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21.
The basic relations of the theory of anisotropic creep of unidirectional glass-reinforced plastics (GRPs) in a three-dimensional stress state are found using a model of a material with inhomogeneous structure and the rheological properties of the resin. These relations are suitable for investigating the stress state of GRPs for resin stresses not exceeding certain values. The phenomena of simple creep and stress relaxation are studied with reference to a unidirectional GRP with an epoxy-maleic resin matrix.Mekhanika Polimerov, Vol. 1, No. 2, pp. 64–69, 1965  相似文献   
22.
Let B(H) be the algebra of all bounded linear operators on a complex Hilbert space H and A(H) ? B(H) be a standard operator algebra which is closed under the adjoint operation. Let F: A(H)→ B(H) be a linear mapping satisfying F(AA*A) = F(A)A*A + Ad(A*)A + AA*d(A) for all AA(H), where the associated linear mapping d: A(H) → B(H) satisfies the relation d(AA*A) = d(A)A*A + Ad(A*)A + AA*d(A) for all AA(H). Then F is of the form F(A) = SA ? AT for all AA(H) and some S, TB(H), that is, F is a generalized derivation. We also prove some results concerning centralizers on A(H) and semisimple H*-algebras.  相似文献   
23.
利用多普勒原理对Cr原子束进行横向准直.应用激光感生荧光技术稳定激光器的频率,把激光器的中心频率稳定在偏离Cr原子共振中心频率-5±0.26MHz的位置.根据理论计算出准直激光束的最小尺寸为13.7mm.根据实验数据选择合适的参数,实现利用多普勒原理横向准直Cr原子束,使原子束的横向分布缩小到原来的1/3. 关键词: 激光准直 激光感生荧光稳频 多普勒冷却  相似文献   
24.
This work deals with numerical solution of transonic flow in turbine cascades. We compare results achieved by SST, TNT and EARSM turbulence models and we also present results achieved by two equations turbulence model with an algebraic bypass transition model. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   
25.
在pH 7.40的Tris-HC1缓冲溶液体系中,采用荧光光谱法和同步荧光光谱法研究了甲基紫(MV)与牛血清白蛋白(BSA)相互作用.结果表明MV与BSA相互作用两者存在一个结合位点,结合常数(KA)为7.628×103 L/mol,MV与BSA主要发生疏水作用,反应是一个吸热、熵增的自发过程.  相似文献   
26.
Serum paraoxonase-1 (PON1) is the most studied member of the group of paraoxonases (PONs). This enzyme possesses three enzymatic activities: lactonase, arylesterase, and paraoxonase activity. PON1 and its isoforms play an important role in drug metabolism as well as in the prevention of cardiovascular and neurodegenerative diseases. Although all three members of the PON family have the same origin and very similar amino acid sequences, they have different functions and are found in different locations. PONs exhibit substrate promiscuity, and their true physiological substrates are still not known. However, possible substrates include homocysteine thiolactone, an analogue of natural quorum-sensing molecules, and the recently discovered derivatives of arachidonic acid—bioactive δ-lactones. Directed evolution, site-directed mutagenesis, and kinetic studies provide comprehensive insights into the active site and catalytic mechanism of PON1. However, there is still a whole world of mystery waiting to be discovered, which would elucidate the substrate promiscuity of a group of enzymes that are so similar in their evolution and sequence yet so distinct in their function.  相似文献   
27.
Empirical expression for experimentally obtained functional dependence between the results of total -activity and integral -activity activity of fallout, measured during May, 1986, at a control point: 44°47 northern latitude and 20°32 eastern longitude, has been established in order to enable estimation of the level of fallout contamination by -emitters when total -activity values are known.  相似文献   
28.
Résumé On a mis au point une méthode d'analyse par activation neutronique du lanthane et de l'or en quantités inférieures au ppm dans l'acier, sans détermination du rendement chimique. La méthode consiste à isoler quantitativement les activités de La et d' Au par des procédés d'échange d'ions et à faire ensuite une spectrométrie NaI(T1). La limite de détection est abaissée jusqu'à 10 et 5 ppb pour La et Au respectivement. Il n'y a pratiquement pas d'interférence avec les autres éléments habituellement présent dans l'acier.   相似文献   
29.
In this work the vibrational analysis of (hydroxypyridin-3-yl-methyl)phosphonic acid (MC5) is presented using both experimental and theoretical methods. FT-IR spectra of the solid state MC5 precipitated at certain pH values in which consecutive deprotonations of this ligand occurs were recorded. Thus, we were able to measure IR spectra of cationic, two anionic and zwitterion forms of MC5. Additionally, the geometry optimization and vibrational frequencies were performed at the B3PW91 level with the 6-31G** basis set for each species. As was shown, FT-IR spectra could be fairly good reproduced by a theoretical method applied here. Additionally, charge distributions and aromaticity index were calculated for discussed MC5 forms by using generalized atomic polar tensor and harmonic oscillator model of aromaticity, respectively.  相似文献   
30.
A novel bipolar conjugated polymer containing triphenylamine and 1,3,4-oxadiazole units was synthesized by Suzuki reaction.Its structure and properties were characterized by NMR,IR,UV-Vis,PL spectroscopy and electrochemical measurement. The photoluminescent spectroscopy and cyclic voltammograms measurement demonstrated that the resulting polymer shows blue emission (477 nm) and possesses both electron and hole-transporting property.  相似文献   
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