低温贮存较久的血液,血浆中哪种离子浓度升高A.Na+B.K+C.Cl-D.Ca2+

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问题:

低温贮存较久的血液,血浆中哪种离子浓度升高

A.Na+
B.K+
C.Cl-
D.Ca2+

考点:普通考研西医综合西医综合
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属于兴奋性突触的描述的是()

A.突触间隙≤20nm

B.前后膜对称性增厚

C.突触小泡为S型

D.突触前栅为细孔10~20nm

E.突触小泡为F型

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视觉感受器的细胞应位于眼球的()

A.视神经

B.视网膜

C.晶状体

D.角膜

题型:单项选择题

进入老年后,( )通常会发生一定程度的退行性变化。

A.感知觉

B.思考能力

C.行动能力

D.记忆能力

题型:单项选择题

The central problem of economics is to satisfy the people’s and nation’s wants. The problem we are faced with is that our (1) , here identified as money, are (2) . The only way we can resolve our (3) is to make choices. After looking at our resources, we must examine our list of (4) and identify the things we need (5) , those we can postpone, and (6) we cannot afford. As individuals, we face the central problem involved in economics — deciding just how to allocate our limited resources to provide ourselves with the greatest (7) of our wants.
Nations face the same problem. As a country’s population (8) , the need for more goods and services grows (9) . Resources necessary to production may increase, but there are (10) enough resources to satisfy the total desires of a (11) . Whether the budget meeting is taking place in the family living-room, in the conference room of the corporation (12) of directors, or in the chamber of the House of Representatives in Washington, the basic problem still exists. We need to find (13) of allocating limited resources in order to satisfy unlimited wants.
A short time ago, economists divided goods into two categories, free and economic. The former, like air and water, were in (14) abundance that economists had no concern about (15) of scarcity and what to do about it. Today many of these "free goods" are in (16) very expensive to use. Pollution has made clean air and water expensive for producers who have to filter their waste products, for consumers who ultimately pay for the producers’ extra costs, and (17) tax-payers who pay for the government’s involvement in cleaning the environment.
In the 1990s, almost all goods are (18) . Only by effort and money can they be (19) in the form people wish.
Meeting the needs of people and the demands from resources available leads to the basic activity of production. In trying to (20) unlimited wants from limited economic goods, production leads to new problems in economics.

题型:单项选择题

磁铁矿的损失包括()。

A、技术损失

B、技术损失和管理损失

C、管理损失料

D、运输损失

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