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81.
Mulder A Jukovic A Lucas LN van Esch J Feringa BL Huskens J Reinhoudt DN 《Chemical communications (Cambridge, England)》2002,(22):2734-2735
The binding of TSPP by a dithienylethene-tethered beta-cyclodextrin dimer can be altered reversibly by irradiation with light. 相似文献
82.
R.-D. Herzberg N. Amzal J.E. Bastin F. Becker P.M.T. Brew P.A. Butler A.J.C. Chewter J.F.C. Cocks O. Dorvaux K. Eskola J. Gerl P.T. Greenlees N.J. Hammond K. Hauschild K. Helariutta F. Heßberger M. Houry A. Hürstel R.D. Humphreys G.D. Jones P.M. Jones R. Julin S. Juutinen H. Kankaanpää H. Kettunen T.L. Khoo W. Korten P. Kuusiniemi Y. Le Coz M. Leino A.P. Leppänen C.J. Lister R. Lucas M. Muikku P. Nieminen R.D. Page T. Page P. Rahkila P. Reiter Ch. Schlegel C. Scholey G. Sletten O. Stezowski Ch. Theisen W.H. Trzaska J. Uusitalo H.J. Wollersheim 《The European Physical Journal A - Hadrons and Nuclei》2002,15(1-2):205-208
In-beam conversion electron spectroscopy experiments have been performed on the transfermium nuclei 253, 254No using the conversion electron spectrometer SACRED in nearly collinear geometry in conjunction with the gas-filled separator
RITU at the University of Jyv?skyl?. The experimental setup is discussed and the spectra are compared to Monte Carlo simulations.
The implications for the ground-state configuration of 253No are discussed.
Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002
RID="a"
ID="a"e-mail: rdh@ns.ph.liv.ac.uk
RID="b"
ID="b"Present address: GANIL, F-14021 Caen, France.
RID="c"
ID="c"Permanent address: IReS Strasbourg, IN2P3-CNRS, F-67037-Strasbourg, France.
RID="d"
ID="d"Present address: CEA/DIF DCRE/SDE/LDN F-91680 Bruyeres-le-Chatel.
RID="e"
ID="e"Present address: Daresbury Laboratory, Daresbury WA4 4AD, UK.
RID="f"
ID="f"Permanent address: IPN Lyon, IN2P3-CNRS, F-69037 Lyon, France. 相似文献
83.
The change of the FWHM of the mass distribution of the fission products as a function of angular momentum is interpreted as a signature for a mechanism which is intermediate between compound nucleus formation and deep inelastic reactions. An intermediate composite system is assumed to be formed during the reaction, which undergoes fission. This kind of mechanism can therefore be called fast fission phenomena. It is related to the existence of a long lifetime component in déep inelastic reactions. Within the framework of a simple statistical model a qualitative as well as a quantitative estimate is done for a particular system. The conditions under which such a mechanism can be observed are discussed. 相似文献
84.
In the reaction of Reformatsky reagents (R-CHZnBr-CO2R') with aromatic β-aminoketones (C6H5-CO-CH2-CH2-NR″2, mixtures of erythro and threo diastereomeric amino-hydroxyesters, with the former predominating, were obtained.The proposed bicyclic transition states involve the participation of the neighbouring nitrogen atom, and support the direction and the magnitude of the observed asymmetric induction. The relative stabilities of diastereomeric transition states are discussed in terms of steric and electronic effects. 相似文献
85.
86.
To obtain a state-of-the-art benchmark potential energy surface (PES) for the archetypal oxidative addition of the methane C-H bond to the palladium atom, we have explored this PES using a hierarchical series of ab initio methods (Hartree-Fock, second-order M?ller-Plesset perturbation theory, fourth-order M?ller-Plesset perturbation theory with single, double and quadruple excitations, coupled cluster theory with single and double excitations (CCSD), and with triple excitations treated perturbatively [CCSD(T)]) and hybrid density functional theory using the B3LYP functional, in combination with a hierarchical series of ten Gaussian-type basis sets, up to g polarization. Relativistic effects are taken into account either through a relativistic effective core potential for palladium or through a full four-component all-electron approach. Counterpoise corrected relative energies of stationary points are converged to within 0.1-0.2 kcal/mol as a function of the basis-set size. Our best estimate of kinetic and thermodynamic parameters is -8.1 (-8.3) kcal/mol for the formation of the reactant complex, 5.8 (3.1) kcal/mol for the activation energy relative to the separate reactants, and 0.8 (-1.2) kcal/mol for the reaction energy (zero-point vibrational energy-corrected values in parentheses). This agrees well with available experimental data. Our work highlights the importance of sufficient higher angular momentum polarization functions, f and g, for correctly describing metal-d-electron correlation and, thus, for obtaining reliable relative energies. We show that standard basis sets, such as LANL2DZ+1f for palladium, are not sufficiently polarized for this purpose and lead to erroneous CCSD(T) results. B3LYP is associated with smaller basis set superposition errors and shows faster convergence with basis-set size but yields relative energies (in particular, a reaction barrier) that are ca. 3.5 kcal/mol higher than the corresponding CCSD(T) values. 相似文献
87.
Grimault S Lucas T Quellec S Mariette F 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2004,170(1):79-87
MRI thermometry methods are usually based on the temperature dependence of the proton resonance frequency. Unfortunately, these methods are very sensitive to the phase drift induced by the instability of the scanner which prevents any temperature mapping over long periods of time. A general method based on 3D spatial modelling of the phase drift as a function of time is presented. The MRI temperature measurements were validated on gel samples with uniform and constant temperature and with a linear temperature gradient. In the case of uniform temperature conditions, correction of the phase drift proved to be essential when long periods of acquisition were required, as bias could reach values of up to 200 degrees C in its absence. The temperature uncertainty measured by MRI was 1.2 degrees C in average over 290 min. This accuracy is coherent with the requirements for food applications especially when thermocouples are useless. 相似文献
88.
Stefania Gabelli Evan Houston Thomas G. Lucas 《Journal of Pure and Applied Algebra》2004,194(3):281-298
Generalizing work of Gilmer and Heinzer, we define a t#-domain to be a domain R in which for any two distinct subsets and of the set of maximal t-ideals of R. We provide characterizations of these domains, and we show that polynomial rings over t#-domains are again t#-domains. Finally, we study overrings of t#-domains. 相似文献
89.
Sheridan B Martin DS Power JR Barrett SD Smith CI Lucas CA Nichols RJ Weightman P 《Physical review letters》2000,85(21):4618-4621
Introducing reflection anisotropy spectroscopy (RAS) as a new probe for solid-liquid interfaces, we present results for the Au(110)/electrolyte interface which serves as a model system. We demonstrate that RAS is sensitive to surface phase transitions, step morphology, and electronic surface states. Using an empirical approach, the RA spectra are reproduced and features are identified which reflect the known character of the bias voltage driven (2x1) to (1x1) phase transition. RAS is established as an experimental technique to probe the electronic structure of solid-liquid interfaces in real time to study a wide range of interface properties. 相似文献
90.
Ji-Won Moon Lucas W. Yeary Adam J. Rondinone Claudia J. Rawn Melanie J. Kirkham Yul Roh Lonnie J. Love Tommy J. Phelps 《Journal of magnetism and magnetic materials》2007
The magnetic susceptibility (κRT) and saturation magnetization (MS) of microbially synthesized magnetites were systematically examined. Transition metal (Cr, Mn, Co, Ni and Zn)- and lanthanide (Nd, Gd, Tb, Ho and Er)-substituted magnetites were microbially synthesized by the incubation of transition metal (TM)- and lanthanide (L)-mixed magnetite precursors with either thermophilic (TOR-39) or psychrotolerant (PV-4) metal-reducing bacteria (MRB). Zinc incorporated congruently into both the precursor and substituted magnetite, while Ni and Er predominantly did not. Microbially synthesized Mn- and Zn-substituted magnetites had higher κRT than pure biomagnetite depending on bacterial species and they exhibited a maximum κRT at 0.2 cationic mole fraction (CMF). Other TMs’ substitution linearly decreased the κRT with increasing substitution amount. Based on the MS values of TM- and L-substituted magnetite at 0.1 and 0.02 CMF, respectively, Zn (90.7 emu/g for TOR-39 and 93.2 emu/g for PV-4)- and Mn (88.3 emu/g by PV-4)-substituted magnetite exhibited higher MS than standard chemical magnetite (84.7 emu/g) or pure biomagnetite without metal substitution (76.6 emu/g for TOR-39 and 80.3 emu/g for PV-4). Lanthanides tended to decrease MS, with Gd- and Ho-substituted magnetites having the highest magnetization. The higher magnetization of microbially synthesized TM-substituted magnetites by the psychrotroph, PV-4 may be explained by the magnetite formation taking place at low temperatures slowing mechanics, which may alter the magnetic properties compared to the thermophile, through suppression of the random distribution of substituted cations. 相似文献