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排序方式: 共有170条查询结果,搜索用时 31 毫秒
11.
Fernand Pla 《Macromolecular Symposia》1995,92(1):243-252
The main parameters which may affect both reactor performance and polymerization processes in heterogeneous media are described. Viscosity and its influence on heat and mass transfer, residence time distribution in tubular reactor, as well as, influence of agitation on coagulum formation and of monomer feed rate on polymerization rate in semi-batch processes are examined. 相似文献
12.
Fernand Ellyin 《Experimental Mechanics》1970,10(5):195-202
Ten steel plates weakened by the penetration of an oblique circular cylindrical aperture have been tested. The generator of the aperture makes 0-, 15-, 30- and 45-deg angles with the normal to the plate surface. In the case of the first seven models, the tractions were applied in the direction normal and parallel to the plane of symmetry. The strain distributions around the aperture are presented in nondimensional forms along three generators 45 deg apart. The last three models, with large aperture diameter, were tested to investigate the effect of thickness-to-diameter ratio for the three angles of skewness. The experimental results are compared with the theoretical predictions. It is noted that, for most of the plates, there was a fairly good agreement for the stress distribution throughout the thickness. The results of the experiments for uniaxial state of stress have been superimposed in order to obtain the response for various biaxial conditions. 相似文献
13.
Gabelli J Reydellet LH Fève G Berroir JM Plaçais B Roche P Glattli DC 《Physical review letters》2004,93(5):056801
We present the first study of the statistics of GHz photons in quantum circuits, using Hanbury Brown and Twiss correlations. The super-Poissonian and Poissonian photon statistics of thermal and coherent sources, respectively, made of a resistor and a radio frequency generator, are measured down to the quantum regime at milli-Kelvin temperatures. As photon correlations are linked to the second and fourth moments of current fluctuations, this experiment, which is based on current cryogenic electronics, may become a standard for probing electron/photon statistics in quantum conductors. 相似文献
14.
W. R. Plaß T. Dickel M. Petrick D. Boutin Z. Di T. Fleckenstein H. Geissel C. Jesch C. Scheidenberger Z. Wang 《The European physical journal. Special topics》2007,150(1):367-368
A novel system consisting of RF quadrupole and time-of-flight sections
is proposed, in which ions can be cooled, bunched, mass separated with a resolution sufficient to
differentiate between isobars, and guided to different experimental setups, e.g. for precision mass
measurements or mass-resolved decay spectroscopy. It enables multiplexed operation of
several connected experiments and interleaved measurements using different nuclides in one connected experiment.
Such a system could be employed advantageously at in-flight facilities, at which experiments with stopped
exotic nuclei are made possible using gas-filled stopping cells, such as SHIPTRAP at GSI, or potentially
at ISOL facilities. First results for individual stages of the system are presented. 相似文献
15.
This study presents a natural convection problem with a temperature-dependent viscosity fluid, driven by buoyancy and influenced
by horizontal temperature gradients. A numerical linear stability analysis of the stationary solutions is studied. The horizontal
temperature gradients tend to localize motion near the warmer zones and favour pattern formation in the direction perpendicular
to the gradient. In fact, the problem is almost 2D in the uniform heating case, but becomes totally 3D in the non-uniform
heating case. 相似文献
16.
Addition of proline in acetic anhydride to propiolic and pbenylpropiolic ester gave rise to two isomeric pyrroles 5 and 6 . Addition under the same conditions, to electrophilic alkenes pY-PhCH = C(X) (CN) led to a pyrroline-2 8 which eliminated HCN and produced pyrrole 9 . Addition of proline to fumarodinitrile is unusual, the reaction led to a new α-amino acid 10 and compound 11 . The structure of this product 11 was confirmed by X-ray measurements. 相似文献
17.
In recent years, Mitogen-Activated Protein Kinase (MAPK) pathways have emerged as major regulators of cellular physiology. In the fungal pathogen Candida albicans, three different MAPK pathways have been characterized in the last years. The HOG pathway is mainly a stress response pathway that is activated in response to osmotic and oxidative stress and also participates regulating other pathways. The SVG pathway (or mediated by the Cek1 MAPK) is involved in cell wall formation under vegetative and filamentous growth, while the Mkc1-mediated pathway is involved in cell wall integrity. Oxidative stress is one of the types of stress that every fungal cell has to face during colonization of the host, where the cell encounters both hypoxia niches (i.e. gut) and high concentrations of reactive oxygen species (upon challenge with immune cells). Two pathways have been shown to be activated in response to oxidative stress: the HOG pathway and the MKC1-mediated pathway while the third, the Cek1 pathway is deactivated. The timing, kinetics, stimuli and functional responses generated upon oxidative stress differ among them; however, they have essential functional consequences that severely influence pathogenesis. MAPK pathways are, therefore, valuable targets to be explored in antifungal research. 相似文献
18.
Chati F Léon F Décultot D Maze G 《The Journal of the Acoustical Society of America》2011,129(4):1899-1904
This paper revisits the vanishing of the transverse component of the particle displacement vector in free surfaces of an isotropic homogeneous plate, for both symmetric and antisymmetric Lamb waves. Drawing on well-known analytical expressions from Viktorov's book [(1967) Rayleigh and Lamb Waves: Physical Theory Applications, Chap. II, pp. 67-121], two distinct frequency-thickness product expressions, in cases where this vanishing occurs, are derived: one for the symmetric modes and another for the antisymmetric modes. At these frequency-thickness products, phase and group velocities have appreciable values which are discussed herein. It appears that these velocities depend on the transverse bulk wave velocity only. This is the specific condition of the Lame? modes. Moreover, theoretical and experimental investigations of displacements in the surface of a plate in air have been carried out. The theoretical part shows that the normal and transverse displacements have, respectively, a local maximum and a local minimum in the vicinity of these frequency-thickness products. The experimental part corroborates the presence of the local maximum of the S(0) Lamb mode for various materials. 相似文献
19.
V. M. Ruutu J. J. Ruohio M. Krusius B. Plaçais E. B. Sonin E. V. Thuneberg Wen Xu 《Czechoslovak Journal of Physics》1996,46(1):9-10
The maximum number of vortex lines at a given angular velocity Ω is obtained during deceleration when vortices annihilate at the wall of the container. The width of the vortex-free region in the decelerated state has been measured by cw NMR for vortex lines with singular and continuous core structures. It corresponds to the limit of stability of peripheral vortices for single and double quantization respectively. 相似文献
20.
1-Dimethylamine-1-carba-closo-dodecaborane(1), 1-(CH3)2NH-1-CB11H11, can be smoothly demethylated with iodine in weakly alkaline solution to produce 1-methylamine-1-carba-closo-dodecarborane(11), 1-CH3NH2-1-CB11H11. The latter compound undergoes formylation with formaldehyde and iodine to give 1-hydroxymethylene-methylamine-1-carba-closo-dodecaborane(11). Further chemical transformations of both compounds are reported. 相似文献