(netweight)净重NA-cement低碱水泥nacre珍珠母,珍珠层,珍珠质nailconcrete可钉混凝土naildrawer拔钉钳nailhammer钉锤nakedwire裸线nameplate铭牌nanoammeter毫微安计nanocurie毫微居里nanograde毫微级nanogram毫微克,纤克nanometer毫微米(10-9m)NanyoCementWorks日本南阳水泥厂narrow(railway)track窄轨(运输线)narrow-gaugetrack窄轨(运输线)naturalaggregate天然集料naturalaircooling自然空气冷却naturalcement天然水泥naturalconservation自然资源保护naturaldraftventilation自然通风naturalfrequencyconveyor摇臂式输送机naturalgas天然气naturalpumice天然浮石naturalrefractory天然耐火材料naturalventilation自然通风natural-vibrationfrequency固有振动频率navvypick挖土镐NDT(non-destructivetest)非破坏性试验neatcementpaste水泥净浆neatpaste(水泥)净浆neatPortlandcement纯硅酸盐水泥neckbearing中间轴承,辊筒轴承,颈轴承needle(roller)bearing滚针轴承needlegate棒闸,针开闸门needlevalve针阀negativeallowance(尺寸的)负公差negativemoment负弯矩negativepressure负压nephelinite霞岩neptunicrock水成岩,沉积岩nestofsieves套筛netfilt