题目内容

适用于内外形状均需表达且不对称的形体的剖面图是( )。

A. 局部剖面图
B. 全剖面图
C. 半剖面图
D. 阶梯剖面图

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系统图中,应标出与平面图相对应的立管编号,注于立管的( )。

A. 顶端
B. 底端
C. 左侧
D. 右侧

It may be debated whether individual neurons are "tuned" to react to only asingle tastant such as salt or sugar--and therefore signal only one tastequality--or whether the activity in a given neuron contributes to the neuralLine representation of more than one taste. Studies show that both peripheral and(5) central gustatory neurons typically respond to more than one kind of stimulus,and although each neuron is attuned most acutely to one tastant, it usually alsogenerates a reaction to others with dissimilar taste qualities. How then can thebrain represent various taste qualities if each neuron is receptive to manydifferent-tasting stimuli(10) Electrophysiological studies of gustatory sensory neurons, first performedby Pfaffmann, demonstrated that peripheral neurons are not specificallyresponsive to stimuli representing a single taste quality (which might besymbolized by the pattern of activity across gustatory neurons because theactivity of any one cell was ambiguous) but instead record a spectrum of tastes.(15) But in the 1970s and 1980s several scientists began to accumulate data indicatingthat individual neurons are tuned maximally for one taste, and they interpretedthis as evidence that activity in a particular type of cell represented a given tastequality--an idea they called the labeled-line hypothesis. According to this idea,activity in neurons that experience the strongest reaction to sugar would signal(20) "sweetness," activity in those that are most sensitive to acids would signal"sourness", and so forth.Smith later proved that the same cells that previous researchers hadinterpreted as labeled lines actually defined the similarities and differences inthe patterns of activity across taste neurons, suggesting that the same neurons(25) were responsible for taste-quality representation, whether they were viewed aslabeled lines or as critical parts of an across-neuron pattern. These investigatorsfurther established that the neural distinction among stimuli of differentqualities depended on the simultaneous activation of different cell types, muchas with the function of color vision, but unlike auditory perception. These and(30) other considerations have led us to favor the idea that the patterns of activityare key to coding taste information.Scientists now know that things that taste similarly evoke similar patternsof activity across groups of taste neurons. Furthermore, we can compare thesepatterns and use multivariate statistical analysis to plot the similarities in the(35) patterns elicited by various tastants. Taste researchers have generated suchcomparisons for gustatory stimuli from the neural responses of hamsters andrats and these correspond very closely to similar plots generated in behavioralexperiments, from which we may infer which stimuli taste alike and which tastedifferent to animals. Such data show that the across-neuron patterns contain(40) sufficient information for taste discrimination and this may be a reasonableexplanation for neural coding in taste, though researchers continue to debatewhether individual neuron types play a more significant role in taste coding thanthey do in color vision. Scientists question whether taste is an analytic sense, inwhich each quality is separate, or a synthetic sense like color vision, where(45) combinations of colors produce a unique quality. Which of the following laboratory results, if found, would be LEAST consistent with the author's explanation of the neurophysiology of taste()

A group of taste neurons is found which only responds to sweet taste when stimulated by sweet foods.
B. A brain-wave analysis of a rat genetically engineered to lack a sense of sweet tastes is nevertheless found to have a sense of sour tastes.
C. Most tastes are found to have strikingly different neurological effects on humans they do upon animals.
D. A brain-wave analysis of a hamster demonstrates a similar pattern of activity in a given neurological area for both sour and ,sweet stimuli.
E. A group of taste neurons is found which provides insufficient information for taste discrimination.

Crosby’s recent study of American historical demography is blithely basedon the reconstitution of the records of single parishes, a method that oftenexcludes migrants. Moreover, it is troublesome for historians to obtainLine information on the birthdates of people who relocated to the parish, and equally(5) difficult to follow those who had migrated to new places of residence. Thus, theexclusion of migrants also followed from the way spatial units were onceconceived by the parishioners themselves, a stable and unchanging pre-moderncountryside of interchangeable towns unlike "modern" flows to cities.As a result, migration was improperly assumed to be irrelevant because the(10) small units in the countryside were interchangeable and migrants into a parishcould thus stand as a proxy for those who had left. In any case, it was thoughtthat migration in the countryside was repetitive and occurred only in response tolife course events, such as finding a spouse, and thus, like the parishionersthemselves, Crosby complacently equates the demographics of migrants to those(15) of more sedimentary populations. In the passage, the author is primarily concerned with()

A. summarizing the findings of a study
B. placing new research within its historical context
C. evaluating the methodology of a historian
D. comparing various demographical techniques
E. establishing categories

总平面图上应点出( ),以表明建筑物的朝向。

A. 指南针
B. 指北针
C. 风向频率图
D. 风玫瑰

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