① It refers to the ability to avoid interference of other coexisting components in the sample when a certain analytical method is used to determine a component.
At the specifiedMeasurement accuracyThe ratio between the allowable amount of coexisting components and the content of components to be measured n=W (coexisting components)/W (components to be measured)
② SpecificallyReaction selectivity, also called reactionSpecificity。Onechemical reactionIf multiple products can be generated at the same time, one of which is the most desirable, the yield of this product represents the selectivity of the reaction.
For example, oxidation of naphthalene tophthalic anhydride, and will generatecarbon dioxideAnd carbon, both of which are undesirable products.The higher the fraction of naphthalene converted to phthalic anhydride, the better the selectivity of the reaction.Reaction selectivity is an important indicator to evaluate the efficiency of a reaction.
Selectivity and specificity:
Selectivity refers to the speed or result of reaction to different things.Specificity means only reacting to something.such asglucoseAndConcentrated nitric acidOr something elseoxidation, the results are different.Gold only dissolves inAqua regiaIt is specificity.If the raw materialConversion rateIs X, the yield of the main product is Y, then the selectivity of the product is S=Y/X
Selectivity in a broad sense is to express the nature of "selectively"."Selectivity XX" means "selectively" in some aspect, that is, selectivity.(YesChoice phobiaInstead of“Selective phobia”"Choose barriers" instead ofSelective obstacleThe misuse of the word "selectivity" is a grammatical misuse.)
Since the word "selectivity" has been applied in various scientific fields, it can be regarded as a profoundPhilosophical category(but ignored for a long time).Selectivity can be divided into active selectivity and passive selectivity.
Selectivity in analytical chemistry
Announce
edit
Selectivity is often related to the method or reaction used. Therefore, the most appropriate method and reaction should be selected for the analysis of different substances.In other words, the higher the selectivity of the method or reaction used, the fewer interference factors.In this way, the operation steps of analysis can be reduced, so thatAnalysis processMeet the requirements of fast, accurate and simple.Therefore, selectivity is a very important sign to measure analytical methods and reactions.The selectivity of methods is not invariable, it can be improved or enhanced through different ways.There are two common ways: ① improve the instrument, for example, adoptHigh performance liquid chromatographyThe method can be greatly improvedchromatographic analysis Selectivity of.stayUltraviolet visible spectrophotometryThe use of multiple derivative processing in can not only improve the sensitivity, but also improve the method selectivity. ②Improve the conditions corresponding to the analysis, which is reasonableSelective responseAcidity, medium, reaction ionValence stateAnd usesequestrant Etc.
Audience inprocess informationIt is a selective tendency at that time, which means that in the mass information, what the audience perceives is often those parts that are consistent or close to their own existing interests, habits, needs, etcexperimental study Proved thisSelective cognitionBoth tendency and selective cognition are constraintscommunication effect Important factors.
PerceptualSelective actionAnthropogenicobjective thingsIt is numerous and diverse, and people can't feel it all clearly in an instant;However, according to a certain need and purpose, you can actively and deliberately select a few things (or a part of things) as the object of perception, or unconsciously be attracted to something, take it as the object of perception, and produce a clear and distinct perceptual image of it, while taking the rest of the surrounding things as the background of perception, only producing a relatively vague perceptual image.The selectivity of perception is influenced by the characteristics of the perceptual object and is also affected byPerceiverThe influence of my subjective factors, such as interest, attitude, hobbies, emotionsKnowledge and experience, observation ability orAnalytical capabilityEtc.The selectivity of perception is inseparable from other characteristics of perception. The selected perception object is usually complete, relatively stable and understandable.
selective attention
selective attention (Selective attention) refers to only paying attention to some stimuli or some aspects of stimuli, while ignoring other stimuli.In a sense, the word attention itself has a selective meaning, so the word is redundant.However, its synthetic form is still often used for emphasis.
Human senses may receive a large number of stimuli at any moment, but perception does not respond to all stimuli.Selective retention of perception ensures that people can focus on important stimuli or important aspects of stimuli, eliminate the interference of secondary stimuli, and more effectively perceive and adapt to the external environment.
Three classical theories of selective attention:Filter theory，Attenuator theory, post selection theory.The post selection model believes that the importance of information depends on many aspects, not only on whether the content is of great significance to individuals, but also on people's awakening state. If people are in a high awakening state, even secondary information will beControl processing。
Selective attention is easy to cause illusion.
Selective understanding
Selective understandingThis is the core of the audience's psychological selection process, also known asInformation disseminationThe decoding process of.Information with the same content will have different understandings for different audiences, sometimes even the opposite. The reason for this is that the audience's psychology, feelings, experiences, needs and environment are different.
Joseph Crabbe, an American communication scholar, summarized the audience's selective psychology into selective acceptance, selective understanding andSelective memory。Due to too much interference information, the audience willDisseminatorThe understanding deviation of subjective intention discrepancy belongs to the category of selective understanding.Therefore, the communicatorCommunication processWe should fully consider the role of selective understanding, control and guide the content of communication, and try to eliminate or reduce the possibility of causing audience understanding deviation.sendinformation encodingTry to be clear and improve the quality of information accepted and understood by the audience.
Selective memory
Definition: People can only remember information that is beneficial to them, or only remember information that they are willing to remember, while other information is often forgotten.This choice of memory is called selective memory.
Selective memory is one of the theories of audience selectivity in communication science. It means that the audience always selects useful, beneficial and valuable information from the information that has been noticed and understood according to their own needsInformation storageIn the brain.
The main factors affecting selective memory are:
(1) Needs: information that can meet their own needs, and the degree of memory is generally high.
(2) Simplification: Information with less content is easy to remember.
(3) Image: concrete image, high memory.
(4) Moderate repetition.
(5) Novelty.
(6) Understanding.
selective amnesia
selective amnesia It refers to a person who forgets something he does not want to remember or escapes from, or "self deception selective amnesia" after external stimulation or brain collision.
Selective amnesia is adefense mechanism。Generally speaking, if a person encounters a powerful stimulus that is unacceptable to the person, then,the subconsciousHe will choose to forget this matter, which will lead to "selective amnesia".However, although it seems to forget this matter on the surface, its shadow still exists.When you do something, you will be unconsciously affected by it. Maybe you don't know it clearly, and it will gradually become a knot.
Some people hope to selectively lose memory because of major setbacks. Under strong mental pressure, they will feel that some things have not happened, and even make up another situation in their minds to deceive themselves in an imaginary way. In fact, it is possible, which is essentially out of self-protection.But whether this is medical "selective amnesia" is not certain.It may be self deception, so it will not forget.
Selectivity bias
Selectivity bias（selectionBias) means that people like to divide things into several typical categories, and then, when estimating the probability of events, overemphasize the importance of this typical category, regardless of the evidence of other potential possibilities.The consequences of selective bias are bound to make people tend to perceive this pattern in the actually random data series, thus causing systematic prediction bias.
Selective Twist
Selective TwistIt means that people selectively distort certain information to make it conform to their own intentions.
Selective distortion is a kind of inclination, which distorts information so that it conforms to our own meaning and understands information in a way that conforms to our expectations.
Even if the stimulus attracts people's attention, it may not achieve the desired goal.This is because when people face objective things, they have a tendency to combine the information input from the outside with the patterns that already exist in their minds.This tendency to interpret information according to people's existing ideas is called selective misinterpretation.
Selectivity in Biology
Announce
edit
Natural selection itself has already embodied the "selectivity" of nature.
It means that one mutation site is adjacent due to the recent strong positive natural selectionDNAOnnucleotideThe difference between them is reduced or eliminated.
When a new mutation occurs, making the individual more adaptable to other group members, it maySelective Clear。Natural selection is conducive to the survival of individuals with strong adaptabilityAllele frequencyGradually increase.As the increase becomes more and more, neutralgenetic variationAnd new mutationsLinkage inheritancemore and more.genomeThe selective clearance area on theSelectingOfHaplotype。The genetic variation in this region is greatly reduced.
Selective toxicity
Under certain conditionsToxic effectIt has certain selectivity.A poison is harmful to one kind of organism or tissue, while it is harmful to other organisms orTissue and organIt has no toxic effect, and its toxic effect on organisms is calledSelective toxicity。The damaged organism or tissue is calledTarget organismortarget organ。
Selective medium
Selective mediumAccording to certain microorganismsSpecial nutritionRequired or designed for resistance to certain chemical or physical factorsculture medium。Its function is to make the inferior bacteria in the mixed bacteria sample become the superior bacteria, so as to improve theScreening efficiency。
other
Announce
edit
Selective law enforcement
In legal practiceobjective existenceThere are two different versions of its definition: one is that the subject of law enforcement deliberately adopts different treatment to different jurisdictional objects, which violates the justice of law enforcement;The second refers to the adjustment made by the state in law enforcement in an attempt to obtain flexibility and effectiveness according to the changing circumstances.BecauseSelective law enforcementPromoting with less law enforcement resourcesLaw enforcementAt the same time, there is also an inevitable focus, which runs counter to the goal of the rule of law. Therefore, it is reasonable that it is given two different definitions, which reflect the contradiction between fairness and efficiency.However, it must be affirmed that selective law enforcement is a necessary law enforcement strategy, and its positive and negative effects may be derived. Therefore, all research on it can only consider how to make up for, regulate, and keep efficiency and fairness abreast, rather than giving up.
What economists use to describe expectationspurchaserWhen considering buying a specific brand or model
The behavior of the product.
Ion selective electrode
It is a kind of method that uses membrane potential to measure ions in solutionactivityOr concentrationElectrochemical sensorWhen it contacts with the solution containing the ion to be measuredPhase interfaceGenerated on theIonic activityDirectly related membrane potential.Ion selective electrodeAlso calledmembrane electrodeThis kind of electrode has a special electrode membrane, which has a selective response to specific ions, and the relationship between the potential of the electrode membrane and the content of the ion to be measured is consistent withNernst formula。This type of electrode is characterized by good selectivity and short balance timePotentiometryMost usedIndicator electrode。
Selective crushing
English name: selective cracking
Refers to the utilization of coal andwaste(or other ingredients)FriabilityThe difference between them makes them subject to different degrees of fragmentation.
Selective silence
An indifferent refusal to communicate, unable to bear the signal of pressure.
Performance: accustomed to smiling and modestly answering questions for customers, but never commenting on friends to share online
Log of;Accustomed to the customer's life-threatening calls, but unwilling to take the initiative to contact friends;Accustomed to typing a document in a formula to reply to customersholiday and vacationsFriends' greetings were ignored;In the past, the habit of being busy and mixing everything has also changed. In the face of friends' greetings and concerns on various contact tools, the only feeling is that they are speechless
Urban lifeCommunication is developed, but some young people become more and more introverted and take the initiative to sendBlessing SMS. Fewer and fewer people politely reply to greetings. In their words, they are not unwilling to reply, but "too lazy to reply".Not excited, passive, indifferent, lack of response to external concerns.For SMS, phone, emailmicro-blogNot willing to reply“Selective silence”Performance.
Selective Distribution
The manufacturer selects several (more than one) similar products according to certain conditionsmiddlemanThe channel formed by the distribution of products.Selective distribution It is usually composed of strong middlemen and can be effectively maintainedManufacturer brandReputation, establish a stable market andcompetitive edge。Such channels are mostly in consumer goodsOptionsandSpecial products, spare parts in industrial products, etc.The advantage of selective distribution channels is that they can save expenses, improve marketing efficiency and control the market.However, selective distribution channels make it difficult for enterprises toMarketing environmentRealized under loose conditionsDiversificationObjectives;The channel lacks sufficient adaptability to non optional goods;The enterprise should provide more services for the selected middlemen and undertake certainmarket risk 。
Selective specialization
It means that the enterprise selects several with good profit potential and structural attractiveness, and meetsEnterprise objectivesAnd resourcesSegmentsAstarget market, where each market segment is less connected with other market segments.
Selective IgA deficiency
fingerserumIgA is lower than 0.05g/L, whileIgGandIgMSymptoms with normal content.It isimmunodeficiencyThe most common type in.The sweeping rate in the population is about 1/700.The disease is sporadic, partly familial, and affects several generations.For the six ethnic groups in different regions of Chinaepidemiological investigation , indicating that the disease has ethnic and regional differences.Αheavy chaincodeStructural geneAbnormality may not be the main cause;At Bcell differentiationEarly IgA production BCellsMaturity stagnation or IgASpecificityInhibiting the activation of T cells and preventing the maturation of B cells may be the cause of disease.
……
Selective Capriccio
Announce
edit
Selectivity is one of the basic properties of the world. All the facts that happen belong to the result of selective reflection and expression.
Uniqueness and selectivity:
(1) Uniqueness: All existence is unique and true (this "truth" refers to absolute truth).
(2) Selectivity: expressing the nature of "selectively".
Embodiment: "I" must have a measure of the existence that "I" understands (active and selective);Conditionally freeInevitability(passive selectivity).
Life lies in never - ending choice.general ruleIt is popular, and things have their own choices.
Selectivity is the basis of cognitive facts.
We "see" an object is the object's "selective reflection" of us, and we "understand" an object is the object's "selective expression" of us.(It is assumed that there is only me and the object)
"Reflection" is the pre process of "recognition", while "expression" is the pre process of "knowledge". "Reflection" and "expression" are the pre process of "cognition" and the basis of cognition.
Two principles of selection:
wrongRandom principle: purposeful and targeted selection.Random principle: choose randomly.
Seeing things“Trichotomy”: One divides into two,One divides into threeOne divides into many.Different methods are adopted according to different situations. For example, when debating with someone, one divides into two; when dealing with people, one divides into three (the third choice is similar, stalemate, win-win, similar, etc.); when creating an invention, many aspects should be considered.
