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1.
2.
Hadi Salehi 《International Journal of Theoretical Physics》1997,36(9):2035-2042
A dynamical theory is studied in which a scalar field ϕ in Einstein-Minkowski space is coupled to the four-velocityN
μ of a preferred inertial observer in that space. As a consistent requirement on this coupling we study a principle of duality
invariance of the dynamical mass term of ϕ at some universal length in the small-distance regime. In the large-distance regime
duality breaking can be introduced by giving a background value to ϕ and a background direction toN
μ. It is shown that, in an appropriate approximation, duality breaking can be related to the emergence of a characteristic
phase in which the condensation of the ground state allows massive excitations with a characteristic scale of squared mass
which agrees with the present observational bound for the cosmological constant. 相似文献
3.
Hadi Mohammadi Bidhandi 《Annals of Operations Research》2006,143(1):237-250
This paper develops a mathematical model for project time compression problems in CPM/PERT type networks. It is noted this
formulation of the problem will be an adequate approximation for solving the time compression problem with any continuous
and non-increasing time-cost curve. The kind of this model is Mixed Integer Linear Program (MILP) with zero-one variables,
and the Benders' decomposition procedure for analyzing this model has been developed. Then this paper proposes a new approach
based on the surrogating method for solving these problems. In addition, the required computer programs have been prepared
by the author to execute the algorithm. An illustrative example solved by the new algorithm, and two methods are compared
by several numerical examples. Computational experience with these data shows the superiority of the new approach. 相似文献
4.
Abdol R. Hajipour Shadpour E. Mallakpour Iraj Mohammadpoor-Baltork Hadi Adibi 《Monatshefte für Chemie / Chemical Monthly》2003,134(1):45-49
Summary. Benzyltriphenylphosphonium peroxymonosulfate in the presence of catalytic amounts of bismuth chloride was found to be an
efficient and mild reagent for the oxidative cleavage of oximes and semicarbazones to the corresponding carbonyl compounds
under microwave irradiation.
Corresponding author. E-mail: haji@cc.iut.ac.ir
Received March 4, 2002; accepted (revised) April 8, 2002 相似文献
5.
K. Adibi M. H. George J. A. Barrie 《Journal of polymer science. Part A, Polymer chemistry》1981,19(1):57-64
A relatively high-molecular-weight polyurethane based on MDI and ethylene glycol was prepared and characterized. This polymer was metalated with sodium hydride in N,N-dimethylformamide (DMF) at about 0°C. Metalation was confirmed principally by spectroscopic identification of the N-methyl derivative obtained by coupling the metalated polymer with methyl iodide. Under appropriate reaction conditions the metalated polyurethane was used for the anionic graft polymerization of the reactive monomers acrylonitrile and ethylene and propylene sulfides. Attempted anionic graft polymerizations with other monomers, including styrene and ethylene and propylene oxides, were unsuccessful. The polyurethane grafted with acrylonitrile was separated by fractionation from accompanying small amounts of polyacrylonitrile, a low-molecular-weight homopolymer. One sample of polyurethane grafted with acrylonitrile was identified by microanalysis, IR, NMR, and increase in weight and was also characterized by differential thermal analysis. 相似文献
6.
Regioselective oxidative bromination of electron-rich aromatic rings has been studied using potassium bromide as a bromine source in the presence of benzyltriphenylphosphonium peroxymonosulfate as oxidant under nearly neutral reaction conditions. In most cases we obtained monobrominated derivatives regioselectively and in good to high yields without the aid of strong acids. 相似文献
7.
Shengfei Jin Hang T. Dang Graham C. Haug Viet D. Nguyen Hadi D. Arman Oleg V. Larionov 《Chemical science》2020,11(34):9101
Construction of C–C bonds at the α-carbon is a challenging but synthetically indispensable approach to α-branched carbonyl motifs that are widely represented among drugs, natural products, and synthetic intermediates. Here, we describe a simple approach to generation of boron enolates in the absence of strong bases that allows for introduction of both α-alkyl and α-aryl groups in a reaction of readily accessible 1,2-dicarbonyls and organoboranes. Obviation of unselective, strongly basic and nucleophilic reagents permits carrying out the reaction in the presence of electrophiles that intercept the intermediate boron enolates, resulting in two new α-C–C bonds in a tricomponent process.α-Branched carboxylic acids and other carbonyls are readily accessed by a metal- and base-free deoxygenative α-alkylation and α-arylation of 1,2-dicarbonyls via boron enolates, resulting in a tricomponent coupling with unconventional electrophiles. 相似文献
8.
Oxathioacetalization of carbonyl compounds and transoxathioacetalization of O,O-acetals/ketals are reported under nearly neutral conditions promoted by iron(III) trifluoroacetate [Fe(CF3CO2)3] or trifluoromethanesulfonate [Fe(CF3SO3)3] as recyclable and highly efficient Lewis acid catalysts. 相似文献
9.
ZnO biointerfaces with serum albumin have attracted noticeable attention due to the increasing interest in developing ZnO-based materials for biomedical applications. ZnO surface morphology and chemistry are expected to play a critical role on the structural, optical, and electronic properties of albumin-ZnO complexes. Yet there are still large gaps in the understanding of these biological interfaces. Herein we comprehensively elucidate the interactions at such interfaces by using atomic force microscopy and nanoshaving experiments to determine roughness, thickness, and adhesion properties of BSA layers adsorbed on the most typical polar and non-polar ZnO single-crystal facets. These experiments are corroborated by force field (FF) and density-functional tight-binding (DFTB) calculations on ZnO-BSA interfaces. We show that BSA adsorbs on all the studied ZnO surfaces while interactions of BSA with ZnO are found to be considerably affected by the atomic surface structure of ZnO. BSA layers on the surface have the highest roughness and thickness, hinting at a specific upright BSA arrangement. BSA layers on surface have the strongest binding, which is well correlated with DFTB simulations showing atomic rearrangement and bonding between specific amino acids (AAs) and ZnO. Besides the structural properties, the ZnO interaction with these AAs also controls the charge transfer and HOMO-LUMO energy positions in the BSA-ZnO complexes. This ZnO facet-specific protein binding and related structural and electronic effects can be useful for improving the design and functionality of ZnO-based materials and devices. 相似文献
10.
Hooman Moradpour Mohsen Javaherian Ebrahim Namvar Amir Hadi Ziaie 《Entropy (Basel, Switzerland)》2022,24(6)
Relying on the quantum tunnelling concept and Maxwell–Boltzmann–Gibbs statistics, Gamow shows that the star-burning process happens at temperatures comparable to a critical value, called the Gamow temperature () and less than the prediction of the classical framework. In order to highlight the role of the equipartition theorem in the Gamow argument, a thermal length scale is defined, and then the effects of non-extensivity on the Gamow temperature have been investigated by focusing on the Tsallis and Kaniadakis statistics. The results attest that while the Gamow temperature decreases in the framework of Kaniadakis statistics, it can be bigger or smaller than when Tsallis statistics are employed. 相似文献