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951.
The epitaxial growth process of β-FeSi2 on Si(100) surface under ultrahigh vacuum condition has been studied by low energy electron diffraction (LEED) and low energy ion scattering spectroscopy (LEIS). The LEED pattern of Si (100)-2×1 changes into amorphous structure with Fe deposition of about 10 Å at room temperature. With annealing at 540 °C, the LEED pattern shows 2×2 structure corresponding to the formation of the epitaxial β-FeSi2 (100) template layer. The α-scan in Li+-LEIS and X-ray diffraction (XRD) study strongly suggest that the topmost surface of the 2×2 structure is terminated by Si atoms. By XRD, it is shown that the β-FeSi2 develops with characteristic orientation even if iron reactant is deposited onto the template surface. 相似文献
952.
The electrical and optical properties of silver indium selenide thin films prepared by co-evaporation have been studied. X-ray diffraction indicates that the as prepared films were polycrystalline in nature. The lattice parameters were calculated to be a=0.6137 and b=1.1816 nm. Composition was determined from energy dispersive analysis of X-ray. Silver indium selenide thin films were also prepared by bulk evaporation of powdered sample for comparative study. They have an optical band gap (Eg) of 1.25 eV and it is a direct allowed transition. Refractive index (n) and extinction coefficient (k) were calculated from absorption and reflection spectra. Steady-state photoconductivity was measured from 300 to 400 K. Carrier lifetime was calculated from transient photoconductivity measurements at room temperature at different intensities of illumination. 相似文献
953.
Four-hexagonal polytype films of nanocrystalline silicon carbide (4H-nc-SiC) were deposited by plasma enhanced chemical vapor deposition method with more than 3×104 W m−2 threshold of power density, high hydrogen dilution ratio, and bias pretreatment. The source gases were silane, methane and hydrogen. Our work showed that under conditions similar to those used for the growth of μc-SiC—except a higher power densities over a threshold, a bigger bias pretreatment on substrates, and a moderate bias deposition—nc-SiC films could indeed be achieved. The Raman spectra and transmission electron microscopy diffraction patterns demonstrated that the as-grown films from the H2-CH4-SiH4 plasma consist of amorphous network and phase-pure crystalline silicon carbide which has the 4H polytype structure. The microcolumnar 4H-SiC nanocrystallites of a mean size of approximately 1.6×10−8 m in diameter are encapsulated by amorphous SiC networks. The photoluminescence spectra of 4H-SiC at room temperature, peaking at 8.10×10−7 m using a wavelength of 5.145×10−7 m of argon ion laser, were obtained at room temperature; the luminescence mechanism is thought to be related to transitions in the energy band gap which could be ascribed to the surface states and defects in the structure of 4H-SiC nanocrystalline in these films due to its small size. The as-grown films showed an optical transmittance of 89% at 6.58×10−7 m. This higher transmittance is believed to be from the small size and amorphous matrix. 相似文献
954.
Semiconductor materials with wide band gap have been extensively used to fabri-cate the blue laser light emitting diodes and ultraviolet photodetectors, which are impor-tant elements of semiconductor instruments, such as displays, optical data storages, ul-traviolet sensors, electroluminescent devices and solar-blind detectors. This kind of ma-terials is now becoming a hot research object in semiconductor physics. GaN was the first suitable ultraviolet laser material people found in this real… 相似文献
955.
王学华 《武汉理工大学学报(材料科学英文版)》2004,19(1)
1 IntroductionInrecentyears ,theoreticalandexperimentalinvesti gationsonthetitaniumoxidefilmsareconductedonac countoftheirremarkableproperties .Titaniumdioxidefilmshaveattractedconsiderableattentiontoapplytomi croelectronicdevices ,opticalthin filmdevice… 相似文献
956.
为得到高灵敏度的光传感器,研究了真空蒸发的CdS和CdSe双层光电导薄膜掺杂Cu和Cl对光电性质的影响.研究发现,适当选择Cu和Cl的掺杂比,可以使光电导薄膜的暗电导显著减少而光电导显著增加.这种掺杂光电导薄膜的响应时间约为5~10 ms,而对非掺杂薄膜的响应时间大于100ms.这种光电导薄膜已被成功地应用于大屏幕显示和光信息处理的可见光液晶光阀,并制成了红外液晶光阀,以用于可见光-红外光动态图像转换系统. 相似文献
957.
ZnO:Al(AZO)薄膜制备工艺参数的正交优化设计 总被引:1,自引:0,他引:1
采用正交设计法,对溶胶-凝胶方法制备AZO薄膜的工艺参数进行了优化研究;确定了最佳工艺参数,为制备AZO薄膜的工业化控制提供了一种可行的方法。 相似文献
958.
类金刚石薄膜的折射率研究 总被引:1,自引:0,他引:1
利用脉冲真空电弧镀方法在硅基底上沉积类金刚石薄膜,研究薄膜折射率和工艺参数以及折射率与薄膜本征硬度的关系,结果表明:无氢类金刚石薄膜的折射率在2.5~2.7之间;不同的工艺参数可以得到不同折射率的薄膜;通过改变工艺条件来制备不同折射率的薄膜,和不同的基底材料的折射率匹配,使其有一定的机械强度。 相似文献
959.
基于遗传算法的窄带滤光片膜系最佳设计 总被引:3,自引:0,他引:3
提出了基于遗传算法的窄带滤光片的最佳设计方法。介绍了遗传算法的运算原理、适应度函数和运行参数,给出其遗传算法的程序设计方法;并且设计出一组50GHz的窄带滤光片。结果表明,遗传算法适用窄带滤光片的膜系设计。 相似文献
960.
Structural and electrochemical properties of vanadium oxide thin films grown by d.c. and r.f. reactive sputtering at room temperature 总被引:7,自引:0,他引:7
Vanadium oxide thin films were grown at room temperature by direct current and radio-frequency reactive sputtering systems to compare the structural and electrochemical properties. Rutherford backscattering spectrometry and Fourier transform infrared measurements reveal that the composition of the as-deposited films consists of the V2O5 phase regardless of the deposition methods. Wide-angle X-ray diffraction measurements show that the crystallinity of the as-deposited V2O5 films is different depending on the deposition method. Films deposited by direct current reactive sputtering were amorphous, whereas films deposited by radio-frequency reactive sputtering were crystalline. Scanning electron microscopy measurements show that the V2O5 films grown by radio-frequency reactive sputtering had a large grain size but the films grown by direct current reactive sputtering were amorphous. Charge–discharge measurements taken at room temperature with a constant current clearly indicate that the films grown by direct current sputtering demonstrated typical amorphous behavior, whereas the V2O5 films grown by radio-frequency sputtering demonstrated the discharge behavior of crystalline V2O5. The origin of the structural and electrochemical properties of film grown by radio-frequency reactive sputtering is a self-bias effect. The self-bias effect induces ion bombardment during the growth of vanadium oxide thin film. These results suggest that direct current reactive sputtering is more desirable for growing amorphous V2O5 thin film than radio-frequency reactive sputtering. 相似文献