heteropoly acids (hpa) and their salts have advantages as catalysts which make them both economically and environmentally attractive, strong br?nsted acidity, exhibiting fast reversible multi-electron redox transformations under rather mild conditions, very high solubility in polar solvents, fairly high thermal stability in the solid states, and efficient oxidizing ability, so that they are imp...

learning a second or foreign language requires the manipulation of four main skills, namely, listening, reading, speaking, and writing which lead to effective communication. it is obvious that vocabulary is an indispensible part of any communication, so without a vocabulary, no meaningful communication can take place and meaningful communication relies heavily on vocabulary. one fundamental fac...

over the past decades a number of approaches have been applied for forecasting mortality. in 1992, a new method for long-run forecast of the level and age pattern of mortality was published by lee and carter. this method was welcomed by many authors so it was extended through a wider class of generalized, parametric and nonlinear model. this model represents one of the most influential recent d...

126 abstract: in this research we studied the effects of cyclic hydration and dehydration of cysts of artemia urmiana and artemia parthenogenetica on the hatching percentage, survival and growth. the experiment was carried out in 3 treatments (1-3 hydration/dehydration cycles) with 3 replicates for each treatment. later effects of cold preservation at -20°c during three time periods were ...

this study focuses on jane austens representation of her heroines in two of her novels: pride and prejudice, and mansfield park. i have concentrated only on a single idea: how jane austen takes her heroines through a course of psychogical reformation to which almost everything else in her novel is subsidiary. although i have discussed only pride and prejudice, we can trace austens carefully pla...

building on previous studies on the effectiveness of different types of written corrective feedback, the present study aimed at investigating whether direct focused corrective feedback and direct unfocused corrective feedback produced any differential effects on the accurate use of english articles by efl learners across two different proficiency levels (low and high). in current study, the par...

the present paper deals with criminal issues. for example, legal injunction on the necessity of returning a deposit has a legal nature and legal injunction on the punishment of those who breach the trust has a criminal nature. existing social issues are the basis of classification of some instances into the issue, some of which are based on variation and others on quality. therefore, the motiva...

introruction khawf in(iran)-herat and mazaresharif and shirkhan bandar in (afghanistan)-dushanbe in (tajikistan)_(kirgizstan)-kashghar in(china) project railway network is under construction that it is as a significant corridor for revitalizing silk road corridor in the region .at the present there are three different gauge in the region central asia with 1,520 mm gauge and turkey-islamic repu...

the effect of learning strategies on the speaking ability of iranian students in the context of language institutes abstract language learning strategies are of the most important factors that help language learners to learn a foreign language and how they can deal with the four language skills specifically speaking skill effectively. acknowledging the great impact of learning strategies...

abstract the present thesis studies different question sentences in persian and russian languages comparatively. sentence is a syntactic unit that matches a lot of dimensions together. sentence includes syntactic structure definite meaning & concept and different applied demotions. in applied, question and imperative sentences based on speakers aim. predicative sentences state a kind of info...