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101.
Giancarlo Marafioti Robert R. Bitmead Morten Hovd 《International Journal of Adaptive Control and Signal Processing》2014,28(6):536-552
Model predictive control (MPC) is a well‐known and widely used advanced control technique, which is model‐based and capable of handling both input and state/output constraints via receding horizon optimization methods. Fundamentally, MPC is a nondynamic or memoryless state feedback control. Because of its use of a model, MPC should be amenable to adaptive implementation and to on‐line tuning of the model. Such an approach requires guaranteeing signal properties, known as ‘persistent excitation’, to ensure uniform identifiability of the model, often expressed in terms of spectral content or ‘sufficient richness’ of a periodic input. We propose an approach to augment the input constraint set of MPC to provide this guarantee. This, in turn, requires equipping the controller with its own state to capture the control signal history. The feasibility of periodic signals for this condition is established. A computational example is presented illustrating the technique and its properties. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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Study results of developing control system for spacecraft formation proximity operations between a target and a chaser are presented. In particular, a coupled model using dual quaternion is employed to describe the proximity problem of spacecraft formation, and a nonlinear adaptive fault-tolerant feedback control law is developed to enable the chaser spacecraft to track the position and attitude of the target even though its actuator occurs fault. Multiple-task capability of the proposed control system is further demonstrated in the presence of disturbances and parametric uncertainties as well. In addition, the practical finite-time stability feature of the closed-loop system is guaranteed theoretically under the designed control law. Numerical simulation of the proposed method is presented to demonstrate the advantages with respect to interference suppression, fast tracking, fault tolerant and practical finite-time stability. 相似文献
104.
6-SPS机构位姿矩阵采用四元数法描述,并将该矩阵和矢量坐标扩展为4维形式,推导出无间隙机构的运动方程,得到了机构运动的新型雅克比矩阵J_A和J_B;在此基础上,利用连续接触模型得到了两个含间隙S副共连杆和异杆时机构的运动系数矩阵。分别把各个运动系数的行列式展开,得到含间隙机构第一类奇异和第二类奇异的轨迹方程,利用MATLAB得到了机构在给定位置时的第一类位姿奇异轨迹和第二类位姿奇异三维轨迹曲面;通过将两类含间隙机构奇异轨迹曲面的比较,发现机构间隙对第二类奇异的影响大于对第一类奇异的影响;在两类奇异轨迹中,当S副异杆时,机构间隙的影响均大于S副共连杆时的影响。以无间隙机构奇异轨迹曲面上奇异点作为参考点,通过含间隙机构奇异轨迹曲面上与参考点相对应奇异点的相互比较,发现存在一个关于参考点的奇异域。 相似文献
105.
In this investigation, biogas (BG) was used as an alternative fuel in a single-cylinder, four-stroke, air-cooled, direct injection (DI) diesel engine that was operated on a dual fuel mode. Biogas was produced from a non-edible seed de-oiled cake-pongamia pinnata (Karanja), which was collected from the biodiesel industries. The BG was inducted along with the air in suction of the engine at four different flow rates varying from 0.3?kg/h to 1.2?kg/h in steps of 0.3?kg/h. The investigation results revealed that BG inducted at a flow rate of 0.9?kg/h gives better combustion characteristics of engine behaviour than those of other flows throughout the engine operation. The ignition delay (ID) and combustion duration of the engine run by dual fuel operation at a BG flow rate of 0.9?kg/h were found to be longer by about 2 °CA and 2.9 °CA, respectively, in comparison with diesel at full load. The cylinder peak pressure was found to be overall higher by about 11?bar than that of diesel at full load. 相似文献
106.
Factors Influencing Dual Phase Steel Flanging Limit Punching 总被引:1,自引:0,他引:1
Based on pre punching to hot rolled martensitic and bainitic dual phase steels with similar elongation and work hardening index (n), as well as similar thickness and hole expansion test using taper die, analysis of the hole expansion rate indicated significant difference in their flanging performance. The results indicated that mechanical property was not the only major factor that influenced flanging. Further analysis of the hole border microstructure, work hardening condition, and fracture property showed that the fracture property of sheets was the major factor that influenced flanging performance. 相似文献
107.
In order to implement the dynamic characteristic of a dual power-split transmission,a dynamic mechanics model is built. Firstly,according to the method of theoretical analysis of the tooth contact analysis ( TCA) and loaded tooth contact analysis ( LTCA) ,the actual meshing process of each gear pairs is simulated, and the time-varying mesh stiffness excitations are obtained,which can improve the numerical precision. Secondly,by using the lumped mass method,the bending-torsional coupling three dimensional dynamic model of the dual power-split transmission is established,and the identical dimensionless equations are deduced by eliminating the effect of rigid displacement and the method of dimensional normalization. Finally,by the method of the fourth order Runge-Kutta algorithm with variable step lengths,the responses of this system in a frequency domain and time domain are obtained,and the dynamic load change characteristics of each gear pairs are analyzed. The results show that the establishment,solution and analysis of the system dynamics model could provide a basis for the dynamic design,and have an important significance for the dynamic efficiency analysis and dynamic performance optimization design of the dual power-split transmission. 相似文献
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Ahmed Iqbal I. Ani Rizwan Rajput 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2012,87(2):177-188
BACKGROUND: Generally the fabrication of polymeric membranes is a complicated and expensive process since it involves several steps. The preliminary preparation steps involve polymer drying and dissolution and is very time consuming and expensive. Currently, conventional electrothermal heating (CEH) is used to dissolve polyethersulfone in an aprotic solvent for membrane fabrication. Usually CEH requires 6 to 8 h at temperatures of 80 to 95 °C. This paper reports the fabrication and characterization of polyethersulfone (PES) asymmetric ultrafiltration membrane made from microwave (MW) synthesis casting solution consisting of various compositions of double solvents and lithium bromide (LiBr) additive. RESULTS: Homogeneous dual solvent dope solutions prepared via microware irradiation took only 1 h instead of the 7 h when prepared using CEH. The results also revealed that the membrane permeation and rejection rates, pore size and porosity were dependent on the ratio of LiBr to acetone. Membranes with LiBr kept at 2 and 3 wt% exhibited both high rejection and permeation rates with minimum pore sizes of 1.067 and 1.214 nm respectively. The presence of LiBr and the occurrence of chain scission were elucidated using Fourier transform infrared (FTIR) spectroscopy while its hydrophilic property was confirmed by water absorption and contact angle measurements. CONCLUSIONS: It was concluded that the microwave technique is capable of producing 1 L membrane solutions in less than 1 h. The membranes prepared from the microwave solutions show good rejection and permeation rates. Copyright © 2011 Society of Chemical Industry 相似文献