有环的

If R satisfies =0 for any elements x ,y in R then ⑴when k =1, R is commutative;⑵when R has the unity, R is commutative;⑶when R has at least one right regular element and f 2 (t 1,t2) has no terms with degree1 such that Fn= F then R iscommutative when R has at least one right regular element. Here we would like to point out that the above results generalized the results of Fu changlin ,moreover generalized some results of other references . This results enriched the commutative conditions of any ring.

若任取R 中元x， y均有=0 那么⑴k =1时R 为交换环；⑵R 有单位元时R 为交换环；⑶f_2 (t_1，t_2)中t_2的次数不小于k -1且R 中至少有一个右正则元时R 为交换环。

Based on the needs of system control strategy and the output of the active inverter, a switch function method was adopted to build the average model of switch cycle for the active inverter in order to accurately analyze operation characteristic of active inverter, a feed forward and double loop control strategy is put forward, its double control includes a inductor current inner loop control and instantaneous voltage outer loop control.

中文摘要：为准确分析有源逆变器的运行特点，根据系统控制策略的需要，在考虑了有源逆变器输出的基础上采用开关函数法建立了有源逆变器的开关周期平均模型。提出一种前馈加双环控制的控制策略，它的双环控制包括一个电感电流内环控制和一个瞬时电压外环控制。

This dissertation is mainly focused on the reactivity of methylenecyclopropanes and comprises six parts. 1 The reactions of methylenecyclopropanes with phenylsulfenyl chloride, phenylselenyl chloride and diphenyl diselenide; 2 The coupling reactions of the ring-opening products derivated from methylenecyclopropanes; 3 The palladium-catalyzed ring-enlargement of mono-aryl group substituted methylenecyclopropanes to cyclobutenes. 4 The gold-catalyzed domino ring-opening and ring-closing hydroamination of methylenecyclopropanes with sulfonamides; 5 The Lewis acid-catalyzed reactions of mono-aryl group substituted methylenecyclopropanes with diethyl ketomalonate in the presence of water; 6 The iodobenzene diacetate mediated novel 1,3-dipolar cycloaddition of methylenecyclopropanes, vinylidenecyclopropanes, and methylenecyclobutane with phthalhydrazine.

本论文主要研究了亚甲基环丙烷类化合物的一些化学反应性能，共由以下六部分组成：1、亚甲基环丙烷类化合物与苯硫氯、苯硒氯及二苯基二硒的反应；2、亚甲基环丙烷类化合物开环产物的偶联反应；3、单芳基取代的亚甲基环丙烷类化合物在钯催化剂作用下的扩环反应；4、金化合物催化磺酰胺对亚甲基环丙烷类化合物的串联开环关环氨氢化反应；5、路易斯酸催化亚甲基环丙烷类化合物与丙酮二羧酸二乙酯在有水存在下的反应；6、醋酸碘苯促进的亚甲基环丙烷类化合物、亚乙烯基环丙烷类化合物及亚甲基环丁烷类化合物与邻苯二甲酰肼的新型1，3-偶极环加成反应。

Glass-epoxy system used for steel parts, casting a variety of mechanical parts or electronic components as a sealing material, the preparation of polyamide anti-corrosion paintings, as well as a zinc-rich epoxy primer, epoxy primer Iron Cloud, epoxy stone painting, epoxy paint, bituminous coal, chemical corrosion, paint, etc. have also been used widely

用于制环氧玻璃钢制件，浇铸各种机械零件或作为电子元件的密封材料，配制聚酰胺防腐涂料，以及用作环氧富锌底漆、环氧云铁底漆、环氧石漆、环氧煤沥青漆等，在化工防腐，涂料等方面也有广泛用途。

In1932, nineteen year old Arthur Chin and thirteen other young Chinese-Americans sailed for Shanghai, China.2 The hair styles braids and chignons were also shown to reflect the reality of Chin Dynasty.

如发型有螺纹式、浪式；发辫有三股、股，盘曲扭结，走向清楚，丝丝头发，清晰可见；发束有单环、环、环、环，表现出真实生活中束发络髻的各种式样。

Get conclusion:(1 ) the Taihu around region holding basketball game have the advantage;(2) the Taihu around region holding basketball game to have the developping(;3) in Taihu around region farmer basketball game hold worse (4) in Taihu around region basketball sport develop, the game opens exhibition existence the difference of the region;(5)School basketball game opens the exhibition aspect high school not to make widely available, the high level ball team is too little; The high school is more universal, but Be valuing with support"s degree not enough(;6) region of officers and workers" basketball game hold is different greatly and not universal(;7) the Taihu around basketball league match hold more and successfully, but Be taking part in a game a troops and contesting way, ball team real strenght, sponsor company...etc. to still exist some problems, influence the quality of league match development.

得出结论：(1)环太湖地区开展篮球赛事有其优势性；(2)环太湖地区开展篮球赛事有其持续性；(3)环太湖地区农民篮球开展较差；(4)环太湖地区的篮球运动发展，赛事开展存在地域的差异性；(5)学校篮球赛事开展方面高校不普及，高水平球队太少；中学较普及，但在重视和支持程度不够；(6)职工篮球赛事开展地域的差异性大，不普及；(7)环太湖篮球联赛举办较成功，但在参赛队伍、竞赛办法、球队实力、赞助商等方面还存在一些问题，影响联赛发展的质量。

Bulk ceramic tower packing has excellent acid and heat resistance, except hydrofluoric acid outside the capability of various inorganic acids, organic acids and organic solvents, corrosion can be a variety of high-temperature, low-temperature occasions the use of a wide range of applications can be used to chemical industry, metallurgy, gas, oxygen and other industries drying tower, absorption tower, cooling tower, regeneration tower Jincheng packing are: Raschig rings, wash ring, different saddle ring, low ring, cross ring, pall ring, moment saddle ring, ladder ring, SK chain, combined plum blossom ring.

陶瓷散堆塔填料具有优异的耐酸耐热性能，能耐除氢氟酸以外的各种无机酸、有机酸及有机溶剂的腐蚀，可在各种高温、低温场合使用，应用范围十分广泛，可用于化工、冶金、煤气、制氧等行业的干燥塔、吸收塔、冷却塔、再生塔等。金诚填料有：拉西环、洗涤环、异鞍环、低环、十字环、鲍尔环、矩鞍环、阶梯环、 SK 连环、组合梅花环等。

At the initial observation of leakage, judge on the leaking part of the foundation, and then manually set car observation, if the leakage were no significant changes in static and dynamic sealing ring has questions; such as disk when leakage can be concluded that there is significant change are moving , static friction ring problem exist; such as leakage of medium along the jet axis, the actin ring seal problem exist mostly, leakage to the surrounding medium or from the water spray cooling holes in the leakage, the many for the static seal ring failure.

在初步观察泄漏量、判断泄漏部位的基础上，再手动盘车观察，若泄漏量无明显变化则静、动环密封圈有问题；如盘车时泄漏量有明显变化则可断定是动、静环摩擦副存在问题；如泄漏介质沿轴向喷射，则动环密封圈存在问题居多，泄漏介质向四周喷射或从水冷却孔中漏出，则多为静环密封圈失效。

Leakage in the initial observation to determine the basis of the leakage site, and then manually set car observation, if the leakage were no significant changes in static and dynamic sealing ring problem; such as the disk when there are significant changes in leakage can be concluded that the dynamic , static friction ring problems; such as leakage of medium along the jet axis, while moving most of Central ring problems, leakage to the surrounding medium or from the water spray cooling holes in the leakage, the seal ring for static failure.

在初步观察泄漏量、判断泄漏部位的基础上，再手动盘车观察，若泄漏量无明显变化则静、动环密封圈有问题；如盘车时泄漏量有明显变化则可断定是动、静环摩擦副存在问题；如泄漏介质沿轴向喷射，则动环密封圈存在问题居多，泄漏介质向四周喷射或从水冷却孔中漏出，则多为静环密封圈失效。

Leakage in the initial observation to determine the basis of the leakage site, and then manually set car observation, if the leakage were no significant changes in static and dynamic sealing ring problem; such as the disk when there are significant changes in leakage can be concluded that the dynamic , static friction ring problems; such as leakage of medium along the jet axis, while moving most of Central ring problems, leakage to the surrounding medium or from the water spray cooling holes in the leakage, the seal ring for static failure.

在初步察看泄漏量、断定泄露部位的基本上，再手动盘车视察，若泄漏量无显明变更则静、动环密封圈有问题；如盘车时泄漏量有显著变更则可判断是动、静环摩擦副存在问题；如泄漏介质沿轴向喷射，则动环密封圈存在问题居多，泄漏介质向四周喷射或从水冷却孔中漏出，则多为静环密封圈失效。

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％。