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991.
C. Brunnemann B. Kosmann J. Klein G. Kennepohl E. Thilo C. Mohr Albert G. Loges J. H. Vogel und J. S. Wells 《Fresenius' Journal of Analytical Chemistry》1888,27(1):249-253
Ohne Zusammenfassung 相似文献
992.
Neil R. Curtis Jeremy C. Prodger Geracimos Rassias Andrew J. Walker 《Tetrahedron letters》2008,49(44):6279-6281
A high yielding and selective method for producing methyl 5-amino-2H-1-benzopyran-8-carboxylate derivatives via gold(I)-catalysed intramolecular alkyne hydroarylation has been developed. 相似文献
993.
Ruthenium complexes of phosphinoferrocenylaminophosphine ligands (BoPhoz™ ligands) have been prepared by combining the ligands with tris(triphenylphosphine)ruthenium dichloride and precipitating the complexes. The optimal species exhibit high enantioselectivities for the asymmetric hydrogenation of functionalized ketones, particularly β-ketoesters. 相似文献
994.
Colin R. Edwards Michael J. Readhead Neil J. Tweddle 《Journal of heterocyclic chemistry》1987,24(2):495-496
A practical synthesis of 2,3-dihydro-2-benzofurancarboxylic acid is reported in five steps and approximately 40% overall yield. The methodology offers a useful new route to 2-substituted-2,3-dihydrobenzofurans. 相似文献
995.
Martin T. Wells Ram C. Tiwari 《Annals of the Institute of Statistical Mathematics》1994,46(3):487-495
The large-sample frequentist property of a frequentist bootstrap for a posterior mean with respect to a Dirichlet prior of the survival function for a randomly censored data is given. The weak convergence of a bootstrap version of the Susarla-Van Ryzin estimator is established on the whole real line. An illustration of the technique and some Monte Carlo studies are also given. 相似文献
996.
Humans are exposed to whole-body vibration in many types of environment. In almost all cases, the vibration to which the human is exposed comprises multi-axis vibration, such that vibration occurs in all directions simultaneously. Despite the complex nature of vibration to which humans are exposed in the workplace, almost all laboratory studies investigating the biomechanical response of the person have been completed using single-axis simulators. This paper presents a study whereby 15 male subjects were exposed to single-axis whole-body vibration in the x-, y- and z-directions and dual-axis vibration in the xy-, xz-, and yz-directions using a 6 degree-of-freedom vibration simulator. All vibration magnitudes were 0.4 ms−2 rms in each axis. Acceleration and force was measured in the x-, y-, and z-direction during all trials. Subjects sat in two postures (‘back-on’ and ‘back-off’) on a flat rigid seat. Apparent masses measured using single-axis and dual-axis vibration stimuli showed comparable results; similarly, cross-axis apparent masses (i.e. the ratio of the force in one direction to the acceleration in another direction) were almost identical for the single- and dual-axis vibration stimuli. All results were in agreement with data previously published using single-axis vibration. In most cases, the peaks in the apparent mass and the cross-axis apparent mass occurred at a slightly lower frequency for the dual-axis vibration than for the single-axis vibration. It is hypothesised that this change is due to a nonlinear effect, analogous to that which occurs with increasing vibration magnitude for single-axis vibration. 相似文献
997.
998.
David White B. Craig Taverner P.G.L. Leach Neil J. Coville 《Journal of computational chemistry》1993,14(9):1042-1049
A new, generalized, method for measuring the steric size of ligands and substituents has been developed. The method is based on the solid angle concept, the solid angle being generated by the pairwise addition of spheres (atoms). The problem of overlapping spheres (atoms) has been solved analytically and the algorithm provided permits evaluation of the steric space occupied by any combination of spheres (atoms). A range of solid angles for commonly encountered ligands and substituents has been determined and compared to literature values for linear cone angles. © John Wiley & Sons, Inc. 相似文献
999.
The kinetics of the solvolysis of the hydrophobic ion, Co(4-t-Bupy)4Cl2+, have been followed in mixtures of water with co-solvents having a hydrophilic tendency, ethane-1,2-diol and 2-methoxyethanol. The variation of In(rate constant) with the reciprocal of the dielectric constant is nonlinear for both co-solvents. The enthalpy and the entropy of activation are rather insensitive to changes in the solvent composition in both mixtures, but low maxima may exist at mol fractions of co-solvent Ca. 0.10–0.20. The application of a Gibbs energy cycle to the process of the initial state going to the transition state suggest that, in water-rich conditions, the increase in the stability of the emergent solvated CoIII ion in the transition state relative to the increase in the stability of Co(4-t-Bupy)4Cl2+ in the initial state as the co-solvent content rises is greater for 2-methoxyethanol than for ethane-1,2-diol. © 1995 John Wiley & Sons, Inc. 相似文献
1000.