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991.
本文叙述了采用铜圆柱体试件确定螺旋摩擦压力机做功能力所要考虑的各种影响因素,分析了各种因素对计算结果影响的变化规律。在保证较高精度的条件下综合出一可简化计算过程的确定做功能力图表。 相似文献
992.
介绍了一种新的仅用一台激光器测定激光线宽或频率稳定的测量方法,用稳定的无源腔透过曲线腰处斜率将激光的频率扰动转为电压扰动。用所研制的测量装置对自制的边疆波染料激光频率的线宽和频率稳定性进行了测量。 相似文献
993.
NUMERICAL SIMULATION OF SEA SURFACE DIRECTIONAL WAVE SPECTRA UNDER TYPHOON WIND FORCING 总被引:4,自引:2,他引:2
Numercial simulation of sea surface directional wave spectra under typhoon wind forcing in the South China Sea (SCS) was carreid out using the WAVEWATCH-Ⅲ wave model. The simulation was run for 210 h until the Typhoon Damrey (2005) approached Vietnam. The simulated data were compared with buoy observations, which were obtained in the northwest sea area of Hainan Island. The results show that the significant wave height, wave direction, wave length and frequency spetra agree well with buoy observations. The spatial characteristics of the signifciant wave height, mean wave period, mean wave length, wave age and directional spectra depend on the relative position from the typhoon center. Also, the misalignment between local wind and wave directions were investigated. 相似文献
994.
M. Husain Beer Pal Singh Sushil Kumar T. P. Sharma P. J. Sebastian 《Solar Energy Materials & Solar Cells》2003,76(3):399-415
II–VI polycrystalline semiconducting materials have come under increased scrutiny because of their wide use in the cost reduction of devices for photovoltaic applications. Cd1−xZnxSe is an important semiconducting alloy because of the tunability of its physical parameters such as band gap and lattice parameters by controlling its stoichiometry. Many more material characteristics of it would be altered and excellently controlled by controlling system composition x.Polycrystalline thin films of Cd1−xZnxSe with variable composition (0x1) have been deposited onto ultra-clean glass substrates by sintering process. The optical, structural and electrical transport properties of Cd1−xZnxSe thin films have been examined. The optical band gap and optical constants of these films were determined by using double beam spectrophotometer. The DC conductivity and activation energy of the films were measured in vacuum by two-probe technique. The Schottky junction of Cd1−xZnxSe with indium was made and the barrier height and ideality factor were determined using current–voltage characteristics. The nature of sample, crystal structure and lattice parameters were determined from X-ray diffraction patterns. The films were polycrystalline in nature having cubic zinc-blende structure over the whole range studied.Sintering is very simple and viable compared to other cost intensive methods. The results of the present investigation will be useful in characterizing the material, Cd1−xZnxSe, for its applications in photovoltaics. 相似文献
995.
A. Hattab F. Meyer Vy Yam D. Bouchier R. Meyer O. Schneegans C. Clerc 《Microelectronic Engineering》2003,70(2-4):240-245
In this work, we investigated electrical and morphological properties of W/p-type Si Schottky diodes with intentional inhomogeneities introduced by macroscopic Ge-islands embedded beneath the interface. The Si-cap layer thickness (or the island-distance to the interface) was progressively reduced by successive chemical etching cycles. Electrical characterizations were achieved through reverse current–voltage (I–V) at room temperature and forward I–V measurements as a function of the temperature. In parallel, Rutherford backscattering spectroscopy analyses were performed to follow the Si-cap/Ge islands chemical thinning down with increasing the number of etching cycles. In addition, the comparison of topographical and electrical properties of the etched silicon-cap layer was carried out by conductive atomic force microscopy analyses with a nanometer-scale resolution. Our results indicate that the areas on the top of islands exhibit lower resistance than those which covered the wetting layer. This lateral variation of resistance at the surface of the semiconductor may correspond to Schottky barrier height inhomogeneities observed on broad area I–V characteristics of Schottky contacts. 相似文献
996.
M. T. Hirsch K. J. Duxstad E. E. Haller S. Ruvimov Z. Liliental-Weber 《Journal of Electronic Materials》1998,27(11):1236-1239
We correlate structural and electrical characteristics of as-deposited and low-temperature annealed Ti contacts on GaN. Temperature
dependent currentvoltage measurements are used to determine the effective barrier heights of the respective contacts, while
high-resolution transmission electron microscopy is utilized for structural characterization. As-deposited Ti contacts are
slightly rectifying with an effective barrier height of ∼200 meV. After annealing at 230°C, the barrier height increases to
values of ∼450 meV. A similar behavior of Schottky contacts with more strongly rectifying diodes upon low-temperature annealing
is observed for Zr metal contacts on GaN. As-deposited Ti already forms a thin TiN layer at the GaN interface. After annealing
at 230°C, the average thickness and the distribution of TiN grains remain practically unchanged, but the interface with GaN
roughens. We correlate the observed barrier height changes with interface roughness and phase formation and we discuss the
results in terms of interface damage and the Schottky-Mott theory. 相似文献
997.
露天矿汽车运输功与台阶高度的关系 总被引:1,自引:0,他引:1
以18m台阶和12m台阶的露天为例,分析了台阶高度与矿岩势能、矿岩运距及汽车运行速度的关系,认为单一汽车运输的露天矿,随着台阶高度的增加,汽车运输功有减小的趋势。 相似文献
998.
999.
1000.
钢筋混凝土梁板有效高度及截面设计 总被引:1,自引:0,他引:1
就混凝土梁板有效高度以及经济截面设计进行了分析 ,并提出其有效高度与经济配筋率的核心范围 ,指明只有在该核心范围内才能保证工程安全 ,全面达到降低工程造价 ,提高经济效益的目的。 相似文献