尖端

In order to calculate the crack expansion life in the action of variable amplitude load for the metal bar with V-shaped notch, the formula of bar fracture frequency was obtained theoretically by setting a size of bar fracture region applied in the engineering. Based on it, the mathematic expression of crack expansion life of bar V-shapednotch tip in the action of variable amplitude load was built.

针对金属棒料在变幅载荷作用下需要较精确地获取其V形槽尖端裂纹扩展寿命的问题，通过给定一个工程上能接受的瞬断区尺寸，获得了棒料断裂频率的计算公式，在此基础上，建立了变幅载荷作用下棒料V形槽尖端裂纹扩展寿命的数学表达式。

With the adoption of the rate-sensitive constitutive relationship, it is asymptotically investigated the propagating tip fields of antiplane mode III crack under the condition of incompressibility, and the dynamics equations are obtained separately governing the stress and strain fields at the crack-tip.

采用这种率敏感型本构关系，本文对不可压缩条件下反平面Ⅲ型扩展裂纹的尖端场进行了渐近分析，分别求得了其裂纹尖端应力和应变场的动力学控制方程。

With the adoption of the rate-sensitive constitutive relationship, it is asymptotically investigated the propagating tip fields of plane strain mode Ⅰ,Ⅱ and antiplane mode Ⅲ crack under the condition of incompressibility, and the dynamics equations are obtained separately governing the stress and strain fields at the crack-tip.

采用这种率敏感型本构关系，本文对不可压缩条件下平面应变Ⅰ型、Ⅱ型和反平面Ⅲ型扩展裂纹的尖端场进行了渐近分析，分别求得了其裂纹尖端应力和应变场的动力学控制方程。

Take for the amount of test materials, precision that set, place beaker, unless otherwise specified, may be added 40ml of water and hydrochloric acid solution (1-2) 15ml, and then set on a magnetic stirrer, stirring allows the dissolved, together with potassium bromide 2g insert platinum - platinum electrode, it will insert the solution of the following buret tip is about 2 / 3, using sodium nitrite titration solution (0.1mol / L, or 0.05mol / L) rapid titration, side drops while stirring, to near point, Burette tip surface will be presented with a small amount of water leaching cutting-edge, lotion, and solution and continue titration slowly until the sudden deflection of galvanometer pointer, namely, titration end point.

取供试品适量，精密称定，放置烧杯中，除另有规定外，可加水40ml与盐酸溶液（1-2）15ml，而后置电磁搅拌器上，搅拌使溶解，再加溴化钾2g，插入铂-铂电极后，将滴定管的尖端插入溶液下面约2/3处，用亚硝酸钠滴定液（0.1mol/L或0.05mol/L）迅速滴定，边滴边搅拌，至近点时，将滴定管的尖端提出液面，用少量水淋洗尖端，洗液并溶液中，继续缓缓滴定，至电流计指针突然偏转，即为滴定终点。

The constant term and non-singular terms, which are called general T-stress here, play a significant role in determining the stress and strain fields around a crack tip which in turn can affect the calculation of stress intensity factor of the crack.

裂纹尖端的奇异应力场可以表达为Williams级数展开的形式，其中常数项和非奇异项对裂纹尖端的应力应变场有着很大的影响，这些影响反过来作用于裂纹应力强度因子的计算。

Both theory and experimental results show that decrease of the band width has little effect on the faradic current at the ultramicroelectrodes, however, the non-faradic current is proportional to the area of those electrodes.

开创了用等离子刻蚀法制备纳米金柱电极的方法，电极的最小尖端直径可达30nm，这是目前报道的最小的电极尖端。详细讨论了制备条件对制备电极的影响。

Generally, electric-conductivity materials such as metal, conductive polymers, and graphite are coated on the outside surface of the capillary tip followed by the application of an external high voltage on the tip to provide a sufficient electric field to generate electrospray in seathless interface. Thus, the fabrication of the electric-conductivity material on the surface of fused-silica is one of the main issues when using sheathless interfaces.

一般来说通常需要将金属、导电高分子、或石墨等导电材料涂布於毛细管样品出口尖端，外加第二组电压於导电尖端以提供电喷洒时所需要的电场，但如何将导电材料稳定地涂布於矽氧材质的尖端表面一直是此界面探讨的主题之一。

In this thesis, a pulled bare capillary tip was proposed to be used as the ESI emitter. The outside surface of the tip was neither coated with electric-conductivity materials nor subjected to an external high voltage. Thus, there is no concern such as short lifetime that generally observed in conventional sheathless tips.

本论文尝试直接利用高温拉制及氢氟酸处理过的毛细管尖端做为电喷洒尖端，此设计不需要涂布导电材料及施加第二组电压於毛细管尖端处，此无鞘流界面因此能够避免因导电材料涂布不密合稳定而造成的易脱落及寿命短等问题。

Remember, dog-ears commonly arise from two situations: the angle of the ellipse is too obtuse,or the length discrepancy between the two limbs is too great to allow for a "stealing" stitch.

三角形尖端的缝合法：先从一侧皮肤进针，从创缘内出针后再横行穿过三角形皮瓣尖端的真皮下或皮下，然后由对侧创缘相应厚度进针，穿出皮肤，轻轻拉拢结扎，使三角瓣尖端与两边皮肤对合好。

The main research tasks and results are as follows:(1) Through comparing the stress intensity factor of compact tension specimen calculated by finite element software with the theoretical value, the feasibility of calculating fracture parameters of crack tip in ABAQUS software was verified.(2) The relationship between the elastic modulus of the material and research scale was studied based on deriving the cohesive stress theory and other relevant theories. And the elastic modulus of the material on meso-scale was determined.(3) Global model and sub-model of the finite element were built in th...e macro-scale, and stress-strain field nearby the crack tip was analyzed, and the results show that the detailed stress-strain in the crack tip could be obtained by using the sub-model technique.(4) In meso-scale, the crack growth model was also established by assuming the crack propagating along the grain boundary, and the detailed stress-strain field in the crack tip was obtained.(5) The effect of crack length on Von Mises stress, and maximum principal stress and strain was analyzed in meso-scale when equivalent KI equals 30MPa.m1/2. And the results show that except for crack tip area, the stress-strain distribution in whole specimen is not affected.

主要完成研究内容和取得成果如下：(1)利用有限元软件计算出紧凑拉伸试样的裂纹尖端应力强度因子KI值，其结果与理论值一致，从而验证了利用ABAQUS计算裂纹尖端相关断裂参量的可行性；(2)在研究内聚应力等相关理论的基础上，推导出了研究尺度与材料弹性模量的近似关系，并确定了介观尺度上的弹性模量；(3)在宏观尺度上建立了全局有限元计算模型和子模型，得到了裂纹尖端应力应变场分布，结果表明利用子模型技术获得比较准确的裂纹尖端应力应变场分布是可行的；(4)在介观尺度上利用平均晶粒尺度的方式建立了裂纹沿晶扩展模型，得到了裂纹尖端断裂过程区的微观应力应变场；(5)当应力强度因子为30MPa.m1/2时，分析了介观尺度上在裂纹沿晶扩展过程中裂纹长度对Mises应力、最大主应力和应变的影响，结果表明，裂纹扩展长度对试样整体应力应变分布影响不大，而对裂纹尖端区域有较大影响；(6)介。。。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。