum elastase activity was obtained when the cells were cultivated at 30 ℃. This result was verified by batch fermentation in 5-L bioreactor under 37 ℃ and 30 ℃ temperature, respectively. The specific cell growth rate at 37 ℃ was higher than that at 30 ℃ latory temperature cultivation mode were evaluated in the next study. When compared to single temperature of 37 ℃ or 30 ℃, both two-stage temperature shift strategy and oscillatory temperature strategy improved biomass but did not yield the same result as expected for elastase production. The maximum biomass (both 8.6 g/L) was achieved at 30 h at 37 ℃, but at 42 h using two-stage temperature cultivation strategy. The highest elastase production (652 U/ml) was observed at 30 ℃ in batch process. It was concluded that cultivation at constant temperature of 30 ℃ was appropriate for elastase production by Bacillus sp. EL31410. 相似文献
10.
羽毛的生物降解及其酶学性质的研究 总被引：1，自引：0，他引：1
羽毛角蛋白是一种环境污染有机废弃物,通过微生物对角蛋的进行降解为合理利用,可以使它成为丰富的饲料蛋白来源。适当的降解方法对于羽毛资源的转化有着重要作用。采用正交设计优化地衣芽孢杆菌细胞转化羽毛的条件,得出角蛋白酶的合成和羽毛的分解指标,三因子最合适配比为:液料比20:1,反应pH 7.5,BC细胞加量0.5克,40℃下120 r/min处理72 h,其中细胞加量对羽毛分解有关键影响。粗酶液最适温度在37℃,在35℃~40℃有很好的热稳定性。不同pH下酶活变化明显,在pH 5-8范围内比较稳定。 相似文献