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71.
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
72.
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
73.
Summary We describe here a sensitive, selective and rapid method to quantitate plasma catecholamines, especially dopamine, using high-performance liquid chromatography with electrochemical detection. This method requires a 10-minute run time and has a threshold for detection of 2 picograms, (10pg/ml).A number of commonly employed mobile phases for catecholamine analysis have been tested and have failed to detect dopamine in biological samples. Neither acetonitrile (3–7%) or methanol, (5–8%) in the mobile phase has produced consistently interpretable data either due to inability to detect or interference from co-eluting substances. Optimal detection was achieved with a mobile phase containing sodium acetate (6.8g), citric acid (5.9g), EDTA (48mg), di-n-butylamine (270l), Na-1-octane sulfate (850mg), methanol (100 ml) (amounts refer to 1 liter aqueous solution) (pH 4.3). The mobile phase was passed through a Waters 5 resolve C18 column using a Waters 590 pump and m460 electrochemical detector and 740 data module, Flow rate was 0.9ml/min. Using this method, normal values in human and swine left ventricular myocardium and human and swine plasma have been established for norepinephrine, epinephrine, and dopamine. 相似文献
74.
75.
B. S. Shasha D. Trimnell F. H. Otey 《Journal of polymer science. Part A, Polymer chemistry》1981,19(8):1891-1899
A simple method of encapsulating water-insoluble pesticides in a starch matrix is described. The method consists of mixing the pesticide with alkali starch followed by precipitation with a calcium chloride solution. A starch–calcium adduct that entraps the pesticide in small cells within granular particles is formed. Liquid and solid pesticides were successfully encapsulated by the new method. By use of the herbicide trifluralin [2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl) benzenamine] as core material more than 90% recovery and encapsulation was achieved. Use of acid-modified starches and flours resulted in a lower percentage of encapsulation. Effective encapsulation was also achieved by replacing calcium chloride with strontium chloride or barium chloride. 相似文献
76.
A simple and sensitive polarographic method has been developed for the determination of micro quantities of vanadium(V) and molybdenum(VI), based on the reduction of bromate, which is catalysed by these metal ions in the presence of 2,4-dihydroxyacetophenone oxime. Interference by various cations and anions has been investigated. 相似文献
77.
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
78.
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
79.
80.
The oxidation of 2,6-di-tert-butylphenol with tert-butylhydroperoxide (ButO2H) has been studied using polymer (XAD4) anchored salicylaldoxime, 1,3-propylene-bis-salicylaldimine and o-phenylene-bis-salicylaldimine complexes of molybdenum and vanadium in acetonitrile. The predominant products formed in the oxidation reactions were 2,6-di-tert-butylbenzoquinone (BQ) and 3,3′-5,5′-tetra-tert-butyldiphenoquinone (dPQ), whereas with some only 2,6-di-tert-butylbenzoquinone was formed. This is the first reported use of polymer anchored molybdenyl and vanadyl complexes in selective oxidation of 2,6-di-tert-butylphenol. Solvent plays an important role in this reaction. The effects of varying the ligand, metal and the support on the catalytic activity in the oxidation of 2,6-di-tert-butylphenol have been studied. With polymer anchored MoO2(salpen), 81% of 2,6-di-tert-butylbenzoquinone was formed from 2,6-di-tert-butylphenol. 相似文献