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李思忠 《河南师范大学学报(哲学社会科学版)》1985,(3)
一、黄鳝Monopterus albus(zuiew)的地理分布黄鳝同黄鱓、黄(鱼旦)。又简名鳝鱼或鱓鱼。山、陕亦名蛇鱼。两千多年前的山海经内就有“灌河之水其中多(鱼旦)”的记载。是我国人民习见和喜食的淡水鱼类之一。但迄今其地理分布尚无专文研究。不少文献称黄鳝分布于我国各处,或称除西北、西南外我国各处均产;但事实远非如此。据笔者研究在我国仅见于辽河下游;沿滦河向上约略过承德(海拔375.2米)、滦平(534.7米);沿海河水系分布于太行山东侧平原地带;沿黄河向上约 相似文献
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Projectile made of carbon fiber composite material shell and metal warhead penetrates concrete target at speeds of 336 m/s, 447 m/s and 517 m/s. The angles between the perpendicular of target surface and projectile axis are 0° and 30° . The thickness of concrete target is 200 mm and the compression strength is 30 MPa. The experimental results indicate that the strength of composite material structure is high. Composite projectile can go through concrete target without fiber segregation and breakage. The percent fill is 18.5% in the composite material projectile. It is about twice as that of metal projectile, if the density of metal is taken as 7.8 g/cm^3. Comparing with metal projectile, low-density, high-strength composite material can lessen projectile weight, improve charge-weight ratio of detonator and enhance destructive powder. 相似文献
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近日,竹溪县南部山区乡镇教师交通费定额补助纳人今年的县财政预算。这标志着从2012年起,该县南部9个乡镇的809名教师,每年可享受总计63.72万元的交通费定额补助。 相似文献
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