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71.
We establish an explicit isomorphism between two realizations of the quantum affine algebra
given previously by Drinfeld and Reshetikhin-Semenov-Tian-Shansky. Our result can be considered as an affine version of the isomorphism between the Drinfield/Jimbo and the Faddeev-Reshetikhin-Takhtajan constructions of the quantum algebra
. 相似文献
72.
Sergei D. Kirik Julia N. Zaitseva Igor S. Yakimov Nikolay N. Golovnev 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(11):i159-i160
Lithium sodium aluminium fluoride was obtained as a white powder by melting a stoichiometric mixture of AlF3, NaF and LiF at 1223 K, and then cooling to 923 K and sintering at this temperature for 4 h. The ab initio crystal structure determination was carried out using X‐ray powder diffraction techniques. The monoclinic structure of LiNa2AlF6 can be related to cubic elpasolite. The Li and Al atoms lie on inversion centres. The main octahedral AlF6 structural elements are not deformed, but are rotated slightly with respect to the unit‐cell axes. The Li atoms have octahedral coordinations, whereas the Na atoms have cubo‐octahedral coordinations. The Na coordination polyhedron is distorted in comparison with that of elpasolite. 相似文献
73.
Synthesis and properties of monodisperse oligofluorene-functionalized truxenes: highly fluorescent star-shaped architectures 总被引:2,自引:0,他引:2
Kanibolotsky AL Berridge R Skabara PJ Perepichka IF Bradley DD Koeberg M 《Journal of the American Chemical Society》2004,126(42):13695-13702
This paper describes the strategy toward novel monodisperse, well-defined, star-shaped oligofluorenes with a central truxene core and from monofluorene to quaterfluorene arms. Introduction of solubilizing n-hexyl groups at both fluorene and truxene moieties results in highly soluble, intrinsically two-dimensional nanosized macromolecules T1-T4. The radius for the largest oligomer of ca. 3.9 nm represents one of the largest known star-shaped conjugated systems. Cyclic voltammetry experiments reveal reversible or quasi-reversible oxidation and reduction processes (Eox = +0.74 to 0.80 V, Ered = -2.66 to 2.80 eV vs Fc/Fc+), demonstrating excellent electrochemical stability toward both p- and n-doping, while the band gaps of the oligomers are quite high (EgCV = 3.20-3.40 eV). Close band gaps of 3.05-3.29 eV have been estimated from the electron absorption spectra. These star-shaped macromolecules demonstrate good thermal stability (up to 400-420 degrees C) and improved glass transition temperatures with an increase in length of the oligofluorene arms (from Tg = 63 degrees C for T1 to 116 degrees C for T4) and show very efficient blue photoluminescence (lambdaPL = 398-422 nm) in both solution (PhiPL = 70-86%) and solid state (PhiPL = 43-60%). Spectroelectrochemical experiments reveal that compounds T1-T4 are stable electrochromic systems which change their color reversibly from colorless in the neutral state (approximately 340-400 nm) to colored (from red to purple color; approximately 500-600 nm) in the oxidized state. 相似文献
74.
N. I. Giricheva N. V. Belova G. V. Girichev S. A. Shlykov I. K. Igumenov 《Journal of Structural Chemistry》1993,33(6):831-837
Ivanovsk State University. Translated from Zhurnal Strukturnoi Khimii, Vol. 33, No. 6, pp. 76–83, November–December, 1992. 相似文献
75.
Summary The liquid phase oxidation of gold in donor-acceptor organic and aqueous-organic media has been studied. The compounds [AuCl(Me2S)], [AuBr(Me2S)], [AuBr3(Me2S)], [Me3S][AuBr4], [Me3S][AuBr4(Me2S)]·H2O, [Me3SO]-[AuBr4]·H2O, [Me3S][Au2Br7(Me2S)2]·3H2O, [Me3S]2-[Au2Br8]·2DMSO·H2O, [Me2(Bu)SO][AuBr4]·H2O and [Me3S]Br were isolated by dissolution of Au0 in DMSO-RX mixtures (R = H or Bu; X = Cl or Br). The products were characterized by elemental analysis and i.r. spectroscopy. The nature of the Au0-DMSO-RX systems and the oxidant species are discussed in terms of a newly-developed concept of donor-acceptor electron transport (DAET) systems. 相似文献
76.
Popov IA Chen H Kharybin ON Nikolaev EN Cooks RG 《Chemical communications (Cambridge, England)》2005,(15):1953-1955
A simple, fast and direct method is presented for detecting traces of solid explosives on cotton swabs or in particulate samples: ions are transferred into a mass spectrometer after thermal desorption and corona discharge chemical ionization in ambient air; specificity is enhanced using ambient ion/molecule reactions or by conventional tandem mass spectrometry. 相似文献
77.
Luminescence spectra and luminescence decay kinetics of uranyl sulphate water and uranyl nitrate acetone solutions of different concentrations have been studied. Similar experiments have been done with uranyl sulphate powder under vacuum. It has been experimentally shown that the hydrolysis of uranyl sulphate in water takes place, and under low salt concentrations (0.1-4.0 times 10-4 M) a luminescence of a basic form of the photoexcited ion with a tentative structure of UO2 OH+ * has been observed. The luminescence of the acidic form UO+ * has been observed under higher salt concentrations (1–4 times 10-2 M) in water and under any salt concentration in acetone. The acidic form has the characteristic emission spectrum possessing vibrational structure. The luminescence concentrational quenching of both photoexcited uranyl forms and exciplex emission have not been observed. The effect of a number of organic quenchers and molecular oxygen on uranyl luminescence has been studied. There is no luminescence quenching by O2 up to 2 times 106 Pa (20 atm) pressure. The low effectiveness of energy transfer from the photoexcited uranyl forms has been explained in terms of strong steric screening of 5f-uranium (VI) orbital by oxygen atoms and by external filled up uranium electronic shells. 相似文献
78.
Synthesis, properties, and structure of dimethylgold(III) complexes [(CH3)2AuI]2 and (CH3)2AuS2CN(C2H5)2 总被引:1,自引:0,他引:1
Volatile diethyldithiocarbamate of dimethylgold(III) was prepared by the interaction of dimethylgold(III) iodide with sodium diethyldithiocarbamate. The complex is examined by the elemental analysis, DTA, IR and electronic spectroscopy. The starting dimeric complex [(CH3)2AuI]2 and a novel monomeric volatile gold(III) complex (CH3)2AuS2CN(C2H5)2 with the AuC2S2 coordination core were investigated by single crystal X-ray diffraction for the first time. 相似文献
79.
Igor E. Uflyand Andrei G. Starikov Vladimir S. Savostjanov Anatoly D. Pomogailo 《Transition Metal Chemistry》1991,16(1):126-129
Summary The spatial and electronic structures of the complexes [Co(AAm)4(H2O)2](NO3)2 (1), Co(AAm)4Cl2 (2), [Ni(AAm)4(H2O)2](NO3)2 (3) and Ni(AAm)4Cl2 (4), where AAm is acrylamide, and the products of their radical, frontal and post-grafting polymerization have been studied by electronic spectroscopy. The complexes (1), (3) and (4) were found to have pseudooctahedral structures in both the solid and solution phases. A change in the spatial structure of complex (2) was established in going from the crystal (tetragonally distorted octahedral) to solution (tetrahedral). The coordination environment of the metal centre does not change markedly during polymerization of the metal-containing monomers. 相似文献
80.
Critical factors for high-performance physically adsorbed (dynamic) polymeric wall coatings for capillary electrophoresis of DNA 总被引:2,自引:0,他引:2
Doherty EA Berglund KD Buchholz BA Kourkine IV Przybycien TM Tilton RD Barron AE 《Electrophoresis》2002,23(16):2766-2776
Physically adsorbed (dynamic) polymeric wall coatings for microchannel electrophoresis have distinct advantages over covalently linked coatings. In order to determine the critical factors that control the formation of dynamic wall coatings, we have created a set of model polymers and copolymers based on N,N-dimethylacrylamide (DMA) and N,N-diethylacrylamide (DEA), and studied their adsorption behavior from aqueous solution as well as their performance for microchannel electrophoresis of DNA. This study is revealing in terms of the polymer properties that help create an "ideal" wall coating. Our measurements indicate that the chemical nature of the coating polymer strongly impacts its electroosmotic flow (EOF) suppression capabilities. Additionally, we find that a critical polymer chain length is required for polymers of this type to perform effectively as microchannel wall coatings. The effective mobilities of double-stranded (dsDNA) fragments within dynamically coated capillaries were determined in order to correlate polymer hydrophobicity with separation performance. Even for dsDNA, which is not expected to be a strongly adsorbing analyte, wall coating hydrophobicity has a deleterious influence on separation performance. 相似文献