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101.
102.
Boundedness and stability for nonautonomous bidirectional associative neural networks with delay 总被引:1,自引:0,他引:1
Haijun Jiang Zhidong Teng 《Circuits and Systems II: Express Briefs, IEEE Transactions on》2004,51(4):174-180
The paper studies the nonautonomous bidirectional associative neural networks systems with time-varying delays. By applying Lyapunov functional method, introducing many parameters, and combining this with the techniques of inequality analysis, a series of criteria of the uniform ultimate boundedness, global exponential stability, and the existence of periodic solutions are obtained. The results obtained in this paper are new and useful. 相似文献
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The dramatically increasing growth of computer network has brought us more and more complex systems that reveals plenty of nonlinear complex phenomena. On the other hand, cellular automaton model used to be in the study of a variety of nonlinear and spatially extended systems. This paper proposes a simplified cellular model for computer network, namely the NaSch network model, which is originated at the NaSch model of road traffic. Typically, the NaSch network model is a one-dimension cellular automaton and consists of two kinds of cells, i.e. node cell and link cell. In this paper, the node cell stands for switch nodes in computer network, such as routers and switchers, while the link cell is the abstract of the lines of communication among these switch nodes. The simulation results show that this model indeed captures some of properties of flux of computer networks. The space-time plots illustrate that the randomization in this modeling plays an important role in the emerging of self-organization of congestion. It also demonstrates that the density of packet is another key factor to having influence on congestion. On the contrary, the boundary condition has few contribution to our model. 相似文献
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This paper proposes a new control approach for an active (motorized) robotic walking support system based on passive behavior concept. The control approach aims to enhance the interaction between the support system and the user. The passive behavior of a support system allows the user to safely interact with the system since it removes the system's capability to move when there is no user's intention. This passive behavior is realized using imposed apparent dynamics, which uses the user's intention represented by the applied force/torque to derive the system's desired motion. The control approach is extended into a user-oriented motion control algorithm to adapt user's controlling characteristics. This is implemented by varying the point of application of the apparent dynamics. The control approach is further extended to use environment information and realize environment feedback concept. This is implemented by varying the parameters of the apparent dynamics based on environment data. Experimental results are presented to show the validity of the proposed control approach. [All rights reserved Elsevier]. 相似文献
107.
Yuanyuan Zhou Guohao Jiang Cheng Zhang Zhidong Wang Zhongtao Zhang 《Advanced Robotics》2013,27(19):985-995
Flexible endoscopes are widely used in minimally invasive surgical robot systems. Various kinematic models have been developed for describing the deformation of such endoscopes. For joint-type flexible endoscopes, most existing models neglect the effect of internal friction and cannot precisely show the shape.In this paper, we propose a new nonlinear bending model. The rubber tube and metal net at each joint are approximated as a tube under elastic deformation and are assigned an equivalent bending stiffness. The internal friction force is also taken into account to build the moment balance equation at each joint. Groups of experiments were performed to validate the nonlinear model. The results closely confirm the model’s predictions. The model’s tip position error during the bending and unbending phases are 1.48?±?0.99?mm and 1.68?±?0.91?mm respectively; the bending angle errors are ?5.50?±?2.54° and 1.68?±?3.66°, respectively The model can also take account of the hysteresis effect of the bending, which is quite common for cable-driven flexible robots. Moreover, the model has good computational efficiency, making it suitable for real-time control. 相似文献
108.
Hongjuan Yang Zhentao Cong Zhiwu Liu Zhidong Lei 《International journal of remote sensing》2013,34(23):6047-6060
In water-deficient areas, water resource management requires evapotranspiration at high spatiotemporal resolution – an impossible situation given the trade-off between spatial and temporal resolutions in space-borne systems. Some researchers have suggested sharpening the Moderate Resolution Imaging Spectroradiometer (MODIS) land-surface temperature product with a resolution from 1 km to 250 m and a functional relationship between surface temperature (T r) and normalized difference vegetation index (NDVI). Evapotranspiration at 250 m resolution can be obtained once every few days using this technique. Based on the interpretation of the triangular T r–NDVI space and assuming uniform soil moisture conditions in a coarse pixel, this paper suggests an alternative algorithm – the triangle algorithm – for sharpening. The triangle algorithm was tested using Landsat 7 Enhanced Thematic Mapper Plus (ETM+) data from an arid zone. Sharpened surface temperatures and reference temperatures were compared at 60 m and 240 m resolutions. Root mean square errors with the triangle algorithm are smaller than those with a functional relationship between T r and NDVI. This paper will also discuss the impact of soil moisture variations in the coarse pixel on the triangle algorithm. Finally we should mention that the triangle algorithm only applies to regions with non-stressed vegetation canopies. 相似文献
109.
特高压直流(UHVDC)风火联合外送可实现西部、北部风电跨区远距离输送,扩大风电消纳范围。提出了优化特高压直流风火打捆外送配套电源规模的研究方法,首先研究了UHVDC输送火电、风电的技术性约束,包括UHVDC输电运行方式,以及对风电、火电配套规模的影响,提出了配套电源的研究原则及思路;其次,建立了特高压直流风电、火电联合外送配套电源规模的优化方法;最后,以酒泉-湖南±800 kV特高压直流输电工程为例,给出了酒泉-湖南特高压直流风电、火电配套规模,验证了方法的科学性。提出的研究方法对扩大我国北部风电消纳范围,提高特高压直流通道输送效率具有重要意义。 相似文献
110.