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101.
Heparanase degrades heparan sulfate (HS) chains on proteoglycans; elevated levels of heparanase expression correlate with tumour cell metastatic potential and vascularity, and reduced post-operative survival of cancer patients. Consequently, heparanase expression is considered a biomarker for cancer detection. Although several heparanase assays have been developed, most require the preparation of heterogeneous, (radio)labelled HS substrates and rely on the separation of enzymatically-degraded products on the basis of molecular size. In studies directed towards the development of a more direct heparanase assay, a series of glucuronides and glycosyl glucuronides were synthesised as putative heparanase substrates. These compounds were designed with various aryl aglycones that could be measured spectrophotometrically upon hydrolysis of the glycosidic linkage by heparanase. It was found that the N-sulfated 4-nitrophenyl glycosyl glucuronide 24 and the N-sulfated methylumbelliferyl glycosyl glucuronide 26 were hydrolysed by recombinant human heparanase. These compounds represent the simplest substrates of heparanase reported to date. 相似文献
102.
Recently, a simple scaling argument was introduced that allows us to map, with some precautions, Brownian and Monte Carlo dynamics for spherical particles. Here, we extend the scaling to study systems that have orientational degrees of freedom and carefully asses its validity over a wide region of temperature and density. Our work allows us to devise a Brownian Monte Carlo algorithm that produces, to a good approximation, physically meaningful trajectories with a minimum programming effort, although at the expense of some sampling efficiency. 相似文献
103.
G. Lacagnina S. Grizzi M. Falchi F. Di Felice G. P. Romano 《Experiments in fluids》2011,50(4):1153-1167
In this paper, interferometric laser imaging droplet sizing—ILIDS—is applied to incipient cavitation in the wake of a marine
propeller model with the aim to evaluate simultaneously bubbles velocity and diameter. Until now, the feasibility of this
technique has been demonstrated especially in sprays of water droplets in air where an optimal light scattering is obtained
thanks to the spherical shape and to the given relative refractive index. In the present setup, to allow simultaneous size–velocity
measurements, a single camera is used and the object distance over lens diameter ratio is kept as small as possible, thus
increasing the size measurement resolution. These details, together with the algorithms used for image analysis at each single
frame and in two consecutive frames, allow deriving cavitation bubble size and velocity distributions in the propeller wake. 相似文献
104.
We study degree spectra of structures with respect to the bi‐embeddability relation. The bi‐embeddability spectrum of a structure is the family of Turing degrees of its bi‐embeddable copies. To facilitate our study we introduce the notions of bi‐embeddable triviality and basis of a spectrum. Using bi‐embeddable triviality we show that several known families of degrees are bi‐embeddability spectra of structures. We then characterize the bi‐embeddability spectra of linear orderings and study bases of bi‐embeddability spectra of strongly locally finite graphs. 相似文献
105.
Mycelia of Aspergillus oryzae display high enantioselectivity towards (R)-flurbiprofen and can be efficiently used in pure organic solvent for the resolution of (R,S)-flurbiprofen through esterification. The use of the lyophilized mycelia facilitates the separation process so that in one step the two enantiomers of flurbiprofen, which are both valuable for pharmaceutical applications, can be easily separated. The biotransformation can be carried out in different apolar solvents using different primary alcohols as nucleophiles under very mild conditions. 相似文献
106.
Dino Boccaletti Francesco Catoni Vincenzo Catoni 《Advances in Applied Clifford Algebras》2007,17(4):611-616
The use of hyperbolic numbers for studying space-time geometry and trigonometry is extended for demonstrating the Frenet’s
formulas in space-time.
By means of this introduction the twin paradox for non-uniformly accelerated motions is formalized in a straightforward way. 相似文献
107.
Ch. Zgheib E. Nassar M. Hamad R. Nader P. Masri J. Pezoldt G. Ferro 《Superlattices and Microstructures》2006,40(4-6):638
The effect of the germanium coverage prior to the epitaxial growth of 5 μm thick 3C-SiC on Si(100) substrates were evaluated with Atomic Force Microscopy and μ-Raman spectroscopy. The 3C-SiC layers were grown by atmospheric pressure chemical vapor deposition via a special procedure leading to layers with compressive instead of tensile stress. The Ge amount was varied from 0 up to 2 ML. The obtained results showed that the residual stress inside the layers is shifted in the compressive direction; the crystalline quality is improved with the Ge introduction but on the account of the surface roughness. These results open the route for the use of Ge-modified Si(100) as a potential substrate in order to improve the heteroepitaxial growth of 3C-SiC on silicon substrates. 相似文献
108.
This paper is devoted to the molecular dynamics simulation of structural organization inside a polydispersed liquid crystal (LC) droplet under competing boundary conditions. The droplet is assumed to be placed at the liquid crystal interface between two different regions of the solid polymer matrix, which accordingly separates the droplet into two hemispheres: the first of these is under radial boundary conditions; the second hemisphere is under bipolar boundary conditions. The droplet is considered as a jagged sphere filled with LC molecules, modelled as classical spins (unit vectors), whose centres of mass are associated with sites of a cubic lattice inside the cavity. The orienting action of the polymer matrix, and hence the resulting boundary conditions, are modelled by the interaction between the internal LC molecules (possessing only orientational degrees of freedom), and those of a delimiting surface layer (a jagged spherical shell), whose orientations are fixed, radial or bipolar, respectively. All interactions are modelled by the short range McMillan pair potential. The molecular orientation inside the LC droplet has been determined for various anchoring strengths of the interaction between internal spins and boundary layers. We have investigated the structure of the spherical defect resulting in the central region of the droplet, as well as of the boojum - like defects existing near the poles of the droplet. It has been found that a change of relative radial and bipolar anchoring strengths can affect both central and boojum - like defects. The effect of an external field on the molecular orientation inside the droplet has also been investigated. It has been found that a sufficiently strong external field increases the radius of the spherical defect placed in the central region of the droplet. 相似文献
109.
F. Raiola B. Burchard Zs. Fülöp Gy. Gyürky S. Zeng J. Cruz A. Di Leva B. Limata M. Fonseca H. Luis M. Aliotta H. W. Becker C. Broggini A. D'Onofrio L. Gialanella G. Imbriani A. P. Jesus M. Junker J. P. Ribeiro V. Roca C. Rolfs M. Romano E. Somorjai F. Strieder F. Terrasi 《The European Physical Journal A - Hadrons and Nuclei》2006,27(1):79-82
110.
The syndiotactic polystyrene can crystallize in different forms, depending on thermal and solvent treatments. The influence of the polymorphism on the dynamic-mechanical behavior has been analyzed. Thermogravimetric and calorimetric analysis were also carried out. The effects of phase transitions and solvent release on the relaxation phenomena were observed, and the correlations between structure and dynamic behavior allow to better understand some aspects of the polymorphism phenomena. 相似文献