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911.
The rheological properties of PA-6/EPM polymer blends, non-compatibilized and compatibilized with grafted ethylene propylene
rubber (EPM-g-MA), have been investigated. Linear and non-linear (relaxation both in shear and extension) experiments were
realized. Stress relaxation experiments coupled with scanning electron microscopy (SEM) analysis showed the existence of one
relaxation time and non-deformed droplets for the immiscible blend, and two relaxation times and deformed droplets for the
compatibilized ones, the second relaxation being more pronounced for higher compatibilizer contents. These results clearly
indicate that, despite the high viscosity and elasticity ratios, if high amounts of compatibilizer are added to the blend,
interfacial slip is suppressed and a high-enough adhesion between the phases is achieved for the high-viscosity dispersed
phase to be deformed.
Paper presented at the 3rd Annual European Rheology Conference, April 27–29, 2006, Crete, Greece 相似文献
912.
Lewis acidic properties of transition aluminas whose surfaces have been doped with alkaline-earth metal cations (Ca2+ and Ba2+) were studied by means of the room temperature adsorption of carbon monoxide. The vibrational features of CO adsorbed at
the surface of doped aluminas were investigated by IR spectroscopy in comparison with pure parent aluminas, while the quantitative
and energetic features were studied by adsorption microcalorimetry. Various CO adspecies were found to form at the surface
of both pure and doped-alumina, owing to the structural heterogeneity of the Al2O3 surface and to the presence of alkaline-earth metal cations. The surface heterogeneity was revealed by different vco stretching frequencies, namely vco≈2230, 2218 and 2205 cm−1 for coordinatively unsaturated tetrahedral Al3+ cations in different crystallographic configurations, and vco≈2186 and 2172 cm−1 for coordinatively unsaturated Ca2+ and Ba2+ cations, respectively. Heats of adsorption of ≈80, 70 and 55 kJ/mol were assigned to the formation of Al3+/CO complexes, ≈45 kJ/mol for Ca2+/CO and ≈30 kJ/mol for Ba2+/CO complexes. The latter value was estimated through a correlation curve existing between vco stretching frequencies and adsorption enthalpies. This correlation, already proposed in the past for CO adsorbed on non-d/d0/d10 metal cations, has been revisited and confirmed here, by including Al2O3 data for which an apparent lack of correlation between the two parameters was first observed. With respect to pure alumina,
the population of Lewis acidic sites was found to be significantly depressed by the presence of alkaline-earth cus metal cations.
These acidic sites are intrinsically weaker than tetrahedral cus Al3+ cations, as witnessed by smaller upward shifts of the vco stretching frequencies with respect to CO gas and lower heats of adsorption, in accordance with expectations from the charge/ionic
radius ratios. Ca2+ cations were found to compete in adsorbing CO with Al3+ cations more efficiently than the larger Ba2+ cations. In the case of CaO/Al2O3 systems outgassed at 1023 K, a thin surface layer of calcium aluminate, not detected by XRD or HRTEM, was suggested to form. 相似文献
913.
J. A. Vera 《Nonlinear dynamics》2009,55(1-2):191-201
We consider the noncanonical Hamiltonian dynamics of a triaxial gyrostat in the three body problem. By means of geometric-mechanics methods, we will study the approximated dynamics that arises when we develop the potential in series of Legendre and truncate the series to the second harmonics. Working in the reduced problem, we will study the existence of equilibria that we will denominate of Euler in analogy with classic results on the topic. In this way, we generalize the classical results on equilibria of the three-body problem and many of those obtained by other authors using more classic techniques for the case of rigid bodies. The instability of Eulerian equilibria is proven in this approximate dynamics if the gyrostat is close to the sphere. The rotational Poisson dynamics of the gyrostat placed at an Eulerian equilibrium and the study of the nonlinear stability of some equilibria is considered. The analysis is done in vectorial form avoiding the use of canonical variables and the tedious expressions associated with them. 相似文献
914.
Vera V. Baturo Sergey S. Lukashov Sergey A. Poretsky Anatoly M. Pravilov 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2017,71(9):227
This paper is an overview of our recent experimental investigations of the RgI2 van der Waals complexes, Rg = He, Ar, Kr, performed by means of laser induced fluorescence spectroscopy, optical-optical double resonance and supersonic molecular beam techniques. Spectroscopic parameters of these complexes in the E0 g + ion-pair state, such as binding energies and several spectroscopic constants, have been determined. Most likely, the potential energy surfaces of the all RgI2(E) complexes under study present T-shaped minima. Vibrational and electronic predissociations of the RgI2(E) complexes were analyzed. Relative contributions of the different electronic predissociation channels and vibrational distributions of the decay products were determined. Possible mechanisms of the complexes decay are suggested and discussed. 相似文献
915.
Galo Crdenas T. Elizabeth Salgado C. Viviana Vera L. Miguel J. Yacamn 《Macromolecular rapid communications》1996,17(11):775-780
Styrene/ethyl methacrylate (SEMA) colloids were obtained by cocondensation at 77 K of the monomers with several metals such as Au, Pd, In and Sn. The colloids were polymerized with 2,2′-azoisobutyronitrile and dibenzoyl peroxide as radical initiators at 60°C for 3.5 h. A viscosity average molecular weight (104 < M v < 105) was obtained depending upon the metal used. The particle size of these clusters dispersed in the copolymers ranges from 20 to 31 Å. The metal clusters are incorporated in the copolymers. 相似文献
916.
Aarne Pajunen Fernando Cmara Jose M. Dominques‐Vera Enrique Colacio 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(2):e49-e50
In the title compound, [Cu(C10H18N5)(CH4O)]ClO4, four N atoms from the deprotonated ligand derived from bis(3‐aminopropyl)amine and 2‐imidazolecarboxaldehyde are coordinated to the Cu atom. The four N atoms occupy equatorial positions with Cu—N bond distances ranging from 1.998 (2) to 2.046 (3) Å. The methanol O atom occupies one axial position with a Cu—O bond distance of 2.295 (2) Å. 相似文献
917.
918.
Hashimoto JC Paschoal JA Queiroz SC Ferracini VL Assalin MR Reyes FG 《Journal of AOAC International》2012,95(3):913-922
A simple method using LC/MS/MS was developed and validated to determine residues of malachite green (MG) and leucomalachite green (LMG) in fish fillet. A modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) technique was used to perform the sample preparation. The optimal extraction and cleanup conditions were established using an experimental design. The validation parameters obtained to determine both MG and LMG complied with the requirements established by regulatory agencies for the presence of such substances in fish, which establish that the method must attain, at least, a minimum required performance limit of 2 ng/g. The accuracy values ranged between 95 and 107%, and the precision values were lower than 11.2%. The method was used in the analysis of tilapia samples (n = 20) commercialized in Campinas, SP, Brazil. None of the samples presented detectable levels of MG or LMG residues. 相似文献
919.
920.
Melanie Heghmanns Andreas Rutz Yury Kutin Vera Engelbrecht Martin Winkler Thomas Happe Müge Kasanmascheff 《Chemical science》2022,13(29):8704
Correction for ‘The oxygen-resistant [FeFe]-hydrogenase CbA5H harbors an unknown radical signal’ by Melanie Heghmanns et al., Chem. Sci., 2022, 13, 7289–7294, https://doi.org/10.1039/D2SC00385F.The authors realized that incorrect references were cited following the sentence “In conjunction with the signal''s significant width, the frequency dependence clearly indicates spin–spin interaction between the F-clusters.” The correct references are shown below as ref. 1 and 2.Additionally ref. 36 and 37 were reversed in the reference list. The correct ref. 36 is shown below as ref. 3 and the correct ref. 37 is shown below as ref. 4.The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers. 相似文献