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81.
通过检测激光光斑中心位置偏移的方法来监测路基沉降,是一种便携易布设的方法。而激光光斑中心的检测可以使用重心法、圆拟合、椭圆拟合、高斯曲面拟合。采用重心法运算简单精度低,而采用拟合法精度更高,由于光轴与靶面间存在夹角,光斑更近似看作一椭圆,应用椭圆拟合,辅之以亚像素精度分割,Canny边缘提取后获得了较为理想的沉降监测精度。 相似文献
82.
王关勤 《高校化学工程学报》1994,8(2):118-123
本文应用根据激光光声原理和技术建立的流体热力学性质测量实验装置,测定了七个温度下苯、四氯化碳液体中,苯与四氯化碳二元溶液中的声速(u)、密度(ρ),计算了等熵压缩性系数(K_s)等热力学数据。用多项幂级数,以最小二乘法拟合声速u与温度t的数学关系。实测的声速值与文献值比较,相对误差小于0.04%,等熵压缩性系数与文献数据也相当吻合。 相似文献
83.
A new approach to evaluate activation energy for nucleation in metal chemical vapor deposition (CVD) is presented. Deposition
is performed by laser induced chemical vapor deposition (LCVD) using a low laser power and a high scan speed, so that only
discrete particles in the initial nucleation stage are formed. The nucleation activation energy is then obtained from a relationship
between the laser-induced surface temperature distribution and the particle distribution. The activation energy is directly
related to the nucleation barrier, and hence the difference in the nucleation activation energies on different substrates
may be used to explain the chemical selectivity which is often observed during metal CVD processes. This approach is experimentally
applied to aluminum CVD using dimethylethylamine alane (DMEAA) precursor, and its nucleation activation energy is found to
be 25kcal/mol on silicon surface. 相似文献
84.
85.
Velocity measurements and flow field characteristic analyses in a turbo air classifier 总被引:2,自引:0,他引:2
Turbo air classifier is one of the most widely used powder classification equipment. The rotor cage as a rotary component can create a forced centrifugal field, so it is a key part for turbo air classifier. In order to investigate the effect of structural variations of the rotor cage on flow field characteristics, three dimensional velocity measurements of the annular region in a turbo air classifier equipped with two different rotor cage bottom plates (A and B type) are performed by laser Doppler velocimeter (LDV). It is found that the different bottom plates have different axial and tangential velocity distributions in the annular region. However, the structural variations of the rotor cage have hardly any effect on the radial velocity. Based on the classification principle, the relation between the classification performance and the flow field characteristics is investigated in great detail.The results of the flow field measurements were tested by the classification experiments carried out with cement raw meal and ground calcium carbonate. The results demonstrate that B type bottom plate can realize the production of narrow particle size distributions, so it is more favorable for classification than A type bottom plate. Classification experiment results are in good agreement with the results of the flow field measurements. 相似文献
86.
87.
激光精密加工及切割已被应用在如太阳能晶硅切割、手机面板切割、半导体晶圆切割,Laser CNC等精密加工上面。如何通过调整能量强度来满足不同材质上切割,而呈现出有层次感的效果,这些都是高端运动控制产品所面临的新挑战。在本文中将讨论如何克服精密激光加工时所遭遇的新挑战,以及通过实例证明的解决方案。 相似文献
88.
A detailed study of the flow behaviour in the near wall region of pulp suspensions up to 4.7% have been performed using Laser Doppler Anemometry (LDA) in pipe flow. Axial mean velocity profiles show a distinct plug flow and an increase of the plug region as the flow rate decreases and fibre concentration increases. An attempt is made to relate the LDA data‐rate to fibre concentration, which indicates a dilution region at 1‐2 mm from the wall that is larger than the annulus region. The dilution region increases with increasing flow rate, decreasing concentration and when using longer pulp fibres. 相似文献
89.
Jiaqing Li 《Electrochimica acta》2006,51(23):4942-4949
The method of Ti/TiO2 photoelectrode prepared by using laser calcination method instead of oven calcination process was introduced. The prepared TiO2 film was observed with AFM and XRD. Photoelectrocatalytic degradation of rhodamine B (RB) using this electrode was investigated, and anodic potential and pH were optimized. The laser power applied in this electrode preparation was also discussed, and it indicated that TiO2 particle prepared with high laser power was crystallized adequately and the photoelectrocatalytic ability was satisfactory. RB degradation was investigated under different conditions, and it showed that photoelectrocatalytic degradation could achieve efficient and complete mineralization of organic pollutant. The photoelectrocatalytic oxidation using the Ti/TiO2 electrode calcinated by laser was compared with that of the electrode calcinated by furnace, and it showed that the reaction rate of RB degradation using the electrode by laser was faster than that by furnace. Additionally, electrochemical impedance spectroscopy (EIS) was performed at the two different photoelectrodes, which verified the higher photocatalytic activity of the laser-treated electrode further. 相似文献
90.
激光在大气传输过程中,由于同大气分子与气溶胶粒子之间的相互作用而产生了一系列的效应,即大气衰减和大气湍流效应,导致能量不断减弱,并影响激光的远场能量密度分布.根据设计的激光远场能量密度分布测试系统进行外场实际试验测试,只能获得指定位置上的远场能量密度分布数据和激光光斑图像,为了获得任意位置的激光传输特性,研究了大气衰减和大气湍流对激光传输的影响.根据上述系统测得的指定位置的光斑图像及能量分布数据,通过软件仿真分析,估算任意位置的激光光斑能量密度分布,通过伪彩色变换,将激光光斑的灰度图像转换为连续变化的伪彩色图像,可以直观地观察光斑的远场能量密度分布. 相似文献