阻环

Therefore, this paper analyzes the influences of pipeline length and diameter on the annularly carrying cutting parameter through calculating the friction resistance of pipelines with different geometrical size.

为此，通过对不同几何尺寸排砂管线的摩阻的计算，重点对比分析了排砂管线长度、直径对环空携岩参数的影响，为今后气体钻井排砂管线优选提供了重要的参考依据。

THE FIRST TOTAL SYNTHESIS OF TAXAMAIRIN B Taxamairin B, representive of rare naturally-occuring rearrang-ed 9(10→20)-abeo-8, 11, 13-triene diterpenoids, has been firstsynthesized by a eleven-step route in an overall yield of 8.19%,starting from commercially available catechol and 1,3-cyclohexan-dione. The improved Friedel-Crafts annulation, thermodynamicallycontrolled-geminal pairing methylation, the selective oxidation ofallyl group and the selective reduction of the less-hindrancecarbon-carbon double bond are the key steps.

二。美丽红豆杉素B的全合成研究 1，美丽红豆杉素B的首次全合成以价廉，易得的邻苯二酚和1，3-环己二酮为原料，经过改良的Friedel-Crafts烷基化反应，热力学控制的α，β-不饱和酮结构的α一位双烷基化，烯丙位的选择性氧化，以及选择性还原位阻较小的碳碳双键等十一步反应，以8.19％的总收率首次完成了美丽红豆杉素B的全合成。

Application of closed-loop gain shaping algorithm in rudder roll damping system.

闭环增益成形算法在舵阻摇系统中的应用。

The results indicate that the carbon and the oxygen in the —COOH group,and the nitron in —2—NH group come into formation of different large π bonds with the benzene rings,and there is a dihedral angle of 63.2° because of place blocking and conjugate effect.

结果显示，该分子羧基的碳氧原子、磺酰胺基的氮原子与苯环形成不同的离域大π键，空间位阻效应和共轭效应使两个苯环不在同一平面，二面角为63.2°。

The main products the company has: Hinge 、Casting Container、Locking Gear、Door Locks、Plug、Fitting Hook、Door Seal、Aluminum Profile、 Profile、Meal Hook、Fixation、Track、Cargo Bar、Support Plate、Chuck、Pull Ring、Tache、Buckle、Hook、Pulley、STTMR、Spring catch、Centeral wedge、Buffer block、Rubber lock、Euphroe 、Rope hook、Spiling、Plate、Flashboard、Mudguard、Fender、Military shelter lock、Military step-ladder、Military shelter corner casting、Guardrail、Tarpaulin、Parts for tarpaulin、Electricity Cabinet lock、Air leg、Gas springs、Rubber rolls、Solid tired wheel、Jacks and parts for tow. We also welcome special orders made according to clients' drawings or samples as well.

公司主要产品有：铰链、合页、栏板颌、侧门铰链、集装箱箱角、钢琴铰链、长排铰链、门锁、后门锁、厢式车后门锁、盒锁、工具箱锁、插销、门风钩、门阻、门搭钩、窗封条、门封条、铝型材、包角、厢式车包边、铝围框、肉钩、轨道、固定架、护板、撑杆、撑头、撑板、卡头、卧环、地板钩、拉环、搭扣、带扣、带钩、钩子、滑轮、拉紧器、卡紧器、搭锁、弹簧销、减震块、缓锁器、缓冲块、橡胶块、紧绳器、绳钩、板钩、插桩、钢压板、插板、挡泥板、挡泥罩、军用三岔锁、军用踏梯、军用方舱角件、护栏、漏水器、篷布、软篷系列配件、电柜门锁、气动杆、气弹簧、胶轮、实心轮、千斤顶等拖车配件，并可承接来样，来图加工订做产品。

By synthesizing three amine types inhibitor,we separately put them into top coat and ground coatings measuring with Electrochemical Impedance test and Salt fog test,the conclusion:corrosion inhibiting coal tar-epoxy coatings have more corrosion resistance than coal tar-epoxy coatings.

在环氧煤沥青的底漆和面漆中分别加入自行合成的胺类缓蚀剂R、Y和Z后，采用交流阻抗和盐雾实验等方法测试，结果表明，涂层的耐蚀性能有较大提高，涂层针孔电阻Rfp的值阻提高 2～ 3个数量级，并且涂层的物机性能不受影

This paper analyzes the reason producing surface leakage current of high resistivity detector ,and adopts guard ring to reduce the leakage current.

定性分析了高阻硅探测器表面漏电流的产生，同时介绍了一种有效降低漏电流的方法，即保护环结构。

This presumable suggested that the distance between phenyl ring fusing heterocycle and sulfonyl group is of importance, a shorter distance may not be beneficial, owing to a steric hindrance.

这反映了杂环并合的苯基与SO_2之间距离对活性的影响，距离过近对抑制作用有不利趋势，可能是位阻影响所致。

Using Hexamethylenetetramine as the catalyst and P-Hydroxyanisole as the inhibitor, glycidyl methacrylate were prepared by two-step method successfully.

本论文以六次甲基四胺为催化剂，对羟基苯甲醚为阻聚剂，采用酯化闭环两步法制备出甲基丙烯酸缩水甘油酯。

According to the contrasts between the structure of PANI and that of POT, the conclusion could be made that steric hinderance effect of methyl groups in the poly-O-methylaniline is more prominent than induction effect and hyperconjugation.

比较聚苯胺和聚邻甲苯胺的结构可知，甲基取代苯环中的一个氢原子后，甲基对聚邻甲苯胺的空间位阻效应明显大于诱导效应和超共轭效应。

Singer Leona Lewis and former Led Zeppelin guitarist Jimmy Page emerged as the bus transformed into a grass-covered carnival float, and the pair combined for a rendition of "Whole Lotta Love".

歌手leona刘易斯和前率领的飞艇的吉他手吉米页出现巴士转化为基层所涵盖的嘉年华花车，和一双合并为一移交&整个lotta爱&。

This is Kate, and that's Erin.

这是凯特，那个是爱朗。