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991.
992.
P.A. Forsyth S. Marčelia D.J. Mitchell B.W. Ninham 《Advances in colloid and interface science》1978,9(1):37-60
The role played by statistical mechanics in the ordering of colloidal systems is examined. This role is made explicit through a study of phase (order-disorder) transitions in 1, 2 and 3 dimensions which exist in the examples provided by clay plate, tobacco mossaic virus and latex sphere suspensions. Essentially the statement is that the extrapolation of DLVO theory which attributes stability to a balance between attractive and repulsive two-body forces is not always a panacea. The ideas of Langmuir and Onsager who dealt with statistical mechanics and repulsive forces and considered that attractive long-range forces are not always important are paramount for some systems and must be built into existing theories. 相似文献
993.
994.
995.
Terence N. Mitchell 《Magnetic resonance in chemistry : MRC》1975,7(12):610-614
The proton and carbon-13 NMR spectra of thirteen trialkylmetal derivatives of pyridine, several of which were previously unknown, have been recorded and analysed. The proton NMR spectra show variations in proton chemical shifts but not in proton-proton coupling constants when the metal substituent is changed; the ring proton-metal coupling constants nJ(M? H) in the tin and lead derivatives correspond closely with the corresponding proton-proton couplings nJ(H? H) in pyridine. The carbon-13 chemical shifts of the carbons bound to the metal can apparently be correlated with the electron-donating ability of the trialkylmetal group. In the trimethylstannylpyridines the value of 1J(Sn? Cring) varies greatly with the position of the Me3Sn group. 相似文献
996.
The phosphorescence lifetimes of ω-alkenyl esters of p-benzophenone-carboxylic acid have been measured in dilute solution in degassed acetic acid solution. The lifetimes were extrapolated to infinite dilution. Intramolecular quenching was not very significant in benzophenone-4-CO2(CH2)nCHCH2 for n = 1, 2 or 4. For n = 9 the phosphorescence lifetime was found to be 2 μs compared to 70 μs for n = 1, 2. These results are interpreted to mean that the quenching complex has a specific geometric requirement with the CHCH2 group approaching within a van der Waals distance of the ketone carbonyl group. 相似文献
997.
998.
999.
P.C.H. Mitchell 《Polyhedron》1984,3(4):515
1000.
A force sensor is ordinarily used as a part of a larger system such as a testing machine, test stand, weighing system or process-control system. When a force sensor is calibrated in a standards laboratory and then installed and used in a different system, there may be a significant shift in sensor response due to differences in many factors such as machine-sensor mechanical interaction, loading sequence, loading rate and environmental conditions. NBS research is directed toward establishing the magnitude of the errors due to these factors and developing methods for controlling these errors. Some initial results in the study of machinesensor interaction, hysteresis, thermoelastic effect and creep are discussed here. A long range objective is to enable users to make informed judgments about the adequacy of their own force measurements, based on an understanding of their own measurement process rather than a routine calibration at a standards laboratory. 相似文献