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71.
72.
S. Andrieu F. Ferrieu F. Arnaud d'Avitaya 《Applied Physics A: Materials Science & Processing》1989,49(6):719-722
In this paper, we present an analysis of antinomy deposition on silicon in the range of 0.1 to 1 monolayer by in situ spectroscopic ellipsometry. After a careful choice of viewpoint material, ellipsometric measurements are found to be sensitive to small surface perturbations, especially with antimony. In fact, less than a 0.1 monolayer of antimony on silicon at room temperature is detectable. Moreover, a linear dependence of the ellipsometric signal on Sb coverage is observed in the monolayer range. Consequently, the signal versus time variation directly gives the Sb adsorption kinetics on silicon. The saturation to one monolayer of compact antimony on silicon surface is used in order to calibrate the spectra. 相似文献
73.
Regis D. Gougeon Dr. Marianna Lucio Arnaud De Boel Moritz Frommberger Dr. Norbert Hertkorn Dr. Dominique Peyron Dr. David Chassagne Dr. François Feuillat Dr. Philippe Cayot Prof. Andrée Voilley Prof. Istvan Gebefügi Dr. Philippe Schmitt‐Kopplin Priv.‐Doz. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(3):600-611
A non‐targeted, ultra‐high‐resolution mass spectrometric, direct analysis of oak‐wood extracts from two species (Quercus robur L. and Quercus petraea Liebl.) from three French forests, and of a wine aged in barrels derived therefrom has been performed to identify families of metabolites that could discriminate both the species and the geographical origin of woods. From 12 T ultra‐high‐resolution Fourier transform ion cyclotron resonance mass spectra of wood extracts, hundreds of mass signals were identified as possible significant biomarkers of the two species, with phenolic and carbohydrate moieties leading the differentiation between Q. robur and Q. petraea, respectively, as corroborated by both FTMS and NMR data. For the first time, it is shown that oak woods can also be discriminated on the basis of hundreds of forest‐related compounds, and particular emphasis is put on sessile oaks from the Tronçais forest, for which sugars are significantly discriminant. Despite the higher complexity and diversity of wine metabolites, forest‐related compounds can also be detected in wines aged in related barrels. It is only by using these non‐targeted analyses that such innovative results, which reveal specific chemodiversities of natural materials, can be obtained. 相似文献
74.
A regio- and stereoselective iodination has been performed on vicinal diols located on ketopyranose templates using the controlled- Garegg conditions. 3-O-Benzyl-1,2-O-isopropylidene-β-d-fructo- or psicopyranoses (1 or 4) were selectively iodinated, respectively, at C-5 or C-4 of the ketoses to afford the l-sorbo or d-sorbo iodohydrins. 相似文献
75.
Mei Wang Nathalie Simon Gaelle Charrier Muriel Bouttemy Arnaud Etcheberry Musen Li Rabah Boukherroub Sabine Szunerits 《Electrochemistry communications》2010,12(3):351-354
While it is clearly established that oxidation of as-grown boron-doped diamond (BDD) interfaces results in the introduction of different surface oxygen functions such as ether, carbonyl and hydroxyl groups, there is no reported approach which can clearly distinguish between the different surface functions. For further surface functionalization, it is important to quantify the presence of each group on the diamond surface. In this paper, the presence and amount of surface hydroxyl groups is identified using esterification of the COH groups with trifluoroacetic acid. The presence of CF3 group in the acid allowed the identification and estimation of the amount of surface hydroxyl groups using X-ray photoelectron spectroscopy (XPS). 相似文献
76.
Krylova G Brioude A Ababou-Girard S Mrazek J Spanhel L 《Physical chemistry chemical physics : PCCP》2010,12(45):15101-15110
The additive free heteronucleation and nanocrystallization of ternary Zn(x)Ti(y)O(z) sols and coatings is presented. A proper adjustment of the Zn/Ti ratio in the sol allows the formation of elaborate superhydrophilic cubic spinel-like Zn(2)TiO(4), c-ZnTiO(3) or h-ZnTiO(3)-ilmentite/r-TiO(2)-rutile films. Their morphology and natural superhydrophilicity can be fine-tuned by the inclusion of 5% silica. This doping step delivers high dye intake capacities and water contact angle values below 3°. XPS analysis indicates that Zn and Si enrichment enables greater surface hydroxylation and thus improved water wetting behaviour. The transparent h-ZnTiO(3)-ilmenite/r-TiO(2) nanocomposite coatings deposited on glass and Si-wafers show a remarkable activity in the photomineralization of fatty-acids. 相似文献
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79.
Waves scattered by a weakly inhomogeneous random medium contain a predominant single-scattering contribution as well as a multiple-scattering contribution which is usually neglected, especially for imaging purposes. A method based on random matrix theory is proposed to separate the single- and multiple-scattering contributions. The experimental setup uses an array of sources/receivers placed in front of the medium. The impulse responses between every couple of transducers are measured and form a matrix. Single-scattering contributions are shown to exhibit a deterministic coherence along the antidiagonals of the array response matrix, whatever the distribution of inhomogeneities. This property is taken advantage of to discriminate single- from multiple-scattered waves. This allows one to evaluate the absorption losses and the scattering losses separately, by comparing the multiple-scattering intensity with a radiative transfer model. Moreover, the relative contribution of multiple scattering in the backscattered wave can be estimated, which serves as a validity test for the Born approximation. Experimental results are presented with ultrasonic waves in the megahertz range, on a synthetic sample (agar-gelatine gel) as well as on breast tissues. Interestingly, the multiple-scattering contribution is found to be far from negligible in the breast around 4.3 MHz. 相似文献
80.
Loredo A Plessy A El Hafidi A Hamzaoui N 《The Journal of the Acoustical Society of America》2011,129(4):1905-1918
A numerical vibroacoustic model that can manage multilayered plates locally covered with damping patches is presented. All the layers can have an on-axis orthotropic viscoelastic behavior. Continuity of displacements and transverse shear stresses at each interface is enforced, which permits to write the entire displacement field in function of the displacements of the--common--first layer, leading to a two-dimensional plate model. The problem is then discretized by Rayleigh-Ritz's method using a trigonometric basis that includes both sine and cosine functions in order to treat various boundary conditions. The excitation can be of mechanical kind (concentrated or distributed forces) or of acoustic kind (plane wave of any incidence, diffuse field, etc.). The model permits to compute different vibroacoustic indicators: the mean square velocity of the plate, the radiation efficiency, and the transmission loss. Comparisons between the present model and numerical results from literature or finite element computations show that the model gives good results in both mechanical and acoustical aspects. Then, a comparison of the effects of different distributions of patches is presented. The role of the surface covering rate is first discussed, followed by a study involving different geometries for the same surface covering rate. 相似文献