排序方式: 共有207条查询结果,搜索用时 31 毫秒
141.
分析了教育能否实现产业化以及教育产业化是否会导致教育不公平和丧失教育的公益性等问题。指出了高等教育产业化的必要性 ,并提出了如何规范和促进教育产业化发展的一些观点。 相似文献
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Shu-jie Liu Bi-dong Wu Jia-ni Xie Zhi-min Li Chong-wei An Jing-yu Wang Xiao-dong Li 《防务技术》2021,17(5):1775-1781
Insensitive energetic materials are promising in the defense weapons field. However, energetic materials still suffer from great challenges and the concern about their safety limits their utilization. In this work, insensitive energetic explosive 3,3′-diamino-4,4′-azoxyfurazan/hexahydro-1,3,5-trinitro-1,3,5-triazine (DAAF/RDX) microspheres were fabricated by self-assembly method. Rod-like DAAF/RDX was prepared by mechanical ball milling for comparison. DAAF/RDX composites with different mass ratios (90:10, 80:20, and 70:30) were obtained. The morphologies and structures of as-obtained DAAF/RDX composites were characterized by scanning electron microscopy (SEM), powder x-ray diffraction (PXRD) and fourier transform infrared spectroscopy (FT-IR). The results showed that DAAF/RDX microspheres exhibited regular shaped microspheres with sizes from 0.5 to 1.2 μm. There was no crystal transition during the modification process. The thermal properties of as-obtained materials were then evaluated by differential scanning calorimetry (DSC) and materials studio software. DAAF/RDX microspheres showed an advanced decomposition peak temperature compared with rod-like DAAF/RDX. The binding energy and peak temperature values at zero βi (TP0) of DAAF/RDX (90:10) increased by 36.77 kJ/mol, 1.6 °C, and 58.11 kJ/mol, 12.3 °C compared to DAAF/RDX (80:20) and DAAF/RDX (70:30), indicating the better thermal stability of DAAF/RDX (90:10). The characteristic drop height (H50) of DAAF/RDX (higher than 100 cm) composites was higher than that of raw RDX (25 cm), suggesting significant improvements in mechanical safety. The preparation of DAAF/RDX microspheres is promising for the desensitization of RDX and useful for the formation of other materials and future wide applications. 相似文献
143.
Yue Yang Xiao-dong Li Yan-tao Sun Jian-an Tian Hui-min Liu Bi-dong Wu Jing-yu Wang 《防务技术》2021,17(2):650-656
Hexagonal boron nitride nanosheets(HBNNSs)have huge potential in the field of coating materials owing to their remarkable chemical stability,mechanical strength and thermal conductivity.Thin-layer hBNNSs were obtained by a liquid-phase exfoliation of h-BN powders and incorporated into EVA coatings for improving the safety performance of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX).HBNNSs and ethylene-vinyl acetate copolymer(EVA)were introduced to HMX by a solvent-slurry process.For com-parison,the HMX/EVA and HMX/EVA/graphene(HMX/EVA/G)composites were also prepared by a similar process.The morphology,crystal form,surface element distribution,thermal decomposition property and impact sensitivity of HMX/EVA/hBNNSs composites were contrastively investigated.Results showed that as prepared HMX/EVA/hBNNSs composites were well coated with hBNNSs and EVA,and exhibited better thermal stability and lower impact sensitivity than that of HMX/EVA and HMX/EVA/G composites,suggesting superior performance of desensitization of hBNNSs in explosives. 相似文献
144.
相关干扰是目前研究的对抗联合战术信息分发系统(JTIDS)比较有效的干扰样式,文中主要针对相关干扰对JTIDS接收机的干扰效果问题进行了深入研究。在建立了AGWN信道中相关干扰下JTIDS接收机模型的基础上,推导了接收机输出误比特率公式,并通过仿真和分析,得到了不同信噪比条件下接收机的最佳检测门限值以及误比特率与干信比的关系曲线,最后研究了干扰频偏对干扰效果的影响。研究表明,相关干扰对JTIDS接收机有着良好的干扰效果,并且对干扰频偏敏感。 相似文献
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中介语理论及其在英语翻译教学中的应用 总被引:1,自引:0,他引:1
成年外语学习者在学习第二语言过程中的各个方面都会受到其母语的影响,并且会彤成一种既不同于其母语、又不同于目标语的一种被称为“中介语”的特殊的暂时语言形式。中介语不可避免地会影响到翻译教学,教师在教学过程中应该充分注意中介语的影响,并积极利用中介语理论以促进英语教学。本文将运用中介语在外语学习特别是翻译过程中的影响,分析有关翻译谬误并提供一些可能的解决办法。 相似文献
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舰船的舷角是鱼雷攻击时的重要参数,同时也是海航避碰中避碰线路确定的计算依据。在基于视觉的识别中,获取目标舰船的舷角即可确定其相对拍摄视角,从而大大缩小在全方位视野特征库中的搜索范围,提高识别速度。然而现有的舷角测量方法均是采用连续跟踪解算实现的,无法实时测量。为解决实时测量的问题,首先推导了基于视觉的目标舰船舷角测量原理,然后针对摄像机倾斜的情况提出基于水天线校正的改进方法,最后通过实验验证,结果表明方法简单易操作、实时性好。 相似文献
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研究以色列区域导弹防御系统的发展动因、进展、影响与趋势,重点分析了以色列近程、中程、远程导弹防御系统的技术和能力,探讨了以色列区域导弹防御系统的影响及发展趋势。 相似文献
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