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51.
52.
Kyle M. Lancaster James B. Gerken Alec C. Durrell Joshua H. Palmer Harry B. Gray 《Coordination chemistry reviews》2010,254(15-16):1803-1811
The properties of RuII complexes involving the imidazole moiety are discussed. Complexes [Ru(bpy)2(L)]2+ [bpy = 2,2′-bipyridine, L = 2-(2′-pyridyl)imidazole (2-pimH) and 4-(2′-pyridyl)imidazole (4-pimH)] have been synthesized and fully characterized. Reduction potentials are 0.76 V vs. Fc+/Fc0 for both complexes in acetonitrile solution, and the deprotonated complexes undergo irreversible electrochemical oxidation at 0.38 V vs. Fc+/Fc0. Density functional theory (DFT) calculations suggest that oxidation of the protonated complexes is primarily metal-based and that of the deprotonated complexes is ligand-centered. The pKa of the 4-pimH complex was found to be 9.7 ± 0.2; the pKa of the 2-pimH complex is 7.9 ± 0.2. Luminescence lifetimes (L = 4-pimH, 277 ns; 2-pimH, 224 ns; 4pim?, 40 ns; 2pim?, 34 ns in 5% methanol/water solution) combined with quantum yield data and acid–base behavior suggest that the non-coordinated imidazole nitrogen tunes deactivation pathways. 相似文献
53.
Barber SM Costanzo PJ Moore NW Patten TE Lancaster KS Lebrilla CB Kuhl TL 《The journal of physical chemistry. A》2006,110(13):4538-4542
We have developed an efficient method for producing difunctional, bilateral nanospheres. A monolayer of nanoparticles was prepared followed by deposition of a thin layer of metal. By varying the base particle and metal deposited, bilateral nanoparticles were formed. The different regions of the nanoparticles were selectively functionalized with polymer linkers containing specific terminal groups, thereby creating bilateral, difunctional nanoparticles. Subsequent covalent cross-linking of different nanoparticles enabled the formation of stable architectures with programmed hierarchy and controlled chemical composition. 相似文献
54.
Mackinnon AJ Patel PK Borghesi M Clarke RC Freeman RR Habara H Hatchett SP Hey D Hicks DG Kar S Key MH King JA Lancaster K Neely D Nikkro A Norreys PA Notley MM Phillips TW Romagnani L Snavely RA Stephens RB Town RP 《Physical review letters》2006,97(4):045001
Protons accelerated by a picosecond laser pulse have been used to radiograph a 500 microm diameter capsule, imploded with 300 J of laser light in 6 symmetrically incident beams of wavelength 1.054 microm and pulse length 1 ns. Point projection proton backlighting was used to characterize the density gradients at discrete times through the implosion. Asymmetries were diagnosed both during the early and stagnation stages of the implosion. Comparison with analytic scattering theory and simple Monte Carlo simulations were consistent with a 3+/-1 g/cm3 core with diameter 85+/-10 microm. Scaling simulations show that protons>50 MeV are required to diagnose asymmetry in ignition scale conditions. 相似文献
55.
56.
Crowhurst L Lancaster NL Pérez-Arlandis JM Welton T 《Journal of the American Chemical Society》2004,126(37):11549-11555
In this work we report the effect of ionic liquids on a class of charge-neutral nucleophiles. We have studied the reactions of (n)butylamine, di-(n)butylamine, and tri-(n)butylamine with methyl p-nitrobenzenesulfonate in [bmpy][N(Tf)(2)], [bmpy][OTf], and [bmim][OTf] (bmpy = 1-butyl-1-methylpyrrolidinium; bmim = 1-butyl-3-methylimidazolium) and compared their reactivities, k(2), to those for the same reactions in the molecular solvents dichloromethane and acetonitrile. It was shown that all of the amines are more nucleophilic in the ionic liquids than in the molecular solvents studied in this work. Comparison is also made with the effect of ionic liquids on the reactivity of chloride ions, which are deactivated in ionic liquids. The Eyring activation parameters revealed that changes in the activation entropies are largely responsible for the effects seen. This can be explained in part by the differing hydrogen-bonding properties, as shown by the Kamlet-Taft solvent parameters, of each of these solvents and the formation of hydrogen bonds between the solvents and the nucleophiles. 相似文献
57.
Aequationes mathematicae - 相似文献
58.
G.M. Lancaster J.A. Taylor A. Ignatiev J.W. Rabalais 《Journal of Electron Spectroscopy and Related Phenomena》1978,14(2):143-153
A source and differential pumping system for producing high intensity resonance line radiation from rare gas atoms and ions for ultrahigh vacuum (UHV) photoelectron spectroscopy has been developed. Photoelectron count rates from a gold sample, as measured with a double-pass cylindrical mirror analyzer at pass energy 15 eV and 0.10 eV resolution, are ~ 300,000 c s?1 for the He(I) (21.22 eV) line and ~30000 c s?1 for the He(II) (40.81 eV) line. The source design is based on the principle of the electrostatic charged particle oscillator and is capable of sustaining discharges over the pressure range 1 to ~ 10?6 torr. The discharge segment consists of a cylindrical cold cathode surrounding two tungsten rod anodes which are held at high positive potential. Three stages of differential pumping are employed in order that the vacuum in the main spectrometer chamber can be maintained at 2 × 10?10 torr during operation. The calculated helium flow reaching the main chamber under these conditions is < 101 s?1. Details of the construction and operating characteristics of the source are presented. 相似文献
59.
60.
D B Borders K J Sax J E Lancaster W K Hausmann L A Mitscher E R Wetzel E L Patterson 《Tetrahedron》1970,26(13):3123-3133