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121.
We have observed a large nonresonant third-order nonlinear susceptibility, X
(3) (-; , 0, 0) in the isotropic phase of a nematic liquid crystal 4-n-hexyl-4-cyanobiphenyl (K18). The highest value of X
(3) obtained at 632.8 nm is 1.16274×10-18 m2V-2 corresponding to a temperature 29.3°C. The observed second-order pretransitional temperature T
* from our measurements is 1.2°C below the first-order nematic to isotropic transition temperature. The dependence of the Kerr constant on (T-T
*)-1 is found to be in good agreement with the predictions of the Landau-de Gennes model. 相似文献
122.
123.
124.
K. Premchand B. Seetharami Reddy B. Mallikarjuna Rao K. Parthasaradhi M. V. R. Murti K. S. Rao 《Il Nuovo Cimento D》1993,15(1):73-76
Summary An attempt is made to study theK
α
L
1 satellite multiplet structure of chlorine atoms in different compounds by photon excitation. A comparison of the averageK
α
L
1 group energy shift from the diagram line with those based on Dirac-Fock evaluations with different number ofM-shell electrons shows a reasonable agreement. The
intensity ratios are found to be higher than those studied in Mg compounds in general. 相似文献
125.
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
126.
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
127.
P. Cloudy J. M. Létoffé P. Germain J. P. Bastide A. Bayol S. Blasquez R. C. Rao B. Gonzalez 《Journal of Thermal Analysis and Calorimetry》1991,37(11-12):2497-2506
Study and characterization of molecular complexes between cholesterol and beta cyclodextrin has been done using X-ray diffraction, thermogravimetric analysis (TG), differential scanning calorimetry (DSC) and nuclear magnetic resonance spectroscopy (13C NMR). Whatever the value of the molar ratio cholesterol/βCD used during the preparation, the same compound is always obtained. Corresponding to a molar ratio 1/3 (cholesterol/βCD), this compound is a stable hydrate which, contrary toβCD, contains at room temperature a large amount of molecules of water. It can be dehydrated under low pressure but the thermal degradation occurs at 200°C (250°C forβCD). This implies that cholesterol is strongly bounded toβCD. 相似文献
128.
Titrimetric and spectrophotometric methods have been developed for the determination of hydrogen peroxide at mmole and mumole levels respectively. In these methods thallium(III) is used as the oxidant and the reduced thallium(I) is determined oxidimetrically with potassium bromate in the titrimetric method and by measuring the absorbance of thallium(III) at 260 nm in the presence of 0.1M hydrochloric acid and 1M perchloric acid in the spectrophotometric method. Photochemical redox methods for the estimation of hydrogen peroxide in the presence of a number of diverse ions are described. 相似文献
129.
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
130.