螺旋形成

The formation of tooth face is analyzed based on the theory of original curve and area as well as the logarithmic spiral polar coordinates equation.

提出了一种新型锥齿轮-对数螺旋线齿锥齿轮传动形式，并以基曲线和基曲面滚动原理为基础，结合对数螺旋线极坐标方程，分析了对数螺旋线以及对数螺旋线齿锥齿轮齿面的形成过程，建立其了齿面方程。

We found that during the growth process the double steps first grow separately and the connected by short bridge before tangential growth. After eighth or ninth layer the spiral steps would merge into intact elliptic layers. At the merging point right-handed spiral sources might appear but the left ones always overgrow it which made the whole growth topography looked like left-handed apparently. It indicated that the EAFP molecules has strong ability to adjust itself to adapt the environment. 5. Through various analysis of interactions in the EAFP crystals it indicated that there were 218 residue interactions between 12 symmetry-related EAFP molecules around one EAFP molecule, 18 strong ones and 72 weak ones .

EAFP在低过饱和度下的螺旋生长过程中会出现台阶的合并，从而表现出单-双的螺旋台阶，在小范围扫描中捕获到了这种现象，使得对螺旋生长台阶的合并过程有了更加深入的认识；并且台阶的生长受到沿晶体学b轴方向上的21螺旋对称的控制；当台阶生长至第八到第九层时，螺旋台阶会自动地形成完整的生长层，这充分说明了EAFP分子或分子簇具有良好的自身调节能力，这样在晶体生长过程中，晶体的缺陷减少，晶体质量提高，这也可说明EAFP晶体的x射线衍射能力很强的原因。

The growth and nucleation rates of〓 cleavage face of YbYAB crystal are all very fast, because so many growth steps and growth centers were formed within only 2～3 second at the temperature near the saturate point. No spiral growth steps can be found, so growth mechanism is twodimensional nucleation. When the flux temperature increases for only 0.5℃ above the saturate point, the spiral melting holes are formed. The transformation from growth morphologies to melting morphologies is very sensitive to the temperature. When the temperature increases another 1℃, the spiral melting holes transform into two-dimensional nucleation melting holes.

YbYAB的〓解理面的生长及成核速度都非常快，在比饱和点低0.5～1℃的温度下，当生长2～3秒钟时，可以看到许多生长中心与生长台阶的形成，在较宽的台阶上还可以看到二维核的形成，没有看到螺旋中心，说明生长机理是二维成核生长；当温度比饱和点高0.5℃时，在〓解理面上形成螺旋状熔坑，这表明形貌由生长到熔化的转变与温度的关系是非常敏感的；当温度比饱和点高1.5℃时，螺旋状熔坑转变为二维成核状熔坑。

The mathematical model of ruled helicoids on torus is constructed and two expression methods of ruled helicoids are discussed.

基于圆柱螺旋面和圆环螺旋线的形成原理，构建了圆环直纹螺旋面的数学模型，讨论了圆环直纹螺旋面的两种表示方法。

Objective To explore the inhibitory effect of triplex forming oligodeoxynucleotides on replication of HBV and synthesis of antigen.

目的 探讨三螺旋形成寡核苷酸抗乙型肝炎病毒作用。

Long stretches of the continuous DNA molecule wind around these clusters of proteins, or histones, forming beadlike complexes known

这些螺旋和超螺旋形成致密的染色体组结构。每个长链DNA与组蛋白和非组蛋白一起构成染色质物质。

In Polymer, helix is a quite universal configuration Recent experiments show thatsome polymers such as bacterial flagellar filaments can form bistable helices in ionsolutions, which means that left handed helix and right handed helix can coexist in thesame environment The mechanism of this phenomenon has not been explainedsatisfactorily.

在高分子中，螺旋是一种很普遍的高分子组态。近来实验发现，一些高分子，如细菌鞭毛丝，在离子溶液中能够形成双稳态螺旋，即左螺旋与右螺旋在相同的条件下能够同时存在。

The formation mechanism of the hollow and helical fibers was proposed. During the heat treatment, the hollow fibers could be formed when the inner gel of the thinner precursor fibers was separated from the center and contracted to surface. However, the helical fibers could be generated when larger gel fibers were broken helically under thermal stress in the process of gel decomposing and contracting.

分析了中空纤维和螺旋纤维的形成机理，直径较小的前驱体纤维在热处理过程中内部凝胶向表层迁移收缩形成中空纤维；螺旋纤维是由直径较大的前驱体纤维在热处理过程中产生的强大的热应力导致纤维产生螺旋破裂形成的。

The steps include selecting a mould, injecting low temperature hot melt materials, drying the low temperature hot melt material mould, taking out the low temperature hot melt material mould, coating with slurry and sand spraying, drying the sand mould, heating for allowing the low temperature hot melt materials to demould, casting and forming, destroying the sand mould, cutting and processing to obtain the finished product.

取一成型模具：该成型模具包括两个对合的半模，于成型模具内设有一螺旋转子的成型模穴及浇铸道；灌注低温热熔材：于浇铸道灌入熔融的液态低温热熔材，液态低温热熔材即填充于对合的两螺旋转子心轴模穴、及两转子螺旋部半模穴；干燥：液态低温热熔材干燥凝固，形成一具有螺旋转子外型的低温热熔材

The central 5, 5'-disubstituted bipyridine units of each ligand coordinate theNi or Fe ion, while all the terminal 6-monosubstituted bipyridine units of the ligands keep free of coordination, as the result trinuclear triple-stranded helicate 〓 can not form. This is considered to be caused by the steric hindrance of the methylene substituents α to the chelating nitrogens of the terminal bipyridine units and the strain caused by linkage mode.

配体L〓与Ag作用得到〓，两个配体链相互缠绕着两个Ag离子周围形成双股螺旋结构并以头尾式排列(见图3)，由于配体中位于配位N原子α或β位的末端甲基或次甲基取代基的空间位阻阻碍了头对头式异构体的形成，也正是由于配体头尾式排列而使Ag双股螺旋得以形成，这一结果表明该螺旋体的组装过程中自发地采取了空间阻碍尽可能小的那个构型。

As she looked at Warrington's manly face, and dark, melancholy eyes, she had settled in her mind that he must have been the victim of an unhappy attachment.

每逢看到沃林顿那刚毅的脸，那乌黑、忧郁的眼睛，她便会相信，他一定作过不幸的爱情的受害者。

Maybe they'll disappear into a pothole.

也许他们将在壶穴里消失