The different arrangements of atoms caused by rotation about a single bond are called conformations (构象)of the molecule, and a specific conformation is called a conformer (构象异构体, conformation isomer). An analysis of the energy changes that a molecule undergoes as groups rotate about single bonds is called a conformational analysis (构象分析)

1 . A reaction has the stoichiometric equationA+B=2R. What is the order of reaction? 2. A reaction with stoichiometric equationhas the following rate expressionWhat is the rate expression for this reaction if thestoichiometric equation is written as A+2B=2R+S?A B R S2

Define the following terms: 1. design feature:are features that define our human languages,such as arbitrariness,duality,creativity,displacement,cultural transmission,etc. 2. function: the use of language tocommunicate,to think ,etc.Language functions inclucle imformative function,interpersonal function,performative function,interpersonalfunction,performative function,emotive function,phatic communion,recreational function and metalingual function

Quinones are an interesting and valuable class of compounds because of their oxidation-reduction, or redox, properties. The redox properties of quinones are important to the functioning of living cells, where compounds called ubiquinones(泛醌) act as biochemical oxidizing agents to mediate the electro-transfer processes involved in energy production

Many other pairs of reagents that form cabocations (orcarbocationlike species) may be used as well

More environment-friendly methods Natural insect attractants — instead pesticide Less reactive compounds organic refrigerants and aerosol propellant — instead Freon (that destroy the Earth’s ozone layer) Cars with more efficient combustion engines — reduce the massive amount of automobile

Carboxylic acids are just one member of a class of acyl derivatives, RCOY, where the acyl group is bonded to an electronegatives substituent -Y that can act as a leaving group in substitution reactions. Numerous acyl derivatives are possible, but we’ll be concerned only with four of the more common ones, in addition to carboxylic acids themselves: acid halides, acid anhydrides, esters, and amides

The dtft provides a frequency-domain representation of discrete-time signals and lti discrete-time systems Because of the convergence condition, in many cases. the dtft of a sequence may not exist as a result. it is not possible to make use of such frequency-domain characterization in these cases Copyright C 2001, S K. Mitra

Problem: Maintain a dynamic collection of pairwise-disjoint sets= {S1, S2, .. S } Each set S; has one element distinguished as the representative element, rep[]

Good to see you. I am sorry I am not able to be there for your birthday. Jackie and I really loved our visit last year, and I am sure we would have enormously enjoyed what I expect will be a great party, but at the moment we have a previous engagement somewhere in Thailand. I have known Claudio since he was a mere lad of 22, a young graduate student of Johnnie Wheeler when I first came to Princeton. He then stayed on as an Assistant