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1.
Received on 1 July 1991. Behaviour-scoring systems for authorizations enable the riskof a customer defaulting to be quantified. These risks mustbe incorporated into a credit strategy which assigns creditlimits and makes authorization decisions in the most effectivemanner. This paper introduces the concept of marginal risk whichhas proved a useful tool in defining credit limit strategiesfor a mail-order company. Behaviour scores for authorizations are similar to credit applicationscores in that they predict the overall risk of a customer defaulting.If a cut-off risk can be established, then the optimal strategywould appear to be to withhold credit for customers exceedingthis risk and to grant unlimited credit for the remainder (thisis analogous to application strategies). The notion of grantingunlimited credit is often commercially unacceptable (particularlyif customers are to be informed of their credit limits!) andso strategies which give all or nothing are of limited valueand need further refinement. In order to overcome this problem, the concept of marginal riskhas been devised. The marginal risk is the risk of the last£ of an account being defaulted. This reflectsthe fact that small-balance customers may well pay off theircurrent balance only to default on larger subsequent purchases.Although the overall risk of customers with a given behaviourscore defaulting is relatively constant, their marginal riskwill vary according to their outstanding balance. This paperexplores the relationships between marginal risk and overallrisk and between marginal risk and outstanding balance. A modelwhich summarizes these relationships is proposed, and contoursof equal marginal risk are built on the basis of this model.These contours provide strategies for allocating credit limitswhich are both practical and optimal for a well formulated cut-offrisk and which suggest that the probability of defaulting isnot the best criterion for allocating credit limits. The results of the application of this approach will be demonstrated.Some of the problems that have been overcome are discussed,as are some of the outstanding problems. 相似文献
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Abstract— Chlorella cells were cultured in darkness on glucose and examined for pigment composition, capacity to evolve oxygen, and capacity to photo-oxidize artificial electron donors to Photosystems II and I. Evidence was obtained which indicated that such cells lack oxygen-evolving centers and the Mn pool associated with such centers but possess fully active System II and I trapping centers. Brief illumination ( t 1/2 ˜ 2–3 min) of dark-grown cells resulted in incorporation of Mn into the O2 -evolving centers and the capacity to evolve O2 (photo-activation). Kinetic data from flashing or continuous light showed that the photoactivation is a multi-quantum process involving several rate limitations and a photosensitive state of limited stability. Measurements of oxygen-yield oscillations indicated that throughout the photoactivation process each newly formed oxygen-yielding center was independent of its neighbors. It is concluded that photoactivation of the Mn-containing oxygen-yielding catalyst is a fundamental process in all photosynthetic oxygen-evolving tissue. 相似文献
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A dielectric study is proposed in order to describe the behaviour of a composite polymer conductor such as the combination polypropylene-carbon black, as a function of the charge volume fraction in the range from direct current to 5 GHz by time domain reflectometry (TDR). A mixture law generalization leads to the dielectric characterization of the charge embedded in the composite. 相似文献
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Seven cesium and 86 oxidized cesium clusters, CsnOm (0 < m < n; n = 3-14), are ionized in a one-photon process by means of a tunable cw dye laser and detected in a mass spectrometer. 相似文献
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J. BOIDEN PEDERSEN MARTIN J. HANSEN ANATOLE A. NEUFELD MASANOBU WAKASA HISAHARU HAYASHI 《Molecular physics》2013,111(9):1349-1354
Magnetic field effects on the hydrogen abstraction reaction of 4-methoxybenzophenone with thiophenol in several solvents of different viscosity have been reported, and the observed magnetic field dependence was explained as caused by the Δg and a polarized initial triplet radical pair state. The present work reports a quantitative analysis of the data based on a recently derived general analytical formula. It is found that the observed magnetic field dependence can be explained as originating from an unpolarized triplet state, if both the coherent mixing caused by different g values of the two radicals and the incoherent mixing due to spin relaxation are included. Several different expressions for the magnetic field dependence of the longitudinal and transverse relaxation rates were applied. Rather surprisingly, the different models gave almost identical fits. However, the values obtained of the microscopic parameters depended significantly on the model. Physically sensible parameter values were obtained only when the complete magnetic field dependence of the two relaxation times were used. For this model it was found that both the anisotropy factor of the g tensors and the diffusion coefficient agreed with expectations. 相似文献
7.
The Helmholtz free energy of highly charged plates immersed in an electrolyte solution in a finite container is investigated using mean field theory. Exact solutions of the Poisson-Boltzmann equation under Dirichlet and Neumann boundary conditions lead to analytical expressions for the free energies. Adiabatic potentials of the charged plates, which are derived from the free energy, have long-range weak attractive parts and medium-range strong repulsive parts, irrespective of the type of boundary conditions. The repulsion results mainly from the osmotic pressure of the excess ions trapped between the plates by the large surface charges and the attraction arises essentially from an electric pull from the intermediate cloud of excess counterions shared by the plates. 相似文献
8.
CLAIRE BOISSET HENRI CHANZY MARTIN SCHULEIN BERNARD HENRISSAT 《Cellulose (London, England)》1997,4(1):7-20
Because cellulases are finding more applications in the textile and detergent industries, their effect on cotton fibres must
be evaluated. For this purpose, the action of a recombinant cellulase, endoglucanase V from the fungus Humicola insolens,
has been followed by scanning electron microscopy (SEM) in classical longitudinal views as well as in cross-sections of cotton
fibres. The experiments were conducted at large enzyme dilution typical of conditions where cellulases are used for biopolishing,
i.e. for the removal of defects created by mechanical abrasion. Endoglucanase V appears to restrict its action to the hydrolysis
of the loose fibrils created at the surface of the fibres and no indication of extensive enzyme penetration and damage to
the interior of the fibres could be detected by SEM. The adsorption sites for endoglucanase V on cotton fibres were examined
by transmission electron microscopy (TEM) on ultrathin cross-sections after immuno-gold labeling of the enzyme. This approach
showed that the enzymes did not penetrate the fibres but remained at their surface. The use of an immuno-gold labeled cellulase
provides a new way to probe the surface features of cotton fibres
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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