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941.
Francisco Alcaide Garbiñe Álvarez Oscar Miguel María Jesús Lázaro Rafael Moliner Ana López-Cudero José Solla-Gullón Enrique Herrero Antonio Aldaz 《Electrochemistry communications》2009,11(5):1081-1084
Carbon nanofibers synthesized via the thermo catalytic decomposition of methane were investigated for the first time as an electrocatalyst support in PEMFC cathodes. Their textural and physical properties make them a highly efficient catalyst support for cathodic oxygen reduction in low temperature PEMFC. Tests performed in MEAs showed that Pt supported on carbon nanofibers exhibited an enhancement of ca. 94% in power density at 0.600 V, in comparison with a commercial catalyst supported on conventional carbon black, Pt/Vulcan XC-72R. 相似文献
942.
M. A. V. Ribeiro da Silva Ana Filipa L. O. M. Santos 《Journal of Thermal Analysis and Calorimetry》2009,95(2):333-344
The present work is part of a broader research program on the energetics of formation of heterocycles, aiming the study of
the enthalpic effects of the introduction of different substituents into heterocycles. In this work we present the results
of the thermochemical research on sulphur heterocycles of the type substituted thiophenes with different kind of substituents,
mainly alkyl, ester, acetyl, carboxamide, acetamide, carbonitrile and carboxaldehyde.
The standard (p
o=0.1 MPa) molar enthalpies of formation, in the condensed phase, at T=298.15 K, of a large number of substituted thiophenes, were derived from their standard massic energies of combustion, measured
by rotating-bomb combustion calorimetry, while the standard molar enthalpies of vaporization or sublimation of those compounds
were obtained either by high temperature Calvet Microcalorimetry, or by the temperature dependence of their vapour pressures
determined by the Knudsen effusion technique. The standard molar enthalpies of formation, of the studied sulphur heterocycles
in the gaseous phase, were then derived. The results are interpreted in terms of structural contributions to the energetics
of the substituted thiophenes, the internal consistency of the results is discussed and, whenever appropriate and possible,
empirical correlations are suggested for the estimation of standard molar enthalpies of formation, at T=298.15 K, of substituted thiophenes. A Table of enthalpic increments for different group substituents in positions 2 or 3
of the thiophene ring has been established. 相似文献
943.
W. Seth Horne Dr. Christian A. Olsen Dr. John M. Beierle Ana Montero Dr. M. Reza Ghadiri Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(26):4718-4724
Fooling enzymes with mock amides : Analogues of apicidin, a cyclic‐tetrapeptide inhibitor of histone deacetylase (HDAC), were designed with a 1,4‐ or 1,5‐disubstituted 1,2,3‐triazole in place of a backbone amide bond to fix the bond in question in either a trans‐like or a cis‐like configuration. Thus, the binding affinity of distinct peptide conformations (see picture) could be probed. One analogue proved in some cases to be superior to apicidin as an HDAC inhibitor.
944.
Anaïs Geny Dr. Nicolas Agenet Dr. Laura Iannazzo Max Malacria Prof. Dr. Corinne Aubert Dr. Vincent Gandon Dr. 《Angewandte Chemie (International ed. in English)》2009,48(10):1810-1813
Cobalt cyclopentadienyl complexes incorporating a fumarate and a CO ligand (see picture) efficiently catalyze inter‐ and intramolecular [2+2+2] cycloadditions of alkynes, nitriles, and/or alkenes to give benzenes, pyridines, or 1,3‐cyclohexadienes. Unlike catalysts such as [CpCo(CO)2] or [CpCo(C2H4)2] (Cp=C5H5), they are air‐stable, easy to handle, compatible with microwave conditions, and do not necessarily require irradiation to be active.
945.
946.
Applications of capillary electrophoresis to the determination of antibiotics in food and environmental samples 总被引:1,自引:0,他引:1
Ana M. García-Campaña Laura Gámiz-Gracia Francisco J. Lara Monsalud del Olmo Iruela Carmen Cruces-Blanco 《Analytical and bioanalytical chemistry》2009,395(4):967-986
In this paper we review applications of capillary electrophoresis (CE) to the determination of antibiotic residues in food
derived from animals and in environmental samples. Although many CE methods have been used to determine antibiotics in the
pharmaceutical field (drug quality control or therapeutic monitoring in biological samples), food and environmental applications
have been increasing in recent years. Due to the maximum residue limits established by the EU, in Directive 2377/90/EEC, for
foodstuffs of animal origin and considering the low levels that can be found in environmental or waste waters or soils, different
strategies to increase sensitivity have been developed, including off-line preconcentration, on-line stacking modes to use
higher sample volumes, or in-line solid-phase extraction. Also, several detection techniques, such as fluorescence, laser-induced
fluorescence, electrochemical detection, or mass spectrometry have been used; the last of these also enables unequivocal identification
of the residues, required by Commission Decision 2002/657/EC. All these aspects will be discussed in this paper, in relation
to the main groups of antibiotics used in veterinary and human medicine, for which applications in food and environmental
samples have been developed by using CE as an efficient alternative to liquid chromatography. 相似文献
947.
Ana de Bettencourt-Dias Rose M. Beeler Sharon S. Tse 《Journal of chemical crystallography》2011,41(2):192-197
Abstract
Dipyridylamine has been coupled with phenyl groups to yield new organic ligands. During the course of one reaction a lithium salt of dipyridylamine was isolated as the product. These new compounds were characterized by single crystal X-ray diffraction, which reveals that π–π stacking interactions as well as hydrogen bonding permeate the isolated compounds in the solid state. BrPhDPA, compound 1, crystallizes in the monoclinic P21 space group with cell parameters a = 5.8291(1), b = 8.8504(2), c = 13.2341(3) ? and β = 91.928(1)°. 3-ThPh(DPA)2, compound 4, crystallizes in the orthorhombic C2/c space group with cell parameters a = 14.8033(7), b = 11.4124(4), c = 16.11780(7) ? and β = 115.911(3)°. Finally the lithium salt, [Li(HDPA)(H2O)2](H2DPA)(Cl)2(H2O), compound 5, crystallizes in the monoclinic Cmcm space group with cell parameters a = 14.043(3), b = 12.370(3) and c = 13.389(3) ?. 相似文献948.
Adriana Hernández Calva Ana Lilia Padilla Velasco Ángel Mendoza Martínez Aarón Pérez-Benítez Sylvain Bernès Enrique González Vergara 《Journal of chemical crystallography》2011,41(10):1461-1466
Abstract
One salt and two Cu(II) complexes (H2hsm)(ox), 1, [Cu(hsm)(ox)], 2, and [Cu(hsm)(ox)H2O], 3, have been synthesized and X-ray characterized (hsm is histamine and ox2− is the oxalate dianion). Starting from the prochiral tetracoordinated complex 2, pentacoordinated complex 3 crystallizes as a racemic mixture of the enantiomeric Δ and Λ isomers, in space group P21/c. In all cases, the side chain of the hsm group is gauche, allowing the formation of strong hydrogen bonds in the salt 1, and to chelate the metal center in complexes 2 and 3. The combination hsm/ox seems to favor the formation of 2D supramolecular structures (planes or wavy planes), through efficient networks of N–H···O hydrogen bonds. Cell parameters: 1, P21/c, a = 6.260 (2) ?, b = 11.500 (4) ?, c = 12.525 (4) ?, β = 104.047 (17)o; 2, C2/c, a = 10.7966 (13) ?, b = 15.5622 (16) ?, c = 11.3996 (15) ?, β = 106.261 (11)o; 3, P21/c, a = 7.0627 (6) ?, b = 7.1323 (6) ?, c = 20.0296 (19) ?, β = 91.529 (7)o. 相似文献949.
Rosa Carballo Berta Covelo Nuria Fernández-Hermida Ana B. Lago Ezequiel M. Vázquez López 《Journal of chemical crystallography》2011,41(12):1949-1954
Abstract
A new mixed-ligand nickel(II) coordination compound [Ni(bz)2(phen)2] (1) (bz = benzilate and phen = 1,10-phenanthroline) has been synthesized by refluxing nickel(II) acetate with benzilic acid and 1,10-phenantholine. Compound 1 has been characterized by elemental analysis, IR and electronic absorption spectroscopy, magnetic measurements, thermogravimetric analysis and single-crystal X-ray diffraction The crystal of 1 belongs to monoclinic crystal system, space group C2/c and its unit cell parameters are a = 25.881(3), b = 11.1728(15), c = 17.609(2) ? and β = 124.104(3)°. The effect of non-covalent interactions, such as π···π and C–H···π, on the 3D supramolecular organization of this molecular complex is analyzed. 相似文献950.