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991.
Eliane Espuche Jocelyne Galy Jean-Franois Grard Jean-Pierre Pascault Henry Sautereau 《Macromolecular Symposia》1995,93(1):107-115
Fully cured epoxy networks having different architectures were prepared by introducing either a monoamine acting as a chain extender or an aliphatic epoxy monomer. As expected an increase in the amount of the difunctional amine leads to a decrease in the crosslink density whereas the introduction of an aliphatic epoxy comonomer leads to more flexible chains between crosslinks. Values of the Young modulus and the dependence of the yield stress as a function of temperature were related to the occurrence and amplitude of secondary relaxations. The fracture toughness at room temperature was clearly associated with the glass transition temperature as a consequence of plastic deformation, rather than with chain scission. 相似文献
992.
993.
Olivier Musse Jean-Paul Armspach Izzie Jacques Namer Fabrice Heitz Franciszek Hennel Daniel Grucker 《Magnetic resonance imaging》1998,16(10):1227-1235
This paper presents a data-driven method for the reconstruction and visualisation of curvilinear slices from three-dimensional (3D) magnetic resonance (MR) scans of the head. Visualisation of curvilinear slices, rather than standard planar slices, produces symmetrical views of the cortex and allows small abnormalities to be detected by comparing the two hemispheres of the brain. In our method, the surface defined by the upper half of the brain is used as a reference shape for curvilinear reconstructions. The brain is first segmented from the 3D scan using a 3D region growing method associated to an unsupervised threshold selection technique. The upper half of the segmented brain is then extracted and fitted by a deformable surface model. This surface is finally interactively moved by the operator in the 3D scan, to visualise the desired curvilinear slice, which is projected on the screen as a two-dimensional image. We show an application of this visualisation technique to the localisation of cerebral epileptogenic lesions. The procedure has proven efficient and handy in clinical use. 相似文献
994.
Eliane Alexandre Jacques Cinqualbre Daniel Jaeck Lysiane Richert François Isel Pierre J. Lutz 《Macromolecular Symposia》2004,210(1):475-481
Macromonomer based poly(ethylene oxide) (PEO) hydrogels were tested with respect to their ability to serve as a template for the survival and the growth of hepatocytes. Two systems were considered : either the surface of preexisting hydrogels, with controlled structural parameters, were seeded with isolated rat hepatocytes or the hepatocytes were dispersed in physiological medium containing the macromonomer/initiator and heated to 37°C. In the first case, cells were examined at given times after spreading over two days. The results were compared to those observed for the dispersion of fibroblasts onto a surface of the same type of hydrogels. The effects of the structure of the hydrogels and its chemical nature on the extent of hepatocyte attachment (or encapsulation) and the morphology were investigated. 相似文献
995.
996.
997.
Jean-Pascal Brison Loïc Glmot Hermann Suderow Andrew Huxley Shinsaku Kambe Jacques Flouquet 《Physica B: Condensed Matter》2000,280(1-4):165-171
The quest for a precise identification of the symmetry of the order parameter in heavy fermion systems has really started with the discovery of the complex superconducting phase diagram in UPt3. About 10 years latter, despite numerous experiments and theoretical efforts, this is still not achieved, and we will quickly review the present status of knowledge and the main open question. Actually, the more forsaken issue of the nature of the pairing mechanism has been recently tackled by different groups with macroscopic or microscopic measurement, and significant progress have been obtained. We will discuss the results emerging from these recent studies which all support non-phonon-mediated mechanisms. 相似文献
998.
Jacques Patarin 《Designs, Codes and Cryptography》2000,20(2):175-209
In 1 Matsumoto and Imai developed a new public key scheme, called C*, for enciphering or signing. (This scheme is completely different from and should not be mistaken with another scheme of Matsumoto and Imai developed in 1983 in 7 and broken in 1984 in 8). No attacks have been published as yet for this scheme. However, in this paper, we will see that—for almost all keys—almost every cleartext can be found from its ciphertext after only approximately m
2
n
4 log n computations, where m is the degree of the chosen field K and mn is the number of bits of text. Moreover, for absolutely all keys that give a practical size for the messages, it will be possible to find almost all cleartexts from the corresponding ciphertexts after a feasible computation. Thus the algorithm of 1 is insecure. 相似文献
999.
Alain Walcarius Jérôme Devoy Jacques Bessiere 《Journal of Solid State Electrochemistry》2000,4(6):330-336
Pure silica particles were dispersed within carbon paste and the resulting modified electrode was applied to the selective
voltammetric detection of mercury(II) species after their accumulation at open circuit. The remarkable selectivity observed
between pH 4 and 7 was attributed to the intrinsic adsorption mechanism which involves a condensation reaction between mercury(II)
hydroxide and hydroxyl groups on the silica surface, leading to the formation of an inner-sphere-type surface complex. After
optimization with respect to the electrode composition, the detection medium, and the voltammetric scan mode, a linear response
was obtained in the concentration range between 2 × 10−7 M to 1 × 10−5 M, by applying anodic stripping square wave voltammetry. Various silica samples were used and their sorption behavior was
discussed in relation to their specific surface area and porosity. The effect of chloride and pH on the accumulation of mercury(II)
on silica was also investigated.
Received: 4 September 1999 / Accepted: 5 January 2000 相似文献
1000.
Buncha Pulpoka Jong Sueng Kim Seung Hwan Yang Jacques Vicens 《Journal of heterocyclic chemistry》2001,38(6):1383-1385
Two novel calix[4]cryptands were synthesized from 1,3‐alternate calix[4]bis‐azacrown. “Mappemonde II” consists of one 1,3‐calix[4]bis‐azacrown wrapped by a benzo‐crown ether loop. “Mill II” is composed of two 1,3‐calix[4]bis‐azacrowns linked by two benzo‐crown ether strands. 相似文献