| 释义 |
pico-, prefix|ˈpiːkəʊ, ˈpaɪkəʊ|
[f. Sp. pico beak, peak, (in phrases) little bit.]
Prefixed to the names of units to form the names of units 1012 times smaller, i.e. one million-millionth part of them (symbol p), as picoamp (so picoammeter), pico-curie, pico-farad, pico-gramme, pico-litre, pico-volt (so pico-voltmeter), pico-watt. Also picosecond.
1915W. H. Eccles Wireless Telegr. 18 Symbols for multiples and sub-multiples{ddd}10-12{ddd}Pico-{ddd}p or µµ. 1947Compt. Rend. de la 14me Conf. (Union Internat. de Chimie) 115 The following prefixes to abbreviations for the names of units should be used to indicate the specified multiples or sub-multiples of these units:..p pico- 10-12×. 1952Wireless World Jan. 19/2 The suggestions to adopt new prefixes, ‘nano’ and ‘pico’ for small capacitance values, would permit any value to be expressed as a whole number. 1952[see nano-].
1975Physics Bull. Feb. 67/1 A range of stabilized high voltage power supplies and picoammeters manufactured by V G Electronics Ltd will also be shown. Ibid. June 249/2 (Advt.), Sensitivities down to 1 microvolt, 10 picoamps, and 1 milliohm are founded on Keithley's lifetime of expertise in designing and building low-level instrumentation.
1963Times 15 Feb. 8/1 The level of 150 picocuries over a three-month period is considered by scientists to be the tolerable limit for humanity. 1976Globe & Mail (Toronto) 16 Jan. 1/3 The readings in 30 of these, however, are less than three picocuries of radon for each litre of air, the exposure level that Government standards allow the public. For workers in atomic plants, the standard is 30 picocuries a litre.
1926Gloss. Terms Electr. Engin. (Brit. Engin. Stand. Assoc.) 26 Picofarad, a unit of electrostatic capacity equal to 10-12 farad. Symbol: µµF. 1945Electronic Engin. XVII. 473/2 At a working frequency of ½ Mc/s., a difference of about 1/10 picofarad can be readily observed. 1976Gramophone Jan. 1283/1 A slight platform rise of up to about 2 dB from 12 kHz upwards was measured which I take to be a result of the Dual's low capacitance cable, whereas Shure recommend 400 to 500 pico-farads per channel.
1951Picogram [see nanogramme s.v. nano-]. 1967Oceanogr. & Marine Biol. V. 271 If carbon content is compared with the surface area of [plankton] cells, the range of variation is smaller, 0·11 to 0·66 picograms/µ2. 1975Williams & Wilson Biologist's Guide to Princ. & Techniques Pract. Biochem. iii. 72 It has very high sensitivity and can detect as little as one picogramme of these compounds.
1973Sci. Amer. Sept. 160/2 (Advt.), For electron probe sampling, hundreds of picoliter fluid droplets are positioned automatically under an electron beam.
1971Physics Bull. Nov. 678/2 The picovolt measuring system permits the detection of small voltages from sources at low temperatures which would be overwhelmed by thermal voltages in the leads to a room temperature instrument. Ibid. 678/3 The picovoltmeter will be useful for the measurement of low temperatures by means of thermocouples.
1967D. H. Hamsher Communication Syst. Engin. Handbk. xvi. 10 The noise power measurement without any weighting of the frequency response of the instrument is expressed usually in picowatts (10-12 watt = pw). 1977Sci. Amer. Feb. 62/2 At the earth station the 30-metre dish antenna collects a scant three picowatts of energy and feeds it into a low-noise receiver. |