环

The results showed that the MS2 fragmentation pathways of DASSSB were affected by the character and position of substitutes on salicylidene phenyl. The C=N cleaving to form fragmentation ion [M+H-283](superscript +) was dominant for DASSSB compounds with electron-donating group on the C4 of the salicylidene phenyl; while fragmentation ion [M+H-254] (superscript +) forming by C-C cleavage of the β-position of C=N was dominant for DASSSB compounds with electron-withdrawing group on the C5 of the salicylidene phenyl.

结果显示，这些化合物的ESI-MS/MS裂解方式与它们分子中水杨醛苯环上取代基的性质和位置有关：当水杨醛苯环上4位连接供电子取代基时，分子以CN双键断裂为主，生成[M+H-283]碎片离子；当水杨醛苯环上5位连接吸电子取代基时，分子以CN双键β位的C-C键发生断裂为主，生成[M+H-254]碎片离子。

Firstly we prove that 〓 ifR satisfied the stable range 1 condition,〓,whereNis a subgroup of Ugenerated by 〓〓U}.Moreover,we give more concrete results of the semiperfect rings andVBN rings.

首先，对稳定秩为1的环R及其理想I，证明了〓U/N，其中N为U中由{1+ab+ad+cd+〓：a∈I，b∈R，c∈I，d∈I，1+ab+ad+cd+abcd∈U(R，I}生成的子群，进一步，对半完全环和VBN环的相对〓群给出了更具体的结果。

The concept of semialgebra is given,then the realitionship between the additive can-cellation semialgebras with triviality congruence and algebras over semiring.

给出半环上半代数的概念，证明了半环上加法可消半代数，且只有非平凡同余，那么该半代数是半环上的代数。

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香港环盛实业有限公司属下几家公司（深圳环盛科技、乐清市环盛电子）专业生产KCD系列船形开关、AC插座、指示灯、按键开关、RCA型同芯插座、DS限位开关、DC电源插座、外接式插座、微动开关、拨动开关、轻触开关、叶片开关、端子、塑壳连接器、EJ插座、S端子等几十种系列产品，广泛用于电视机、手机、充气机、礼品、车载音响、数码相册、移动硬盘、电动自行车、电动工具开关、电焊机、电脑、空调、冰箱、多媒体产品、台灯、汽车配件等家用电器。

At the same time,we have tried the precess for the preparation of 3-exomethylene cepham sulfoxide ester by the improved ring-expanding method over Kukolja, in which the different acid scavengers are employed in the presence of tolune, NCP and stannic chloride.

同时尝试了改进的Kukolja扩环法合成3—环外亚甲基头孢亚砜酯。以甲苯为溶剂，NCP为卤化试剂，无水SnCl_4为路易斯酸，通过选用了不同的酸清除剂，以制备闭环产物。

Described in chapter 3 is the immediate application of the Clemmensen reductive rearrangement reaction to the polycyclic system as illustrated in a elaboration of the 5-6-7 tricyclie core skeleton of Stemona alkaloids in 5 steps: N-alkylation, [3, 2] -sigmatropic rearrangement, Dieckmann condensation, oxidative cyclization, reductive rearrangement, starting from ethyl pipecolinate hydrochloride.

我们以哌啶酸乙酯为起始原料，经氮烷基化，[3，2]-σ重排，Dieckmann缩合，自由基环化，6-6-6元环系到5-6-7元环系的还原重排五步反应，高收率地构筑了百部生物碱的5-6-7氮杂三环骨架，并用X射线晶体衍射法确定了其结构。

The investigative object of the article is the stepless speed regulating system.

研究的对象是汽车空调风机的无级调速系统，该系统采用双闭环控制，内环和外环都采用模糊PI控制策略。

LY series desulfurizers are synthesized by sterically hindered fatty amine, ethylene oxide andpropylene oxide, which is a ring-splitting polymerization reaction at the catalysts.

采用带有空间位阻基团的脂肪胺在催化剂的作用下与环氧丙烷和环氧乙烷开环聚合，合成LY系列脱硫剂。

Considering gas-solid flow in annular space and BoYun Guo's hydrodynamic parameters model, For aired underbalanced drilling, combined with the minimum energy Angel law and based on the mininum gas injection scale at the key points, it is established a bottom-hole pressure model for gas-solid two phase stream; meanwhile, calculated the downhole depth of the Downhole-Deployment-Valves; and then fabricated the corresponding calculation software. For streamingly underbalanced drilling, it is fully given a step-by-step solution based on analysis from the relationship of various wellbore pressures at the course of underbalanced drilling as well as from the streaming behavior in different wellbore sections, adding consideration on multiphase stream pressure drop and Downhole-Deployment- Valve into account, it is of common application for development wells.

对于气体欠平衡钻井，考虑环空为气固两相流，参考BoYun Guo的流体力学参数计算模型，结合Angel的最小动能法标准，从满足关键点处的最小注气量入手，建立了气固两相流的井底压力计算模型，同时对套管阀的下入深度进行了计算，并利用VB语言编制了相应的计算软件；对于液体欠平衡钻井，考虑环空为多相流，在充分分析欠平衡钻井井内基本压力关系的基础上，从环空多相流压降分析入手，通过对井筒内各段的流态分析，逐段求解。

It deliberated that magnesium sulphate and epichlorohydrin affecting on synthetization of starch xanthate, mass ratio of synthetic starch xanthate and Magnesium sulphate was...

研究了MgSO_4和环氧氯丙烷对DX合成的影响，得出淀粉和MgSO_4的重量比为8：1，淀粉和环氧氯丙烷的重量比为10：1，MgSO_4和环氧氯丙烷对黄原酸化程度没有影响，但能增强交联程度和不溶性。

Do you know, i need you to come back

你知道吗，我需要你回来

Yang yinshu、Wang xiangsheng、Li decang,The first discovery of haemaphysalis conicinna.

1〕 杨银书，王祥生，李德昌。安徽省首次发现嗜群血蜱。