N-type oxide gas sensor,N型氧化物气敏元件

nuclear electric quadrupole moment resonance spectroscopy,核四极共振波谱法

Nuclear Instrument Module (NIM),核仪器模块

nuclear magnetic double resonance,核磁双共振（法）

nuclear magnetic resonance magnetometer,核磁共振磁强计

nuclear magnetic resonance spectroscopy;NMR spectroscopy,核磁共振波谱法

nuclear radiation thickness meter,核辐射厚度计

(nuclear)radiation transducer [sensor],（核）辐射式传感器

nuclei counter,计核器

nude source,裸式离子源

null measurement,指零测量

null method,零位法

null method of measurement,零位测量法；指零测量法；零差测量法

null reading method,零读法

number of degrees of freedom,自由度数

number of effective plate,有效板数

number of theoretical plate,理论板数

numeric key,数字键

numerical aperture (NA),数值孔径

numerical control,数值控制

numerical value (of a quantity),（量的）数值

nutating disc flowmeter,（章动）圆盘流量计

nutating flowmeter,章动流量计

nutrients,营养盐

nutrients analyzer for seawater,海水营养盐分析器

Nyquist plot,奈奎斯特图

object language,目标语言

object plane,物面

object program,目标程序

object wave,物体声束

objective evidence,客观证据

objective lens of the scanning electron microscope,扫描电子显微镜物镜

objective lens of the transmission electron microscope,透射电子显微镜物镜

oblique visibility,斜能见度

observability,可观测性；能观测性

observation and recording device,观察和记录装置

ocean bottom seismograph,海底地震仪

ocean date station,浮标站

oceanographic geological instrument,海洋地质仪器

oceanographic instrumentation,海洋仪器

oceanographic measuring system,海洋测量系统

oceanographic observation,海洋观测

oceanographic survey,海洋调查

octave,倍频程

octave(bandwidth)filter,倍频程（宽带）滤波器

octave filter set,倍频程滤波器组

odd-even check,奇偶校验

off-axis response,离轴响应

off-line,离线

off-line processing,离线处理；脱机处理

off-line system simulation,离线系统仿真

office automation (OA),办公自动化

office automation system (OAS),办公自动化系统

office information system (OIS),办公信息系统

officially recognized standard,官方认可标准

offset,静差

offset coefficient,静差系数

oil-filled enclosure (Ex o),充油外壳（Ex o）

oil-water meter,原油水分仪

omegatron mass spectrometer,回旋质谱计

omnidirectional microphone,全向传声器

on-cold column injector,冷柱头进样器

one-dimensional location,线定位；一维空间定位

on-line,在线

on-line assistence,在线帮助

on-line measurement and frequency spectrum analysis,在线测量频谱分析

on-line process gas chromatograph,在线过程气相色谱仪

on-line processing,在线处理；联机处理

on-line real-time processing,在线实时处理

on-line real-time system,联机实时系统

on-line system simulation,在线系统仿真

on-off action,通断作用

on-off controller,通断控制器

one-man atmospheric submersible,常人常压潜水器

one-third octave filter,1/3倍频程滤波器

one-turm time of output shaft,输出轴每转时间

one-way communication,单向通信

open-circuit intermediate voltage,开路中间电压

open front case with pressure relief,带泄压装置的前开式外壳

open front case without pressure relief,无泄压装置的前开式外壳

(open hole) caliper,井径仪

open-jet wind tunnel,开口式风洞

open loop,开环

open loop control,开环控制

open loop control system,开环控制系统

open loop electronic balance,开环式电子天平

open-loop frequency response,开环频率响应

open-loop gain,开环增益

open-loop gain characteristic,开环增益特性

open loop pole,开环极点

open loop process control,开环过程控制

open loop remote control system,开环遥测控制系统

open loop stabilization,开环稳定

open loop transfer function,开环传递函数

open loop voltage gain,开环电压增益

open loop zero,开环零点

open source,裸式离子源

open system,开放系统；开环系统