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101.
Ameni Brahmia Riadh Marzouki Jan Rohlicek Ahmad Irfan Abdullah G. Al-Sehemi Rached Ben Hassen 《Acta Crystallographica. Section C, Structural Chemistry》2019,75(12):1617-1627
The new aminocoumarin derivatives 3‐[1‐(3‐hydroxyanilino)ethylidene]‐3H‐chromene‐2,4‐dione, ( 1 ), 3‐[1‐(4‐hydroxyanilino)ethylidene]‐3H‐chromene‐2,4‐dione, ( 2 ), and 3‐[1‐(2‐hydroxyanilino)ethylidene]‐3H‐chromene‐2,4‐dione, ( 3 ), all C17H13NO4, were synthesized by reacting an equimolar amount of 3‐acetyl‐4‐hydroxycoumarin and the corresponding aminophenol in absolute ethanol. Structural and spectroscopic analysis of these phases revealed that derivatives ( 1 ) and ( 2 ) are isomers of previously reported ( 3 ) [Brahmia et al. (2013). Acta Cryst. E 69 , o1296]. The crystal structures of meta derivative ( 1 ) and para derivative ( 2 ) were ab initio determined from powder X‐ray diffraction data using the direct‐space approach. Both ( 1 ) and ( 2 ) adopt the orthorhombic space group P212121. These isomers show hydrogen bonds and rich π–π stacking, together with π…H interactions, which are built by conjugated systems of coumarin and phenol rings. In the crystalline lattice, the packing of ( 1 ) and ( 3 ) are mainly stabilized through O—H…O hydrogen bonding between neighbouring coumarin molecules, while hydrogen bonds between coumarin and water molecules build the stable crystal structure of derivative ( 2 ). A big similarity in the skeletons of the IR spectra of these isomers was noticed. Derivative ( 2 ) exhibits two weak bands which were not present in the spectra of the other two derivatives, at 2370 and 2948 cm?1, which can be assigned to the O—H vibrations of the solvent (H2O) trapped in the structure of ( 2 ). These aminocoumarin derivatives display absorption maxima in the visible region, attributed to π–π delocalization involving the whole electronic system of the compounds with a considerable charge‐transfer character originating from the aminophenyl ring and pointing towards the coumarin system which is characterized by a high electron‐accepting character. Additionally, the isolated molecular ground‐state geometries were optimized at the PBE0/TZP level and the electronic properties, molecular electrostatic potential and Hirshfeld charges were determined. 相似文献
102.
The synthesis of gamma-functionalized cyclopentenones was carried out in a few steps, starting firstly with the preparation of nitroketonic intermediates 2, which were readily transformed into 1,4-diketones using the Nef conversion. The intramolecular cyclization of the gamma-diketones 3 in a basic medium, led to the functionalized cyclopentenones 4. 相似文献
103.
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105.
Bouchékif H Philbin MI Colclough E Amass AJ 《Chemical communications (Cambridge, England)》2005,(30):3870-3872
Well-defined polyoxetane with low polydispersivity has been synthesized via a novel living polymerisation process using 3-phenoxypropyl 1,4-dioxanium hexafluoroantimonate (3-PPD) as a model of a living "monomeric polyoxetane" initiator, in 1,4-dioxane at 35 degrees C. 相似文献
106.
Alkyl α-(hydroxymethyl)acrylates are prepared in high yields on a synthetic scale by hydroxymethylation of the corresponding acrylates using 30% aqueous formaldehyde in THF or DME as solvent and DABCO as the catalyst. 相似文献
107.
Hassen Bel Abed Nils Weißing Jens Schoene Jannik Paulus Norbert Sewald Marc Nazaré 《Tetrahedron letters》2018,59(19):1813-1815
A simple and novel methodology for the synthesis of 3-perfluoroalkylated-2H-indazole derivatives has been elaborated. The perfluoroalkylation of readily available 2-nitrobenzaldimines bearing electron donating groups was performed using the Ruppert-Prakash reagent and its analogues to afford α-difluoromethylated, α-trifluoromethylated and α-pentafluoroethylated benzylamines. A final reductive cyclization mediated by SnCl2·2H2O led to 2H-indazoles containing perfluoroalkyl groups via the generation of a new NN bond in moderate to good yields. 相似文献
108.
The AgPO3-LaP3O9 system was investigated for the first time by DTA, X-ray diffraction, and IR spectroscopy. The only definite compound observed in the system was AgLa (PO3)4, which melted incongruently at 800°C. The method of preparation, powder diagram and crystallographic data of AgLa(PO3)4 are given. AgLa(PO3)4 crystallises in the monoclinic system P21/C with a unit cell: a = 12.38(2) Å; b = 12.88(2) Å; c = 7.33(1) Å; β = 127°91(6) z = 4. Its IR absorption spectrum is typical of a chain phosphate. 相似文献
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110.
Hassen Suleman Esmael MOHAMMED Tongtong LI Huixiang CHEN 《Frontiers of Mathematics in China》2015,10(6):1415
We study the Hopf *-algebra structures on the Hopf algebra H(1, q) over ? . It is shown that H(1, q) is a Hopf *-algebra if and only if |q| = 1 or q is a real number. Then the Hopf *-algebra structures on H(1, q) are classified up to the equivalence of Hopf *-algebra structures. 相似文献