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101.
Surmont R Verniest G De Schrijver M Thuring JW ten Holte P Deroose F De Kimpe N 《The Journal of organic chemistry》2011,76(10):4105-4111
Fluorinated pyrazoles bearing additional functional groups that allow further functionalization are of considerable interest as building blocks in medicinal chemistry. The developed synthetic strategy for new 3-amino-4-fluoropyrazoles consists of a monofluorination of β-methylthio-β-enaminoketones using 1-(chloromethyl)-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (Selectfluor) toward the corresponding monofluorinated enaminoketones, followed by condensation with different hydrazines. 相似文献
102.
DNA block copolymer doing it all: from selection to self-assembly of semiconducting carbon nanotubes
103.
Jason P. Hagen 《光谱学快报》2013,46(1):58-61
Inductively coupled plasma–optical emission spectrometry was used to determine copper, iron, and zinc in both whole Crayfish and tail meat of crayfish from selected areas in southwestern Louisiana. Also included was a comparison between male and female crayfish. Results showed no significant difference between male and female crayfish and individuals from different sites. Iron was approximately four times greater in concentration for whole crayfish compared with tail meat. 相似文献
104.
105.
A. ten Bosch F. Celestini 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1993,28(4):293-297
We discuss a theoretical model for a surface transition in a nonspherical geometry. We study the stationary states of coexistence within a droplet of given volume. We show that finite range interactions with the matrix act to stabilize a finite non-spherical surface layer which is thickest in zones of highest curvature. At a certain temperature, the core tends to a spherical shape, becomes unstable and coexistence is no longer possible. 相似文献
106.
A. Marshall B. Børresen G. Hagen S. Sunde M. Tsypkin R. Tunold 《Russian Journal of Electrochemistry》2006,42(10):1134-1140
Iridium-based oxides are highly active as oxygen evolving electrocatalysts in PEM water electrolyzers. In this work XRD reveals
that Ir-Sn oxides contain a single rutile phase with lattice parameters between those of pure IrO2 and SnO2. Addition of Ru leads to the synthesis of a core-shell type material due to the strong agglomeration of Ru colloids during
the preparation procedure. The shell of this material consists of an Ir-Sn-Ru oxide deficient in Ru relative to the bulk.
This leads to a decrease in the surface noble metal concentration (as found by XPS), which in turn results in a significant
reduction in electrochemically active surface area. Polarization analysis indicates that the addition of Ru can influence
the rate-determining step or mechanism by which oxygen is evolved. In a PEM water electrolysis cell, small additions of Sn
do not significantly reduce the operating performance, however larger additions cause a performance loss due to a reduction
in active surface area and increased ohmic resistance. When a pure IrO2 anode is used, a cell voltage is 1.61 V at 1 A cm−2 and 90°C.
Published in Russian in Elektrokhimiya, 2006, Vol. 42, No. 10, pp. 1260–1267.
The text was submitted by the authors in English. 相似文献
107.
In this paper we consider a parameter estimation procedure for shallow sea models. The method is formulated as a minimization problem. An adjoint model is used to calculate the gradient of the criterion which is to be minimized. In order to obtain a robust estimation method, the uncertainty of the open boundary conditions can be taken into acoount by allowing random noise inputs to act on the open boundaries. This method avoids the possibility that boundary errors are interpreted by the estimation procedure as parameter fluctuations. We apply the parameter estimation method to identify a shallow sea model of the entire European continental shelf. First, a space-varying bottom friction coefficient is estimated simultaneously with the depth. The second application is the estimation of the parameterization of the wind stress coefficient as a function of the wind velocity. Finally, an uncertain open boundary condition is included. It is shown that in this case the parameter estimation procedure does become more robust and produces more realistic estimates. Furthermore, an estimate of the open boundary conditions is also obtained. 相似文献
108.
C. Athanasiou G. Marnellos J. E. ten Elshof P. Tsiakaras H. J. M. Bouwmeester M. Stoukides 《Ionics》1997,3(1-2):128-133
The catalytic and electrocatalytic behaviour of the La0.6Sr0.4Co0.8Fe0.2O3 (LSCF) perovskite deposited on yttria stabilized zirconia (YSZ), was studied during the reaction of methane oxidation. Experiments
were carried out at atmospheric pressure, and at temperatures between 600 and 900 °C. When, instead of cofeeding with methane
in the gas phase, oxygen was electrochemically supplied as O2−, considerable changes in the methane conversion and product selectivity were observed. The non-faradaic effects (NEMCA) were
also studied and compared to those observed with metal catalysts.
Paper presented at the 4th Euroconference on Solid State Ionics, Renvyle, Galway, Ireland, Sept. 13–19, 1997 相似文献
109.
Absorption spectra from 4000 to 1200 cm?1 of amorphous solid water and polycrystalline ice Ic have been measured between 10 K and 140 K. Warm up and recooling of an H2O sample prepared at 10 K gives rise to both irreversible and reversible changes in the peak frequency, band width, and peak height as well as the integrated intensity of the OH stretching band. These spectral effects are related to structural differences. The structure of amorphous solid water also depends on deposition conditions. The optical constants of amorphous so water are determined at 10 K and 80 K from a Kramers-Kronig analysis of the transmission spectra taking into account reflection and interference losses. The astrophysical implication of the temperature dependence of peak frequency and band width of the 3250 cm?1 band in amorphous solid water is discussed briefly. 相似文献
110.
A. ten Bosch J. L. Morán-López K. H. Bennemann 《Zeitschrift für Physik B Condensed Matter》1978,29(4):363-366
The metal-non-metal transition in liquid alloys such as Cs1–x
Au
x
and Li1–x
Pb
x
is explained as resulting from concentration dependent electron charge transfer causing short range atomic order and a change from metallic to ionic bonds. Numerical results for the electronic density of states, the electron charge transfer, the free energy of mixing and the volume change are given. 相似文献