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981.
982.
王昌龄是唐代著名的边塞诗人,他对当时边塞战争的认识经历了一个不断深化的过程,从他的边塞诗中,我们可以清楚地看到其对当时边塞战争的态度。青年时代漫游边关,慷慨激昂,热情讴歌、积极支持保卫边关的战争;深入了解边塞和戍边士卒的现实情况后,他开始厌倦没完没了的开边战争;随着人生阅历的增加,他对边塞战争给人民带来的苦难有了更深的认识,到晚年他更是明确反对穷兵黩武的开边、扩边战争。 相似文献
983.
984.
戴建国 《湖南文理学院学报(自然科学版)》2017,29(2)
为构造最佳对数线性模型,通过λ系数构造λ相关系数矩阵,将其作为对数线性模型中交互项选择的方法,并用于分析肺癌治疗数据。结果表明,选出的交互项可以构造最佳的模型对数据进行准确的分析,因此在应用对数线性模型分析前,先用相关系数矩阵进行探索性研究分析是很有必要的。 相似文献
985.
设计并实现了一个高扩展性、高可用性的数据网格系统RFGrid来处理海量的铁路货运数据.RFGrid提出一个虚拟化数据模型,集成全国各个铁路局所有的数据,提供全局统一的数据视图,支持灵活高效的构件化业务开发模式.RFGrid采用分布处理的模式,将任务分解到各个路局并行执行,所有处理细节对用户透明,降低了分布式数据处理的复杂性,提高了资源利用率.最后,利用真实的货运生产应用作为负载进行性能分析,结果显示RFGrid能显著提升货运数据处理的性能,提高了货运分析的效率,对提高运输组织水平有重要意义. 相似文献
986.
Reactive ion etching was used to etch barium strontium titanate thin films in a CHF3/Ar plasma.BST surfaces before and after etching were analyzed by X-ray photoelectron spectroscopy to investigate the reaction ion etching mechanism,and chemical reactions had occurred between the F plasma and the Ba,Sr and Ti metal species.Fluorides of these metals were formed and remained on the surface during the etching process.Ti was almost completely removed because the TiF4 by-product is volatile.Minor quantities of Ti?F could still be detected by narrow scan X-ray photoelectron spectra,and Ti?F was thought to be present in the form of a metal-oxy-fluoride.These species were investigated from O1s spectra,and a fluoride-rich surface was formed during etching.BaF2 and SrF2 residues were difficult to remove because of their high boiling point.The etching rate was limited to 12.86 nm/min.C?F polymers were not found on the surface,indicating that the removal of BaF2 and SrF2 was important for further etching.A 1-min Ar/15 plasma physical sputtering was carried out for every 4 min of surface etching,which effectively removed remaining surface residue.Sequential chemical reaction and sputtered etching is an effective etching method for barium strontium titanate films. 相似文献
987.
In order to investigate the aggregation mechanism of green macroalgae (Enteromorpha prolifera) on the Qingdao coastline, the macroalgal drift characteristics in the Yellow Sea during June and July in 2008 and 2010 were
simulated using a three-dimensional wave-tide-circulation coupled model. In June 2008, the monthly-mean surface current flowed
onshore and its direction was almost perpendicular to the Qingdao coastline, which was identified as the main reason for a
huge accumulation of algae in the coastal waters off Qingdao. The current became parallel to the coastline in July 2008; this
shift in current direction led to little accumulation of algae near Qingdao and thus relieved the environmental pressure on
the Olympic sailing events. By using the coupled model, we predicted that there would be no serious algal accumulation at
Qingdao in late June 2010, which was later confirmed by observations. This study demonstrated that the drift path of macroalgae
near Qingdao is mainly controlled by the surface current, which is primarily driven by wind. Regional climate change is therefore
one of the means by which physical processes affect marine ecosystems. 相似文献
988.
QiuSheng Dai 《科学通报(英文版)》2011,56(25):2758-2763
The pinhole gamma camera is the basis of the newly developed method of high-resolution pinhole single photon emission computed tomography (SPECT). In this paper, a pinhole gamma camera system was examined using the channel model of information theory. The model pinhole gamma camera was simplified from a noisy, lossy channel to a noiseless, lossless channel by assuming a plane source. An approximate formula of average mutual information for the pinhole gamma camera was then derived from the model. Imaging experiments validated the applicability of the analytic formula. The findings demonstrated that the pinhole gamma camera can be adequately described using the channel model of information theory, and that average mutual information can be considered a figure of merit for the optimizing design of the pinhole gamma camera. 相似文献
989.
Magnetic properties of surface soils across the southern Tarim Basin and their relationship with climate and source materials 总被引:1,自引:0,他引:1
JinBo Zan XiaoMin Fang JunSheng Nie ShengLi Yang ChunHui Song Shuang Dai 《科学通报(英文版)》2011,56(3):290-296
The magnetic susceptibility (χ) of surface soils on the Chinese Loess Plateau (CLP) has strong positive correlation with mean annual precipitation.It is widely accepted that ultrafine magnetite/maghemite grains produced during pedogenesis are responsible for the enhancement of χ,and loess χ on the CLP has been widely used as a proxy for the intensity of the East Asian summer monsoon.However,few works have investigated mechanisms for the enhancement of χ in the case of surface aeolian sediments in westerly-dominated inland China,north of the Tibetan Plateau.Here detailed rock magnetism and grain size studies of 49 surface samples taken across the southern Tarim Basin for different rainfall/temperature/altitude conditions are presented.The results show that samples taken from desert have the lowest χ values and that χ of loessic sand and loess samples decreases with increasing altitude.In addition,the rock magnetism studies suggest that the magnetic properties of surface soils across the southern Tarim Basin are mainly controlled by the concentration of coarse aeolian ferrimagnetic minerals.The contribution of ultrafine pedogenically produced magnetic grains to χ is very limited. 相似文献
990.