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101.
An important question in the manufacture of superconducting electronics is how to control the two-level systems found in amorphous insulators. The present article shows that hydrogen has a marked impact on the two-level systems in thin films of reactively sputtered Al2O3, a standard tunnel oxide for Josephson junctions. The magnitude of dielectric relaxation current in Al2O3 films, believed to be caused by two-level systems, is shown to increase monotonically with the flow rate of H2 into the chamber during deposition. This points toward a potential need for controlling hydrogen during the manufacture of superconducting electronics utilizing Al2O3. 相似文献
102.
Hong Van Nguyen Duong Thuy Tran Hung Khac Pham 《The European Physical Journal B - Condensed Matter and Complex Systems》2017,90(2):37
Network structure as well as structural and compositional heterogeneities in aluminosilicate (Al2O3-2SiO2) under compression is investigated by analysis and visualization of simulation data. Structural and compositional heterogeneities are clarified through analysis of topology structure and size distribution of TO x -clusters (T = Si, Al; x = 3, 4, 5, 6) as well as OT y -clusters (y = 2, 3, 4). The TO x -cluster can be considered as TO x -grains. It appears that the structure of aluminosilicate is the mixture of TO x -grains with a different short-range order structure and this is the origin of structural heterogeneity. Regarding their composition, the OSi y - and OAl y -clusters can be considered as silica- and alumina-grains respectively, and the structure of aluminosilicate can thus be considered to be formed from silica- and alumina-grains. This results in compositional heterogeneity. Moreover, the degree of polymerization and polyamorphism as well as dynamic heterogeneity is also discussed in detail. 相似文献
103.
Pham Khac Hung Fumiya Noritake Luyen Thi San To Ba Van Le The Vinh 《The European Physical Journal B - Condensed Matter and Complex Systems》2017,90(10):185
A systematic analysis on sodium-silicate melt with various silica contents was carried out. The simulation revealed two diffusion mechanisms occurred in the melt: the bond-breaking and hopping between sites. The local structure was analyzed through T-simplexes. It was revealed that T-clusters have a non-spherical shape and represent the diffusion channel, in which Na atoms are dominant, but no any O atoms are located. The SiO2-poor melt acquires a long channel. In contrast, the SiO2-rich melt consists of unconnected short channels. The simulation also revealed the immobile and mobile regions which differ in local structure and constituent composition. We propose a new CL-function to characterizing the spatial distribution of different atom component. The spatial distribution of mobile and immobile atoms is found quite different. In particular, the immobile atoms are concentrated in high-density regions possessing very large density of immobile atoms. The spatial distribution of mobile atoms in contrast is more homogeneous. 相似文献
104.
Ha Thi-Thanh Vu Hanh Thi-Minh Pham Tuyen Viet Nguyen Hieu Khac Ho 《The European Physical Journal B - Condensed Matter and Complex Systems》2017,90(4):65
In this paper, the moment method in statistical mechanics has been employed to study the pressure effects on thermodynamic and mechanical properties of zinc-blende zinc telluride using many-body potential. We have derived the analytical expressions of the pressure-dependent lattice parameter, volume compression as well as mean-square displacement of zinc-blende type compound. Numerical calculations performed for ZnTe compound up to 12 GPa are found to be in good and reasonable agreement with available experimental data as well as with previous theoretical studies. These results have been used to evaluate the bulk modulus and its first pressure derivative of ZnTe. The present moment method has taken into account the quantum zero-point vibrations at low temperature and the higher-order anharmonic terms in the atomic displacements. This research shows the advantage of moment method on extensively studying thermo-mechanical properties of materials under high pressures. 相似文献
105.
Gobeaux F Fay N Tarabout C Mériadec C Meneau F Ligeti M Buisson DA Cintrat JC Nguyen KM Perrin L Valéry C Artzner F Paternostre M 《Journal of the American Chemical Society》2012,134(1):723-733
Among noncovalent forces, electrostatic ones are the strongest and possess a rather long-range action. For these reasons, charges and counterions play a prominent role in self-assembly processes in water and therefore in many biological systems. However, the complexity of the biological media often hinders a detailed understanding of all the electrostatic-related events. In this context, we have studied the role of charges and counterions in the self-assembly of lanreotide, a cationic octapeptide. This peptide spontaneously forms monodisperse nanotubes (NTs) above a critical concentration when solubilized in pure water. Free from any screening buffer, we assessed the interactions between the different peptide oligomers and counterions in solutions, above and below the critical assembly concentration. Our results provide explanations for the selection of a dimeric building block instead of a monomeric one. Indeed, the apparent charge of the dimers is lower than that of the monomers because of strong chemisorption. This phenomenon has two consequences: (i) the dimer-dimer interaction is less repulsive than the monomer-monomer one and (ii) the lowered charge of the dimeric building block weakens the electrostatic repulsion from the positively charged NT walls. Moreover, additional counterion condensation (physisorption) occurs on the NT wall. We furthermore show that the counterions interacting with the NTs play a structural role as they tune the NTs diameter. We demonstrate by a simple model that counterions adsorption sites located on the inner face of the NT walls are responsible for this size control. 相似文献
106.
Tien Thanh Nguyen Huu Hao Ngo Wenshan Guo Jianxin Li Andrzej Listowski 《Applied biochemistry and biotechnology》2012,167(6):1678-1687
The performance of a novel sponge-submerged membrane bioreactor (SSMBR) was evaluated to treat primary treated sewage effluent at three different activated sludge concentrations. Polyurethane sponge cubes with size of 1?×?1?×?1?cm were used as attached growth media in the bioreactor. The results indicated the successful removal of organic carbon and phosphorous with the efficiency higher than 98% at all conditions. Acclimatised sponge MBR showed about 5% better ammonia nitrogen removal at 5 and 10?g/L sludge concentration as compared to the new sponge system. The respiration test revealed that the specific oxygen uptake rate was around 1.0?C3.5?mgO2/gVSS.h and likely more stable at 10?g/L sludge concentration. The sludge volume index of less than 100?mL/g during the operation indicated the good settling property of the sludge. The low mixed liquor suspended solid increase indicated that SSMBR could control the sludge production. This SSMBR was also successful in reducing membrane fouling with significant lower transmembrane pressure (e.g. only 0.5?kPa/day) compared to the conventional MBR system. Further study will be conducted to optimise other operating conditions. 相似文献
107.
108.
109.
We derive low-complexity matrix-free finite element algorithms for simplicial Bernstein polynomials on simplices. Our techniques, based on a sparse representation of differentiation and special block structure in the matrices evaluating B-form polynomials at warped Gauss points, apply to variable coefficient problems as well as constant coefficient ones, thus extending our results in Kirby (Numer Math, 2011, in press). 相似文献
110.
N.H. Ngo N. Ibrahim X. Landsheere H. Tran P. Chelin M. Schwell J.-M. Hartmann 《Journal of Quantitative Spectroscopy & Radiative Transfer》2012,113(11):870-877
The integrated intensities, self- and air-broadening coefficients of thirteen transitions of H216O in the 11980–12260 cm?1 region, belonging to the 2ν1+ν2+ν3 band, were measured. Using a tunable diode laser system, spectra were recorded at room temperature for a wide range of pressure (2–15 Torr for pure H2O and 50–760 Torr for H2O in air). Line parameters were adjusted from experiments using three line-shape models: the Voigt profile (VP), the (hard collision) Rautian profile (RP) and the speed dependent Voigt profile (SDVP). The results show that the RP and SDVP are in better agreement with measurements than the VP and that they lead to larger values of the line parameters (about 5% for the line broadening, and 0.8% for the line intensity). Comparisons of the present results with HITRAN 2008 [Rothman et al., JQSRT 2009, 110:533-72] show that the HITRAN intensities of the studied lines are overestimated by about 9.4%, suggesting a more complete study of the H2O line parameters in the considered region. The Dicke narrowing and speed dependence parameters deduced from this work are also presented and discussed, demonstrating the need for a more refined line-shape model. 相似文献