نتایج جستجو برای: high amounts of cu
تعداد نتایج: 21320317 فیلتر نتایج به سال:
abstract the present study was conducted to investigate the effectiveness of a rather newly developed method in language teaching that is the use of paragraph reading task and whole reading task and their effects on improving efl learner’s speaking ability. to fulfill the purpose of the study, first 90 participants studying their course at sa eedi high school in tehran were chosen by means of ...
در طی سالهای اخیراستفاده ازمنابع انرژی تجدید پذیر در شبکه های مدرن بنا به دلایل زیست محیطی و اقتصادی به طور گسترده استفاده شده است همچون نیروگاههای بادی و خورشیدی .ولتاژتولیدی این نیروگاهها اغلب به فرم dc می باشد وادوات الکترونیک قدرت به عنوان مبدل و پل بین شکل موج dc وac استفاده می شوند.این پروسه باعث ایجاد پالسهایی برروی شکل موج خروجی می شود که می تواند وارد تجهیزات قدرت همچون ترانسفورماتور ی...
according to webster and wind (1972) and anderson et al (1987), “organizational buying is a complex process and involves many people from different functional areas, multiple goals and potentially conflicting decision criteria. moreover, the customers of today are also more knowledgeable and selective when making their purchasing decisions. since a key to organizational survival is the retentio...
abstract english language learning in iran has become significant in recent years, and english has been included in the curriculum of iranian schools and universities, and considerable attention has been paid to this language in our society. nevertheless, teaching and learning english in iranian schools has not been able to satisfy the specified goals, so different efl institutes have been est...
This study investigated the impact of air pollution on the spectral reflectance of the epiphytic lichen Ramalina lacera, indicated by the normalized difference vegetation index (NDVI), on the integrity of chlorophyll, indicated by the ratio OD435 nm/OD415 nm, and on the integrity of cell membranes, indicated by electric conductivity. Data relating to physiological parameters of injury were inte...
a simple, highly sensitive, accurate and selective method was presented for determination of trace amounts of cu (ii) in water samples. the stability of an n, n´ -disalicylideneethylenediamine modified nano geraphene especially in concentrated hydrochloric acid was studied which used as a recycling and pre-concentration reagent for further uses of n, n´-disalicylideneethylenediamine modified na...
Increasing amounts of magnesium in LaCu intermetallic are shown to bring drastic electronic, chemical and mechanical changes. Based on DFT methodologies this is quantified for the cohesive energies, relative charge transfers, bulk modules, electronic structures and bonding properties for the three compounds LaCu, LaCuMg and LaCuMg4. Particularly the cohesive energies increase with Mg amounts: T...
Vanadium (III) gives a greenish- yellow complex with anthranilic acid in presence of pyridine. The complex is extractable with chloroform and is used for photometric determination of vanadium by measuring the absorbance at 390 nm against a reagent blank. Beer's Law holds good in the range of 1-20 pg V/ml. Moderate amounts of Pb (II) , Ca (II) , Sr (II) , Ba (II) , Cd (II) , Mg (II) , Mn (II...
Copper is an essential micronutrient for plant growth which is involved in many metabolic processes. However excessive amounts of copper may cause environmental pollution. With an increase in the contamination of urban areas with heavy metals, more attention should be paid to the role of ornamental plants in removing pollutants from the soils. The effects of heavy metals on the growth parameter...
The discovery of a natural quasicrystal, icosahedrite (Al63Cu24Fe13), accompanied by khatyrkite (CuAl2) and cupalite (CuAl) in the CV3 carbonaceous chondrite Khatyrka has posed a mystery as to what extraterrestrial processes led to the formation and preservation of these metal alloys. Here we present a range of evidence, including the discovery of high-pressure phases never observed before in a...
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