نتایج جستجو برای: good yields
تعداد نتایج: 506625 فیلتر نتایج به سال:
BACKGROUND High pregnancy rates have been noted after oocyte donation (OD). Multiple pregnancies should be avoided, because oocyte recipients have an increased risk of obstetric complications. METHODS We analysed our OD results from 2000-2001 when elective single embryo transfer (eSET) was introduced as a recommended policy for all recipients if at least one good quality embryo was available....
Marine reserves (MRs) are used worldwide as a means of conserving biodiversity and protecting depleted populations. Despite major investments in MRs, their environmental and social benefits have proven difficult to demonstrate and are still debated. Clear expectations of the possible outcomes of MR establishment are needed to guide and strengthen empirical assessments. Previous models show that...
A convenient microwave irradiation protocol was utilized for the synthesis of b-ketosulfones 1-5 in good yields. These sulfones reacted with alkenes through a radical oxidative cyclization mediated by Mn(OAc)3. Dihydrofurans 6-10 were obtained in moderate to good yields starting from 1,1-disubstituted alkenes. Dihydrofurans 11-15 were synthesized in moderate yields and unexpected cyclopropanes ...
The potassium salt of E- and Z-2,3-diphenylpropenoic acids prepared in situ could be esterified efficiently in DMSO with the appropriate alkyl halides at room temperature. In this way 10 previously undescribed esters of these acids were synthesised and characterised. Excellent yields were observed for most of the E isomers and the more hindered Z esters were also obtained in good yields, far be...
Single frequency bioelectrical impedance analysis is an inexpensive, quick and painless means of estimating body composition. However, current approaches to estimating body composition from segment resistivity have some drawbacks. The purpose of this study was to overcome these limitations by developing a better model of the relationship between resistivity and body composition. A three-compart...
a convenient, rapid, and one-pot method for the synthesis of azo dyes has been developed. in this protocol, diazotization reagent (arn2+ -cro3–sio2) was prepared via grinding of aromatic amines, nano2, wet sio2 and nano silica chromic acid (nano-sca) without solvent at room temperature. the obtained diazotization reagent was sufficiently stable to be kept at room temperature in the dry state fo...
A practical and new method for the synthesis oxindole substituted pyrrolo[2,3-d]pyrimidines by the condensation of isatin, acetophenone and 6-amino-uracil under ultrasound irradiation conditions at 60 °C was described. The reaction was developed via a sequential tandem process to afford the oxindole substituted pyrrolo[2,3-d]pyrimidines in good to excellent yields. All reactions performed effic...
melamine trisulfonic acid (mtsa) as an efficient heterogeneous catalyst has been used for the one-pot preparation of triazolo[1,2-a]indazole-1,3,8-trione and 2h-indazolo[2,1-b]phthalazine-1,6,11-trione derivatives by the three-component condensation reaction of urazoles or phthalhydrazide, dimedone or 1,3-cyclohexanedione, and aldehydes under solvent-free conditions in good to excellent yields ...
sulfonic acid functionalized sba-15 as a nanoporous acid catalyst was used in the synthesis of 2-aryl benzoxazoles 4 by the condensation of 2-aminophenol 1 and benzoyl chlorides 2 under microwave irradiation in solvent free reaction conditions. the advantages of this methodology are good product yields (60-98%), being environmentally benign, short reaction times and easy work up.
we have used tungestophosphoric acid to catalyze oxidative amidation reaction from benzyl alcohols and methylarens with hydrochloride salts of amines. to achieve this purpose, modified magnetic nanoparticles (γ-fe2o3@sio2@h3pw12o40) were applied as catalyst and tbhp as external oxidant. after optimizing, different derivates of benzamides were synthesized in good yields. also, the result of two ...
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