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91.
Robert Lunsford David Gillis Jacob Grun Jeff Bowles Pratima Kunapareddy Charles Manka Sergei Nikitin 《Journal of Raman spectroscopy : JRS》2012,43(10):1472-1476
In complex environments, the ability to identify the constituent chemicals within a mixture is extremely important. By utilizing a Pearson correlation algorithm to compare sets of multi‐wavelength resonance‐Raman signatures, we demonstrate the automated identification of chemicals within a mixture. Applying a linear mixture model, we are also able to estimate the fractional volumetric abundances contained therein. The multi‐wavelength resonance‐Raman signature used for identification is obtained by illuminating the unknown mixture with a series of 21 sequential laser wavelengths. This signature is then compared with the signatures of a set of known chemicals. By maximizing the Pearson correlation coefficient between the signature of the mixture and a weighted superposition of the signatures of the pure chemicals, we are able to determine the mixture components with 100% accuracy. The linear superposition of the selected chemicals, which minimizes the least squares distance between the signatures of the mixture, and its mathematical recreation determines the corresponding fraction, by volume, of each chemical within the mixture. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
92.
The measurement of crystallinity and orientation in poly(ethylene terephthalate) is discussed. A simple procedure is given for the estimation of orientation from the (1 05) plane, and it is shown that methods which use the equatorial planes are subject to certain disadvantages. In addition a method is given for the measurement of x-ray crystallinity. The technique is applied to fibers and films of various treatments and a linear relation is found between density and x-ray crystallinity. 相似文献
93.
A post-column reagent mixture of Eriochrome Black T and magnesium-EDTA complex is added to the eluent from an ion-chromatograph. Eluted metal cations displace the magnesium, which then forms a complex with the Eriochrome Black T. The absorbance of this complex is measured at 520 nm. Detection limits for several cations are in the mug/ml range. 相似文献
94.
Changes to the financial framework regulating housing associations require them to create a sinking fund that will accrue the necessary cash for future maintenance work to their stock. This paper presents an alternative to the conventional methods by using a Linear Programming model to obtain sinking fund strategies. The relevance of such modelling is discussed with reference to the evolving Sinking Fund system in the UK and European Housing Association movements. The methodology is applied to data from a Housing Association in Scotland. The paper concludes that the LP model offers a degree of flexibility not found in existing practice. The work has relevance to the long-term maintenance management of any built asset. 相似文献
95.
A theory of the modified (distance dependent) electronic mass effect for two-electron diatomic molecules is presented. The modified electronic mass correction is compared with the diagonal Born-Oppenheimer correction to the potential energy curves of H2, suggesting that the adiabatic correction is almost exactly accounted for by this effect. 相似文献
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Sharma P MacNeil JA Bowles J Leaist DG 《Physical chemistry chemical physics : PCCP》2011,13(48):21333-21343
Freezing-point and vapor-pressure osmometry data are reported for aqueous sodium decanoate (NaD) solutions and aqueous NaD + NaCl solutions. The derived osmotic coefficients are analyzed with a mass-action model based on the micelle formation reaction qNa(+) + nD(-) = (Na(q)D(n))(q-n) and Guggenheim equations for the micelle and ionic activity coefficients. Stoichiometric activity coefficients of the NaD and NaCl components and the equilibrium constant for micelle formation are evaluated. Illustrating the remarkable but not widely appreciated nonideal behavior of ionic surfactant solutions, the micelle activity coefficient drops to astonishingly low values, below 10(-7) (relative to unity for ideal solutions). The activity coefficients of the Na(+) and D(-) ions, raised to large powers of q and n, reduce calculated extents of micelle formation by up to 15 orders of magnitude. Activity coefficients, frequently omitted from the Gibbs equation, are found to increase the calculated surface excess concentration of NaD by up to an order of magnitude. Inflection points in the extent of micelle formation, used to calculate critical micelle concentration (cmc) lowering caused by added salt, provide unexpected thermodynamic evidence for the elusive second cmc. 相似文献