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991.
Nanometer scale Al/AlN multilayers have been prepared by dc magnetron sputtering technique with a columnar target. A set of Al/AlN multilayers with the Al layer thickness of 2.9 nm and the AlN layer thickness variation from 1.13 to 6.81 nm were determined. Low angle X-ray diffraction (LAXRD) was used to analyze the layered structure of multilayers. The phase structure of the coatings was investigated with grazing angle XRD (GAXRD). Mechanical properties of these multilayers were thoroughly studied using a nanoindentation and ball-on-disk micro-tribometer. It was found that the multilayer hardness and reduced modulus showed no strong dependence on the AlN layer thickness. Al2.9 nm/AlN1.13 nm multilayer had more excellent tribological properties than single layers and other proportion multilayers with a lowest friction coefficient of 0.15. And the tribological properties of all the multilayers are superior to the AlN single layer. 相似文献
992.
The use of phase-Doppler anemometry (PDA) to characterize the detail in-flight plasma sprayed particle behavior has been demonstrated
previously [Ma et al. Plasma Chem Plasma Process 24(1):85; 25(1):56] The present articles shows further that a direct relationship
may exist between the PDA measured particle volume flux and the coating microstructure and deposition efficiency (DE). In
the situation when the precise particle temperature information is not available, the PDA measured particle volume flux may
provide an alternative to predict quantitatively the variation of the coating microstructure and the DE. By monitoring the
in-flight particle volume flux variations, instead of the particle velocity, size and temperature individually and simultaneously,
the optimal settings of the plasma spraying parameters may also be determined conveniently. However, it is noted that the
effective applications of such approach depend largely on the particle surface morphology and the pre-determination of the
particle size range. 相似文献
993.
994.
Blundell Tom L. Bolanos-Garcia Victor Chirgadze Dimitri Y. Harmer Nicholas J. Lo Thomas Pellegrini Luca Sibanda B. Lynn 《Structural chemistry》2002,13(3-4):405-412
Signaling in living systems needs to achieve high specificity, to be reversible, and to achieve high signal to noise. Signaling mediated by multiprotein systems has evolved that avoids the requirement for high-affinity binary complexes that would be difficult to reverse and which, in the overcrowded cell, would lead to excessive noise in the system. Symmetrical structures are only occasionally formed. When they are, it is principally to colocate components, for example, the tyrosyl kinases of growth factors, where dimers form. Symmetry is, however, often broken, presumably to create more sensitivity and specificity in the signaling system by assembling other components, into higher-order multiprotein systems. The binding of a single heparin to two 1:1 FGF:FGFR complexes is an example, as is the binding of a single ligase to the Xrcc4 dimer, perhaps so creating a further DNA-binding site. 相似文献
995.
A generalized linear differential equation in a Banach space is studied. The construction of a phase space and solutions with the help of the spectral theory of linear operators, ergodic theorems, and degenerate semigroups of linear operators is carried out. 相似文献
996.
The lanthanide sulfotellurides (LS)2Te1+x (0 ≤ x < 0.50) show order-disorder phenomena. Above 450°C, they crystallize in a partially disordered structure, orthorhombic with cell parameters a, b, and c close to 4.1, 5.2, and 13.6 Å, respectively. This structure is determined from diffractometer data on a (HoS)2Te1.34 crystal (R = 0.061). It is built up along the c axis from (L4S) tetrahedra layers, separated by Te planes. Disorder and nonstoichiometry are related to the two vacant Te sites. 相似文献
997.
T Kusama T Soga Y Ono E Kumazawa E Shioya Y Osada S Kusumoto T Shiba 《Chemical & pharmaceutical bulletin》1991,39(8):1994-1999
Two novel analogs of a biosynthetic precursor of lipid A (2) were synthesized. The one analog (3) has acyl groups identical to those of 2, and the other (4) has tetradecanoyl groups in place of the (R)-3-hydroxytetradecanoyl groups of 2. Both 3 and 4 possess an alpha-glycosidically-bound phosphonooxyethyl group in place of the alpha-glycosyl phosphate group of 2. Compounds 3 and 4 exhibited definite antitumor activity against Meth A fibrosarcoma and low toxicity in rabbits, as the original compound 2 does. The replacement of the hydroxytetradecanoyl groups with tetradecanoyl groups barely affected the antitumor activity, but slightly enhanced the toxicity in rabbits. 相似文献
998.
G. V. Pshenichnii Samekh Khamo V. A. Mashenkov L. S. Stanishevskii 《Chemistry of Heterocyclic Compounds》1991,27(1):104-107
The stereomeric 1-benzyl-3-hydroxy-3-methyl-6e-(2-bemyloxyphenyl)-4-piperidones on debenzylation and subsequent reaction with formaldehyde are converted into cis- and trans-1,3,4-10b-tetrahydro-3-hydroxy-3-methyl-2-oxopyrido-[1,2-c][1,3]benzoxazines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 124–127, January, 1991. 相似文献
999.
V. A. Nikitenko S. V. Mukhin S. P. Pivneva G. R. Vlas'yants I. A. Karetnikov S. G. Stoyukhin 《Journal of Applied Spectroscopy》1991,54(6):578-581
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 54, No. 6, pp. 960–964, June, 1991. 相似文献
1000.