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【单选题】
从税基的形式看,可以将税种划分为()。
A.
从价税和从量税
B.
价内税和价外税
C.
比例税、累进税和累退税
D.
中央税和地方税
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举一反三
【单选题】Which of the following is NOT true?
A.
Roots are not necessarily free morphemes.
B.
Bound morphemes are always affixes.
C.
All free morphemes are roots.
D.
All affixes are bound morphemes.
【简答题】Programmed temperature gas chromatography中文是()
【简答题】“咆哮体”是指带许多什么标点符号的词或句子?
【多选题】Write down basic principles and applications of gas chromatography, high-performance liquid chromatography and capillary electrophoresis.
A.
CE: separations of large organic species on the basis of their rate of migration through a medium under the effect of an electrical gradient, which is determined by the mass and charge of the species, the permeability of the supporting medium, and of course the magnitude of the electrical gradient. Hence species can often be separated on the basis of differences with regard to these characteristics. Better resolution than for similar HPLC separations can thus be obtained. Detection of the eluted components is typically achieved using detectors based on molecular spectrometry.
B.
Gas chromatography: To provide the higher resolutions required by modern analyses, the use of long, small diameter capillary columns is the norm. Contemporary GC analysis of trace organic materials uses open tubular capillary columns where a liquid phase has been bound to the internal wall.
C.
HPLC is almost exclusively performed in the reverse phase mode (RP-HPLC), using stationary phases of silica gel derivatised with silylated aliphatic hydrocarbons such as octasilyl (C-8) and octadecylsilyl (ODS) moieties. These are used in conjunction with mobile phases that are predominantly aqueous. HPLC is of most utility where the organic analytes have a large molecular mass, and hence have low volatility, and where the molecule is polar or contains many polar substituents.
D.
Atomic absorption spectrometry (flame or electrothermal) (AAS, ET-AAS), atomic fluorescence spectrometry (AFS), inductively coupled plasma optical (or atomic) emission spectrometry (ICP-OES or ICP-AES), neutron activation analysis (NAA), X-ray fluorescence (XRF), proton-induced X-ray emission (PIXE), spark source or isotope dilution mass spectrometry (SSMS, IDMS), electrochemical (anodic stripping voltammetry and polarography) or inductively coupled plasma-mass spectrometry (ICP-MS).
【单选题】In gas chromatography, the ______responds to analytes containing oxidizable carbon atoms such as hydrocarbons.
A.
injection system
B.
flame ionization detector
C.
column system
D.
carrier gas
【简答题】英译中:capillary column gas chromatography
【单选题】The distinction between free morpheme and bound morpheme is whether morphemes can be other morphemes.
A.
connected to
B.
independent of
C.
supplemented to
D.
reliable on
【判断题】“福利刚性”专指人们对于自己的福利待遇具有允许其在一定范围内上下波动的心理预期
A.
正确
B.
错误
【单选题】In the gas-liquid chromatography, the stationary phase in the column is ( )
A.
the general solid substance
B.
the solid adsorbent
C.
the support
D.
the support and the stationary liquid
【单选题】______ can be used independently without being combined with other morphemes.
A.
Free morphemes
B.
Bound morphemes
C.
Affixes
D.
Roots
相关题目:
【多选题】Write down basic principles and applications of gas chromatography, high-performance liquid chromatography and capillary electrophoresis.
A.
CE: separations of large organic species on the basis of their rate of migration through a medium under the effect of an electrical gradient, which is determined by the mass and charge of the species, the permeability of the supporting medium, and of course the magnitude of the electrical gradient. Hence species can often be separated on the basis of differences with regard to these characteristics. Better resolution than for similar HPLC separations can thus be obtained. Detection of the eluted components is typically achieved using detectors based on molecular spectrometry.
B.
Gas chromatography: To provide the higher resolutions required by modern analyses, the use of long, small diameter capillary columns is the norm. Contemporary GC analysis of trace organic materials uses open tubular capillary columns where a liquid phase has been bound to the internal wall.
C.
HPLC is almost exclusively performed in the reverse phase mode (RP-HPLC), using stationary phases of silica gel derivatised with silylated aliphatic hydrocarbons such as octasilyl (C-8) and octadecylsilyl (ODS) moieties. These are used in conjunction with mobile phases that are predominantly aqueous. HPLC is of most utility where the organic analytes have a large molecular mass, and hence have low volatility, and where the molecule is polar or contains many polar substituents.
D.
Atomic absorption spectrometry (flame or electrothermal) (AAS, ET-AAS), atomic fluorescence spectrometry (AFS), inductively coupled plasma optical (or atomic) emission spectrometry (ICP-OES or ICP-AES), neutron activation analysis (NAA), X-ray fluorescence (XRF), proton-induced X-ray emission (PIXE), spark source or isotope dilution mass spectrometry (SSMS, IDMS), electrochemical (anodic stripping voltammetry and polarography) or inductively coupled plasma-mass spectrometry (ICP-MS).