19 resultados para 1478
Resumo:
Unusual hierarchical stacked superstructures of cubic beta-In2S3 were fabricated via a facile hydrothermal process in the presence of a surfactant cetyltrimethylammonium bromide CTAB; the 3D superstructures were developed by helical propagation of surface steps from microflakes of 10-20 nm thickness.
Resumo:
海面风场系统对天气变化起着至关重要的作用。本文对ERS-2散射计风场数据进行了分析,并将其与NCEP再分析风场和浮标观测风场进行了比较。对连续13年中国海海区ERS-1/2和QuikSCAT散射计海面风场资料进行插值平均处理,得到一个中国海月平均海面风场资料集。首先对该资料集进行了逐月多年平均风场分析,进而对该资料集的距平风场进行矢量经验正交函数(Vector EOF)分解,分别探讨了中国海海面风场的年际和年代际变化特征。年际EOF分解得到的第一模态具有较好的年变化波动周期,与多年平均风场中的冬季风和夏季风(当时间系数为负值时)流型相近,表现为冬-夏振荡型,反映了影响整个中国海的东亚季风强盛时期的风场特征。第二模态与多年平均风场中的季节转换流型相近,表现为春-秋振荡型,反映了冬季风和夏季风之间的转换过渡时期的风场特征。年代际EOF分解得到的第一模态反映了中国海季风的年代际变化特征。第二模态时间系数分布与滞后4个月Nino3.4指数分布相似,反映了中国海海面风场对El Nino的响应。第三模态时间系数分布与南方涛动(SOI)指数分布相似,反映了ENSO现象对中国海海面风场异常的影响。 本文利用一种新的风浪成长关系计算了瞬时风场下的有效波高分布,并利用经验公式计算了风浪充分成长状态下的有效波高分布。分别以NCEP与QuikSCAT的混合风场和NCEP风场为输入,利用第三代海浪数值模式WAVEWATCH Ⅲ对2000年1月东中国海的风浪场进行了模拟,再现了当时的风浪演化过程。通过计算结果与实测的比较,说明将WAVEWATCH Ⅲ模式应用于东中国海海域进行大区域范围的风浪预报是可行的。 最后分析了WAVEWATCH Ⅲ模式计算得到的有效波高的月平均分布,并利用经验正交函数(EOF)方法对有效波高距平值进行分解,探讨了中国海有效波高的年际变化特征。有效波高距平场的前两个模态的时间系数分布和空间结构与海面风距平场的前两个模态基本相似,说明中国海风、浪之间有很好的相关性。第一模态表现为冬-夏振荡型,反映了冬季有效波高的分布特征及海面风场对有效波高分布的影响。第二模态表现为春-秋振荡,反映了季风转换过渡时期有效波高偏差的分布特征。第三模态反映了中国海地形对有效波高偏差分布的影响。
Resumo:
本发明涉及一种水母雪莲毛状根细胞系R0405,其保藏号CGMCC No.1557;本发明的水母雪莲毛状根细胞系能够在无激素培养中自主生长,而且毛状根中的生物碱含量得到提高,可达到干重的2.1%。将有利于离体培养条件下生产目的产物研究,并有助于下一步解决天然雪莲资源匮乏的问题的研究。
Resumo:
As a key issue of ionospheric weather study, systemic studies on ionospheric storms can not only further improve our understanding of the response of the ionosphere to solar and geomagnetic disturbances, but also help us to reveal the chemical, dynamic and electro-dynamic mechanisms during storms. Empirical modelling for regional ionospheric storm is also very useful, because it can provide us with tools and references for the forecasting and further practical application of ionospheric activity. In this thesis, we focus on describing and forecasting of ionospheric storms at middle and low latitudes. The main points of my investigations are listed as follows. (1) By using magnetic storms during the period over 50 years, the dependence of the type, onset time and time delay of the ionospheric storms on magnetic latitude, season and local time at middle and low latitudes in the East-Asian sector are studied. The results show that the occurrences of the types of ionospheric disturbances differ in latitude and season. The onset of the ionospheric storms depends on local time. At middle latitudes, most negative phase onsets are within the local time interval from night to early morning, and they rarely occurred in the local noon and afternoon sectors. At low latitudes, positive phases commence most frequently in the daytime sector as well as pre-midnight sector. The average time delays for both the positive and negative ionospheric storms increase with descending latitudes. The time delay has significant dependence on the local time of main phase onset (MPO). The time delay of positive response is shorter for daytime MPO and longer for night-time MPO, whereas the opposite applies for negative response. (2) Based on some previous researches, a primary empirical model for mid-latitude ionospheric disturbance is set up. By fitting to the observed data, we get a high accuracy with a mean RMSE of only 12-14% in summer and equinox. The model output has been compared with the output of STORM model, and the results show that, our model is much better than STORM in summer and a little better for some mid-latitude stations at equinox. Especially, for the type of two-step geomagnetic storm, our model can present twice descending of foF2 very well. In addition, our model can forecast positive ionospheric storms.