Q
QSAR See quantitative
structure–activity relationship.
QSMR See quantitative
structure–metabolism relationship.
quadrivalent Having a valency of
four.
quadrupole A set of four point
charges that has zero net charge and
dipole moment. An example of a
quadrupole is a carbon dioxide (CO 2 )
molecule. Quadrupole interactions
are much smaller than dipole interactions. Transitions involving
quadrupole moments are much
weaker than transitions involving dipole moments, but can allow transitions forbidden in dipole moment
transitions.
quadrupole mass spectrometer
See mass spectroscopy.
qualitative analysis See analysis.
quantitative analysis See analysis.
quantitative structure–activity
relationship (QSAR) A statistical algorithm that quantitatively deÜnes
the relationship between the chemical structure of a drug and its effect
on an organism. QSAR studies are
often used to predict the activity or
toxicity of new drugs. Similar methods can be used to predict the metabolism of new drugs (quantitative
structure–metabolism relationships).
quantitative structure–metabolism relationship (QSMR) See
quantitative structure–activity
relationship.
quantum (pl. quanta) The minimum amount by which certain properties, such as energy or angular
momentum, of a system can change.
Such properties do not, therefore,
vary continuously, but in integral
multiples of the relevant quantum,
and are described as quantized. This
concept forms the basis of the *quantum theory. In waves and Üelds the
quantum can be regarded as an excitation, giving a particle-like interpretation to the wave or Üeld. Thus, the
quantum of the electromagnetic Üeld
is the *photon and the graviton is
the quantum of the gravitational
Üeld.
quantum chaos The *quantum
mechanics of systems for which the
corresponding classical system can
exhibit *chaos. This subject was initiated by Einstein in 1917, who
showed that the quantization conditions associated with the *Bohr
theory need to be modiÜed for systems that show chaos in classical mechanics. The subject of quantum
chaos is an active Üeld of research in
which many basic issues still require
clariÜcation. It appears that systems
exhibiting chaos in classical mechanics do not necessarily exhibit chaos
in quantum mechanics.
quantum chemistry The application of quantum mechanics to chemistry. Quantum chemistry mostly
used empirical methods at Ürst but as
computing power has developed it
has been increasingly based on the
Ürst principles of quantum mechanics.
quantum entanglement A phewww.AzShimi.ir www.AzShimi.com
QSAR See quantitative
structure–activity relationship.
QSMR See quantitative
structure–metabolism relationship.
quadrivalent Having a valency of
four.
quadrupole A set of four point
charges that has zero net charge and
dipole moment. An example of a
quadrupole is a carbon dioxide (CO 2 )
molecule. Quadrupole interactions
are much smaller than dipole interactions. Transitions involving
quadrupole moments are much
weaker than transitions involving dipole moments, but can allow transitions forbidden in dipole moment
transitions.
quadrupole mass spectrometer
See mass spectroscopy.
qualitative analysis See analysis.
quantitative analysis See analysis.
quantitative structure–activity
relationship (QSAR) A statistical algorithm that quantitatively deÜnes
the relationship between the chemical structure of a drug and its effect
on an organism. QSAR studies are
often used to predict the activity or
toxicity of new drugs. Similar methods can be used to predict the metabolism of new drugs (quantitative
structure–metabolism relationships).
quantitative structure–metabolism relationship (QSMR) See
quantitative structure–activity
relationship.
quantum (pl. quanta) The minimum amount by which certain properties, such as energy or angular
momentum, of a system can change.
Such properties do not, therefore,
vary continuously, but in integral
multiples of the relevant quantum,
and are described as quantized. This
concept forms the basis of the *quantum theory. In waves and Üelds the
quantum can be regarded as an excitation, giving a particle-like interpretation to the wave or Üeld. Thus, the
quantum of the electromagnetic Üeld
is the *photon and the graviton is
the quantum of the gravitational
Üeld.
quantum chaos The *quantum
mechanics of systems for which the
corresponding classical system can
exhibit *chaos. This subject was initiated by Einstein in 1917, who
showed that the quantization conditions associated with the *Bohr
theory need to be modiÜed for systems that show chaos in classical mechanics. The subject of quantum
chaos is an active Üeld of research in
which many basic issues still require
clariÜcation. It appears that systems
exhibiting chaos in classical mechanics do not necessarily exhibit chaos
in quantum mechanics.
quantum chemistry The application of quantum mechanics to chemistry. Quantum chemistry mostly
used empirical methods at Ürst but as
computing power has developed it
has been increasingly based on the
Ürst principles of quantum mechanics.
quantum entanglement A phewww.AzShimi.ir www.AzShimi.com