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排序方式: 共有139条查询结果,搜索用时 250 毫秒
21.
Zanatta N Schneider JM Schneider PH Wouters AD Bonacorso HG Martins MA Wessjohann LA 《The Journal of organic chemistry》2006,71(18):6996-6998
A simple and regiospecific synthesis of 4-alkoxy(amino)-2-trifluoromethyl pyrroles from 5-azido-4-alkoxy(amino)-1,1,1-trifluoro-pent-3-en-2-ones by an aza-Wittig cyclization of aminophosphoranes is described. The structures of the pyrroles and their synthetic intermediates were supported by NMR and HRMS analysis. 相似文献
22.
Martins MA Rossatto M Prola LD Pizzuti L Moreira DN Campos PT Frizzo CP Zanatta N Bonacorso HG 《Ultrasonics sonochemistry》2012,19(2):227-231
The synthesis of 14 novel N-propargylic β-enaminones from the reaction of β-alkoxy vinyltrihalomethyl[carboxyethyl] ketones [R3C(O)CHC(R1)OMe, where R3 = CF3, CCl3, CO2Et and R1 = Me, Et, Pr, Bu, i-Pent, CH2CH2CO2Me] with propargyl amines [R2NHCH2CCH, where R2 = Pr, PhCH2] is reported. Yields, solvents and reaction times needed for reaction completion, by microwave irradiation (MW), conventional thermal heating (TH) and under ultrasound irradiation (US) are compared. The best results were obtained under US irradiation in good to excellent yields (70-93%). 相似文献
23.
Neves Pérson P. Maia Lauro J.Q. Bernardi Maria I.B. Zanatta Antônio R. Mastelaro Valmor R. Zanetti Sônia M. Leite Edson R. 《Journal of Sol-Gel Science and Technology》2004,29(2):89-96
A modified polymeric precursor method based on the Pechini process was used to synthesize -BaB2O4 (-BBO) crystalline phase. D-sorbitol (C6H14O6) was used as a polymerizing agent to avoid the loss of boron during the samples' calcination and crystallization. The -BBO stoichiometric crystalline phase was only obtained when sorbitol was added to the solution. The results of Raman spectroscopy show that the amorphous phase is only completely eliminated when the samples are heat-treated at 750°C for 20 h. Thin films of -BBO phase displaying a preferred orientation were obtained when crystallized at 750°C for 2 h and deposited on sapphire substrate. 相似文献
24.
Nilo Zanatta Fabio M. da Silva Luciana S. da Rosa Louíse Jank Helio G. Bonacorso Marcos A.P. Martins 《Tetrahedron letters》2007,48(37):6531-6534
A simple one-pot procedure to obtain a series of new 3-alkoxy-3-cyanocarboxylic acids from the reaction of 4-alkoxy-1,1,1-trichloro-but-3-en-2-ones with sodium cyanide is described. 相似文献
25.
Helio G. Bonacorso Marli R. Oliveira Michelle B. Costa Letícia B. Da Silva Arci D. Wastowski Nilo Zanatta Marcos A. P. Martins 《Journal of heterocyclic chemistry》2005,42(4):631-637
A convenient and general method for the regiospecific synthesis of three novel series of 1‐(2‐thenoyl)‐, 1‐(2‐furoyl)‐ and 1‐(isonicotinoyl)‐3‐alkyl(aryl)‐5‐hydroxy‐5‐trifluoromethyl‐4,5‐dihydro‐1H‐pyrazoles, in good yields (53 – 91 %), from the cyclocondensation reactions of 1,1,1‐trifluoro‐4‐alkoxy‐4‐alkyl(aryl)‐but‐3‐en‐2‐ones, where alkyl = H and Me; aryl = ‐C6H5, 4‐CH3C6H4, 4‐CH3OC6H4, 4‐FC6H4, 4‐ClC6H4, 4‐BrC6H4, 4‐NO2CgH4 with 2‐thiophenecarboxylic hydrazide, furoic hydrazide and isonicotinic acid hydrazide, respectively, is reported. Subsequently dehydration reaction of phenyl substituted 2‐pyrazolines with P2O5 furnished the corresponding 1H‐pyrazoles as mixture of regioisomers and in low yields (35 – 36 %). 相似文献
26.
Helio G. Bonacorso Fernando J. Righi Isadora R. Rodrigues Cleber A. Cechinel Michelle B. Costa Arci D. Wastowski Marcos A. P. Martins Nilo Zanatta 《Journal of heterocyclic chemistry》2006,43(1):229-233
A new, efficient and easy route for the preparation of a series of 2‐alkyl(aryl) substituted 4‐oxo‐4H‐pyrido‐[1,2‐a]pyrimidines, where alkyl = CH3; aryl = C6H5, 4‐FC6H4, 4‐ClC6H4, 4‐BrC6H4, 4‐CH3C6H4, 4‐OCH3C6H4, 4‐NO2C6H4 in 45–80 % yield from the reaction of β‐alkoxyvinyl trichloromethyl ketones with 2‐aminopyridine under mild conditions, is then reported. 相似文献
27.
28.
[structure: see text] The total synthesis of the proposed structure for spirofungin B (2) is described. The data for the synthetic material did not compare with that for the natural product leading to the conclusion that the structure 2 assigned for spirofungin B is incorrect. Analysis of the NMR data reported for spirofungins A and B as well as related spiroketals allowed for the reassignment of the stereochemistry of spirofungin B to be that corresponding to 15-epi-spirofungin A (27). 相似文献
29.
Helio Gauze Bonacorso Sandra R. T. Bittencourt Arci D. Wastowski Alexandre P. Wentz Nilo Zanatta Marcos A. P. Martins 《Journal of heterocyclic chemistry》1999,36(1):45-48
The synthesis and isolation of the intermediates N-[1-aryl(alkyl)-3-oxo-4,4,4-trichloro-1-buten-1-yl]-o-phenylenediamines 2a-f and the corresponding 2-trichloromethyl-4-aryl-3H-1,5-benzodiazepines 3c-g or benzimidazoles 4a-b derivatives obtained from the intramolecular cyclization of 2a-f or from direct cyclo-condensation reaction of β-alkoxyvinyl trichloromethyl ketones 1a-g with o-phenylenediamine, is reported. Depending of the structure of the β-alkoxyvinyl trichloromethyl ketones or the N-[1-aryl(alkyl)-3-oxo-4,4,4-trichloro-buten-1-yl]-o-phenylenediamines and the reactions conditions, benzimidazoles or 3H-1,5-benzodiazepines were obtained. 相似文献
30.
Nilo Zanatta Débora Faoro Simone C. Silva Helio G. Bonacorso Marcos A.P. Martins 《Tetrahedron letters》2004,45(29):5689-5691
A convenient synthesis of furan-3-carboxylic acid and derivatives from aromatization of 4-trichloroacetyl-2,3-dihydrofuran followed by nucleophilic displacement of the trichloromethyl group by hydroxide, alcohols, and amines, is presented. 相似文献