已选分类
工学
单选题从高分子的重复结构单元的对称性可知，最易结晶的是______。
单选题______ can be applied to thermoplastics only. A) Reaction injection molding B) Compression molding C) Blow molding D) Casting
单选题What are (or is) not the conditions on which the substitutional solid solution form? A) The solute atoms and the solvent atoms are of similar size. Specifically, the size oftheir atoms do not differ by more than 15/% B) The interstitial atoms are sufficiently small C) The electron configurations ofthe solute atoms and the solvent atoms are comparable D) The solute atoms and the solvent atoms have a common crystalline structure
单选题形成临界晶核时体积自由能的减少只能补偿表面能的______。 (A) 1/3(B) 2/3(C) 3/4
单选题Miller indices for crystal directions are expressed in ______ with no commas separating the numbers. A) ＜ ＞ B) ( ) C) [ ] D) { }
单选题晶体的对称轴中不存在______。
单选题根据整数定律，晶体结构中的坐标轴应该选取______的方向。
a．相互垂直 b．密排面 c．晶体中行列
单选题伯氏矢量为______的位错属于不可滑移位错。
单选题Among the following properties, temperatures have the greatest effect on ______. A) ductility B) impactstrength C) hardness D) strength
单选题欲制造一把锉刀，其最终热处理应选用( )。 A．T12钢，淬火+低温回火 B．Cr12MoV钢，淬火+低温回火 C．45钢，调质处理
单选题下面关于Schottky和Frenkel缺陷的表述中，错误的为______。
单选题Wood should be considered as a valuable engineering material because the raw materials are ______, whereas those for most other materials are not. A) recycled B) cheap C) renewable D) limited
单选题______ is a dynamic testing. A) Hardness test B) Impact test C) Tensile test D) Tensile creep test
单选题在三元共晶水平截面图的三角形区中，存在______平衡。
单选题立方晶体中(111)，(112)，(110)晶面间距最大的是______。
单选题Which ofthe following statement about the thermal conductivity is NOT correct? A) Thermal conductivity ofmaterials has a varied relationship to temperature. B) Oriented polymers have much lower conductivities than unoriented polymers. C) Incorporation of element to metals reduces the thermal conductivity. D) Metals have comparatively high thermal conductivities while polymers have rather low values.
单选题在CaO-Al2O3-SiO2系相图中有低共熔点8个、双升点7个、鞍形点9个，按相平衡规律该系统可划分成______分三角形。(鞍形点为界线与连线的交点) A．8个 B．7个 C．9个 D．15个 E．22个
单选题A substance capable of holding materials together by surface attachment A) Primer B) Substrate C) Adherend D) Adhesive
单选题高分子材料存在不同构象的主要原因是主链上的碳原子可以______。
单选题不能发生攀移运动的位错是______。