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71.
Nelson J Nieuwenhuyzen M Pál I Town RM 《Chemical communications (Cambridge, England)》2002,(19):2266-2267
Exceptionally large complexation constants for oxalate encapsulated within azacryptand hosts are partly explained by pi-stacking interactions between C=O and aromatic rings. 相似文献
72.
Jane L. Butcher David J. Byron Avtar S. Matharu Robert C. Wilson 《Liquid crystals》1995,19(3):387-396
Thirty compounds, ten members of each of three homologous series of esters derived from 4-hydroxy-4'-n-octyl-, -nonyl-, and -decyl-biphenyl and the 5-n-alkylthiophene-2-carboxylic acids (methyl through to decyl homologues) have been prepared. The liquid crystal properties of these esters, which show extensive smectic polymorphism, have been investigated by thermal optical microscopy, differential scanning calorimetry, and miscibility studies. Four members of the corresponding 4-n-alkylbenzoates have also been prepared in order to compare their liquid crystal behaviour with the 5-n-alkylthiophene-2-carboxylate counterparts: both smectic and nematic thermal stability are higher for the 4-n-alkylbenzoates, by 30.6° and 36.8° C, respectively. 相似文献
73.
Jane Cullum 《Journal of Optimization Theory and Applications》1971,8(1):15-34
An explicit procedure for obtaining discrete approximations to general, nonlinear, fixed-time, continuous, optimal control problems with no intermediate trajectory constraints is presented. It is proved that, if the associated system of differential equations is linear in the control variable, then the optimal solutions of these approximationsconverge to extremals of the original continuous problem. 相似文献
74.
75.
76.
J.A. Edgington V.J. Howard I.M. Blair B.E. Bonner F.P. Brady M.W. McNaughton 《Nuclear Physics A》1974,218(1):151-168
We have measured the double differential cross section for bremsstrahlung production in neutron-proton collisions near 130 MeV. Outgoing nucleons were detected at eight pairs of angles simultaneously. The cross sections agree with several theoretical predictions for those four angle pairs in which the proton emerged at 20° (θ = 20°), but are larger than expected in the four cases that θp = 32°. The method of data reduction, and the sources of uncertainty, are discussed in detail. 相似文献
77.
V.J. Howard J.A. Edgington S.S.Das Gupta I.M. Blair B.E. Bonner F.P. Brady M.W. McNaughton N.M. Stewart 《Nuclear Physics A》1974,218(1):140-150
We have measured the np (nd) elastic scattering cross sections at 25(17) angles in the interval 30°–168° (c.m.), using a neutron beam with a broad spectrum peaked near 130 MeV. At backward angles the outgoing charged particles from a liquid hydrogen (deuterium) target were detected; at forward angles we detected neutrons scattered from a hydrogenated (deuterated) scintillating target. Cross sections have been normalized to the energy dependent solution of the Livermore nucleon-nucleon partial wave analysis, evaluated at 130 MeV. The np measurements represent a marginal improvement on previous work; the nd cross sections show some differences from pd measurements, in agreement with earlier indications at an energy of 152 MeV. 相似文献
78.
79.
[structure: see text] Carbaporphyrinoid systems with semiquinone, cycloheptatriene, or indene subunits react under mild conditions with silver(I) acetate to give stable silver(III) organometallic derivatives. 相似文献
80.
Rigby JH Laxmisha MS Hudson AR Heap CH Heeg MJ 《The Journal of organic chemistry》2004,69(20):6751-6760
An efficient protecting group controlled regioselective chromium(0)-mediated three-component higher order cycloaddition of tethered diynes with cyclic trienes that generates five rings and six stereogenic centers in one step is described. Following a sequence of reactions featuring a chemoselective Baeyer-Villiger rearrangement and a regioselective cyclopropane hydrogenolysis, the total synthesis of 9-epi-pentalenic acid was achieved. 相似文献