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111.
112.
Manuel Salmón Armando Cabrera Nieves Zavala Georgina Espinosa-Pérez Jorge Cárdenas Rubén Gaviño Raymundo Cruz 《Journal of chemical crystallography》1995,25(11):759-762
3,4,5-Trimethoxybenzyl alcohol was cyclooligomerized with a bentonite clay used as a catalyst. Results of the crystal structure analysis of the racemic (±) nonamethoxy[1,1,1]orthocyclophane trimer, C30H36O9, are described. The structure was determined by X-ray diffraction at 293 K and shown to belong to the triclinic space group P
. The compound possesses a distorted crown conformation with unusual C–H...O intermolecular interactions, and with a crystal packing not observed before in other related derivatives. The racemic mixture was also discriminated in its two enantiomeric isomers, using proton NMR and Eu(III) as a chiral shift reagent. 相似文献
113.
Manuel Soriano-García Rubén Alfredo Toscano Mario Schatz-Levin 《Journal of chemical crystallography》1987,17(2):207-219
The title compound, IBA-PIC, is 2C12H13NO2·2C6H3N3O7, triclinic,P¯1,a=7.137(1),b=15.355(4),c=18.282(5) Å,=79.72(2),=79.85(2), =76.87(2)°. The structure was solved by direct methods and refined by least-squares techniques to anR factor of 0.068 for 3395 observed reflections. The IBA-PIC complex occurs as two independent molecules with different conformations. The crystallographic evidence for a prominent overlapping between the phenyl and indole rings corroborates earlier conclusions from UV spectroscopy. Molecules of both IBA and picric acid lie approximately parallel to (100) in layers and -bonding interactions across the 3.55 Å spacing. The angles between the indole ring and carboxyl-group planes are 82.9 and 86.9° for the A and B molecules, respectively. 相似文献
114.
Valente Gómez-Benítez Rubén A. Toscano David Morales-Morales 《Journal of inclusion phenomena and macrocyclic chemistry》2004,50(3-4):199-202
The crystal structure of C-phenylcalix[4]resorcinarene in a very solvated environment (DMSO) has been determined. The asymmetric unit contains nine molecules of DMSO and one molecule of water for each molecule of the resorcinarene. The C-phenylcalix[4]resorcinarene adopts an approximate C2v symmetry (boat conformation, also known as flattened-cone conformation) in which two opposite resorcinol rings are almost parallel, while the other two are nearly coplanar.4,6,10,12,16,18,22,24-Octahydroxy-2,8,14,20-tetraphenyl-calix(4) arene.Supplementary data related to this article are deposited with the British Library as Supplementary Publication No. 82308 (3 pages). 相似文献
115.
Barluenga J Vicente R Barrio P López LA Tomás M Borge J 《Journal of the American Chemical Society》2004,126(44):14354-14355
The 1,2- and 1,3-dialkylidenecycloheptane rings are specifically assembled from chromium alkenyl Fischer carbene complexes and allenes via [3+2+2] cyclization reactions. The former cycloadducts are obtained when the cyclization is performed in the presence of 1 equiv of [Ni(cod)2], while the [Rh(cod)Cl]2-catalyzed cyclization leads to the latter cycloadducts. 相似文献
116.
Dr. Elvira Romero Dr. J. Rubén Gómez Castellanos Prof. Dr. Andrea Mattevi Prof. Dr. Marco W. Fraaije 《Angewandte Chemie (International ed. in English)》2016,55(51):15852-15855
Cyclohexanone monooxygenase (CHMO) is a promising biocatalyst for industrial reactions owing to its broad substrate spectrum and excellent regio‐, chemo‐, and enantioselectivity. However, the low stability of many Baeyer–Villiger monooxygenases is an obstacle for their exploitation in industry. Characterization and crystal structure determination of a robust CHMO from Thermocrispum municipale is reported. The enzyme efficiently converts a variety of aliphatic, aromatic, and cyclic ketones, as well as prochiral sulfides. A compact substrate‐binding cavity explains its preference for small rather than bulky substrates. Small‐scale conversions with either purified enzyme or whole cells demonstrated the remarkable properties of this newly discovered CHMO. The exceptional solvent tolerance and thermostability make the enzyme very attractive for biotechnology. 相似文献
117.
Rubén Montalvo‐González Armando Ariza‐Castolo 《Magnetic resonance in chemistry : MRC》2012,50(1):33-39
A structural and conformational analysis of 1‐oxaspiro[2.5]octane and 1‐oxa‐2‐azaspiro[2.5]octane derivatives was performed using 1H, 13 C, and 15 N NMR spectroscopy. The relative configuration and preferred conformations were determined by analyzing the homonuclear coupling constants and chemical shifts of the protons and carbon atoms in the aliphatic rings. These parameters directly reflected the steric and electronic effects of the substituent bonded to the aliphatic six‐membered ring or to C3 or N2. The parameters also were sensitive to the anisotropic positions of these atoms in the three‐atom ring. The preferred orientation of the exocyclic substituents directed the oxidative attack. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
118.
119.
Guadalupe Alcerreca Rubén Sanabria René Miranda Gabriel Arroyo Joaquín Tamariz Francisco Delgado 《合成通讯》2013,43(7):1295-1301
Several benzaldehydes were condensed with barbituric acid under infrared irradiation, in absence of solvent, affording the corresponding 5-benzylidene barbituric acids. 相似文献
120.