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排序方式: 共有8213条查询结果,搜索用时 31 毫秒
1.
随着植物园"旅游经济"的发展,植物园在承担植物科学研究及科普功能的同时,也成为公众日常休闲的重要绿地。本文选取南京中山植物园作为研究对象,建立评价体系并运用模糊综合评价法对游客满意度进行研究,探寻影响植物园游憩功能的显著因子,为未来植物园规划设计提供参考。结果表明:游客对南京中山植物园的游憩功能达到基本满意水平。其中,植物物种多样性、景区分布、建筑景观、声景观的满意度较高,滨水景观的满意度评价值较低。通过Pearson相关系数发现植物色彩丰富度、科普场所、科普内容是影响游客满意度的显著因子。运用IPA图对16项评价因子进行重要度-满意度分析,并对各象限内的因子提出改进方向。最后基于游憩功能满意度评价结果,提出改进策略:加大对植物园休息设施、卫生设施、娱乐设施和商业服务设施的投入;更新科普方式,增添特色游憩主题园区;完善现有道路体系,增强对北部专类园的可达性;增加色叶植物的种类、提高色彩丰富度等。以期为中山植物园游憩功能的优化及其他植物园的规划设计提供借鉴。 相似文献
2.
M.N.M. van Lieshout 《Australian & New Zealand Journal of Statistics》2021,63(1):159-181
We apply the Abramson principle to define adaptive kernel estimators for the intensity function of a spatial point process. We derive asymptotic expansions for the bias and variance under the regime that n independent copies of a simple point process in Euclidean space are superposed. The method is illustrated by means of a simple example and applied to tornado data. 相似文献
3.
Logistic retainment interval dose exploration design for Phase I clinical trials of cytotoxic agents
Thomas A. Murray 《Pharmaceutical statistics》2021,20(4):850-863
Phase I studies of a cytotoxic agent often aim to identify the dose that provides an investigator specified target dose-limiting toxicity (DLT) probability. In practice, an initial cohort receives a dose with a putative low DLT probability, and subsequent dosing follows by consecutively deciding whether to retain the current dose, escalate to the adjacent higher dose, or de-escalate to the adjacent lower dose. This article proposes a Phase I design derived using a Bayesian decision-theoretic approach to this sequential decision-making process. The design consecutively chooses the action that minimizes posterior expected loss where the loss reflects the distance on the log-odds scale between the target and the DLT probability of the dose that would be given to the next cohort under the corresponding action. A logistic model is assumed for the log odds of a DLT at the current dose with a weakly informative t-distribution prior centered at the target. The key design parameters are the pre-specified odds ratios for the DLT probabilities at the adjacent higher and lower doses. Dosing rules may be pre-tabulated, as these only depend on the outcomes at the current dose, which greatly facilitates implementation. The recommended default version of the proposed design improves dose selection relative to many established designs across a variety of scenarios. 相似文献
4.
民族主义是建立在“主权”观念基础上的民族自我意识和情感归属,旨在维护本民族权益、实现本民族和民族国家发展要求的思想观念或意识形态,其在实践中往往演化为建立和发展现代民族国家的社会运动。在民族主义话语中,作为“人民”的民众从历史“后台”向历史“舞台”前置,媒介作为国民的“养成所”,被置于民族救亡与国家建设的中心地位。在人民主权的民族主义话语中,《湘报》报人提出了“报为民史”的传媒属性观、“开启民智”的媒介功能观与“志士精神”的新闻伦理观,推动了湖南新闻思想的近代转型。《湘报》所建构的新闻思想,既接受了“民权”等现代价值观念,又具有儒教的道德激情,其对近代湖湘文化转型,产生了深刻影响。 相似文献
5.
为了全面建设具有中国特色的自然保护地体系,加强对生态功能类自然保护地的空间分布格局及演化特征的基础研究具有十分重要的意义。针对四川省独特的自然地质环境,运用计量地理学以及GIS空间分析等方法,分析1965—2015年期间四川省生态功能类自然保护地的空间分布与演化特征,结果表明:四川省生态功能类自然保护地的空间分布主要为集聚型;虽不均衡但有向平均分布发展的趋势;已演化成以环四川盆地的高密度分布多核区域和高密度分布片区带为主导、川西和川西南呈高密度片区带状分布的格局。研究还发现:四川省生态功能类自然保护地空间分布的重心迁移轨迹呈由东北向西南方向迁移趋势,逐渐接近四川省的几何中心。 相似文献
6.
Duong Thanh Phong Dinh Ngoc Thanh 《Journal of Statistical Computation and Simulation》2019,89(10):1798-1818
We derive the exact expressions of the probability density function (pdf) and the cumulative distribution function (cdf) of Wilks's likelihood ratio criterion Λ and Wilks-Lawley's statistic U in the non-central linear and the non-central planar cases. Those expressions are given in rapidly converging infinite series and can be used for numerical computation. For applications, we compute the exact power of these statistics in a multivariate analysis of variance exercise, and show by simulation the precision of our analytic formulae. 相似文献
7.
8.
Christophe Ange Napolon Biscio Rasmus Waagepetersen 《Scandinavian Journal of Statistics》2019,46(4):1168-1190
We establish a central limit theorem for multivariate summary statistics of nonstationary α‐mixing spatial point processes and a subsampling estimator of the covariance matrix of such statistics. The central limit theorem is crucial for establishing asymptotic properties of estimators in statistics for spatial point processes. The covariance matrix subsampling estimator is flexible and model free. It is needed, for example, to construct confidence intervals and ellipsoids based on asymptotic normality of estimators. We also provide a simulation study investigating an application of our results to estimating functions. 相似文献
9.
A new discrete distribution involving geometric and discrete Pareto as special cases is introduced. The distribution possesses many interesting properties like decreasing hazard rate, zero vertex uni-modality, over-dispersion, infinite divisibility and compound Poisson representation, which makes the proposed distribution well suited for count data modeling. Other issues including closure property under minima, comparison of its distribution tail with other distributions via actuarial indices are discussed. The method of proportion and maximum likelihood method are presented for parameter estimation. Finally the performance of the proposed distribution over other classical and newly proposed infinitely divisible distributions are discussed. 相似文献
10.
Kahadawala Cooray 《统计学通讯:理论与方法》2019,48(8):1902-1919
In this paper we introduced a single parameter, absolutely continuous and radially symmetric bivariate extension of the Farlie-Gumbel-Morgenstern (FGM) family of copulas. Specifically, this extension measures the higher negative dependencies than most FGM extensions available in literature. Closed-form formulas for distribution, quantile, density, conditional distribution, regression, Spearman's rho, Kendall's tau, and Gini's gamma are obtained. In addition, a formula for random variate generations is presented in closed-form to facilitate simulation studies. We conduct both paired and multiple comparisons with Frank, Gaussian, and Plackett copulas to investigate the performance based on Vuong's test. Furthermore, the new copula is compared with Frank, Gaussian, and Plackett copulas using both Kolmogorov-Smirnov and Cramér-von Mises type test statistics. Finally, a bivariate dataset is analyzed to compare and illustrate the flexibility of the new copula for negative dependence. 相似文献