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961.
The real (χ′
n) and imaginary (χ″
n) parts of even harmonic susceptibility (n⩽6) are measured as a function of external DC field (H
dc) in the field increasing (H↑) and decreasing (H↑) cycle. Hysteresis is observed betweenH↑ andH↓ cycles. In theH↓ cycle, at a field,H
comp=4·2G, bothχ′ andχ″ of all the even harmonics vanish indicating a true cancellation of fields in the intergrain region (H
eff≈0) caused by the balance betweenH
dc and the remanent magnetization of the grains. The position of the extrema and the zero of the various harmonics undergo a
shift proportional to the remanent magnetization of the grains at that particular field. 相似文献
962.
Summary Acetoacetanilide reacts with bromine in presence of acid to form a dibromo derivative. Of the two bromine atoms only one is attached to the benzene nucleus and probably the other is attached to the reactive methylene group, the last replacement being reversible. On addition of excess of bromate-bromide mixture to acidified solution of acetoacetanilide and subsequent titration with sodium thiosulphate it has been found that the addition of bromine is quantitative, and one acetoacetanilide molecule is equivalent to two bromine atoms.This property has been utilised in volumetric determination of beryllium. Beryllium is precipitated with acetoacetanilide and the complex is dissolved in hydrochloric acid. By the measurement of bromine absorbed by the acetoacetanilide thus liberated, the amount of beryllium can be determined.The method is applicable to the determination of beryllium in presence of aluminium and iron provided EDTA is added during precipitation and also to the determination of beryllium content of beryl.
Zusammenfassung Acetoacetanilid reagiert mit Brom in saurem Medium zu einem Dibromderivat. Das eine Br-Atom tritt dabei an den Benzolkern, während das andere wahrscheinlich von der aktiven Methylengruppe (reversibel) gebunden wird.Durch Zugabe von überschüssiger Bromat-Bromidlösung zu einer angesäuerten Lösung von Acetoacetanilid und nachfolgende Titration mit Thiosulfatlösung wurde festgestellt, daß die Bromaddition quantitativ verläuft und ein Molekül Acetoacetanilid zwei Bromatomen äquivalent ist.Diese Reaktion wurde zur volumetrischen Bestimmung des Berylliums benutzt. Hierbei wird das Beryllium mit Acetoanilid gefällt, der Niederschlag in Salzsäure gelöst und der Bromverbrauch des so freigesetzten Acetoacetanilids gemessen. Daraus ergibt sich die Menge an Beryllium.Das Verfahren kann auch zur Berylliumbestimmung in Gegenwart von Aluminium und Eisen verwendet werden, wenn man bei der Fällung ÄDTA zugibt. Die Be-Bestimmung in Beryll wird ebenfalls beschrieben.相似文献
963.
C. Wiezorek H. Kräwinkel R. Santo L. Wallek 《Zeitschrift für Physik A Hadrons and Nuclei》1977,283(1):121-123
Analysis of the anomalous behaviour of the gamma band in156Dy demonstrates the interference of the effect of ‘internal’ Coriolis coupling and quadrupole (ΔK=2) coupling. 相似文献
964.
965.
966.
Luciano Canovese Fabiano Visentin Gavino Chessa Claudio Santo Paolo Uguagliati Giuliano Bandoli 《Journal of organometallic chemistry》2002,650(1-2):43-56
Neutral methyl- and acyl-palladium chloro complexes containing pyridylthioether ancillary ligands (R′N---SR) (R′=H, Me, Cl; R=Me, Et, i-Pr, t-Bu, Ph) have been synthesised and characterised by elemental analysis and spectroscopic methods. The reactivity of these complexes toward allene (allene=DMA=1,1-dimethylpropadiene; TMA=1,1,3,3-tetramethylpropadiene) insertion into the palladium–carbon bond has been studied by 1H-NMR and UV–vis techniques. The rate of reaction appears to be strongly influenced by the steric and electronic properties of the ancillary ligand. The distortion induced by the substituent R′ in position 6 of the pyridine ring on the main coordination plane of the substrate (allowed by sulphur sp3 hybridisation) renders the substrate itself more prone to nucleophilic attack by the allene. The rate of allene insertion can further be enhanced by lowering the basicity of the chelating atoms in the N---S moiety which results in an increase of electrophilicity of the palladium core, so that the rate constants measured in the case of the complexes containing the ligand 6-chloro-2-phenylthiomethylpyridine (ClN---SPh) are by far the greatest observed so far for similar reactions. Furthermore, on the basis of the indications emerging from the exhaustive study on the behaviour of all the related pyridylthioether methyl complexes, an associative asynchronous bond making mechanism for the rate determining nucleophilic attack by allene is proposed. 相似文献
967.
Snigdha Banerjee Sanpei Kageyama Bhagwandas 《Annals of the Institute of Statistical Mathematics》1987,39(1):671-679
Summary Two-associate class PBIB designs, having association schemes of GD orL
2 types, are constructed by using patterned matrices and by methods of taking unions of sets of blocks. 相似文献
968.
969.
A statistical model for baryons was suggested leading to an analytical expression for the square modulus ∥ψ(r)∥2 of baryon wavefunctions, which is not only free of constituent quark masses but also devoid of the interaction parameters of the effective linear potential in which a quark moves. Using ∥ψ(r)∥2 as an input the lifetimes of the newly established charmed baryon () and the proton were studied and compared with other existing theoretical estimates. 相似文献
970.
T. Haupt P. V. K. S. Baba S. Banerjee M. Bardadin-Otwinowska K. W. J. Barnham T. Coghen A. Devanand K. Dziunikowska S. N. Ganguli H. Gerhold P. Girtler Y. Goldschmidt-Clermont R. Göttgens G. L. Kaul M. W. Krasny D. Kuhn P. K. Malhotra F. Mandl L. K. Mangotra A. B. Michalowska D. R. O. Morrison Y. Prakash R. T. Ross K. Shankar G. Singh K. Sudhakar M. Szczekowski P. R. S. Wright 《Zeitschrift fur Physik C Particles and Fields》1985,28(1):57-63