نتایج جستجو برای: fields
تعداد نتایج: 245459 فیلتر نتایج به سال:
یک فضای مینکوفسکی ، یک فضای برداری حقیقی با بعد متناهی، مجهز به یک تابعک مینکوفسکی f می باشد. به کمک مشتقات جزیی مرتبه دوم می توان یک متریک ریمان روی این فضای برداری معرفی کرد و ابر رویه شاخص s=f-1(1)را به عنوان یک زیر منیفلد ریمانی آن در نظر گرفت هدف در این پایان نامه مطالعه میدان های برداری آفین روی فضای برداری است. که بطور همزمان نسبت به متریک فانک وابسته به ابررویه شاخص نیز آفین هستند. یک ک...
there have been much speculation and debate concerning the effect of electromagnetic fields (emf) on body systems. various reports have implicated excessive exposure to emf to certain forms of leukemia. it has also been reported that emf may cause alteration in the levels of certain macro- and micro-nutrients such as copper, zinc, selenium, calcium and iron. we have undertaken this study to det...
background: in psychological studies, exposure to electromagnetic field is one of the hazardous factors, which has adverse effects on mental health. exposure to electromagnetic field due to daily use of electricity makes this study so important. the goal of this study was to determine the relationship between psychological symptoms and occupational exposure to electromagnetic field among worker...
abstract background: adjacent treatment fields are commonly used in external beam radiation therapy, such as mantle and inverted-y fields for the treatment of hodgkin’s disease and craniospinal fields used in the treatment of medulloblastoma and head and neck tumors when the lateral neck fields are placed adjacent to the anterior supraclavicular field. in each of these situations, there is a po...
introduction: biological effects of magnetic fields have been investigated by scientists for many years and a vast amount of research using different frequencies and intensities have been performed on humans and laboratory animals. the results of these studies, which have mostly been done by applying high frequencies, have shown that electromagnetic fields are effective on structure and functio...
crop rotation is one of the essential practices in sustainable agricultural systems, be-cause of its effects on soil fertility and other benefits including a reduction in weed compe-tition. a field experiment was conducted at chaparsar rice research station, tonekabon, iran, from 2002 to 2003 to assess the influence of crop rotation, time of planting, and till-age depth on rice (oryza sativa l....
in this paper, a useful classification of all lie subalgebras of a given lie algebraup to an inner automorphism is presented. this method can be regarded as animportant connection between differential geometry and algebra and has many applications in different fields of mathematics. after main results, we have applied this procedure for classifying the lie subalgebras of some examples of lie al...
introduction: depending on mode, intensity and length of application, and stage of development, the low-frequency electromagnetic fields (lfes) can induce a wide variety of biological effects in organisms. the chick limb bud is a powerful experimental system for study pattern formation in vertebrate embryo. the aim of this study was to examine the effects of an application lfes (50hz, 50g) on c...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید