问题 单项选择题

进行生理实验时,常对实验对象施以人为刺激观测反应,首先选择操作方便,定量准确,可重复使用且不容易造成损伤的刺激方法,下列最常使用的是

A.化学刺激
B.电刺激
C.机械刺激
D.冷刺激

答案

参考答案:B

解析: 刺激(stimulation)是指细胞所处环境因素的变化。任何能量形式的理化因素的改变,都可能构成对细胞的刺激。但是刺激要能使细胞发生兴奋,就必须达到一定的刺激量。刺激量通常包括三个参数:刺激的强度、刺激的持续时间和刺激强度对时间的变化率。在实验中经常使用电刺激。

单项选择题
单项选择题

A conventional teacher’s licensee usually requires a university degree in education plus an unpaid term of practice teaching. This has never made much sense. It excludes bright students who take degrees in other subjects, and might teach those subjects; it is costly and time-consuming for career-switchers, who must wait a year or more before they can enter a classroom; it is so rigid that private-school teachers or university professors with years of experience have to jump through hoops before they can start teaching in a state school. And there is virtually no evidence that it creates better teachers. For all that, it is ply backed by schools of education, which have a monopoly of teacher-training, and by teachers’ unions, whose members make more money when it is artificially hard for others to get into the profession.

Now, some 45 states and the Districts of Columbia offer an "alternative route" to a teacher’s licensee, up from only a handful in the 1980s. Alternative certification (AC) generally allows individuals with a university degree to begin teaching immediately after passing an entrance examination. These recruits, watched over by a mentor teach the subject they studied at university, and take education courses at a sponsoring university while drawing their salaries.

The traditional sort of American teacher is likely to be young, white and female. Alternative certification attracts more men and more non-whites. In Texas, for instance, roughly 90% of public-school teachers are white, but 40% of those who have joined through alternative certification are non-whites. The AC route also draws teachers willing to go where they are most needed. A survey of Troops to Teachers, a program that turns exsoldiers into public-school teachers (" Proud to serve again"), found that 39% of those taking part are willing to teach in inner-city schools, and 68% in rural areas.

Are they good teachers Officialdom is reluctant to release the details which might answer that question for certain. But anecdotal evidence suggests they do well. In New Jersey, which has been running this sort of program since 1984, rich districts, which can afford to be choosy, consistently hire more AC teachers than poor districts do. In Houston, Texas, where the Teach of America program (TFA) puts recent university graduates into poor communities as teachers, the most effective teachers are generally the TFA ones. " School principals are our biggest fans," Wendy Kopp, TFA’s president, says proudly.

So why not scrap the cumbersome teacher-licensing laws Frederick Hess, a professor at the University of Virginia, has written a paper for the Progressive Policy Institute arguing that teacher-licensing ought to be stripped to the bare essentials. Prospective teachers should be required only to hold a college degree, pass a test of essential skills, and be checked to make sure they do not have a criminal background. Other training is important, argues Mr. Hess, but the market, not state legislators, should decide what that training looks like. This notion of "competitive certification" has drawn favorable attention from the Bush administration.

How does the author feel about the conventional teacher’s training()

A. Ridiculous

B.Unjust

C. Complicated

D. Irrelevant