营养学上依据食品在人体中代谢产物的酸碱性,一般将食品分成酸性食品和碱性食品.其中显碱性的酸性食品是( ) A B C D 食品 鸡蛋清 葡萄 苹果 草莓 食品类别 酸性食品 碱性食品 碱性食品 酸性食品 pH 7.6-8.0 3.5-4.5 2.9-3.3 3.0-3.5
A.
A
B.
B
C.
C
D.
D
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【判断题】The functions of micronutrients include helping the carbohydrates turn into energy in our cells, providing cushioning and ensuring our cells replicate.
【多选题】Proteoglycans perform many sophisticated functions in addition to providing hydrated space around cells. What are their other functions?
A.
They can form gels of varying pore size and charge density that act as filters to regulate the passage of molecules through the extracellular medium.
B.
They can bind secreted growth factors and other proteins that serve as extracellular signals for cells.
C.
They can block, encourage, or guide cell migration through the matrix.
D.
In all these ways, the matrix components influence the behavior of cells, often the same cells that make the matrix—a reciprocal interaction that has important effects on cell differentiation and the arrangement of cells in a tissue.
【多选题】How do intermediate filaments strengthen cells against mechanical stress?
A.
Intermediate filaments are particularly prominent in the cytoplasm of cells that are subject to mechanical stress.
B.
They are present in large numbers, for example, along the length of nerve cell axons, providing essential internal reinforcement to these extremely long and fine cell extensions.
C.
They are also abundant in muscle cells and in epithelial cells such as those of the skin. In all these cells, intermediate filaments distribute the effects of locally applied forces, thereby keeping cells and their membranes from tearing in response to mechanical shear.
D.
A similar principle is used to strengthen composite materials such as fiberglass or reinforced concrete, in which tension-bearing linear elements such as carbon fibers (in fiberglass) or steel bars (in concrete) are embedded in a space-filling matrix to give the material strength.