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The molecular chain structure and crystalline structure of PB-ET copolyester made by con-densation polymerization are studied by means of ~(13)C nuclear magnetic resonance spectroscopy(~(13)C NMR),dynamic mechanical analysis (DMA),wide angle X-ray scattering (WAXS),depolarized light intensity (DLI) and stress-strain measurement(S-S).It is shown that PB-ETcopolyester is a random copolymer.Because of different ratios of EG(ethylene glycol)to BD(butane diol)in the copolyester,its crystalline forms and mechanical properties vary remarkably.With the increasing amount of BD,its crystallization kinetic parameters n,k and t_(1/2)~(-1) increaserapidly.When EG/BD equals 25/75 (mole ratio),the copolyester has αβ transition as PBTdoes.  相似文献   

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Chinese students learning English face a number of problems resulting from their isolation from the target language. One problem is that they are not exposed to the varieties of expression within the English language. This makes it difficult, for example, for them to distinguish between formal and informal English.  相似文献   

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The indexing transmission chain error of gear cutting machines is an obviously periodic timefunction. If data are acquired properly while surveying and analyzing the error with grating typeinstrument attached to a micro-computer, the analysis will be easier and quicker. In this paper,such a system is introduced; a data acquiring interface is designed. Therefore, real-time samplingcan be performed. The results obtained from the indexing tramsmission chain error of several gearhobbing and shaping machines with this system were satisfactory.  相似文献   

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The effect of different anion on the morphology of electrode, the adsorption of quinoline and the SER spectra are investigeted. The adsorption peak of quinoline appears in cyclic voltammogram in Cl~- (or Br~-) -containing electrolyte, but not in NV_3~- solution. We also find that the adsorption of quinoline is correlated with Cl~- concentration. This indicates some complex consist of Cl~- and quinolne are produced on Ag surface, Scanning electron microscopy is used to evaluate differences in surface morphology subjected to ORC treatment in different anion solution.The surface morphology of Aq electrode roughened in NO_3~- solution on which no SER signal can be observed differs greatly from that of Ag electrode which roughened in Cl~-(or Br~-)-containing electrolyte.  相似文献   

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THERISEANDDECLINEOFTHEUNITEDSTATESSHIPPINGANDSHIPBUILDINGINDUSTRIES¥(CaptainJamesS.C.Chao,DCS,LL.D.JohnJ.Clark,Ph.D.)Abstract...  相似文献   

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Ouite a few English adverbs appear in two forms;one with the suffixly and the other without the suffixly .Though similar in form,some are consideraldy different in meaning and some in usage.How to use them differentially and skilfally?That is a hard nut to crak.This article makes a brief study with some examplea ,trying to provide a solution.  相似文献   

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Two structure models for knitting fabric are set up according to the wet-heat transmission principle of the fabric. Four kinds of knitted fabrics for sportswear are designed and produced. The wet-heat property of these fabrics is researched.  相似文献   

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Drawing tests upon PET POY have been made by using dynamic thermal stress analyser,which show that the dynamic thermal stress of fiber is readily affected by drawing conditions. Aseries of samples have been obtained under different drawing velocities, drawing temperatures anddraw ratios. The variations of structural factors of fiber such as the orientation, crystallinity,crystallite size and the thermal shrinkage have been measured. It is proved through experimentsthat the thermal shrinkage(Y) of the drawn fiber of PET POY is influenced by the orientation (rep-resented by sonic velocity x_1) and crystallinity (x_2) of the fiber. The quantitative relationship is es-tablished using the binary regression method: Y=10.2246+2.2030x_1-26.2670x_2 The mechanical properties such as tenacity, elongation, yield stress, initial modulus and the te-nacity at 10% elongation, etc. have also been measured. The relations between the tenacity at 10%elongation (D) and drawing velocity(V), draw ratio (DR), drawing temperature (T), and sonic ve-locity and crystallinity have been obtained using a method of mathematical statistics: D=4.594-0.009 6V , D=-8.937+7.170DR, D=2.866+0.00629T, D=-7.34+2.866x_1+6.314x_2 These equations fit well with data from the experiments. This work will be benefical to the control of quality of products and the development of newproducts.  相似文献   

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The electronic structure and conduction properties of two kinds of polyyne derivatives with sulfur addition, palythiirene (PTI) and polydithiete (PDT) have been examined using ab initio Hartree-Fock crystal orbital method. Comparison of the results such as energy gap ? ionization-potential and electron affinity of PTI and PDT with those of polyacetylene (PA) indicates that both PTI and PDT have smaller band gaps than PA and they are better intrinsic semiconductors than PA. The π electron of sulfur atoms partly transport to conjugated polyyne chain.  相似文献   

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本文介绍了水处理药剂GMT_A的缓蚀性能与其分子量大小的关系.研究结果表明,经高速离心机分离后所得的GMT_A低分子量组份(Mr=5×102~8×104)具有良好的缓蚀性能,而高分子量组份(Mr>8×105)具有良好的絮凝净化作用.研究还证实,GMT_A水处理剂在絮凝净化与缓蚀两方面都具有比上述单一组份更优越的应用效果,表明药剂GMT_A分子间有协同效应作用.  相似文献   

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In this paper, we are to report that the 4-dimethylamino azobenzene-4‘-sulfonyl chloride (DABS-CI) can be directly synthesized by the reaction of 4-dimethylaminoazobenzene-4‘-sulfonyle with phosphorus pentachloride, from which the yield is higher than from chlorosulfonation. (l) The experimental procedure is simple, and the quality and purity determined by I. R. spectra, X-ray diffraction reach, even surpass the same products by SERV A (German) in some respects.  相似文献   

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I. In recent years, I have done some researches on H_(R. K)(W) space, and solved one type of non-linear sin-gular integration equations with displacement:where the conditions for the existence and uniqueness of the solution can be found there is also a method in-volving successive approximation by which the solution can be estimated. The research on this type of equa-tion provides a theoritical foundation for the solution of the non-linear Riemann boundary value problem.Ha, R_(R. K)(W) defined as follows;  相似文献   

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Based on observations of earthquakes that have occurredin theplains of eastern China during recent yeas, the characteristics origins, classification and distribution patterns of earthquake landforms in alluvial plains are discussed. In such flat areas, earthquakes are capable of complete reversal of topographic gradients; minor hills can be replaced by hollows and depressions can experience uplift. The major factors influencing the development of such landforms in alluvial plain are the force of the earthquake, surface and sub-surface characteristics, the thicknesses of different subsurface layers, the height of the groundwater table and the relief. Earthquake hndforms in alluvial plains may be classified hto three main groups (1) Landforms directly associated with the liquefaction of sand hyers; (2) Landforms associated with the passage of earthquake waves; and (3) Landforms associated with earthquake structures. In turn, these categories can be further sub-divided. Through analysis of the Tangshan earthquake landforms, several characteristics of the distribuinn patterns of earthquake landforms in allu vial plains have been recognised.  相似文献   

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