题目内容
Much of the research on hallucinogenic drugs such as LSD has focused on the neurotransmitter serotonin, a chemical that when released from a presynaptic serotonin-secreting neuron causes the transmission of a nerve impulse across a synapse to an adjacent postsynaptic, or target, neuron. There are two major reasons for this emphasis. First, it was discovered early on that many of the major hallucinogens have a molecular structure similar to that of serotonin. In addition, animal studies of brain neurochemistry following administration of hallucinogens invariably reported changes in serotonin levels.Early investigators correctly reasoned that the structural similarity to the serotonin molecule might imply that LSD’ s effects arc brought about by an action on the neurotransmission of serotonin in the brain. Unfortunately, the level of technical expertise in the field of brain research was such that this hypothesis had to be tested or, peripheral tissue ( tissue outside the brain). Two different groups of scientists reported than LSD powerfully blockaded serotonin’ s action, their conclusions were quickly challenged, however. We now know that the action of a drug at one site in the body does not necessarily correspond to the drug’ s action at another site, especially when one site is in the brain and the other is not.By the 1960’ s technical advances permitted the direct testing of the hypothesis that LSD and related hallucinogens act by directly suppressing the activity of serotonin secreting neurons themselves—the so called presynaptic hypothesis. Researchers reasoned that if the hallucinogenic drags act by suppressing the activity of serotonin-secreting neurons, then drugs administered after these neurons had been destroyed should have no effect on behavior, because the system would already be maximally suppressed. Contrary to their expectations, neuron destruction enhanced the effect of LSD and related hallucinogens on behavior. Thus hallucinogenic drugs apparently do not act directly on serotonin-secreting neurons.However, these and other available data do support an alternative hypothesis, that LSD and related drugs act directly at receptor sites on serotonin target neurons (the postsynaptic hypothesis). The fact that LSD elicits "serotonin syndrome", that is, causes the same kinds of behaviors as does the administration of serotonin in animals whose brains are depleted of serotonin indicates that LSD acts directly on serotonin receptors, rather than indirectly through the release of stores of serotonin. The enhanced effect of LSD reported after serotonin depletion could be due to a proliferation of serotonin receptor sites on serotonin target neurons. This phenomenon often follows neuron destruction or neurotransmitter depletion; the increase in the number of receptor sites appears to be a compensatory response to decreased input. Significantly, this hypothesis is supported by number of different laboratories, It can be inferred that researchers abandoned the presynaptic hypothesis because（）
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数据并发操作通常会带来3类问题，它们是丢失更新、 【10】 和读脏数据。
在广域网中，T1标准规定的速率为______。
数据通信是在20世纪60年代随着______技术的不断发展和广泛应用而发展起来的一种新的通信技术。
"Sloganeering" did not originate in the 1960s. The term has a rich history. It originated from the Gaelic word slaughgharim, which signified a "host-shout," "war cry," or "gathering word or phrase of one of the old Highland clans; hence the shout or battle cry of soldiers in the field." English-speaking people began using the term by 1704. The term at the time meant "the distinctive note, phrase, or cry of any person or body of persons." Slogans were common throughout the European continent during the middle ages, and they were utilized primarily as "passwords to insure proper recognition of individuals at night or in the confusion of battle." The American revolutionary rhetoric would not have been the same without "the Boston Massacre," "the Boston Tea Party," "the shot heard around the world," and shouts of "no taxation without representation."...Slogans operate in society as "social symbols" and, as such, their intended or perceived meaning may be difficult to grasp and their impact or stimulation may differ between and among individuals and groups...Because slogans may operate as "significant symbols" or as key words that have a standard meaning in a group, they serve both expressive and persuasive functions. Harold Lasswell recognized that the influencing of collective attitudes is possible by the manipulation of significant symbols such as slogans. He believed that a verbal symbol might evoke a desired reaction or organize collective attitudes around a symbol, Murray Edelman writes that "to the political scientist patterning or consistency in the context in which specific groups of individuals use symbols is crucial, for only through such patterning do common political meaning and claims arise." Thus, the slogans a group uses to evoke specific responses may provide us with an index for the group’s norm, values, and conceptual rationale for its claims.Slogans are so pervasive in today’s society that it is easy to underestimate their persuasive power. They have grown in significance because of the medium of television and the advertising industry. Television, in addition to being the major advertising medium, has altered the nature of human interaction. Political images are less personal and shorter. They function as summaries and conclusions rather than bases for public interaction and debate. The style of presentation in television is more emotional, but the content is less complex or ideological. In short, slogans work well on television.The advertising industry has made a science of sloganeering. Today, communication itself is a problem because we live in an "overcommunicated" society. Advertisers have discovered that it is easier to link product attributes to existing beliefs, ideas, goals, and desires of the consumer rather than to change them. Thus, to say that a cookie tastes "homemade" or is as good as "Mom used to make" does not tell us if the cookie is good or bad, hard or soft, but simply evokes the fond memories of Mother’s baking. Advertisers, then, are more successful if they present a product in a way that capitalizes on established beliefs or expectations of the consumer. Slogans do this well by crystallizing in a few words the key idea or theme one wants to associate with an issue, group, product, or event. "Sloganeering" has become institutionalized as a virtual art form; and an advertising agency may spend months testing and creating the right slogan for a product or a person.Slogans have a number of attributes that enhance their persuasive potential for social movements. They are unique and readily identifiable with a specific social movement or social movement organization. "Gray Power," for instance, readily identifies the movement for elderly Americans, and "Huelga" (strike in Spanish) identifies the movement to aid Mexican American field workers in the west and southwest. Products sell better if （）
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