Impacts of Overgrazing and Reclamation on Soil Resources in Rangeland Ecosystems in Huailai Basin, Hebei, China

The soil constituents and relations between the variation of soil resources and plant communities in three adjacent sites representing the overgrazing, reclamation and comparatively undisturbed communities respectively were quantified and examined in study area in Huailal Basin, Hebei Province, China. There have been significantly greater constituent of C, N, P in the soilsof shrubland site. Corg, Ntotal, Navail and Pavail were between 1.18 and 3.90 times more concentrated in the soils of shrubland site in comparison with the other two sites. Although the Ptotal concentration was lower in shrubland soils than inovergrazed rangeland soils, the Parval concentration, however, was significantly greater in the soils of shrubland site, and increased by 59. 1% and even 289.6% in the soils of shrubland site comparing to those in the soils of rangeland and millet field sites. Among the three sites, CV exceeding 40% werefound for SO4 , Cl, and F ion. The CV of organic carbon also exceeded 40% but only in the soils of millet field site. The highest CV were found for F, SO4 ion in the soils of shrubland and overgrazed rangeland sites, while for Cl and SO4 ion in those of millet field site. The results also showed that the introductions of shrubs are of vital importance for the accumulation of soil nutrients and maintenance of soil fertilities, and also for the restoration and reconstruction of desertified ecosystems.     

相干式CO_2激光雷达角跟踪系统

本文简述了相干式ＣＯ２激光雷达角跟踪系统的工作原理，讨论了激光雷达距离方程，分析了四象限探测器跟踪方法及误差特性。对于扩展朗伯目标，可采用边沿跟踪。为了提高信噪比，用频率搜索及窄带滤波的方法来检测信号，文中给出了接收机方框图和实验结果，本文还讨论了通道不一致性影响及校正方法。     

噻吩乙胺的合成

噻吩经甲酰化后与硝基甲烷缩合经乙硼烷还原得到噻吩乙胺，总收率达到７０．４％．     

串联系统的可靠性下限评估方法研究

本文针对小子样可靠性统计试验的特点，指出经典可靠性点估计和极大似然区间估计的不足。然后着重介绍了Ｂｕｅｈｌｅｒ精确置信下限评定方法以及ＭＭＬ方法、Ｌｉｎｄｓｔｒｏｍ－Ｍａｄ－ｄｅｎ方法、熵方法、似然比方法、贝叶斯方法等常用的可靠性评定方法及其特点。最后以具体数字实例将文中介绍的近似方法与精确评定方法进行比较，得出较好的适合于小子样无失效情况的核武器可靠性评估方法。本文“挑选”出来的可靠性评定方法还需作更进一步的研究。     

The Importance of Developing Cross-cultural Pragmatic Competence

本文着重分析了跨文化交际的重要性，指出了文化背景知识在交际中的重要作用，从而提出了在外语教学中不仅应注意提高学生准确掌握语言的能力，还应把提高学生的跨文化语用能力放到一个重要位置。     

超宽带雷达频带分割滤波器设计

在分析超宽带雷达频带分割滤波器对于系统性能影响的基础上，提出了基于最小频域方差准则的数字滤波器设计新方法，与经典的Daubechies滤波器相比，采用这种方法设计的滤波器具有较小的频域方差和过渡带，更适合于频带分割滤波器的设计，设计结果证明了该设计方法的有效性。     

无人机载脉冲雷达主杂波抑制的一种方法

本文提出了一种在τ－ｆｄ平面内抑制无人机载毫米波脉冲雷达主杂波的方法，并对其基本原理进行了详细的论述，同时给出了计算机的仿真结果。仿真结果证明了该方法的正确性和可行性。     

The complete mitochondrial DNA sequence and the phylogenetic position of Achalinus meiguensis (Reptilia: Squamata)

The mitochondrial genome complete sequence of Achalinus meiguensis was reported for the first time in the present study. The complete mitochondrial genome of A. meiguensis is 17239 bp in length and contains 13 protein-coding genes, 22 tRNA, 2 rRNA, and 2 non-coding regions (Control regions). On the basis of comparison with the other complete mitochondrial sequences reported, we explored the characteristic of structure and evolution. For example, duplication control regions independently occurred in the evol...     

云计算应用于远程教育的探讨

远程教育有电视媒体和通过Internet两种教学模式,存在资源重复建设、系统扩充能力弱等问题。而云计算可以把所有的远程教育系统集合成一个远程教育"云"系统,该系统应用虚拟化技术,提高了资源的利用率,解决远程教育容量大、空间大、受众面广、共享性强的问题,使远程教育的管理高效便捷。文中介绍了利用云计算在远程教育应该为所有类型资源提供的一个共有的基本功能,同时讨论了云计算远程教育系统的逻辑结构、整体结构设计、核心模块设计等问题。     

吕梁山区五台群顶部地层的Sm-Nd年龄——兼论岩浆源区地幔的特殊性

本文根据Sm-Nd同位素工作结果,给出五台群的顶界年龄为2470Ma,属太古代地层。华北地台基底的太古代地层中几处出现世界上同时代的其它构造单元中尚未发现过的高∈~Nd(T)值,表明当时地幔的局部不均匀性已很可观。岩石的既往亏损史与Nd相对富集的情况相矛盾,可能是由于深部地幔去气流体的补入或形成时间不长的地壳物质的混染。