基于MATLAB的异步电动机线性化控制系统的仿真

从异步电动机在同步旋转坐标系下的状态方程出发，在一定的条件下，对其系数矩阵简化．推出异步电动机的线性化控制模型．并基于该模型得出异步电动机的线性化控制系统．以给定电机为例，对该模型的有效性、响应用MATLAB进行仿真分析．验证的结果说明上述模型具有实用价值．     

Letters to the Editor

The Mathematical Intelligencer encourages comments about the material in this issue. Letters to the editor should be sent to either of the editors-in-chief, Chandler Davis or Marjorie Senechal.     

RO-heparin Inhibits L-Selectin-mediated Neutrophils Adhesion to Vascular Endothelium Under Flow Conditions

Introduction Migrationandrecruitmentofleukocytesfromblood toinflammatorylesionsitesaresequentiallyregulated byadhesionmoleculesandtheirreceptors[1].These lectinfamilyplaysamajorroleininitiatingattachement ofneutrophilstotheactivatedendothelium.P selectin,…     

An ESR study of some group IVB free radical adducts of diethylketomalonate

The formation of the compound RSnX(acac)₂ (acac = 2,4-pentanedionato) by reaction of bis(2,4-pentanedionato)tin(II) on a halide RX with R = CH₃, C₂H₅, C₄H₉, C₆H₅, CH₂I, (C₆H₅)₃SnCH₂, (C₂H₅)₃SnCH₂ and X = I, Br has been studied by polarography. At 25°C, it is in fact an equilibrium whose constant has been measured. The intermediate formation of the ion-pair [RSn(acac)₂⁺X^?] has allowed us to explain the experimental results.     

化学键合吸附剂的合成及吸附行为

在无定型硅胶上化学键合十八烷基三氯硅烷，键合率17%-20％，粒度5μm-10μm，以此键合的吸附剂可有效地吸附香烟烟气中的焦油、亚硝胺，吸附率分别为15%-18％和37%-43％，研究了化学键合吸附剂的粒度和加入量对吸附性能的影响。     

Amber‐Woody Scent: Alcohols with Divergent Structure Present Common Olfactory Characteristics and Sharp Enantiomer Differentiation

Only one out of the four possible trans isomers of the important perfumery alcohol Norlimbanol^® ( 1 ) possesses a very strong amber‐woody smell, the isomer 1A with (1′R,3S,6′S) absolute configuration. Its enantiomer 1B is almost odorless and devoid of amber‐woody character, whereas the diastereoisomers 1C and 1D are considerably weaker and perceptible only by the most‐sensitive persons. The same is true for a whole series of perceptual analogs of 1 , including β‐alkoxy alcohols. These ethers belong to two structural classes: [(2,2,6‐trimethylcyclohexyl)oxy]‐ (see 3, 4 , and 16 ) or {[2‐(tert‐butyl)cyclohexyl]oxy}alkan‐2‐ol derivatives (see 19 and 20 ; Table). A superimposition model allowing for good overlap of the respective hydroxylated side chains offers a tentative explanation for the shared perceptual characteristics of the two classes (Fig. 5). The lipophilic cyclohexane moieties present only a minimal overlap in this model, suggesting that quite larger molecules might possess the same smell. (S)‐Configured β‐alkoxy alcohols can conveniently be obtained on a larger scale by enantioselective reduction of the corresponding ketones (Scheme 9).     

Discovery of a new phosphotyrosine mimetic for PTP1B using breakaway tethering

Protein tyrosine phosphatases play important roles in many signaling cascades involved in human disease. The identification of druglike inhibitors for these targets is a major challenge, and the discovery of suitable phosphotyrosine (pY) mimetics remains one of the key difficulties. Here we describe an extension of tethering technology, "breakaway tethering", which is ideally suited for discovering such new chemical entities. The approach involves first irreversibly modifying a protein with an extender that contains both a masked thiol and a known pY mimetic. The extender is then cleaved to release the pY mimetic, unmasking the thiol. The resulting protein is screened against a library of disulfide-containing small molecule fragments; any molecules with inherent affinity for the pY binding site will preferentially form disulfides with the extender, allowing for their identification by mass spectrometry. The ability to start from a known substrate mimimizes perturbation of protein structure and increases the opportunity to probe the active site using tethering. We applied this approach to the anti-diabetic protein PTP1B to discover a pY mimetic which belongs to a new molecular class and which binds in a novel fashion.