we describe here a suitable approach for the synthesis of n-unsubstituted monocyclic b-lactams under mild reaction conditions by the annelation of imines with substituted acetylchlorides. in this method the reaily available phtalimidoacetyl chloride were allowed to react with - dibenzylideneiminotoluene (hydrobenzamide) in the presence of an equimolar amount of triethylamine in refluxing toluen...

the main objective in sampling is to select a sample from a population in order to estimate some unknown population parameter, usually a total or a mean of some interesting variable. a simple way to take a sample of size n is to let all the possible samples have the same probability of being selected. this is called simple random sampling and then all units have the same probability of being ch...

This research investigated the effects of super absorbentpolymers on root characteristics of Avena fatua under two soil textures and three irrigation regimes. The study was arranged according to a factorial experiment based on a completely randomized design with three replications. Hydrogel compositions included three types of super absorbents (Aquasorb, Boloorab A and Stockosorb) with two leve...

the treatment of in completely formed pulpless teeth has presented considrable problems. these teeth have wide open apexes and the walls of the root canal diverge toward the apical tissues. mechanical preparation cannot be done in the normal manner beacause of the large initial size and the taper of apical part of the canal , a mechanical stop cannot be produced at the apex of the canal and , t...

Salinity is one of the main osmotic stresses on growth and production of plants in arid limit. The use of salt endurance species in the restoration and development rangelands , particularly in arid is very important.Given the importance of annual medics in the restoration and development rangeland and the low awareness level of understanding of this species to salinity, This study aimed to eval...

Silicon (Si) has beneficial effects on the growth, yield, and tolerance of some crops against biotic and abiotic stresses. Considering the absence of Si in the nutrient solutions used in hydroponically-grown cucumber, the present study was conducted to investigate the influence of Si on the growth and yield of two cucumber genotypes (Cucumis sativus L. cvs. Dominus GRC and Super Dominus). In a ...