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411.
高速铁路是复杂的巨系统。京津城际铁路是我国首条工程实践、运营实践的高速铁路,在攻克系统设计与系统集成、轨道高平顺与高稳定、高速列车安全与舒适、运行(营)控制可靠与高效四大方面科技难题和关键技术取得了重大创新成果;历时3年建造,开通运营验证,整体达到世界领先水平;该成果对推进我国铁路网又好又快地建设具有指导性、示范性的重大作用。  相似文献   
412.
《庄子》"谬悠之说,荒唐之言,无端崖之辞,时恣纵而不傥,不以见之也"的独特风格的形成原因,是一种以"虚构"和"幻想"组成的"虚幻"思维。通过深入探析这一思维的结构内核,我们可以发现其对当下的本土奇幻小说的影响。  相似文献   
413.
TiO2-based nanosheets (TiNSs), TiO2-based nanotubes (TiNTs) were prepared by hydrothermal processing, and polyurethane foams with TiO2 nanopowders (P25), TiNSs and TiNTs were synthesized by free-rising foaming method. The Fourier-transform infrared (FT-IR) spectra show that the addition of titanium dioxide does not affect the chemical structure of polyurethane foam. However, microscope observations show that PU/TiNSs composite foams have more uniform cells and the average aperture smaller than that of pure poly-urethane foams. According to the results of thermal analysis, the PU/TiNSs composite foams have better thermal stability, the temperature of decompostion occurring with a maximum weight loss rate is about 30 ℃ higher than that of pure PU foams. The decompostion temperatures are 167 ℃ and 148 ℃ for the PU/P25 composite foams and the PU/TiNTs composite foams respectively, which are lower than that of pure PU foams. Moreover, with the addition of the fillers, the sound absorption property also has changed; the addition of TiNSs improved the sound absorbing property efficiently. The better thermal stability and sound absorption of PU/TiNSs composite foams are mainly due to the uniform cells diffuse and smaller aperture.  相似文献   
414.
关于水利工程钢筋混凝土施工技术的探讨   总被引:1,自引:0,他引:1  
水工混凝土建筑物因所受水荷载及温度变化等条件的不利影响,建成后往往带病运行,运行后又有一个老化过程,因此需要精心地检查、维护和修理才能保证其安全运行。否则,一定期限后就会发生严重事故,许多预防老化病害的措施,在规划设计和施工阶段就应认真考虑并实施。笔者就钢筋混凝土施工中的技术工作进行了探讨。  相似文献   
415.
416.
利用平面分层介质中电磁场Green函数的解析形式,求解位于复杂分层介质结构中的原子电四极自发辐射速率.考虑一特例,结果表明与特殊介质结构中由电磁场模式求解的电四极子衰减速率相同.  相似文献   
417.
检察权监督制约机制分为内部监督制约机制和外部监督制约机制,我国现行内部监督制约机制发挥了巨大作用,但也存在着诸多不足。因此,构建合理的检察权内部监督制约机制,在司法实践中强化其内部监督制约机制作用十分必要。  相似文献   
418.
Pollen assemblages of 53 surface pollen samples from farmlands and wastelands in Northeast China were analyzed. Tree pollen percentages were usually higher than 30%, with Pinus (26.9%), Quercus (0.9%), Betula (0.9%) and Populus (0.7%) as the major types, and herb pollen percentages were usually higher than 50%, with weedy Poaceae (8.7%), Chenopodiaceae (7.1%), Artemisia (1.9%) and Compositae (3.5%) as the major taxa. Thus, the pollen assemblages were consistent with the regional vegetation compositions. However, there were differences in pollen assemblages among regions, especially among different geomorphological units. For example, in the mountains, there were more types of tree pollen and higher total percentages (average 42%) than in other areas, while cereal pollen percentages were lowest (11.2%). In the hills and high plains, herbs made up more than 60% of the pollens, with cereals (average 53.6%) the dominant type. In the low plains, pollen types were similar to those in the hills and high plains, but total pollen concentrations and the proportion of Concentricystes were much higher, while cereal pollen percentages were slightly lower (average 41.6%). Pollen assemblages in different land use types also differed. For example, in farmland, cereal pollen percentages were more than 40% and Chenopodiaceae was usually less than 2.5%, while in wasteland, weedy Poaceae was usually less than 10% and Chenopodiaceae was usually higher than 25%. Total pollen concentrations in farmland (average 3909 grains/g) were much lower than in wasteland (average 15074 grains/g). Redundancy analysis revealed that pollen assemblages were significantly negatively correlated with mean annual temperature (-0.73) and July mean temperature (-0.81) and significantly positively correlated with mean annual precipitation (0.48), indicating that pollen assemblages in the artificial or human-disturbed vegetation reflect regional climate well. Comparison of pollen assemblages in different areas of northern China showed that pollen concentrations reflect the intensities of human impact to some degree. For example, pollen concentrations decrease as human impacts increase in intensity. The cereal pollen proportions in farmland differed by area. In Northeast China, cereal pollen proportions were distinctly higher than in most other areas of northern China, suggesting differences in planting habits and climate.  相似文献   
419.
运用问卷调查法和数理统计法,对宁夏大学校园体育文化节的发展与认知进行了分析,提出了校园体育文化节的各项评价指标,推动了宁夏大学校园体育文化节的发展,为以后更好地开展这项活动提供了理论依据.  相似文献   
420.
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