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991.
992.
In this Letter, different kinds of solutions including breather-type soliton and two-soliton solutions, are obtained for the modified Korteweg-de Vries (M-KdV) equation by using bilinear form, the extended homoclinic test approach and dependent variable transformations. Moreover,we point out that the author did not obtain so-called periodic two-soliton solutions in W. Long (in press) [1]. 相似文献
993.
Marco A. Fontelos Ana I. Muñoz Emanuele Schiavi 《Nonlinear Analysis: Real World Applications》2010,11(4):2350-2365
In this paper we address one of the problems that has attracted much interest in the glaciological scientific community which is the grounding line dynamics. The grounding line is the line where transition between ice attached to the solid ground and ice floating over the sea takes place. We analyze a mathematical model describing the ice flow near the grounding line where the ice is considered a non-Newtonian fluid. This generalizes the results obtained in [M.A. Fontelos, A.I. Muñoz, A free boundary problem in glaciology: The motion of grounding lines, Interfaces Free Bound. (9) (2007) 67–93] for the Newtonian case and allows us to consider a more realistic rheological model. We prove the existence and uniqueness (in a class to be defined) of weak solutions with moving grounding lines and zero contact angle and also determine the shape and asymptotic properties of the free boundary. Finally some finite element numerical simulations will illustrate the local and global behavior of the problem solutions. 相似文献
994.
In this article, we propose a class of additive-accelerated means regression models for analyzing recurrent event data. The class includes the proportional means model, the additive rates model, the accelerated failure time model, the accelerated rates model and the additive-accelerated rate model as special cases. The new model offers great flexibility in formulating the effects of covariates on the mean functions of counting processes while leaving the stochastic structure completely unspecified. For the inference on the model parameters, estimating equation approaches are derived and asymptotic properties of the proposed estimators are established. In addition, a technique is provided for model checking. The finite-sample behavior of the proposed methods is examined through Monte Carlo simulation studies, and an application to a bladder cancer study is illustrated. 相似文献
995.
In this article, we study the time periodic solutions to the following porous medium equation under the homogeneous Dirichlet boundary condition: The existence of nontrivial nonnegative solution is established provided that 0≤α<m. The existence is also proved in the case α=m but with an additional assumption $\mathop{\min}\nolimits_{\overline{\Omega}\times[0,T]}a(x,t){>}{\lambda}_1In this article, we study the time periodic solutions to the following porous medium equation under the homogeneous Dirichlet boundary condition: The existence of nontrivial nonnegative solution is established provided that 0≤α<m. The existence is also proved in the case α=m but with an additional assumption $\mathop{\min}\nolimits_{\overline{\Omega}\times[0,T]}a(x,t){>}{\lambda}_1$, where λ1 is the first eigenvalue of the operator ?Δ under the homogeneous Dirichlet boundary condition. We also show that the support of these solutions is independent of time by providing a priori estimates for their upper bounds using Moser iteration. Further, we establish the attractivity of maximal periodic solution using the monotonicity method. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
996.
The loop space associated to a Riemannian manifold admits a quasisymplectic structure (that is, a closed 2-form which is non-degenerate
up to a finite-dimensional kernel). We show how to construct a compatible almost-complex structure. Finally conditions to
have contact structures on loop spaces are studied. 相似文献
997.
西部地区高技术产业自主创新能力组合评价研究 总被引:3,自引:0,他引:3
为了提高综合评价的全面性、科学性和合理性,分别运用模糊综合评价法和灰色关联投影法对西部7省(区)1市高技术产业自主创新能力进行评价,在此基础上,利用模糊Borda法对两种单一方法的评价结果进行组合,得出组合评价结果.与单一方法相比,组合评价结果具有较高的可信度,可作为全面提升西部地区高技术产业自主创新能力的决策依据. 相似文献
998.
Global asymptotic stability of a generalized SIRS epidemic model with transfer from infectious to susceptible
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In this paper, we propose a generalized SIRS epidemic model with varying total population size caused by the death rate due to the disease and transfer from infectious to susceptible, where the incidence rate employed includs a wide range of monotonic and concave incidence rates. Applying the geometric approach developed by Smith, Li and Muldowey, we prove that the endemic equilibrium is globally asymptotically stable provided that the rate of loss of immuity $\delta$ is in a critical interval $[\eta,\bar\delta)$ when the basic reproduction number $R_0$ is greater than unity. 相似文献
999.
M. I. Cervera C. Medina T. Portolés E. Pitarch J. Beltrán E. Serrahima L. Pineda G. Muñoz F. Centrich F. Hernández 《Analytical and bioanalytical chemistry》2010,397(7):2873-2891
A multi-residue method has been developed and validated for the simultaneous quantification and confirmation of around 130
multiclass pesticides in orange, nectarine and spinach samples by GC-MS/MS with a triple quadrupole analyzer. Compounds have
been selected from different chemical families including insecticides, herbicides, fungicides and acaricides. Three isotopically
labeled standards have been used as surrogates in order to improve accurate quantitation. Samples were extracted by using
accelerated solvent extraction (ASE) with ethyl acetate. In the case of spinach, an additional clean-up step by gel permeation
chromatography was applied. Determination was performed by GC-MS/MS in electron ionization mode acquiring two MS/MS transitions
for each analyte. The intensity ratio between quantitation transition (Q) and identification transition (q) was used as confirmatory parameter (Q/q ratio). Accuracy and precision were evaluated by means of recovery experiments in orange, nectarine, and spinach samples
spiked at two concentration levels (0.01 and 0.05 mg/kg). Recoveries were, in most cases, between 70% and 120% and RSD were
below 20%. The limits of quantification objective for which the method was satisfactorily validated in the three samples matrices
were for most pesticides 0.01 mg/kg. Matrix effects over the GC-MS/MS determination were tested by comparison of reference
standards in pure solvent with matrix-matched standards of each matrix. Data obtained showed enhancement of signal for the
majority of analytes in the three matrices investigated. Consequently, in order to reduce the systematic error due to this
effect, quantification was performed using matrix-matched standard calibration curves. The matrix effect study was extended
to other food matrices such as raisin, paprika, cabbage, pear, rice, legume, and gherkin, showing in all cases a similar signal
enhancement effect. 相似文献
1000.
以二甲基-β-环糊精(DM-β-CD)为手性添加剂,用毛细管电泳法对消旋体药物尼索地平进行拆分研究。考察了二甲基-β-环糊精浓度、背景电解质种类、缓冲溶液pH值、十二烷基硫酸钠(SDS)浓度、分离电压、温度对对映体分离的影响。结果表明,以pH 8.0的30 mmol/L磷酸二氢钠-磷酸氢二钠溶液(含38mmol/L二甲基-β-环糊精,30 mmol/L SDS)为缓冲液,分离电压15 kV,毛细管温度18℃,检测波长254 nm时,尼索地平对映体达到最佳分离,分离度为1.95,对映体迁移时间分别为13.0、13.54 min。该方法简单、快速、经济,可用于尼索地平对映体的手性分离。 相似文献