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991.
Octasubstituted phthalocyanines bearing bulky (cyclopentyl)methyl- and (cyclohexyl)methyl-substituents in non-peripheral positions are prepared and characterised. The synthesis of the precursor phthalonitriles is achieved through nickel-catalysed cross-coupling employing alkylzinc reagents. In the case of the (cyclopentyl)methyl derivative the formal precursor is 5-hexenyl bromide which yields the cyclised material exclusively on formation of the zinc reagent and subsequent cross-coupling. 相似文献
992.
A new synthetic protocol for the synthesis of large diameter (2.5 to 5 μm), temperature-, and pH-responsive microgels via
aqueous surfactant-free radical precipitation copolymerization is presented. We have found that in this size range, which
is not typically attainable using traditional dispersion polymerization approaches, excellent monodispersity and size control
are achieved when the synthesis employs a programmed temperature ramp from 45 to 65 °C during the nucleation stage of the
polymerization. A combined kinetic and thermodynamic hypothesis for large particle formation under these conditions is described.
Particle sizes, volume phase transition temperatures, and pH responsivity were characterized by particle tracking and photon
correlation spectroscopy to illustrate their similar behavior to particles made via more traditional routes. These particles
have been enabling for various studies in our group where microscopic visualization of the particles is required. 相似文献
993.
Xinnan Zhang Gang‐Chi Chen Andrew Collins Solomon Jacobson Paul Morganelli Yadunandan L. Dar Osama M. Musa 《Journal of polymer science. Part A, Polymer chemistry》2009,47(4):1073-1084
New thermosetting materials were developed for reworkable adhesive applications by introducing acetal ester groups as thermally degradable linkages into maleimide compounds. The synthesis of compounds containing maleimide functionality and acetal ester linkages was conducted by a one‐step neat reaction from commercially available materials. The polymerization process and thermal degradation of the synthesized materials were studied. It was found that the acetal ester linkage degraded rapidly above 225 °C, and introduction of this linkage into the adhesive formulation led to improved reworkability of adhesively bonded substrates. A mechanism for reworkability was proposed based on the insight provided by experimental and modeling work. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1073–1084, 2009 相似文献
994.
In this paper, we study a multi-stage production sourcing problem where tariff concessions can be exploited at the firm level using free trade agreements between countries. To solve the problem, an algorithm which embeds a very large-scale neighborhood (VSLN) search into a simulated annealing framework is developed. A numerical study is conducted to verify the effectiveness of the solution approach. 相似文献
995.
This paper presents an approach for determining the linear stability of steady states of partial differential equations (PDEs) on massively parallel computers. Linearizing the transient behavior around a steady state solution leads to an eigenvalue problem. The eigenvalues with the largest real part are calculated using Arnoldi's iteration driven by a novel implementation of the Cayley transformation. The Cayley transformation requires the solution of a linear system at each Arnoldi iteration. This is done iteratively so that the algorithm scales with problem size. A representative model problem of three‐dimensional incompressible flow and heat transfer in a rotating disk reactor is used to analyze the effect of algorithmic parameters on the performance of the eigenvalue algorithm. Successful calculations of leading eigenvalues for matrix systems of order up to 4 million were performed, identifying the critical Grashof number for a Hopf bifurcation. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
996.
Andrs E. Goeta Andrew K. Hughes John M. Malget 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(6):702-703
The structure of the title compound, [Ta2O(C2B9H11)2(C4H9N2)4]·0.5CH2Cl2, contains two (C2B9H11)Ta[NC(Me)NMe2]2 units bridged by a nearly linear [Ta—O—Ta 163.4 (4)°] μ‐oxo ligand. The dichloromethane molecule lies on a twofold axis. 相似文献
997.
998.
Andrew S. Zektzer John G. Stuart Gary E. Martin Raymond N. Castle 《Journal of heterocyclic chemistry》1986,23(5):1587-1593
Phenanthro[3′,4′:3,4]phenanthro[2,1-b]thiophene has been prepared and its highly congested proton and carbon nmr spectra assigned. The nmr assignments required concerted utilization of two-dimensional nmr techniques which included: COSY, direct and long range optimized heteronuclear chemical shift correlation and heteronuclear relayed coherence transfer. 相似文献
999.
Multiple criteria analysis (MCA) is a framework for evaluating decision options against multiple criteria. Numerous techniques for solving an MCA problem are available. This paper applies MCA to six water management decision problems. The MCA methods tested include weighted summation, range of value, PROMTHEE II, Evamix and compromise programming. We show that different MCA methods were in strong agreement with high correlations amongst rankings. In the few cases where strong disagreement between MCA methods did occur it was due to presence of mixed ordinal-cardinal data in the evaluation matrix. The results suggest that whilst selection of the MCA technique is important more emphasis is needed on the initial structuring of the decision problem, which involves choosing criteria and decision options. 相似文献
1000.
Yue Xuan Andrew J. Creese Julie A. Horner Helen J. Cooper 《Rapid communications in mass spectrometry : RCM》2009,23(13):1963-1969
We have applied high‐field asymmetric waveform ion mobility spectrometry (FAIMS) to the analysis of the phosphopeptides APLpSFRGSLPKSYVK, APLSFRGpSLPKSYVK, and APLSFRGSLPKpSYVK. The peptides have identical amino acid sequences and differ only in the site of phosphorylation. The results show that FAIMS is capable of at least partially separating these species. Separation was confirmed by coupling FAIMS with high‐resolution electron transfer dissociation (ETD) mass spectrometry. Phosphorylation is retained on the ETD peptide fragments thereby allowing assignment of the site of the modification. Co‐eluting phosphopeptides which differ only in the site of modification are frequently observed in liquid chromatography/tandem mass spectrometry phosphoproteomics experiments, and therefore these proof‐of‐principle results have implications for the application of FAIMS in that field. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献