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951.
Forget N Cotel A Brambrink E Audebert P Le Blanc C Jullien A Albert O Chériaux G 《Optics letters》2005,30(21):2921-2923
We report on direct observation of temporal contrast degradation of short pulses amplified by optical parametric chirped-pulse amplification. We show that, despite injection seeding, quantum-noise-induced fast modulations (< 50 ps) of the temporal profile of the pump pulse are imprinted on the spectrum of the amplified chirped pulse and give rise to a large picosecond pedestal in the time domain. 相似文献
952.
Lavalette A Tuna F Clarkson G Alcock NW Hannon MJ 《Chemical communications (Cambridge, England)》2003,(21):2666-2667
Metal-ligand interactions are used not only to design metallo-supramolecular architectures but also to assemble multiple hydrogen bond sites at the periphery of these architectures. The hydrogen bond sites aggregate the architectures into polymeric arrays with the selection of anion determining whether this is self H-bond aggregation or anion-mediated H-bond aggregation. 相似文献
953.
954.
Roberto?FernándezEmail author Arnaud?Le?Ny Frank?Redig 《Bulletin of the Brazilian Mathematical Society》2003,34(3):437-455
We restore part of the thermodynamic formalism for some
renormalized measures that are known to be non-Gibbsian. We
determine a necessary and sufficient condition for consistency
with a specification that is quasilocal only in a fixed
direction. This condition is then applied to models with FKG
monotonicity and to models with appropriate directional
continuity rates, in particular to (noisy) decimations or
projections of the Ising model. In this way we establish: (i)
the validity of the second part of the variational principle
for projected and FKG block-renormalized measures, and (ii) the
almost quasilocality of FKG block-renormalized + and –
measures. 相似文献
955.
Raymond Le Goaller Jean-Louis Pierre Paul Arnaud 《Magnetic resonance in chemistry : MRC》1969,1(4):337-340
The meso or threo configuration of diastereoisomeric molecules is elucidated on the basis of respective NMR spectra of either isomers. The symmetry relationship (according to Raban and Mislow) between protons or groups are not identical in each isomer, and the consequent differences in chemical shifts and spin-coupling constants permit assignment of configurations. 相似文献
956.
André Laschewsky Erik Wischerhoff Steffen Denzinger Helmut Ringsdorf Arnaud Delcorte Patrick Bertrand 《Chemistry (Weinheim an der Bergstrasse, Germany)》1997,3(1):34-38
Functional polyanions were prepared by copolymerization of sulfopropyl acrylate and sulfopropyl methacrylate with monomers bearing triaminopyrimidine or barbituric acid functionalities, respectively. Functionalized polyelectrolyte multilayers were assembled from these copolymers by stepwise alternating adsorption with poly(choline methacrylate). These multilayers are suited for molecular recognition of substrates that are complementary to the functional groups incorporated. Thus, multilayers containing triaminopyrimidine moieties selectively bind barbituric acid, and vice versa, when exposed to solutions of the 1:1 complex of barbituric acid and triaminopyrimidine. The molecular recognition process was monitored by UV/Vis spectroscopy, time-of-flight secondary ion mass spectroscopy (ToF-SIMS), and photoelectron spectroscopy (XPS). Remarkably, after successful recognition and binding of the complementary substrates to the multilayers, the stepwise layering could be continued. 相似文献
957.
Degradations photothermiques de polyethylenes reticules—I: Influence de noirs de carbone commerciaux
Introduction of small quantities (<1%) of carbon black in branched polyethylene induces a photothermic degradation at temperatures >70°. An interpretation of variations in the rate of degradation, measured by i.r. absorption or by deformation, with the percentage of carbon black has been given. The effects of different commercial samples of carbon black have been compared. 相似文献
958.
Ab initio molecular orbital calculations of the transition states and barrier heights for the addition of atomic hydrogen to fluoroactylene and 1,1-difluoroethylene are presented. The relative reactivity of these compounds and the regioselectivity of the addition reactions are analyzed in terms of chemically interpretable contributions by means of the energy decomposition scheme proposed by Morokuma. The usual PMO approach of the problem is discussed in this context. A rationalization of some of the experimental rules of radical reactivity is given. 相似文献
959.
Jacques Lacoste Rene Arnaud Jacques Lemaire 《Journal of polymer science. Part A, Polymer chemistry》1984,22(12):3885-3893
Direct evidence of the TiO2 and ZnO photocatalytic decomposition of tert-butyl hydroperoxide and atactic polypropylene hydroperoxides in solution is reported. Molecular and macromolecular hydroperoxides behaved similarly. Untreated TiO2 in the rutile form was a far more efficient photocatalyst than ZnO in solution; the photoactivities of both pigments were limited on preferential absorption sites. In the solid state no preferential reaction sites were observed. When added to preoxidized atactic polypropylene both pigments were photocatalysts of the formation of macromolecular hydroperoxides and of their decomposition. The photoreactivities of untreated TiO2 and ZnO varied less than in solution. 相似文献
960.