home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
The Epic Interactive Encyclopedia 1998
/
Epic Interactive Encyclopedia, The - 1998 Edition (1998)(Epic Marketing).iso
/
B
/
Base
/
INFOTEXT
< prev
Wrap
Text File
|
1992-09-03
|
2KB
|
64 lines
1. (also known as alkali) in chemistry, a
substance that reacts with an acid to give a
salt. Inorganic bases are usually oxides or
hydroxides of metals, which react with dilute
acids to form a salt and water. Many
carbonates also react with dilute acids,
additionally giving off carbon dioxide. A
more general definition of a base is a
compound that combines with protons (hydrogen
ions), such as many organic compounds that
contain nitrogen.
2. In mathematics, the number of different
single-digit symbols used in a particular
number system. Thus our usual (decimal)
counting system of numbers has the base ten
(using the symbols 0, 1, 2, 3, 4, 5, 6, 7, 8,
9). In the binary number system, which has
only the numbers 1 and 0, the base is two. A
base is also a number that, when raised to a
particular power (that is, when multiplied by
itself a particular number of times as in
10^2 = 10 x 10 = 100), has a logarithm equal
to the power. For example, the logarithm of
100 to the base ten is 2. In general, any
number system subscribing to a place-value
system with base value b may be represented
by ...b^4, b^3, b^2, b^1, b^0, b^-1, b^-2,
b^-3,... . Hence in base ten the columns
represent ...10^4, 10^3, 10^2, 10^1, 10^0,
10^-1, 10^-2, 10^-3..., in base two ...2^4,
2^3, 2^2, 2^1, 2^0, 2^-1, 2^-2, 2^-3 ..., and
in base eight ...8^4, 8^3, 8^2, 8^1, 8^0,
8^-1, 8^-2, 8^-3 .... For bases beyond 10,
the denary numbers 10, 11, 12, and so on must
be replaced by a single digit. Thus in base
16, all numbers up to 16 must be represented
by single-digit `numbers', since 10 in
hexadecimal would mean 16 in decimal. Hence
decimal 10, 11, 12, 13, 14, 15 are
represented in hexadecimal by letters A, B,
C, D, E, F.
3. Lending rate The rate of interest to
which most bank lending is linked, the actual
rate depending on the status of the borrower.
A prestigious company might command a rate
only 1% above base rate while an individual
would be charged several points above. An
alternative method of interest rates is
LIBOR.
4. Pair In biochemistry, the linkage of two
base (purine or pyrimidine) molecules in DNA.
They are found in nucleotides, and form the
basis of the genetic code. One base lies on
one strand of the DNA double helix, and one
on the other, so that the base pairs link the
two strands like the rungs of a ladder. In
DNA, there are four bases: adenine and
guanine (purines) and cytosine and thymine
(pyrimidines). Adenine always pairs with
thymine, and cytosine with guanine.