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71.
大学生住宿形态与大学教育目标相呼应。中国近代大学生住宿形态的演变表征了博雅教育向职业教育的转变。博雅教育非常重视学生宿舍建设,因为素质培养往往是生活中的潜移默化;职业教育则比较漠视学生的宿舍建设,因为专业知识和日常生活无直接关联。 相似文献
72.
热喷涂层中扁平粒子间的结合决定涂层的性能。能评价粒子间结合的简单可靠的方法对于涂层的实际应用具有十分重要的意义。然而采用传统的试验方法如拉伸试验难以获得令人满意的结果。可以预料具有去结合机理的一层接一层去除粒子的试验方法将是有效的。实验证明通过控制测试条件,颗粒冲击磨损试验能够通过去结合机理有效地使涂层产生磨损。本论文提出了陶瓷涂层颗粒冲击磨损的模型,基于涂层受颗粒冲击磨损是因一层层的粒子通过去结合而产生的机理,建立了磨损速度与粒子间结合率的关系。定义为ACT-JP值(磨损速度的倒数)的特征值与粒子间结合率的实验相关性证明了粒子间结合对陶瓷涂层磨损的控制作用和利用颗粒冲击磨损试验评价粒子间结合的可行性。 相似文献
73.
74.
Measurements of granular flows in two-dimensional hoppers by particle image velocimetry. Part I: experimental method and results 总被引:1,自引:0,他引:1
Daniel A. Steingart 《Chemical engineering science》2005,60(4):1043-1051
The objective of the present investigation was to test the applicability of particle image velocimetry (PIV), which is normally used for measuring velocities in liquids or gases, to measurement of velocities in granular flow. A second objective was to use PIV to provide experimental data for comparison with mathematical models. The flow of zinc particles, of size 0.4, 0.61 and 0.76 mm size, in a flat-bottomed two-dimensional hopper was measured by PIV. The particles were characterized using ASTM procedures for angle of repose, packing density and flow rate through a funnel. Through PIV, velocities and mass flow rates were determined for exit apertures 5 and 7.5 mm in width and 10, 30 and 50 mm long. The bed of particles in the hopper showed the expected stagnant zones on either side of the aperture. There was a continual avalanche of particles at the “V’’ which forms at the surface of the bed and some images of this avalanche, obtained with a boroscope, are included. 相似文献
75.
A digital imaging approach was applied to investigate mortar morphology in thin sections; in particular, the binder/aggregate ratio and the grading curve of five mortar bars were attained by digital image processing (DIP), using the Image Pro Plus 4.1 software package. The imaging procedure employed image segmentation, to extract mortar aggregate, and image filtering, to fix grain boundaries. The results show that digital image processing may be considered as an alternative method to mechanical sieving for the characterisation of mortar morphology, as it appears to be quicker and more accurate than the traditional method. However, digital image processing exhibits limits, which are discussed in the text. 相似文献
76.
Dielectric characterization of the α-relaxation in polyarylate (PAr) has been carried out by means of a dielectric spectroscopy technique in a frequency range of 10–30 kHz. Complementary thermally stimulated depolarization currents (TSDC) and differential scanning calorimetry d.s.c.) measurements have also been performed. The results are interpreted in terms of the standard Cole-Cole plot and Havriliak-Negami distribution for the dielectric relaxation times. Information about the temperature and frequency dependence of a.c. conductivity is also obtained from the experimental curves. However, the behaviour of the main dielectric relaxation time is deduced from the experimental data in a wide range of temperature around the glass transition. This behaviour results in close agreement with the theoretical predictions of a free-volume approach for the dielectric α-relaxation recently proposed by the authors. 相似文献
77.
A three-dimensional simulation model for colloidal dispersion system with an adsorptive surface under a specified bulk concentration was developed basing on the Brownian dynamics technique, and the adsorption process of electrostatically stabilized colloidal particles with radius of 50 nm onto a planar surface with counter charge was simulated. The particle-particle and particle-surface interactions were modeled on the DLVO theory. The adsorbed particles are found to form hexagonally ordered array, only if the surface coverage is above a certain threshold, which varies depending on the ionic strength or the interaction potentials. Through the analysis of the ordered structure, we found that the determinant factor for the order formation is “one-directional average force” acting between adsorbed particles, which exhibits a common value regardless of the ionic strength. Also, looking at the last process for establishing the order, we developed a model that can predict the potential barrier for the order formation. Further, the order formation was proven to be a stochastic phenomenon, and a model to describe the probability against time was developed and its quantitative validity was demonstrated. 相似文献
78.
An online beam dynamics simulator is being developed for use in the operation of an ion linear particle accelerator. By employing Graphics Processing Unit (GPU) technology, the performance of the simulator has been significantly increased over that of a single CPU and is therefore viable in the demanding accelerator operations environment. Once connected to the accelerator control system, it can rapidly respond to any control set point changes and predict beam properties along an ion linear accelerator in pseudo-real time. This simulator will be a virtual beam diagnostic tool which is especially useful when direct beam measurements are not available. Details about the code structure design, physics algorithms, GPU implementations, and performance are presented. 相似文献
79.
《Expert systems with applications》2014,41(5):2134-2143
In this paper, a hybrid method for optimization is proposed, which combines the two local search operators in chemical reaction optimization with global search ability of for global optimum. This hybrid technique incorporates concepts from chemical reaction optimization and particle swarm optimization, it creates new molecules (particles) either operations as found in chemical reaction optimization or mechanisms of particle swarm optimization. Moreover, some technical bound constraint handling has combined when the particle update in particle swarm optimization. The effects of model parameters like InterRate, γ, Inertia weight and others parameters on performance are investigated in this paper. The experimental results tested on a set of twenty-three benchmark functions show that a hybrid algorithm based on particle swarm and chemical reaction optimization can outperform chemical reaction optimization algorithm in most of the experiments. Experimental results also indicate average improvement and deviate over chemical reaction optimization in the most of experiments. 相似文献
80.