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61.
Ken Suto Jun-ichi Nishizawa 《International Journal of Infrared and Millimeter Waves》2005,26(7):937-952
The THz-wave generator based on the resonance of phonon-polaritons in GaP enabled THz spectral measurements of organic molecules like DNA/RNA-related molecules in wide frequency range (0.6–5.8 THz). High spectral purity of the generated THz-wave enables even the detection of defect structures of organic compounds, and will give a new tool for molecular sciences. We demonstrated THz imaging of a liver cancer. The THz-wave generator can be made small-size, light-weight system. 相似文献
62.
J. Nishizawa T. Sasaki K. Suto T. Tanabe T. Yoshida T. Kimura K. Saito 《International Journal of Infrared and Millimeter Waves》2006,27(7):923-929
We have constructed THz spectrometers using the widely frequency-tunable THz-wave generated from GaP crystal pumped at 1.2
μm region using two Cr:forsterite lasers and compared with that pumped at 1 μm region using a YAG laser and an optical parametric
oscillator (OPO). The systems have sufficient resolution for observation of solids and liquids at room temperature. We have
measured Terahertz absorption spectra of all 20 kinds of amino acids which form proteins. 相似文献
63.
Investigations of phase transition, elastic and thermodynamic properties of GaP by using the density functional theory
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The phase transition of gallium phosphide (GaP) from zinc-blende (ZB) to a rocksalt (RS) structure is investigated by the plane-wave pseudopotential density functional theory (DFT). Lattice constant a0, elastic constants cij, bulk modulus B0 and the pressure derivative of bulk modulus B0' are calculated. The results are in good agreement with numerous experimental and theoretical data. From the usual condition of equal enthalpies, the phase transition from the ZB to the RS structure occurs at 21.9 GPa, which is close to the experimental value of 22.0 GPa. The elastic properties of GaP with the ZB structure in a pressure range from 0 GPa to 21.9 GPa and those of the RS structure in a pressure range of pressures from 21.9 GPa to 40 GPa are obtained. According to the quasi-harmonic Debye model, in which the phononic effects are considered, the normalized volume V/V0, the Debye temperature θ, the heat capacity Cv and the thermal expansion coefficient α are also discussed in a pressure range from 0 GPa to 40 GPa and a temperature range from 0 K to 1500 K. 相似文献
64.
Due to strong absorption of the incident light, the media with high refractive index are considered restrictive for applications in photonic crystals (PhCs). The possibility to resolve this problem by optical saturation effectively minimizing the absorption of the PhC medium is discussed. Such approach might be promising for the significant broadening of the photonic band-gap. 相似文献
65.
GaP中N和NNi对等电子陷阱态的压力行为 总被引:2,自引:0,他引:2
半导体中的局域电子态和半导体的能带结构密切相关,揭示局域电子态和能带结构之间的内在关系是当前半导体电子理论的重要方面。而压力光谱实验对研究这种相互关系提供了重要手段。本文对GaP中深、浅两组能级的不同压力行为作了系统的实验研究。实验观察到无论在室温还是在低温,压力小于3.3 GPa时,以N陷阱束缚激子的发光过程为主,大于3.3 GPa时则以自由激子零声子过程为主,并且所有与N有关的陷阱态都具有压力的非线性行为。根据有效质量随压力的变化提出能谷中不同能量态具有不同的压力关系。基于有效质量随压力变化的能带格林函数方法,对N和NNi对的压力系数作了模型计算,其结果和陷阱态的压力行为符合得相当好。证实了带结构,尤其是能谷曲率随压力的变化是决定陷阱态压力行为的主要因素。 相似文献
66.
The PH3-HCl-Ga-H2 technique for VPE growth of GaP is described. The influence of various growth parameters, including substrate temperature,
orientation, and PH3 flow rate on morphology and growth rate are described. For both VPE and LPE nitrogen doping is known to be a major factor
in obtaining high green luminescence efficiency. The major emphasis of this paper is an examination of the effect of nitrogen
concentration in the range less than 1019 cm−3 (using the Lightowlers correction factor) on the growth process and materials properties, such as defect structure, photoluminescence
spectra (at 300 and 77K) and photoluminescence intensity and lifetime. The LED device performance (B/J and efficiency) is
used as the final test of material quality. Nitrogen is found to be incorporated far in excess of the solubility limit, and
the solid gas distribution coefficient for nitrogen is found to increase rapidly with decreasing temperature below 840°C .
The optimum nitrogen concentration for high diode efficacy, photoluminescence intensity, and lifetime is found to be approximately
5 × 1018 cm−3, where diodes fabricated by Zn diffusion into the VPE GaP have efficiencies at a current density of 10 A/cm2 of 0.1%, comparable to the state-of-the-art in the more widely used grown p-n junctions using LPE. 相似文献
67.
68.
R. Z. Bachrach 《Journal of Electronic Materials》1974,3(3):645-691
Several optical techniques useful for characterizing GaP LPE crystals grown for light emitting diode applications will be
described. The non-exhaustive discussion is primarily in the context of diagnostics developed in studies of the near bandedge
emission and the minority carrier lifetime in GaP in the temperature range 100°-300°K. Optical absorption and transient and
steady state photoluminescence measurements performed with photon counting techniques are emphasized. The diagnostics described
provide many of the parameters pertinent to the luminescent quality of GaP crystals. 相似文献
69.
The structure of = 3, {112} lateral twin boundaries in polycrystalline GaP has been investigated by transmission electron microscopy. The orientation of the polar bonding along the lateral twin boundary was characterized by convergent-beam electron diffraction and found to be mirror symmetric across the {112} interface. Rigid-body lattice translations and grain boundary dislocations along the boundaries were also characterized. The direction of the translation state between adjacent twin-related grains was studied by the -fringe contrast technique. Models of the {112} interface in the GaP lattice are proposed and compared with the experimental observations.
= 3, {112} Lateral Twin Boundaries in GaP相似文献
70.
采用金属Na,白磷和GaCl3为原料,在温和的苯热溶剂条件下制备了直径为20—40nm,长度为200—500nm的GaP纳米棒和直径为20—40nm的球形颗粒.利用X射线衍射(XRD)、透射电子显微镜(TEM)和X射线光电子能谱(XPS)研究了反应条件对产物结晶性和形貌的影响.实验结果表明,当反应温度低于250℃时,产物基本上为GaP纳米棒,并随着反应温度升高,产物逐渐转化为球形纳米颗粒;当反应温度超过280℃时,产物完全为规则的球形.同时,GaP纳米棒的生长遵循SLS生长机理.
关键词:
纳米GaP
苯热
SLS生长机理 相似文献