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1.
I. Longo D. Cros N. Tosoratti 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(2):273-277
We present a numerical and experimental characterization of high-Q whispering gallery resonant modes excited in a fused quartz spherical shell operated in the 18-26.5 GHz band; easy coupling
and selection of modes is a most advantageous feature of the proposed structure with respect to ordinary bulk resonators.
The numerical results, based on a finite element algorithm, well match experimental data, which also show the capability of
our device to perform gaseous spectroscopy measurements.
Received 25 October 2002 Published online 4 February 2003 相似文献
2.
Using a density-functional method that employs linear combinations of atomic orbitals as basis sets, nonlocal norm-conserving pseudopotentials and the generalized gradient approximation for exchange and correlation, we found that at 0 K the atoms of an Fe monolayer on the Ni (111) surface occupy hcp rather than fcc sites, in keeping with previous predictions made using the ab initio all-electron full-potential linearized augmented plane wave method with the local spin density approximation. 相似文献
3.
S. Longo G. Comunale C. Gorse M. Capitelli 《Plasma Chemistry and Plasma Processing》1993,13(4):685-700
Two simple kinetic models of a Ne-buffered XeCl laser discharge are presented based on different simplifications of the chemical kinetics of a complex model that recently appeared in the literature. When applied to the study of a small-volume XeCl laser, the results of both simple and complex models are in satisfactory agreement with the experiments. Shifting to a larger-volume laser, both models show problems due to loss of stability of the discharge. A one-dimensional modelling is performed, and it is found that different assumptions on the kinetics of the NeXe+ ion in the discharge lead to completely different results as regards the effect of a preionization-triggered instability. 相似文献
4.
S. Feng K. Halterman P.L. Overfelt J.M. Elson G.A. Lindsay M.J. Roberts 《Applied Physics A: Materials Science & Processing》2007,87(2):235-244
We present an overview of some of our work on transmission properties and mode characteristics of layered metamaterials and
their potential applications. In particular, we will show how layered metamaterials exhibit unusual transmission properties
and unconventional features of guided modes, such as resonance-induced transparency in multilayer structures and slope reversal
of dispersion curves in coupled waveguides.
PACS 78.67.-n; 73.21.Ac; 61.46.+w; 42.25.Bs; 42.82.Et 相似文献
5.
6.
D. S. Gouveia R. Rosenhaim M. A. M. A. de Maurera S. J. G. Lima C. A. Paskocimas E. Longo A. G. Souza I. M. G. Santos 《Journal of Thermal Analysis and Calorimetry》2004,75(2):453-460
With the aim of obtaining materials with applications in pigments, CoxZn7-xSb2O12 spinels were synthesized using the Pechini method. This method consists in the formation of a polymeric net, where the metallic
cations are homogeneously distributed. In this work, two types of alcohol (ethyl glycol and ethylene glycol) were used for
the synthesis of a zinc antimoniate spinel, CoxZn7-xSb2O12 (x=0-7). The materials were characterized by termogravimetry (TG) and differential thermal analysis (DTA). TG results indicated
a decrease in total mass loss when cobalt was added to the solution substituting zinc, for samples prepared using the two
different alcohols. Decomposition temperatures, obtained by TG and DTA, presented a decreasing behavior as cobalt was added
to the material. In relation to the alcohols, all results indicated a better polymerization of the resin when ethylene glycol
was used, being the most indicated one for cation immobilization. X-ray diffraction did not show differences between the two
alcohols - both presented the spinel phase (Co, Zn)2.33Sb0.67O4. Samples with higher quantity of cobalt also presented ilmenite phase (Co, Zn)Sb2O6.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
7.
M. Zampieri S. R. Lazaro C. A. Paskocimas A. G. Ferreira E. Longo J. A. Varela 《Journal of Sol-Gel Science and Technology》2006,37(1):9-17
Titanium citrate and lead and titanium citrate were prepared by polymeric precursor method in aqueous solution. This citrate
was analyzed by 1H, 13C NMR and gHMBC–NMR (Hetero-nuclear multiple-bond correlation) to investigate the formation of the citrate complexs and influence
of the Pb2+ ion in this complex. These complexs were characterized by interaction between Ti4+ ion and citric acid carboxyls. Quantum mechanic simulations in level ab initio were used to study the electronic structure and natural charges (NBO) to both the complexs. Such techniques indicated the
formation of an octahedral complex with an arrangement similar to Ti atom in the crystalline structure of the PbTiO3. A study using the technique FT-Raman made possible the confirmation of the interaction among the Ti4+ and Pb2+ ions with the citric acid carboxyls. 相似文献
8.
We calculated the geometrical structures and electronic properties of neutral and anionic Fe2Cn clusters (n = 3,4) using a density-functional method that employs linear combinations of atomic orbitals as basis sets, standard nonlocal norm-conserving pseudopotentials, and the generalized gradient approximation to exchange and correlation. We show that the ground-state structures of Fe2C3 and Fe2C4 are essentially the same in the neutral and anionic states, namely, planar rings that feature nonadjacent Fe atoms. For the anionic clusters, these findings contrast with previously published results. 相似文献
9.
10.
Langmuir trough methods and fluorescence microscopy were combined to investigate the phase behavior and microstructure of monolayer shells coating micron-scale bubbles (microbubbles) typically used in biomedical applications. The monolayer shell consisted of a homologous series of saturated acyl chain phospholipids and an emulsifier containing a single hydrophobic stearate chain and polyethylene glycol (PEG) head group. PEG-emulsifier was fully miscible with expanded phase lipids and phase separated from condensed phase lipids. Phase coexistence was observed in the form of dark condensed phase lipid domains surrounded by a sea of bright, emulsifier-rich expanded phase. A rich assortment of condensed phase area fractions and domain morphologies, including networks and other novel structures, were observed in each batch of microbubbles. Network domains were reproduced in Langmuir monolayers under conditions of heating–cooling followed by compression–expansion, as well as in microbubble shells that underwent surface flow with slight compression. Domain size decreased with increased cooling rate through the phase transition temperature, and domain branching increased with lipid acyl chain length at high cooling rates. Squeeze-out of the emulsifier at a surface pressure near 35 mN/m was indicated by a plateau in Langmuir isotherms and directly visualized with fluorescence microscopy, although collapse of the solid lipid domains occurred at much higher surface pressures. Compression of the monolayer past the PEG-emulsifier squeeze-out surface pressure resulted in a dark shell composed entirely of lipid. Under certain conditions, the PEG-emulsifier was reincorporated upon subsequent expansion. Factors that affect shell formation and evolution, as well as implications for the rational design of microbubbles in medical applications, are discussed. 相似文献