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151.
The paper describes the fabrication of a novel miniature sensor for electrical tomography. The sensor comprises a number of copper electrodes that are fabricated around a small hole that is etched through a silicon wafer. Copper electrodes are electroplated to fill channels that are formed in thick photo-resist on top of the silicon wafer. Electrodes with a thickness of 60 μm, surrounding a hole of diameter 300 μm, have been realised. Initial measurements have been made using a commercial LCR meter applied to an eight-electrode sensor and images of a 80 μm diameter wire have been obtained. Future work will consider the integration of measurement circuitry alongside the electrodes in order to reduce parasitic capacitances. 相似文献
152.
We have investigated the static and dynamic behavior of piezoelectric (PZT) actuated SiO2/Si membranes with an off-centered PZT patch. Three-dimensional wide-field interferometer has been used to achieve measurement of membrane topography and bending. It is demonstrated that the piezoelectric coefficient d31 can be extracted directly from these three-dimensional static deformation measurements. We have also shown that polarization voltage of an off-centered PZT patch influences in a different manner the resonant frequency shift of the first and the second vibration modes. Degenerated modes can be also discriminated thanks to the positioning of the PZT patch. 相似文献
153.
154.
《Vacuum》2004,76(4):465-469
STM imaging of Ag atoms adsorbed on the Si(1 1 1)-(7×7) surface is studied. Appearance of a single Ag adatom on perfect surface is compared with images of adatoms interacting with surface defects and adsorbates. Importance of real-time observation of surface processes for image interpretation is demonstrated on imaging Ag adatoms at various situations. Influence of tunnelling conditions (voltage between a tip and surface) on imaging surface objects is studied and visibility of single Ag adatoms and clusters is discussed. 相似文献
155.
Youping Chen 《International Journal of Engineering Science》2004,42(10):987-1000
Polycrystalline solid is composed of randomly distributed grains and grain boundaries. The size of grains is usually in the nano/micro-scale. In this paper, the general micromorphic theory, as well as a specialized micromorphic theory for covalent and ionic crystals, is introduced. A statistical model for polycrystalline material is adopted. Each grain is modeled as crystallized solid by micromorphic theory, while the grain boundaries are modeled as in its amorphous phase by classical continuum theory. Size-dependent material properties of silicon are investigated. Finite element analysis of thermomechanical coupling phenomenon in polycrystalline silicon is performed and numerical results are presented and discussed. 相似文献
156.
A. Roy Chowdhuri 《Thin solid films》2004,457(2):402-405
The transverse optical (TO) and longitudinal optical (LO) phonons of the asymmetric stretch of the O in SiOSi bridging bond in thermal SiO2 show red shift with decreasing oxide thickness. These shifts are primarily due to interface effects like strain and substoichiometric silicon oxides (suboxides). A method to isolate the contributions of strain and suboxide concentration towards the observed shifts is proposed. The procedure, which utilizes simple optical model and effective medium approximation, allows estimation of the average strain and suboxide concentration in films of different thickness. Analysis of infrared spectra shows that suboxide-rich layers in low temperature dry and wet oxides are confined to a distance of ∼1.5 nm from the interface; wet oxidation may generate lower stress near the interface. 相似文献
157.
ZR3#轧机轧制硅钢片横向厚度精度的改善 总被引:2,自引:0,他引:2
在分析武钢ZR3#森吉米尔(Sendzimer)带钢冷轧机(工作辊Φ63.5 mm×1 180 mm,第一中间辊Φ102 mm,第二中间辊Φ173 mm)冷轧硅钢片的轧制工艺和辊型对钢板横向精度控制影响的基础上,调整和改进ASU轧辊的辊型和1~4道次的压下工艺减少压下设定张力,并将上工作辊改为两端带锥度的平辊,下工作辊仍采用3%凸辊.改进后轧制结果表明,ZR3#轧机轧制的无取向低牌号硅钢板的边降区由30~50 mm缩小到25 mm以内,横向厚度差由25 μm减小到15 μm. 相似文献
158.
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
159.
Cubic boron nitride(c-BN) film was deposited on a Si (100) substrate by the RF-magnetron sputtering.The mainly problems for fabrication of c-BN films are the low purity and high intrinsic compressive stress. In order to solve the two problems, the c-BN film with the buffer interlayer was deposited on the substrate which had been implanted with nitrogen and/or boron ions. The results show: the implantation of nitrogen ions can obviously increase c-BN content and reduce the internal stress slightly; while the implantation of boron shows no obvious improvement to the content of c-BN, which can reduce the internal stress in the film obviously. In addition, it is suggested that the implantation of nitrogen and boron shows the best result, which not only can increase the content of c-BN, but also reduce the internal stress in the c-BN film obviously. 相似文献
160.
硅作为重要的植物营养元素,近年来越来越受到人们的关注。本文从植物对硅的吸收及硅在植物体内的输送和分布、硅素在提高植物抗病虫害能力和增强植物抗逆性上的作用、影响土壤硅素肥力的因素以及硅素肥料的施用技术等几个方面,对土壤硅素肥力及植物硅素营养的研究进展进行了综述,并对今后一段时间该领域的研究趋势做了展望。 相似文献