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31.
D. V. Rao R. Cesareo G. E. Gigante 《Applied Physics A: Materials Science & Processing》1993,56(5):401-403
K
and K
X-ray fluorescence cross-sections have been experimentally determined for the elements Cu, Se, Y, and Mo at excitation energies 23.62, 24.68, 36.82, 43.95, 48.60, and 50.20keV using an X-ray tube with a secondary exciter system as the excitation source. The X-ray tube with a secondary target arrangement was used to obtain high intensity with high degree of monochromatization. Experimental values were compared with the theoretical values using tabulated I
ratios based on Hartree-Fock and Hartree-Slater theories calculated by Scofield. The experimental values for all the elements at various excitation energies are in good agreement with the theoretical values. 相似文献
32.
Summary In earlier works, the gauge theorem was proved for additive functionals of Brownian motion of the form
0
t
q(B
s
)ds, whereq is a function in the Kato class. Subsequently, the theorem was extended to additive functionals with Revuz measures in the Kato class. We prove that the gauge theorem holds for a large class of additive functionals of zero energy which are, in general, of unbounded variation. These additive functionals may not be semi-martingales, but correspond to a collection of distributions that belong to the Kato class in a suitable sense. Our gauge theorem generalizes the earlier versions of the gauge theorem.Research supported in part by NSA grant MDA-92-H-30324 相似文献
33.
Molybdenum was reported to be precipitated quantitatively by 8-hydroxyquinoline in the pH range 3.3–7.6, the precipitated compound having the composition MoO2(ox)2. The pH range reported and the composition of the complex do not seem to be compatible with present knowledge of the pH stability of anionic and cationic molybdenum. It is now shown that under defined conditions, the precipitate is not formed at pH values higher than 2.24. In several estimations of other metals, molybdenum was masked by using a complexone at high pH values. It is now pointed out, that maintaining the solution at high pH value is itself sufficient and no other external complexing agent is necessary for masking molybdenum. 相似文献
34.
Hydrazine sulphate is proposed as a primary standard reagent for the direct titrimetric determination of vanadium(V) and chromium(VI) alone and in mixtures with potentiometric and photometric end-points, in 9–12 M phosphoric acid medium. The methods proposed possess advantages over those currently available. The use of phosphoric acid as a reaction medium not only accelerates the hydrazine-vanadium(V) reaction very much but also makes it follow an accurate stoichiometric path. 相似文献
35.
Summary The mixed ligand complex, [Fe(Phen)2(N3)2] can be extracted into nitrobenzene giving a molar absorptivity of 16750 at 510 nm. This is the basis of a photometric method for iron which may be either in the trivalent or bivalent state. The new method is free from interference from a number of substances and is more sensitive than the ferroin method.
Zusammenfassung Der Eisen-Phenanthrolin-Azid-Mischkomplex [Fe(Phen)2(N3)2] ist mit Nitrobenzol extrahierbar und gibt bei 510 nm eine molare Absorption von 16750. Darauf läßt sich eine photometrische Bestimmungsmethode für zweioder dreiwertiges Eisen begründen. Diese wird von vielen Stoffen nicht gestört und ist empfindlicher als die Ferroinmethode.相似文献
36.
Some new metal-containing polyurethanes were synthesized from manganese and lead salts of mono(hydroxyethyl)phthalate by condensing them with hexamethylene diisocyanate and toluene diisocyanate in dimethylformamide as solvent. The polymers were characterized by viscometry, infrared spectroscopy and thermal analysis. The decomposition temperatures of these polymers were found to be significantly lower than those of metal-free polymers of similar structure. However, the rates of decomposition of metal-containing polyurethanes were lower than those of polyurethanes having no metal. Inherent viscosities in DMSO at 30° of these polyurethanes were low, ranging from 0.043 to 0.067. 相似文献
37.
A new method has been developed for the direct titrimetric determination of manganeseII, depending on its oxidation to manganeseIII with potassium dichromate at room temperature in a strong phosphoric acid medium using a potentiometric or photometric endpoint. Oxygen of the air does not interfere. The potentiometric method gives results to an accuracy within ± 0.3% for 20–150 mg of manganese/50 ml of titration solution; with the photometric method 5–17 mg of manganese/40 ml of titration solution can be determined with an error of 0.3–1.0% depending on the amount present. Potassium dichromate in 12.0M phosphoric acid has a formal redox potential of about 1.5 V and this reagent appears to have great possibilities in titrimetric analysis. 相似文献
38.
The L3/L2 white-line intensity ratio in transition-metal oxides deviates widely from the statistical value of 2 : 1 but shows interesting systematics. In a series of oxides of a given metal, the ratio reaches a maximum for the d5 configuration (e.g. MnO) and a minimum for the d0 configuration (e.g. KMnO4). In a series of monoxides, sesquioxides and dioxides of different metals, the ratio is again a maximum at the d5 configuration and decreases as the configuration changes towards d0 or d10. Our results, obtained by electron energy-loss spectroscopy, carried out in an electron microscope, are interpreted on an atomic mechanism involving spin-spin coupling. According to this model, the L2 transition probability decreases in the progression d0 to d5 whereas the L3 transition probability decreases beyond d5. 相似文献
39.
Experimental conditions have been established for the accurate direct titrimetric determination of arsenic(III) with potassium dichromate, using ferroin and N-pnenylanthranilic acid as redox indicators. Interferences have been considered. 相似文献
40.
A procedure has been developed for the determination of ziram (zinc dimethyldithiocarbamate), ferbam (ferric dimethyldithiocarbamate) and zineb (zinc ethylenebisdithiocarbamate) after their decomposition and extraction of the diphenylcarbazone complexes of the zinc or iron into isobutyl methyl ketone. These complexes absorb strongly at 520 nm. The method is rapid, sensitive and selective and can be used for the determination of these dithiocarbamates in commercial and synthetic mixtures. 相似文献