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排序方式: 共有561条查询结果,搜索用时 15 毫秒
1.
The presence of copper atoms as continuous networks at the grain boundaries of an aluminium-copper alloy has been considered not preventing the moving of dislocations during creep (or at least partially). The dislocations can bs absorbed by these boundaries and penetrate through them. That leads to changés of shape and structure of grains and also to the sliding of grains against each other. This was deduced from the accelerating increase in the sensitivity of the steady state creep rate to the applied stress of an aluminium 2·8 wt% copper alloy examined at wide range of temperatures (50–350 °C) and applied stresses (7–170 MPa). This rapid increase in the sensitivity parameter of the steady state creep rate occurs in Al-Cu alloys at quite higher ranges of applied stresses and may be attributed mainly to the contribution of the grain boundary movements to the creep strain. 相似文献
2.
A. Di Maio A. Rocco P. Ferraro M. De Rosa P. De Natale S. De Nicola A. Finizio G. Pierattini G. Coppola M. Iodice V. Striano 《Optics and Lasers in Engineering》2007,45(3):385
In view of the growing interest for non-destructive tests of materials, geodynamical monitoring and in general remote sensing, there is a great effort to bring practical optical sensors from research labs to industrial and environmental applications. In this paper, we employ digital holographic technique as an efficient tool for evaluating the strain measurement capability of fiber Bragg gratings (FBG). A cantilever beam has been employed as a test structure under loading test. The strain measurements results obtained by fiber-based sensors have been compared to those obtained by using full-field digital holographic technique and point-wise strain gauge sensors glued on the same cantilever beam. A simple theoretical model is also presented to interpret and compare the experimental results coming from different techniques. 相似文献
3.
M. A. Macrì C. Del Gratta L. Di Donato S. Di Luzio G. L. Romani S. Della Penna A. Pasquarelli 《Il Nuovo Cimento D》1994,16(5):425-432
Summary A preliminary study is here reported on a new potential marker for biomagnetic measurements. The marker consists of superparamagnetic
polymer microspheres which were detected in the presence of external steady magnetic fields by means of an r.f.-SQUID magnetometer.
The particles were prepared in samples differing in the concentration value and immersed in a homogeneous magnetic field of
variable intensity. A simple model was taken into account for the distribution of the microspheres in the samples, so that
the theoretical values were compared to the marker field values measured by the biomagnetic sensor. The overall sensitivity
of the experimental apparatus and the minimum concentration value of the marker were then estimated. 相似文献
4.
Rocco Duvenhage 《International Journal of Theoretical Physics》2002,41(1):45-61
We first compare the mathematical structure of quantum and classical mechanics when both are formulated in a C*-algebraic framework. By using finite von Neumann algebras, a quantum mechanical analogue of Liouville's theorem is then proposed. We proceed to study Poincaré recurrence in C*-algebras by mimicking the measure theoretic setting. The results are interpreted as recurrence in quantum mechanics, similar to Poincaré recurrence in classical mechanics. 相似文献
5.
Zdenìk Vít Daniela Gulková Ludìk Kalua Miroslav Zdrail 《Reaction Kinetics and Catalysis Letters》2004,83(2):237-244
The effect of support (SiO2-Al2O3, Al2O3,MgO) of the Rh-Mo(S) sulfide catalysts on the synergy in hydrodesulfurization (HDS) of thiophene and hydrodenitrogenation
(HDN) of pyridine was studied. The synergy in HDS was between 7–10 regardless of the kind of support used. The synergy in
HDN varied from none over the MgO supported sample to about 3 over SiO2-Al2O3 supported catalyst, in accord with the positive effect of increasing support acidities.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
6.
Studies of the complexes of pyridinecarboxylic acids with divalent metal ions as a function of the position of the carboxyl groups were extended. The thermal properties of the complexes of quinoline acid (pyridine-2,3-dicarboxylic acid) with several divalent metal ions were determined by thermogravimetry (TG) and differential thermal analysis (DTA). A correlation between these compounds and others obtained by reaction between the studied metal ions with similar acids (lutidinic acid (pyridine-2,4-dicarboxylic acid) and isocinchomeronic acid (pyridine-2,5-di-carboxylic acid) is discussed in terms of the position of the carboxyl group far from the aza group. The thermal stability of the metal complexes is in the order Mn(II) > Fe(II) > Zn(II) ? Co(II) > Ni(II) > Cu(II). 相似文献
7.
In an approach to SRS-A and analogues thereof, the key (5, 6)-epoxy alcohol and its 6-epimer were prepared starting from -araboascorbic acid and -diethyl tartrate, respectively. 相似文献
8.
Arosio D Fontanella M Baldini L Mauri L Bernardi A Casnati A Sansone F Ungaro R 《Journal of the American Chemical Society》2005,127(11):3660-3661
A high-affinity ligand of cholera toxin, the divalent glycocalix[4]arene 1, was obtained by exploiting a combination of structure-based design of glycomimetic monovalent ligands and affinity enhancements by multivalent presentation through a calix[4]arene scaffold. It exhibits a slightly higher affinity for the toxin than its natural ligand, the GM1 oligosaccharide. 相似文献
9.
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