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81.
Stasko DJ Perzynski KJ Wasil MA Brodbeck JK Kirschbaum K Kim YW Lind C 《Inorganic chemistry》2004,43(13):3786-3788
The acid H(2)B(12)(OH)(12) can be isolated as a crystalline solid by protonation of the hydroxylated borane anion, B(12)(OH)(12)(2)(-). This acidic compound has low solubility in water, conducts protons in the solid state, and has thermal stability to a temperature of 400 degrees C. The conductivity mechanism is a Grotthuss mechanism with a low activation enthalpy (9-13 kcal/mol). This new acid represents an addition to the class of oxoacids, of which sulfuric and phosphoric acid are the most prominent examples. 相似文献
82.
Yingyongnarongkul BE How SE Díaz-Mochón JJ Muzerelle M Bradley M 《Combinatorial chemistry & high throughput screening》2003,6(7):577-587
Advances in high throughput screening (HTS), together with the rapid progress in combinatorial chemistry, genomic and proteomic sciences have dramatically stimulated the development of a variety tools to enable the drug discovery process to become more efficient. Major future challenges in HTS include obtaining high density and good quality data based on assays that are rapid, reliable, inexpensive, sensitive, simple and miniaturised. This paper reviews the development and role of bead-based assays for HTS including DNA and single nucleotide polymorphism (SNP) assays, particularly from a multiplex perspective and evaluating the recent advances in bead-based arrays. The encoding strategies that are commonly used in bead-based assays are highlighted, while the importance of magnetic beads in genomic and proteomic purifications is discussed. In conclusion, bead-based assays offer a powerful promising approach for many aspects of drug discovery. 相似文献
83.
Andrew L. Sargent Mark E. Rollog Cassandra T. Eagle 《Theoretical chemistry accounts》1997,97(1-4):283-288
Fenske-Hall molecular orbital calculations have been applied to a new, structurally isolable analog of the intermediate involved
in catalytic rhodium carboxylate carbenoid transformations. Results from the structural characterization of axially ligated
rhodium acetate phenylisonitrile complexes have been utilized in approximate molecular orbital calculations. The results from
the calculations suggest that a significant degree of π back-bonding exists between the metal and isonitrile fragments which,
by analogy, implies that π back-bonding should also exist in the rhodium carbenoid intermediate. Sensitivity of the Fenske-Hall
method to the magnitude of π back-donation in these complexes was gauged through calculations involving different phenylisonitrile
groups in which the π back-bonding ability was modulated through derivativization. The reliability of the Fenske-Hall method
was evaluated through a comparison to a high-level calculation.
Received: 13 December 1996 / Accepted: 18 March 1997 相似文献
84.
Given a reaction mechanism we show how a symbolic computation approach can be used to develop the kinetic equations by identifying the reaction scheme with an equivalent matrix. Our method is also applicable in cases where the stoichiometric matrix approach fails. The specific algorithm that is written applies to schemes where individual reactions are at most ternary, but the way to generalize the procedure is also discussed. By using symbolic computing it is possible to determine general properties of the system. We demonstrate this by showing how to use the matrix to determine the system's conservation laws, which in turn can be used to reduce the number of equations in the system. As another application it is shown how to determine some of the species which have a zero equilibrium state. To illustrate the procedure, example reaction schemes are investigated. 相似文献
85.
The steps in a nonconventional algorithm for self-consistent field calculations are outlined, and calculations on cumulenes are given to demonstrate the convergence properties of the method. The approach is essentially open ended and is likely to be cost effective on computer systems with minimal core. 相似文献
86.
Regioselective ortho lithiation of 2-, 3-, and 4-halopyridines is achieved with lithium diisopropylamide (?78°, tetrahydrofuran) to afford, upon quenching with electrophilic reagents, 2,3- and 3,4-disubstituted pyridines in good to excellent yield. 相似文献
87.
Lázló Markó 《Journal of organometallic chemistry》1981,213(1):271-275
Two new mixed iron cobalt carbonyl sulphide clusters HFe2(CO)9S and Fe2Co(CO)8(NO)S have been prepared and characterized. The hydride complex undergoes acidic dissociation in polar solvents and the resulting anion was isolated as (Et4N)[Fe2Co(CO)9S]. An efficient high pressure synthesis has been found for H2Fe3(CO)9S. 相似文献
88.
Sabine Rentsch Gudrun Hermann Mark Bischoff Dietmar Strehlow Manfred Rentsch 《Photochemistry and photobiology》1997,66(5):585-590
Abstract— The excited state behavior of the red light-absorbing form of phytochrome (Pr) was studied on the femtosecond time scale. After excitation of Pr with 75 fs laser pulses at 616 nm the kinetics of the transient absorption changes was recorded at selected wavelengths probing mainly the bleaching of the Pr ground-state absorption and the stimulated emission. The kinetic data obtained indicate the population of an excited state with a 3 ps lifetime immediately after excitation. This state precedes the formation of another excited state with a 32 ps lifetime. The decay of the latter state is followed by the appearance of a first product state that is assumed to represent lunii-R. In addition, 2,3-dihydrobiliverdin, which is considered to be an adequate model of the Pr chro-mophore, was included in the femtosecond studies. The absorption difference spectra recorded at various delay times show an immediate bleaching of the ground-state absorption. Simultaneously with bleaching a broad transient absorption appears between 410 and 525 nm. The data analysis yields similar kinetic components as they were observed in the decay of Pr. It is suggested from this finding that within the first tens of picoseconds after excitation the excited-state properties of Pr are mainly determined by the properties of the chromophore itself. 相似文献
89.
Photocycloadditlon of (+)-isoplperltenone and cyclobutene-1-carboxylic acid gives an adduct which upon reduction with NaCNBH3 followed by thermolysis yields an isomer of isoaristolactone in an overall yield of 26%. 相似文献
90.
Butler MS 《Natural product reports》2005,22(2):162-195
Natural product and natural product-derived compounds that are being evaluated in clinical trials or in registration (current 31 December 2004) have been reviewed. Natural product derived drugs launched in the United States of America, Europe and Japan since 1998 and new natural product templates discovered since 1990 are discussed. 相似文献