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What is the effect of Verapamil （a Calcium channel blocker) on the action potential of Purkinje cell？

A、The amplitude of phase 0 depolarization reduces

B、The duration of phase 1 repolarization decreases

C、The duration of phase 2 repolarization decreases

D、The duration of phase 3 repolarization decreases

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更多“What is the effect of Verapami…”相关的问题

第1题

Pollution control is management of waste materials in order to minimize the effects of pollutants on people and the environment. The quality of human health and of the natural environment depends on adequate pollution control. In the United States much has been done to control the more noticeable pollutants since 1965: more subtle yet still hazardous pollutants, however, remain to be adequately controlled.

Four general approaches to pollution control are: the intermittent reduction of industrial activities during periods of high air-pollution conditions; wider dispersion of pollutants using such devices as taller smokestacks; reduction of pollutants in industrial emission; and change of an industrial process or activity in order to produce less pollution. Taller smokestacks may reduce the concentrations to which local people are exposed, but they are ineffective in reducing overall pollution.

Pollutants removed from waste flows to reduce emissions to air and water may be disposed of by burial or storage on land, practices that pose potential hazards. Recent legislation requiring extensive emissions reductions has resulted in large investments in pollution-treatment technologies.

The fourth approach — changing a manufacturing process or activity in order to produce less pollution — may involve either the production of fewer residuals, by means of an improved process, or the separation and reuse of materials from the waste stream. This method of pollution control is the most effective and, as the costs of pollution control and waste disposal increase, is considered one of the most efficient.

Pollution-treatment systems have been effective in reducing the massive quantities of water and air pollutants that have clogged and choked urban areas. Although the improvements have been significant, recent pollution-control legislation aims to go further in order to control the less visible but often hazardous chemical and gaseous pollutants that still contaminate many waterways and urban atmospheres.

The costs of pollution control — resulting from capital, maintenance, and labor costs, as well as from the cost of additional residuals disposal — generally go up rapidly as a greater percentage of residuals is removed from the waste stream. Damage from pollution, on the other hand, goes down as a greater amount of contaminant is removed. Theoretically, the level of treatment should correspond to a point at which total costs of treatment and of damage to the environment are minimized or the benefits of further treatment are proportionally much smaller than the increased cost. In reality, costs or damages resulting from pollution can rarely be assessed in terms of dollars.

According to the passage. All of the following can be objectives of pollution control EXCEPT______.

A．reducing polluting substances

B．controlling all the pollutants

C．restricting industrial activities

D．improving the environment and human health

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第2题

What is not mentioned in the passage?

A．Rain does not fall from all the clouds.

B．The effect of the gravity on droplets is minute.

C．The average raindrop contains much more water than a tiny cloud droplets.

D．The shape of the clouds have a great influence on the raindrop.

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第3题

Increasing the inductance level for filter type 3 has the effect of:

A.increasing the output amplitude of the electrical circuit.

B.decreasing the average frequency of sine waves that pass through the circuit.

C.reducing the range of sine-wave frequencies that pass through the circuit.

D.increasing the output frequency of the electrical circuit.

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第4题

The effect of TV__________the life of average people is incalculable．

A．in

B．for

C．about

D．on

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第5题

The relationship hereby established between Supplier and Distributor，during the effective period of this Agreement，shall be solely that of Seller and Buyer，and Distributor shall under no circumstances be considered to be the agent or legal representative of Supplier for any purpose whatsoever and shall have no right or authority to create or assume any obligation or responsibility of any kind，expressed or implied，in the name of or on behalf of Supplier．

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第6题

Among humans, the effects of aging vary from one individual to another. The average life ______ for Americans is around 5 years, almost twice what it was in the early 190Os.

A．spectrum

B．expectation

C．expectancy

D．width

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第7题

Among humans, the effects of aging vary from one individual to another. The average life ______ for Americans is around 75 years, almost twice what it was in the early 1900s.

A．spectrum

B．expectation

C．expectancy

D．width

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