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111.
Two organoaluminium amides have been used to initiate the polymerizations of methyl methacrylate, acetaldehyde and n-butyraldehyde. Methyl methacrylate polymerized through the vinyl function to give amorphous products. The aldehydes reacted through the carbonyl group at low temperatures with high degrees of stereospecificity to give polymers with substantial crystallinity. The molecular weight of the polyacetaldehyde is very high. 相似文献
112.
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Given a graphG onn vertices and a total ordering ≺ ofV(G), the transitive orientation ofG associated with ≺, denotedP(G; ≺), is the partial order onV(G) defined by settingx<y inP(G; ≺) if there is a pathx=x
1
x
2…x
r=y inG such thatx
1 ≺x
j for 1≦i<j≦r. We investigate graphsG such that every transitive orientation ofG contains
2
n
−o(n
2) relations. We prove that almost everyG
n,p satisfies this requirement if
, but almost noG
n,p satisfies the condition if (pn log log logn)/(logn log logn) is bounded. We also show that every graphG withn vertices and at mostcn logn edges has some transitive orientation with fewer than
2
n
−δ(c)n
2 relations.
Partially supported by MCS Grant 8104854. 相似文献
114.
115.
S. F. Biagi M. Bourquin R. M. Brown H. J. Burckhart P. Extermann M. Gailloud C. N. P. Gee W. M. Gibson P. Jacot-Guillarmod J. Perrier K. J. Ragan Ph. Rosselet P. Schirato H. W. Siebert V. J. Smith K. P. Streit J. J. Thresher A. T. Wood C. Yanagisawa 《Zeitschrift fur Physik C Particles and Fields》1987,34(2):175-185
In an experiment at the CERN-SPS charged hyperon beam, we have investigated the inclusive \(\Lambda \bar K^0 \) and \(\Sigma ^0 \bar K^0 \) final states formed in Ξ? Be interactions. In the \(\Lambda \bar K^0 \) channel, we observe a signal at 1826 MeV/c2 which can be identified with the known Ξ(1820) resonance. We determine its mass and width to be:M=1826±4 MeV/c2, Г=12±14 MeV/c2. A moment analysis is consistent with a spin of 3/2 and indicates a negative parity for this spin assignment. Also in the \(\Lambda \bar K^0 \) channel, we observe a 3.6σ signal with the following parameters:M=1963±5 MeV/c2, Г=25±15 MeV/c2. This state, which we call Ξ(1960), is not observed in the \(\Sigma ^0 \bar K^0 \) channel, leading to an upper limit on the ratio of partial widths \(\Sigma \bar K/\Lambda \bar K\) of 2.3 (90% confidence level). A moment analysis of the \(\Lambda \bar K^0 \) final state indicates a spin of 5/2 or greater in the natural spin-parity series 5/2+, 7/2?, etc. 相似文献
116.
S. M. Smith N. J. Cronin R. J. Nicholas M. A. Brummell J. J. Harris C. T. Foxon 《International Journal of Infrared and Millimeter Waves》1987,8(8):793-802
We have shown that a Ga1–xAlxAs/GaAs heterostructure can be used as a sensitive tunable detector of mm-wave/sub-mm-wave radiation. The mechanism for detection requires the application of a magnetic field varying from approximately 0.2T at 94GHz (3.2mm wavelength) to 6.2T at 2500GHz (119m wavelength). The responsivity and N.E.P. at 3.2mm have been roughly estimated at 200V/W and 5×10–11W/Hz respectively. The speed of such a detector could be several orders of magnitude greater than comparable InSb detectors. 相似文献
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