Term 术语 Definition 定义
free wave
自由波
See WAVE.
一种产生作用力停止作用后仍然继续存在的波,与由连续作用力产生和保持的强迫波相反。水面上的自由... more
一种产生作用力停止作用后仍然继续存在的波,与由连续作用力产生和保持的强迫波相反。水面上的自由波是由突然的冲击推力而引发的,此后它仅受摩擦力、水域大小、水介质的扩散特性影响。大多数海洋表面波除潮汐波外均为自由波。参见oscillation(震荡波)。
freezing
NULL
See FROST.
NULL
freezing point
冰点
Temperature of solidification of a liquid in given conditions.
在一定的环境中,液体变成固体所要求的最低限度的温度。
frequency
频率
The number of VIBRATIONS or CYCLES in unit time.
单位时间内的振动次数或者周期数。
frequency: extremely high (EHF)
NULL
See FREQUENCY: RADIO.
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frequency: high (HF)
NULL
See FREQUENCY: RADIO.
NULL
frequency: low (LF)
NULL
See FREQUENCY: RADIO.
NULL
frequency: medium (MF)
NULL
See FREQUENCY: RADIO.
NULL
frequency: natural
固有频率,自然频率
The lowest resonant FREQUENCY of a body or system.
物体或系统的最低谐振频率。
frequency: radio
无线电频率
Any FREQUENCY at which electromagnetic RADIATION of energy is useful for communication. Radio frequencies are usually classed as very low, b... more
Any FREQUENCY at which electromagnetic RADIATION of energy is useful for communication. Radio frequencies are usually classed as very low, below 30 kilohertz; low, 30-300 kilohertz; medium, 300-3,000 kilohertz; high, 3-30 MEGAHERTZ; very high, 30-300 MEGAHERTZ; ultra high, 300-3,000 MEGAHERTZ; super high, 3,000-30,000 MEGAHERTZ; extremely high, 30,000-300,000 MEGAHERTZ.
无线电通信中,电磁波的有效辐射频率。无线电频率通常分为:甚低频(30千赫以内)、低频(30-300千赫)... more
无线电通信中,电磁波的有效辐射频率。无线电频率通常分为:甚低频(30千赫以内)、低频(30-300千赫)、中频(300-3000千赫)、高频(3-30兆赫)、甚高频(30-300兆赫)、特高频(300-3000兆赫)、超高频(3000-30000兆赫)、极高频(30000-300000兆赫)。
frequency: resonant
谐振(共振)频率
Any FREQUENCY at which a body or system vibrates more readily.
物体或系统的固有振动频率。
frequency: super high (SHF)
NULL
See FREQUENCY: RADIO.
NULL
frequency: ultra high (UHF)
NULL
See FREQUENCY: RADIO.
NULL
frequency: very high (VHF)
NULL
See FREQUENCY: RADIO.
NULL
frequency: very low (VLF)
NULL
See FREQUENCY: RADIO.
NULL
frequency band
波段、频带
See BAND OF FREQUENCY.
参见band of frequency(频带)。
frequency channel
频道
See CHANNEL.
频谱中适合某一使用特定发射类别播送的一个连续部分。
frequency modulation
调频
See MODULATION.
对正弦载波的角度调制。调制波的瞬时频率与载波频率的差值,与调制波(幅度)瞬时值成正比。
frequency of soundings
测深密度
See DENSITY OF SOUNDINGS.
参见density of soundings(测深密度)。
freshet
淡水区,暴涨,山洪
An area of compara­tively fresh water at or near the MOUTH of a STREAM flowing into the SEA. A FLOOD or overflowing of a RIVER caused by he... more
An area of compara­tively fresh water at or near the MOUTH of a STREAM flowing into the SEA. A FLOOD or overflowing of a RIVER caused by heavy RAINS or melted SNOW.
位于流入海的河口附近的淡水区。由于大雨或者冰雪融化而引起的洪水或者河水流量过大。