a simple, sensitive and selective method for solvent extraction and spectrophotemetric determination of lanthanum (ii) europium (iii), and cerium (iii) is described , the rare earth metals are extracted into chloroform solution of n-phenylbenzohydroxamic acid (pbha) at ph 9-10 various parameters are studied to optimize the extraction conditions. the molar absorptivity is found to increase from ...

in this thesis, a better reaction conditions for the synthesis of spirobarbiturates catalyzed by task-specific ionic liquid (2-hydroxy-n-(2-hydroxyethyl)-n,n-dimethylethanaminium formate), calcium hypochlorite ca(ocl)2 or n-bromosuccinimide (nbs) in the presence of water at room temperature by ultrasonic technique is provided. the design and synthesis of spirocycles is a challenging task becaus...

deployable scissor type structures are composed of the so-called scissor-like elements (sles), which are connected to each other at an intermediate point through a pivotal connection and allow them to be folded into a compact bundle for storage or transport. several sles are connected to each other in order to form units with regular polygonal plan views. the sides and radii of the polygons are...

as polysemy is encountered frequently in english as foreign language. fl learners’ ability to disambiguate polysemous verbs becomes critical to their comprehension in the target language. this thesis, accordingly, investigated how iranian efl learners achieved comprehension of english polysemous verbs by using three different types of cues: (1) elaborated context, (2) semantic frames, and (...

the west of esfahan province, iran, is one of the most important agricultural areas throughout the country due to the climate variability and life-giving water of zayanderood river. rice is one of the major and economic crops in this area. the most important climatic elements in agricultural activities which should be considered include temperature, relative humidity, precipitation and wind. so...

1- in a search directed to the reaction of compound)23(the cycloaddition reaction of 1,3- diphenylisobenzofurane)14(with p-benzoquinone)19(,followed by addition of cyclopentadiene was carried out.the specific spacial stracture of its ir,nmr,mass spectra. 2- in another attempt the kinetic stability and behavior of compounds)20(and)23(was studied.the main subject of this study was the highly reve...

چکیده : نظام انتخاباتی قواعد و چار چوب های به رسمیت شناخته شده ای است که بیانگر چگونگی تبدیل آرای مردم به مناصب و پست های سیاسی است. این نظام انتخابات باید به گونه ای عمل کند که نتیجه آن فراهم شدن مکانیسم و ساز و کار مطلوب و مناسب برای برگزاری انتخابات سالم و رقابتی باشد. به نظر می رسد نظام انتخاباتی جمهوری اسلامی ایران دارای ضعف ها و نواقصی است که به سبب آن ها نمی توان انتخابات مطلوب را برگزا...

this study investigated the effects of planning on second-language written production with regard to task type. the participants were 75 iranian learners of english as a foreign language attending a private foreign language institution. they were asked to complete two different types of writing tasks (expository writing task and argumentative writing task) in different planned conditions (indiv...