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41.
Rukhsana I. Kureshy Surendra Singh Noor-ul H. Khan Sayed H.R. Abdi Santosh Agrawal Vishal J. Mayani Raksh V. Jasra 《Tetrahedron letters》2006,47(30):5277-5279
Catalytic asymmetric ring opening of cyclohexene oxide and meso-stilbene oxide with anilines was catalyzed by a Ti-(S)-(−)-BINOL complex to afford β-amino alcohols in high yield (up to 95%) and good enantioselectivities (ee up to 55%) under microwave irradiation. The reaction using a microwave was found to be 10 times faster than traditional oil-bath heating with retention of enantioselectivity. 相似文献
42.
The Curtius rearrangement of cyclohex-3-ene carboxylic acid using diphenylphosphoryl azide in the presence of triethylamime and ethanol, t-butanol or benzyl alcohol has been described. As a result the synthesis of ethyl, t-butyl or benzyl N-(1-cyclohex-3-enyl)carbamates has been achieved in one pot, in good chemical yield. A series of transformations of benzyl N-(1-cyclohex-3-enyl)carbamate, such as iodination and epoxidation, as well as opening of the corresponding ring epoxide, have been carried out leading to some useful oxygenated cyclohexylamimo building blocks. 相似文献
43.
Markus Allmendinger Robert Eberhardt Ferenc Molnar 《Journal of organometallic chemistry》2004,689(5):971-979
In situ ATR-IR spectroscopy is applied as a powerful tool to study the factors that control the reaction of epoxides with carbon monoxide in the presence of [Lewis acid]+[Co(CO)4]− salts. Based on these investigations, a consistent mechanistic scheme is presented, comprising the main lactone and polyester products and minor components, e.g., acetone and crotonic acid derivatives. β-Alkoxy-acyl-cobalttetracarbonyl species are shown to be key intermediates from which two reaction routes start in dependence of the applied Lewis acid (LA). Labile LA-alkoxy combinations favor a backbiting process of the oxygen function on the Co-acyl bond, primarily producing lactone products. More stable LA-alkoxy entities are unreactive toward PO conversion and afford a polymerization reaction after the addition of a nucleophile. In that case, the Lewis acid remains bonded to the chain end. 相似文献
44.
Fritz Gerd Weber Christiane Kaatz Reiner Radeglia Hubert Köppel 《Monatshefte für Chemie / Chemical Monthly》1992,123(1-2):81-92
Summary The first synthesis ofthreo chalcone bromohydrins was realized by reaction oftrans chalcone epoxides with SnBr4 in molar ratios from 1:1 to 2:1. The compounds were obtained in high yields and isomeric purity. Their configuration was determined asthreo by different methods based on13C-NMR shifts of C- and C- atoms. 相似文献
45.
Yuriko Akiyama 《Journal of fluorine chemistry》2006,127(7):920-923
Ring-opening fluorination reactions of epoxides using tetrabutylammonium bifluoride (TBABF)-KHF2, or Et3N-3HF under microwave irradiation were applied for the introduction of a fluorine atom into the carbohydrate molecules. When TBABF-KHF2 was used as the fluorination reagent, a fluorine atom was introduced regioselectively and various functional groups can tolerate the conditions. When Et3N-3HF was used under microwave irradiation, the reaction time could be remarkably shortened compared with the conventional oil-bath heating. 相似文献
46.
Vytautas Getautis Maryte Daskeviciene Tadas Malinauskas Vygintas Jankauskas 《Monatshefte für Chemie / Chemical Monthly》2007,138(4):277-283
Summary. Synthesis of a new monomer and polymer containing both ferrocene and hydrazone moieties are reported. The obtained materials
were examined by various techniques including differential scanning calorimetry, UV, IR, NMR spectroscopy, and time of flight
method. These materials may be of particular interest for the development of future electrophotographic photoreceptors as
electron photoemission spectra of the layers showed ionization potentials of 5.35–5.41 eV. The hole drift mobility values
in compositions of the designed structures with bisphenol Z polycarbonate exceeded 10−8 cm2/Vs at strong electric fields. 相似文献
47.
48.
《合成通讯》2013,43(9):1603-1610
Abstract Epoxides were converted to the corresponding β-azidohydrins and β-iodohydrins using SmCl3·6H2O/NaN3 in DMF and SmCl3·6H2O/NaI in acetonitrile respectively. The reactions were highly regioselective, efficient, and gave excellent yields under mild and neutral conditions. 相似文献
49.
Hanna Koenig 《Tetrahedron》2010,66(2):488-493
The boron trifluoride etherate catalyzed reaction of 7-epimeric 3β,7-diacetoxy-9β,11β-epoxy-5α-lanostanes 1 and 2 in acetic anhydride resulted in the formation of a series of skeletally rearranged products, mainly 19(10→9β)abeo-lanostanes. 19(10→9β),30(14→8α)Bis-abeo-lanostane derivative 5 possessing a novel type of the triterpene skeleton was formed as the major product in the reaction of 7α-epimer 2. The direction and extent of rearrangements of 9β,11β-epoxides 1 and 2 depends on the configuration of the 7-acetoxy group. The structures of the new compounds were determined on the basis of spectroscopic methods, mainly 1H and 13C NMR. The structure of compound 5 was confirmed by single-crystal X-ray diffraction. 相似文献
50.
Emmanuelle Quéron 《Tetrahedron letters》2004,45(23):4527-4531
The synthesis of the enantiopure C1-C11 fragment of bafilomycin A1 has been achieved with a 4% overall yield over 18 steps from (R)-(+)-citronellol. Key steps involve Sharpless asymmetric epoxidation, Miyashita reaction of a γ,δ-epoxymethacrylate with trimethylaluminum in the presence of water, bis-OTMS selective Swern oxidations, Corey-Fuchs alkyne formation, Negishi's carbometalation, and stereoselective formation of the C2-C3 trisubstituted bond of the conjugated diene by a Wittig-type olefination of the α,β-unsaturated C3-C11 aldehyde with the ylide derived from the readily available phosphonium salt [Cl−, Ph3P+CH(OMe)COOMe]. 相似文献