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31.
Zhang Jingru 《生物数学学报》1997,(2)
IIntroductionA。ebasicandimport。tbiologicalquestiontoaskiswhetherornotthOSein、Ivedpopu-lati。willbealiveandwellinthelOng。Therefore,po~ceand印出llityofag。Sys-temareInterestingandimPO~bilolgitallyaswellasInathernatically.Sincethep;oneerlflgtheoretitalworkbyShell—t‘),-yworkshwe由以旧dmtheeffectof叩analfaCtOYswhi山playacrucialroleinpennanenceandst北ilityOfp水"lations.Infa戊,the山S严rsalbtweenpat山esdtenco。r。Inecologi]envi。t,and。er」lstlcmeddssh讪dincludethedisp四油p… 相似文献
32.
研究了一类基于比率的具有反馈控制的非自治捕食模型,得到了系统一致持久和其周期系统存在唯一全局渐近稳定的周期解的充分性条件. 相似文献
33.
34.
本文讨论了一类具有强连续时滞的捕食-被捕食模型,分析了各非负平衡点的稳定性,利用区域连续收缩方法,得出非负平衡点全局稳定的充分条件,给出正平衡点全局稳定的充分条件,并给出系统出现Hopf的分支值. 相似文献
35.
Consider the mixed model where xijk's are known constants, βk are unknown parameters and ai, eij are random variables independently and normally distributed with zero means and variances σdi and σ2 respectively, where it is assumed that the di's are known (di >0). This paper presents procedures for estimating the variance components σ, σ2, for testing the hypothesis σ = 0, and for making transformations to random variables with uncorrelated errors and constant variances in order to estimate as well as to test hypothesis concerning the βk's in the model. 相似文献
36.
A. Martín Andrs I. Herranz Tejedor 《Biometrical journal. Biometrische Zeitschrift》2003,45(4):426-436
In applied statistics it is customary to have to obtain a one‐ or two‐tail confidence interval for the difference d = p2 – p1 between two independent binomial proportions. Traditionally, one is looking for a classic and non‐symmetric interval (with respect to zero) of the type d ∈ [δL;δU], d ≤ δ0 or d ≥ δ0. However, in clinical trials, equivalence studies, vaccination efficacy studies, etc., and even after performing the classic homogeneity test, intervals of the type |d| ≤ Δ0 or |d| ≥ Δ0, where Δ0 > 0, may be necessary. In all these cases it is advisable to obtain the interval by inverting the appropriate test. The advantage of this procedure is that the conclusions obtained using the test are compatible with those obtained using the interval. The article shows how this is done using the new exact and asymptotic unconditional tests published. The programs for performing these tests may be obtained at URL http://www.ugr.es/~bioest/software.htm. 相似文献
37.
《Journal of biological dynamics》2013,7(6):619-635
In this paper, the existence and global asymptotic stability of positive periodic solutions of periodic n-species Lotka–Volterra impulsive systems with several deviating arguments are studied. By using the continuation theorem of coincidence degree theory and Lyapunov–Razumikhin method, sufficient conditions are obtained. Some known results are improved and generalized. 相似文献
38.
Global asymptotic stability in Volterra's population systems 总被引:4,自引:0,他引:4
K. Gopalsamy 《Journal of mathematical biology》1984,19(2):157-168
Sufficient conditions which can be verified easily are obtained for the global asymptotic stability of the positive steady state in Volterra's population system incorporating hereditary effects. 相似文献
39.
得到下列非线性差分方程xn 1=xnxn-1 xn-2 axn-1 xnxn-2 a,n=0,1,2,…,其中a∈[0,∞),初值x-2,x-1,x0∈(0,∞),全局渐近稳定性的一个充分条件,并且证明了一个猜测。 相似文献
40.
Anil C. Mathew Elbin Siby Amal Tom Senthil Kumar R 《Journal of Exercise Nutrition & Biochemistry》2021,25(1):30
[Purpose]Many studies have observed a high prevalence of erectile dysfunction among individuals performing physical activity in less leisure-time. However, this relationship in patients with type 2 diabetic patients is not well studied. In exposure outcome studies with ordinal outcome variables, investigators often try to make the outcome variable dichotomous and lose information by collapsing categories. Several statistical models have been developed to make full use of all information in ordinal response data, but they have not been widely used in public health research. In this paper, we discuss the application of two statistical models to determine the association of physical inactivity with erectile dysfunction among patients with type 2 diabetes.[Methods]A total of 204 married men aged 20-60 years with a diagnosis of type 2 diabetes at the outpatient unit of the Department of Endocrinology at PSG hospitals during the months of May and June 2019 were studied. We examined the association between physical inactivity and erectile dysfunction using proportional odds ordinal logistic regression models and continuation ratio models.[Results]The proportional odds model revealed that patients with diabetes who perform leisure time physical activity for over 40 minutes per day have reduced odds of erectile dysfunction (odds ratio=0.38) across the severity categories of erectile dysfunction after adjusting for age and duration of diabetes.[Conclusion]The present study suggests that physical inactivity has a negative impact on erectile function. We observed that the simple logistic regression model had only 75% efficiency compared to the proportional odds model used here; hence, more valid estimates were obtained here. 相似文献