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941.
A novel, 100% water-soluble chalcone based chemosensing receptor {1-[3-(2-Hydroxy-phenyl)-3-oxo-propenyl]-naphthalen-2-yloxy}-acetic acid, L was synthesized and characterized. The receptor L is designed based on the chelation enhanced fluorescence (CHEF) mechanism. The chemosensing properties of L were evaluated by UV–vis and fluorescence spectrometric methods. It exhibits highly selective recognition ability towards aluminum ions in water over other metal ions. The binding stoichiometry of L? Al3+ complex is 2:1 by means of Job’s plot and the detection limit is 5.66?×?10??8 M. 相似文献
942.
Mahmoud H. Saleh Nidal M. Ershaidat Mais Jamil A. Ahmad Basim N. Bulos Mousa M. Abdul-Gader Jafar 《Optical Review》2017,24(3):260-277
Spectral dispersions of index of refraction \({n(\lambda )}\) and extinction coefficient \({\kappa (\lambda )}\) of undoped amorphous selenium (a-Se) films of three thicknesses (d?≈?0.5, 0.75, and 1.0 µm) were evaluated by analyzing experimental room-temperature normal-incidence transmittance-wavelength (\({{T_{{\text{exp}}}}(\lambda )} - \lambda\)) data (λ =?400–1100 µm) of their air-supported {a-Se film/thick glass slide}-stacks using Swanepoel’s transmission envelope theory of uniform films. Above a wavelength \({{\lambda _c}\,\, \approx \,\,640\;{\text{nm}}}\), as-measured \({{T_{{\text{exp}}}}(\lambda )}\,\, - \,\lambda\) spectra display well-resolved maxima and minima, with minor shrinkage in transparent and weak absorption regions (750–1100 nm). Below \({\lambda _{\text{c}}}\), a smeared sharp decline of \({{T_{{\text{exp}}}}(\lambda )}\) with decreasing λ, signifying strong absorption in a-Se films and existence of band-tail localized states. For λ > λ c, the \({n\,(\lambda )}\, - \,\lambda\) data retrieved from algebraic envelope procedures followed a Sellmeier-like dispersion relation, with the best-fit values of high-frequency dielectric constant \({{\varepsilon _\infty }\, \approx \,\,{\text{4.9}}}\), static index of refraction \({{n_{\text{0}}} = n\left( {E\, \to \,{\text{0}}} \right)\,\, \approx \,\,{\text{2.43}}}\), and resonance wavelength \({{\lambda _0}\, \approx \,490\,\,{\text{nm}}}\), which may be assigned to onset of photogeneration in a-Se. Urbach-like dependency of absorption coefficient \({\alpha (h{{\nu }})}\) of a-Se films on photon energy \({h{{\nu }}}\) was realized with an Urbach-tail breadth of 85 meV. All achieved optical parameters were found to be slightly dependent on film thickness. Findings of present algebraic analysis are consistent with reported literature results obtained on the basis of other optical analytical approaches. 相似文献
943.
Mixed convection three-dimensional flow of Jeffrey fluid is studied in the presence of thermal radiation and thermophoresis. The relevant problems are formulated, and series solutions are presented for velocities, temperature, and concentration. Convergence of series solutions is obtained graphically and numerically. Effects of different emerging parameters on the velocities, temperature, and concentration fields are plotted and discussed. 相似文献
944.
Microstructure evolution during surface alloying of ductile iron and austempered ductile iron by electron beam melting 总被引:1,自引:0,他引:1
Alloying and microstructural modification of surfaces by electron beam has become popular to tailor the surface properties of materials. Surface modification of as-received ductile iron, Ni-plated ductile iron and Ni-plated austempered ductile iron was carried out by electron beam melting to improve the surface properties. Martensitic structure evolved in the heat affected zone and ledeburite structure was produced in the molten zone of the ductile iron. Microhardness of the melted specimens enhanced considerably as compared to the as-received samples. However the microhardness of melted Ni-plated samples is lower than that of the unplated specimens. X-ray diffraction clearly revealed the formation of an austenite and Fe3C phases in the electron beam molten zone. The broadening of peaks suggests refinement of the microstructure as well as internal stresses generated during electron beam melting. 相似文献
945.
The Rayleigh-Taylor instability is investigated in a nonuniform dense quantum magnetoplasma. For this purpose, a quantum hydrodynamical model is used for the electrons whereas the ions are assumed to be cold and classical. The dispersion relation for the Rayleigh-Taylor instability becomes modified with the quantum corrections associated with the Fermi pressure law and the quantum Bohm potential force. Numerically, it is found that the quantum speed and density gradient significantly modify the growth rate of RT instability. In a dense quantum magnetoplasma case, the linear growth rate of RT instability becomes significantly higher than its classical value and the modes are found to be highly localized. The present investigation should be useful in the studies of dense astrophysical magnetoplasmas as well as in laser-produced plasmas. 相似文献
946.
The ZnO filler has been introduced into a solid polymeric electrolyte of polyvinyl chloride (PVC)–ZnO–LiClO4, replacing costly organic filler for conductivity improvement. Ionic conductivity of PVC–ZnO–LiClO4 as a function of ZnO concentration and temperature has been studied. The electrolyte samples were prepared by solution casting
technique. The ionic conductivity was measured using impedance spectroscopy technique. It was observed that the conductivity
of the electrolyte varies with ZnO concentration and temperature. The temperature dependence on the conductivity of electrolyte
was modelled by Arrhenius and Vogel–Tammann–Fulcher equations, respectively. The temperature dependence on the conductivity
does not fit in both models. The highest room temperature conductivity of the electrolyte of 3.7 × 10−7 Scm−1 was obtained at 20% by weight of ZnO and that without ZnO filler was found to be 8.8 × 10−10 Scm−1. The conductivity has been improved by 420 times when the ZnO filler was introduced into the PVC–LiClO4 electrolyte system. It was also found that the glass transition temperature of the electrolyte PVC–ZnO–LiClO4 is about the same as PVC–LiClO4. The increase in conductivity of the electrolyte with the ZnO filler was explained in terms of its surface morphology. 相似文献
947.
948.
M. Ahmad P. Kumar N. Suri J. Kumar R. Thangaraj 《Applied Physics A: Materials Science & Processing》2009,94(4):933-937
The crystallization kinetics of Sn10Sb20−x
Bi
x
Se70 (x=0,2,4,6,8) chalcogenide system has been studied. Crystallization studies using differential scanning calorimetry under nonisothermal
conditions with different heating rates are reported. The glass transition temperature is found to increase with the increase
in heating rate as well as with the addition of bismuth. The apparent activation energy for glass transition and that for
crystallization have been determined using the Kissinger equation. Thermal stability and glass forming tendency have also
been studied. 相似文献
949.
A simple all optical system for stopping and storing light pulses is demonstrated. The system consists of an erbium-doped fiber amplifier (EDFA), a semiconductor optical amplifier (SOA), and a fiber ring resonator. The results show that the multisoliton generation with a free spectrum range of 2.4 nm and a pulse spectral width of 0.96 nm is achieved. The memory time of 15 min and the maximum soliton output power of 5.94 dBm are noted, respectively. This means that light pulses can be trapped, i.e., stopped optically within the fiber ring resonator. 相似文献
950.
Saeed Dinarvand Mohammad Mehdi Rashidi Ahmad Doosthoseini 《Central European Journal of Physics》2009,7(4):791-799
In this paper, the problem of laminar, isothermal, incompressible and viscous flow in a rectangular domain bounded by two
moving porous walls, which enable the fluid to enter or exit during successive expansions or contractions is solved analytically
by using the homotopy analysis method (HAM). Graphical results are presented to investigate the influence of the nondimensional
wall dilation rate α and permeation Reynolds number Re on the velocity, normal pressure distribution and wall shear stress.
The obtained solutions, in comparison with the numerical solutions, demonstrate remarkable accuracy. The present problem for
slowly expanding or contracting walls with weak permeability is a simple model for the transport of biological fluids through
contracting or expanding vessels.
相似文献