铁营养状况及不同形态氮素对玉米体内不同铁库铁再利用的影响

采用分根技术、营养液培养方法 ,研究缺铁条件下供应不同形态氮素对玉米苗期体内不同铁库中铁再利用的影响。结果表明 ,缺铁条件下 ,玉米新生叶片铁营养状况不仅受体内铁库强度大小的影响 ,而且也受外界调节措施—氮素形态的调节。研究发现 ,与NO3-N相比 ,不考虑根细胞质外体铁库时 ,供应NH4-N可使初生叶中 32 %的铁再利用 ,考虑根系铁库时 ,初生叶铁变化不明显 ,而可使根系 40 %的铁转移至地上部。无论根系是否有铁库 ,缺铁条件下 ,NH4-N能提高新叶活性铁含量和伤流液中铁浓度。

铁对玉米体内氮代谢的影响

本文用营养液培养方法研究了铁对玉米体内氮代谢的影响。结果表明，铁对玉米体内氮代谢有较大的影响。在尚未对植株生物量产生明显影响的条件下，供铁已显著提高了玉米新叶中全铁和全氮含量，并显著提高了玉米新叶的叶绿素含量。进一步的研究结果表明，缺铁抑制了蛋白质的合成，缺铁条件下，玉米新叶中蛋白质含量下降，而游离氨基酸大量累积，并导致了硝酸还原酶的活性下降。

国际市场生铁货缺价扬

最近国际市场生铁价格有上扬趋势,部分地区的价格涨幅已超过废铁的涨幅。各大市场中生铁供应最紧张的是远东, 目前仅中国内地有定期供货,离岸价已超过150美元/吨,大多数货品都发往韩国。据称韩国、日本。

生龙育凤的八连

“八连刘勇考取北京大学啦!”、“八连刘勇考取北京大学啦!”。 日历翻回到1990年8月20日。刘勇考取北大,像一枚原子弹爆炸,震动了一八二三团,震动了北屯地区附近团场。

Evaluation between Two Brazilian Railway Tracks

Most of Brazilian railways were built more than 100 years ago. Some of them were submitted to rebuilding processes while others were just overloaded by additional layers of ballast. Nowadays, Brazil is going through a new railway transport impulse in relation to the increase of load, despite of the necessary supply capacity. For this reason, there were developed evaluations from some Brazilian railways in order to determine their operational conditions. This work shows a comparative analysis of results from two parts of studied old railway, aiming to determine minimum features to enable them to accept higher load axis. One of these studied old railway parts did not have a sub-ballast layer in contrast to the other one. The strains and stresses of these old railway track parts were generated by the same locomotive.