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61.
Meso-diacylated calix[4]pyrrole was obtained via acid catalysed condensation of meso-acylated dipyrromethane with acetone. Selective presence of flexible substituents at the calix[4]pyrrole periphery led to interesting structural motifs in the solid state along with enhanced binding towards anions, especially dihydrogenphosphate ion via anchoring. 相似文献
62.
The fluorenoazomethine containing chalcogeno podand fluorescent probes having N, O/S/Se coordinating donor unit show donor specific 'turn-on' recognition property towards metals (Cr(III), Fe(II) and Cu(II)), where the fluorescence signals are controlled by the conformational change of the ligand framework on binding with the metal ion. 相似文献
63.
The kinetics of electron transfer from hexacyanoferrate(II) to tris(dimethylglyoximato)-nickelate(IV), Ni(dmg)32?, to produce Fe(CN)63? and Ni(dmgH)2, follows a pseudo-first-order disappearance in the Ni(IV). The pseudo-first-order rate constants kobs are linearly dependent on [Fe(CN)64?]0 in a fiftyfold range of 2 × 10?4?1 × 10?2M, and the average values of kobs/[Fe(CN)64?]0 range from 194M?1·s?1 at pH = 5.20 to 0.2M?1·s?1 at pH = 9.07 in aqueous medium at 35°C and μ = 0.57M. Results are interpreted in terms of a probable mechanism involving rate-determining outer sphere one-electron transfer steps from the reductant and one-protonated reductant species to the unprotonated and one-protonated Ni(IV) species present in solution. The more electrophilic one-protonated reductant species apparently reacts several orders of magnitude faster than the unprotonated one. 相似文献
64.
65.
This paper investigates the problem of free convection flow of a second order liquid in the boundary layer from a semi-infinite vertical plate in which the mean surface temperature varies as a function of the distance from the leading edge of the plate. Study of the oscillatory flow is restricted to small amplitudesε only. Several graphs have been drawn and tables have been presented to depict the effect of elasticity of the liquid and Prandtl number on the velocity and temperature distributions and Nusselt number. 相似文献
66.
Chitta R. Panda Vivekananda Chakravortty Kailash C. Dash 《Transition Metal Chemistry》1988,13(4):287-290
Summary Interaction of ZrOCl2:8H2O, [Zr4(OH)8(H2O)16]Cl8 12H2O, with the heterocyclic, aldimines (PyAlA) and heterocyclic ketimines (AcPyA) in Me2CO in the presence of HC(OEt)3 yields white amorphous compounds of the type [Zr4(OH)12(H2O)8(PyAlA)2]Cl4 and [Zr4(OH)12(H2O)10(AcPyA)]Cl4. Presumably these compounds have a tetrameric dodecahedral structure, derived from the parent. The analytical data, i.r., electrical conductance and t.g. measurements all favour the tetrameric formulation. The t.g. studies also indicate the intermediacy of complex species, which lose water and the Schiff base ligands, with increase in temperature. 相似文献
67.
Reactions of PdL2 complexes, where LH = benzoylacetone, dibenzoyl methane, or dipivaloyl methane, with pyridine and neat β-diketones (L 1H trifluoroacetylacetone, hexafluoroacetylacetone, thenoyltrifluoroacetone and pivaloyltrifluoroacetone) in toluene resulted in the formation of central carbon (C3) bonded hetero-β-diketonate complexes of the formula [Pd(L)(C3-L′)py]. These were characterized by microanalyses, IR and 1H NMR spectral data. 相似文献
68.
The kinetics of oxidation of thiosulfate to tetrathionate by trans-dihydroxotetraoxoosmate(VIII) in aqueous alkaline media have been studied. The oxidation follows a rate expression where KOs is the formation constant of trans-dihydroxotetraoxoosmate (VIII), and K2 and k3, respectively, represent the formation constants of the intermediate complex involving Os(VIII) and S2O and its decomposition constant. The KOs, K2, and k3 values have been computed to be (19.5 ± 3) dm3/mol, (6.12 ± 0.5) and (3.32 ± 0.3) × 10?1 dm3/mol s at 303 K, and I = 0.32 mol/dm3, respectively. The rate law is consistent with a mechanism envisaging the equilibrium formation of an intermediate complex involving Os(VIII) and S2O, followed by a rate-determining decomposition of the complex with concomitant electron transfer. 相似文献
69.
The oxidation of trans-stilbene, phenylacetylene, and diphenylacetylene by Tl(OAc)3 in aqueous acetic acid medium in the presence of HClO4 follows the rate law in [H+] of 0.1–1.0M, the [H+] dependence below 0.1M being marginal. The reactions are strongly dielectric dependent. The order of reactivity among the substrates is styrene > phenylacetylene and trans-stilbene > diphenylacetylene. A mechanism involving the oxythallation adduct by the Tl+(OAc)2 species has been discussed. The use of Ru(III) as a homogeneous catalyst brings a change in the kinetic orders for trans-stilbene, the rate law being The formation constants K for the Ru(III)–alkene π complex at 40, 50, and 60°C are 90.14M?1, 105.2M?1, and 127.7M?1, respectively. Interestingly the oxidation of phenylacetylene and diphenylacetylene does not undergo catalysis by Ru(III). The mechanism involving the metal–arene π complex is discussed. 相似文献
70.
S. Panda B. K. Panda 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,76(2):187-196
In the fractional dimensional space, the ground state properties
of the charged-boson fluid
are studied in a theory which goes beyond the random
phase approximation by including correlations through
a static local-field-factor. The structure factor and static
local field-factor
are obtained in
the self-consistent method.
Qualitative agreement with
the Monte Carlo results on static screening is achieved
by imposing self-consistency
on the compressibility of the fluid in addition to self-consistency
on the structure factor.
Using the structure
factors obtained in these methods, several properties
of the charged boson system such as the energy spectrum of elementary
excitations, the pair-correlation function,
the ground state energy,
the pressure,
the chemical potential and the compressibility are obtained in several
dimensions including both integer and fractional values.
Results obtained in the later method in two and three dimensional
systems are close to the Monte Carlo and hypernetted-chain methods.
The Wigner crystallisation in the lower dimensional system is found at
higher density of bosons. However, it vanishes
in any lower dimensional system whose dimension lies below 2. 相似文献