“buffer”的概念、定义、翻译、参考文献-科学参考

buffer

Chemistry

A solution that resists change in pH when small amounts of an acid or alkali are added over a certain range or when the solution is diluted. Acidic buffers consist of a weak acid with a salt of the acid. The salt provides the negative ion A⁻, which is the conjugate base of the acid HA. An example is carbonic acid and sodium hydrogencarbonate. Basic buffers have a weak base and a salt of the base (to provide the conjugate acid). An example is ammonia solution with ammonium chloride.
In an acidic buffer, for example, molecules HA and ions A⁻ are present. When acid is added most of the extra protons are removed by the base:
$A^{-} {+ H}^{+} \to HA$
When base is added, most of the extra hydroxide ions are removed by reaction with undissociated acid:
${OH}^{-} + HA \to A^{-} {+ H}_{2} O$
Thus, the addition of acid or base changes the pH very little. The hydrogen-ion concentration in a buffer is given by the expression
$K_{a} {= [H}^{+} {] = [A}^{-}] / [HA]$
i.e. it depends on the ratio of conjugate base to acid. As this is not altered by dilution, the hydrogen-ion concentration for a buffer does not change much during dilution.
In the laboratory, buffers are used to prepare solutions of known stable pH. Natural buffers occur in living organisms, where the biochemical reactions are very sensitive to change in pH. The main natural buffers are H₂CO₃/HCO₃⁻ and H₂PO₄⁻/HPO₄²⁻. Buffer solutions are also used in medicine (e.g. in intravenous injections), in agriculture, and in many industrial processes (e.g. dyeing, fermentation processes, and the food industry).

Computer

1. A temporary memory for data, normally used to accommodate the difference in the rate at which two devices can handle data during a transfer. The buffer may be built into a peripheral device, such as a printer or disk drive, or may be part of the system’s main memory. See buffering.
2. Any circuit or device that is put between two others to smooth changes in rate or level or allow asynchronous operation. For example, line drivers can be used to isolate (or buffer) two sets of data lines.

Internet

An area of memory where data is stored, either before it is sent into a network to some device such as a printer, or before being read by a computer as part of the processing of the data.

Electronics and Electrical Engineering

An isolating circuit interposed between two circuits to minimize reaction from the output to the input. Usually it has a high input impedance and low output impedance. It may be used to handle a large fan-out or to convert input and output voltage levels.

Biology

A solution that resists change in pH when an acid or alkali is added or when the solution is diluted. Acidic buffers consist of a weak acid with a salt of the acid. The salt provides the negative ion A⁻, which is the conjugate base of the acid HA. An example is carbonic acid and sodium hydrogencarbonate, in which molecules H₂CO₃ and ions HCO₃⁻ are present. When acid is added most of the extra protons are removed by the base:
${HCO}_{3}^{-} + H^{+} \to H_{2} {CO}_{3}$
When base is added, most of the extra hydroxide ions are removed by reaction with undissociated acid:
${OH}^{-} + H_{2} {CO}_{3} \to {HCO}_{3}^{-} {+H}_{2} O$
Thus, the addition of acid or base changes the pH very little. Basic buffers have a weak base and a salt of the base (to provide the conjugate acid).
Natural buffers occur in living organisms, where the biochemical reactions are very sensitive to change in pH (see acid-base balance). The main natural buffers are H₂CO₃/HCO₃⁻ and H₂PO₄⁻/HPO₄²⁻ (see also haemoglobinic acid). Buffer solutions are also used in the laboratory (e.g. to keep microscopical preparations at their original pHs in order to prevent the formation of artefacts), in medicine (e.g. in intravenous injections), in agriculture, and in many industrial processes (e.g. fermentation processes).

单词	buffer
释义	buffer Chemistry A solution that resists change in pH when small amounts of an acid or alkali are added over a certain range or when the solution is diluted. Acidic buffers consist of a weak acid with a salt of the acid. The salt provides the negative ion A⁻, which is the conjugate base of the acid HA. An example is carbonic acid and sodium hydrogencarbonate. Basic buffers have a weak base and a salt of the base (to provide the conjugate acid). An example is ammonia solution with ammonium chloride. In an acidic buffer, for example, molecules HA and ions A⁻ are present. When acid is added most of the extra protons are removed by the base: $A^{-} {+ H}^{+} \to HA$ When base is added, most of the extra hydroxide ions are removed by reaction with undissociated acid: ${OH}^{-} + HA \to A^{-} {+ H}_{2} O$ Thus, the addition of acid or base changes the pH very little. The hydrogen-ion concentration in a buffer is given by the expression $K_{a} {= [H}^{+} {] = [A}^{-}] / [HA]$ i.e. it depends on the ratio of conjugate base to acid. As this is not altered by dilution, the hydrogen-ion concentration for a buffer does not change much during dilution. In the laboratory, buffers are used to prepare solutions of known stable pH. Natural buffers occur in living organisms, where the biochemical reactions are very sensitive to change in pH. The main natural buffers are H₂CO₃/HCO₃⁻ and H₂PO₄⁻/HPO₄²⁻. Buffer solutions are also used in medicine (e.g. in intravenous injections), in agriculture, and in many industrial processes (e.g. dyeing, fermentation processes, and the food industry). Computer 1. A temporary memory for data, normally used to accommodate the difference in the rate at which two devices can handle data during a transfer. The buffer may be built into a peripheral device, such as a printer or disk drive, or may be part of the system’s main memory. See buffering. 2. Any circuit or device that is put between two others to smooth changes in rate or level or allow asynchronous operation. For example, line drivers can be used to isolate (or buffer) two sets of data lines. Internet An area of memory where data is stored, either before it is sent into a network to some device such as a printer, or before being read by a computer as part of the processing of the data. Electronics and Electrical Engineering An isolating circuit interposed between two circuits to minimize reaction from the output to the input. Usually it has a high input impedance and low output impedance. It may be used to handle a large fan-out or to convert input and output voltage levels. Biology A solution that resists change in pH when an acid or alkali is added or when the solution is diluted. Acidic buffers consist of a weak acid with a salt of the acid. The salt provides the negative ion A⁻, which is the conjugate base of the acid HA. An example is carbonic acid and sodium hydrogencarbonate, in which molecules H₂CO₃ and ions HCO₃⁻ are present. When acid is added most of the extra protons are removed by the base: ${HCO}_{3}^{-} + H^{+} \to H_{2} {CO}_{3}$ When base is added, most of the extra hydroxide ions are removed by reaction with undissociated acid: ${OH}^{-} + H_{2} {CO}_{3} \to {HCO}_{3}^{-} {+H}_{2} O$ Thus, the addition of acid or base changes the pH very little. Basic buffers have a weak base and a salt of the base (to provide the conjugate acid). Natural buffers occur in living organisms, where the biochemical reactions are very sensitive to change in pH (see acid-base balance). The main natural buffers are H₂CO₃/HCO₃⁻ and H₂PO₄⁻/HPO₄²⁻ (see also haemoglobinic acid). Buffer solutions are also used in the laboratory (e.g. to keep microscopical preparations at their original pHs in order to prevent the formation of artefacts), in medicine (e.g. in intravenous injections), in agriculture, and in many industrial processes (e.g. fermentation processes).
随便看	LRM LRO LR parsing LRV LSA mode LSB LSD L-section L-series LSI LSR LSS LSST LST L-system LTE L-tectonite LTI LTP LTPD LTR lub Luba lubrication Lucas critique