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31.
All-optical frequency multiplication/recovery based on a semiconductor optical amplifier ring cavity
Fei Wang 《Optics Communications》2006,257(2):334-339
A novel scheme for all-optical frequency multiplication/recovery based on a semiconductor optical amplifier ring cavity is proposed and investigated numerically. The results show, for a 2.5 GHz driving pulse train, it can be generated 5-25 GHz repetition rate pulse trains with low clock amplitude jitter, polarization independence and high peak power. Furthermore, the extraction of the clock signal from a pseudorandom bit sequence signal can be realized based on the proposed scheme. 相似文献
32.
33.
An improved transmission line model to study the thermal effects in semiconductor laser diodes is reported in this paper.
The temperature effects in the laser characteristics are obtained by incorporating temperature dependent gain and carrier
density equations for the laser cavity. These primary factors are introduced in the regular transmission line laser model
to estimate the static and dynamic characteristics of an 1.3μm InGaAsP double heterostructure laser diode. The results show
good agreement with the experimental observation and solution of rate equations referred in the literature. The key feature
of this model is that it provides the laser spectra at various temperatures. Based on the model, time dependent evolution
of optical spectrum, temperature dependent optical output and frequency chirp are evaluated. Further the distribution of photon
and electron density within the cavity is also determined. 相似文献
34.
X. D. Zhang M. L. Guo C. L. Liu L. A. Zhang W. Y. Zhang Y. Q. Ding Q. Wu X. Feng 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,62(4):417-421
A first-principles study has been performed to evaluate the electronic and
optical properties of wurtzite Zn1-xMgxO. Substitutional doping is
considered with Mg concentrations of x = 0, 0.0625, 0.125, 0.1875 and 0.25,
respectively. Mg incorporation can induce band gap widening due to the
decrease of Zn 4s states. The imaginary part of the dielectric function shows
that the optical transition from band edge emission decreases slightly with
increasing Mg contents. The optical band gap also increases from 3.2 to 3.7
eV with increasing Mg contents from 0.0625 to 0.25. The calculated results
suggest that relatively high Mg concentration is necessary for effective
band gap engineering of wurtzite Zn1-xMgxO. 相似文献
35.
We demonstrate a fiber ring laser with a dispersion compensation fiber (DCF) and a delayed interferometer (DI) with temperature control, which is able to switch eleven wavelengths one by one. In ring cavity, DCF supplies different effective cavity lengths for different wavelengths, DI generates a wavelength comb corresponding to the ITU grid, a flat-gain erbium-doped fiber amplifier (EDFA) provides uniform gain for each lasting wavelength, and a semiconductor optical amplifier (SOA) not only acts as active modulator, but also alleviates homogeneous broadening effect of EDFA. Stable pulse trains with a pulsewidth about 40 ps at 10 GHz have been obtained by injecting external optical control signals into the laser. Wavelength switching process among eleven wavelengths is achieved by merely tuning an intracavity optical delay line. 相似文献
36.
Aycha Jellali Slim Elleuch Besma Hamdi Ridha Zouari 《Journal of Saudi Chemical Society》2019,23(5):600-611
In this work, a new hybrid material (C5H6N2Cl)2[FeCl4].Cl abbreviated (CAP)2[FeCl4].Cl was prepared using room temperature slow evaporation technique. The X-ray diffraction analysis revealed that the compound is crystallized in the centrosymmetric space group P21/c of the monoclinic system. The crystallographic network consists of an Fe(III) ion located on an inversion center and coordinated by four chlorine, isolated Cl– and two (CAP)+ protonated cations linked by N–H...Cl and C–H...Cl hydrogen bonds to form a zero-dimensional network. Hirshfeld surface analysis was used to analyze intermolecular interactions present in the crystal structure. The vibrational properties were inspected by means of Infra-Red absorption and Raman diffusion spectroscopy techniques. In addition, theoretical calculations based on the DFT/B3LYP/LanL2DZ method and the time-dependent density functional theory (TD–DFT) were performed in order to gain more information and help in the examination of over-all properties of the title compound. Good and interesting experimental findings were presented and good consistency was found with the calculated results. 相似文献
37.
By means of ab initio calculation based on density-functional theory (DFT), we have investigated the electronic and optical properties of single layer MoSe2 under chemical doping by various groups, such as ?H, ?OH, ?NH2 and ?CH3. This work is generalized for all polymorph 1H, 1T, 1T′ and the new investigated phase 1T″. We found that all those functional groups (FG) bonded covalently to the chalcogen atom (Se). The evaluation of adsorption energy shows that the hydrogen atom binds more strongly than other functional groups in particular with the T phase. Furthermore, the attachment of functional groups to T-MoSe2 leads to dramatic changes to the structure stability and the optoelectronic properties of the material by tuning its band gap from metallic to a semiconductor. Also, we found that the band gap is strongly depending on the type and the densities of dopants. 相似文献
38.
The current–voltage (I–V) and capacitance–voltage (C–V) characteristics of silicon p–i–n diodes have been investigated both prior to and after radiation-induced damage by 1 MeV neutrons. The results have been analysed and several rates of damage evaluated. The indication is mainly that radiation damage occurs only up to certain fluencies. Beyond these, the material becomes resistant to further damage. Thus, initial heavy radiation damage can be used to achieve radiation-hardness of detector diodes. This result is contrary to previous suggestions that continued irradiation renders the detectors inoperable but is in good agreement with our results on radiation-hardness induced by gold-doping. 相似文献
39.
E. Caldern B. Fernndez L. Durn P. Grima M. Morocoima E. Quintero C. Rincn M. Quintero 《Physica B: Condensed Matter》2009,404(21):4095-4099
Optical absorption measurements were made in the temperature range 9–300 K on the chalcopyrite semiconductor compound AgGaSe2 and the optical energy gap EG determined as a function of temperature T. In order to obtain the values of EG as a function of T, the Elliot-Toyozawa model [R.J. Elliot, J. Phys. Rev. 108 (1957) 1384; D.D. Sell, P. Lawaets, Phys. Rev. Lett. 26 (1971) 311] was employed to perform the analysis of the optical absorption spectra. The resulting EG vs. T curve was fitted to a semi-empirical model that takes into account both the thermal expansion and the electron–phonon interaction contributions. The results have been used to estimate values of the deformation potentials of the valence and conduction bands of the compound. 相似文献
40.
This study investigates ultra-thin potassium chloride (KCl) films on the Si(1 0 0)-2 × 1 surfaces at near room temperature. The atomic structure and growth mode of this ionic solid film on the covalent bonded semiconductor surface is examined by synchrotron radiation core level photoemission, scanning tunneling microscopy and ab initio calculations. The Si 2p, K 3p and Cl 2p core level spectra together indicate that adsorbed KCl molecules at submonolayer coverage partially dissociate and that KCl overlayers above one monolayer (ML) have similar features in the valance band density of states as those of the bulk KCl crystal. STM results reveal a novel c(4 × 4) structure at 1 ML coverage. Ab initio calculations show that a model that comprises a periodic pyramidal geometry is consistent with experimental results. 相似文献