نتایج جستجو برای: reveres wiener indices

تعداد نتایج: 90442  

Journal: :iranian journal of mathematical chemistry 2012
a. yoosofan m. namazi−fard

the mathematical properties of nano molecules are an interesting branch of nanoscience forresearches nowadays. the periodic open single wall tubulene is one of the nano moleculeswhich is built up from two caps and a distancing nanotube/neck. we discuss how toautomatically construct the graph of this molecule and plot the graph by spring layoutalgorithm in graphviz and netwrokx packages. the sim...

Hamid Ahani, Hamid Jalilvand

Forests are biologically diverse systems, representing some of the richest biological areas on Earth. They offer a variety of habitats for plants, animals and micro-organisms. However, forest biodiversity is increasingly threatened as a result of deforestation, fragmentation, climate change and other stressors. Biodiversity is the variation of life forms within a given ecosystem, biome, or on t...

ژورنال: بوم شناسی آبزیان 2017

This study was carried out to investigate the phytoplankton composition in Gorgan Bay. Water samples were collected from 11 selected sites in Golestan bay, monthly from March to February. Thirty five genus were identified among which Bacillariophyta was the dominate group with 17 genus, while the Euglenophyta had the minimum. Abundance and biomass of phytoplankton showed spatial and temporal va...

2003
V. Shankar Raman Costas D. Maranas

This paper addresses the problem of incorporating topological indices as structural descriptors for correlating properties in the design of product molecules with fine-tuned or optimized property values. Three different types of topological indices are considered: Randir's molecular connectivity indices, Kier's shape indices and the Wiener Index. The adjacency matrix representation which provid...

2006
Lou Jost

Entropies such as the Shannon /Wiener and Gini /Simpson indices are not themselves diversities. Conversion of these to effective number of species is the key to a unified and intuitive interpretation of diversity. Effective numbers of species derived from standard diversity indices share a common set of intuitive mathematical properties and behave as one would expect of a diversity, while raw i...

Journal: :محیط زیست طبیعی 0
زهرا نوری دانشجوی دکترای جنگلداری، دانشکده منابع طبیعی، دانشگاه تهران، ایران جهانگیر فقهی دانشیار گروه جنگلداری، دانشکده منابع طبیعی، دانشگاه تهران، ایران قوام الدین زاهدی امیری دانشیار گروه جنگلداری، دانشکده منابع طبیعی، دانشگاه تهران، ایران رامین رحمانی دانشیار گروه جنگلداری، دانشگاه گرگان، ایران

the aim of this study is to investigate the tree species' diversity in a region with no management planning and introduce the calculated indices as the norm for sustainability assessment. dbh of all tree individuals, and their stories were recorded in the inventory grid (75 m × 100 m) sample plots. subsequently, richness, evenness (simpson, smith & wilson) and heterogeneity (simpson, shann...

Hamid Ahani, Hamid Jalilvand

Forests are biologically diverse systems, representing some of the richest biological areas on Earth. They offer a variety of habitats for plants, animals and micro-organisms. However, forest biodiversity is increasingly threatened as a result of deforestation, fragmentation, climate change and other stressors. Biodiversity is the variation of life forms within a given ecosystem, biome, or on t...

Hamid Ahani, Hamid Jalilvand

Forests are biologically diverse systems, representing some of the richest biological areas on Earth. They offer a variety of habitats for plants, animals and micro-organisms. However, forest biodiversity is increasingly threatened as a result of deforestation, fragmentation, climate change and other stressors. Biodiversity is the variation of life forms within a given ecosystem, biome, or on t...

2014
Leilei Tang Chuanpeng Cheng Kaiyuan Wan Ruhai Li Daozhong Wang Yong Tao Junfeng Pan Juan Xie Fang Chen

Weeding and fertilization are important farming practices. Integrated weed management should protect or improve the biodiversity of farmland weed communities for a better ecological environment with not only increased crop yield, but also reduced use of herbicides. This study hypothesized that appropriate fertilization would benefit both crop growth and the biodiversity of farmland weed communi...

Journal: :Complexity 2022

Topological indices are numeric parameters which portray the topology of a subatomic structure. In QSAR/QSPR analysis, topological descriptors play vital role to examine network. An interconnection network is structure whose components connected physically according some pattern. this paper, an network, ternary hypertree, structural combination complete tree and introduced. We have evaluated gr...

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