فرض کنیمr یک حلقه تعویض پذیر ویکدار موضعی باشدو(j(r رایکال جیکوبسن r و(z(r مجموعه مقسوم علیه های صفر حلقه r باشد.گوییم r یک حلقه z- موضعی است هرگاه j(r)^2=. .همچنین برای یک حلقه تعویض پذیر r فرض کنیم c یک عنصر ناصفر از (z( r باشد با این خاصیت که cz( r)=0 گوییم حلقه موضعی r یک حلقه c - موضعی است هرگاه و{0 و z(r)^2={cو z(r)^3=0, نیز xz( r)=0 نتیجه دهد که x عضو {c,0 } است. در این پایان نامه ساخ...

Aim and Background: Today tourism is recognized as the cleanest and most sustainable industry in the world and tourist satisfaction is one of the most important factors in the success and cycle of this industry receiving much attention from many researchers and investors in this industry. Considering ecology and regionalism architecture as effective factor on the satisfaction of tourists is the...

Introduction Being developed or not, causes Iran's villages to face various challenges. This is so when widespread poverty and increasing lack of balance, unemployment growth, and low level of productivity are obvious in the country; Lack of balance between different regions in the process of development leads to Create gap and intensity of regional inequality which are considered as barrier...

Received: 25 Aug, 2015 Accepted: 26 Oct , 2015 Abstract Background & Aims: Access to safe drinking water is important in health and development at national, regional and local levels. The concentration of fluoride in drinking water is highly variable, depending on the individual geological environment from which the water is obtained. Fluoride is an essential microelement for human health...

Introduction Changes in spatial patterns and its structural and functional dynamics which is apparently obvious within physical links and relationships of cities and rural and urban network is fundamentally one of the outcomes of forces that contribute to the controlling process of actual mechanism of capital absorption, its flow, work forces, and population. Such forces play a significant r...