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81.
In this paper, the switched safe tracking control scheme is investigated for the attitude and altitude system of a medium-scale unmanned autonomous helicopter with output constraints and unknown external disturbances. To keep the attitude angles and altitude within the desired constrained range, an output boundary protection approach is adopted to generate an output constrained trajectory which is piecewise differentiable. The disturbance observer-based control method is employed to handle the unknown external disturbances of the system. Because of the piecewise differentiability of the output constrained trajectory, the closed-loop error system with the safe tracking controller can be seen as a switched system with jump dynamics. The multiple Lyapunov function method is adopted to guarantee the tracking performance with designed average dwell time. Simulation results of an example are provided to illustrate the effectiveness of the proposed control scheme for the unmanned autonomous helicopter system. 相似文献
82.
83.
T. Chiarusi S. Cecchini G. Giacomelli S. Manzoor E. Medinaceli L. Patrizii V. Togo 《Radiation measurements》2005,40(2-6):424
CAKE (cosmic abundances below the knee energies) is a prototype balloon experiment for the determination of the charge spectra of the primary cosmic-ray nuclei with Z>28 and the search for exotic heavy particles in the primary cosmic radiation. CAKE is made of stacks of CR39® and Lexan® nuclear track detectors; it has a geometric acceptance of about 1.7 m2 sr for Fe nuclei. Here, the scanning strategy and the algorithms used for tracking in automatic mode of the CR events are presented. 相似文献
84.
Thomas Schweizer 《Rheologica Acta》2007,46(5):629-637
Creep experiments with a solution of polystyrene (M
w = 2.6 MDa, 16 vol.%, 25 °C) in diethyl phthalate are reported for stresses between 100 and 2,500 Pa (≈ 3G
N
0/4). The aim was to look for a flow transition as reported for strongly entangled poly(isobutylene) solutions. The experiments
with the polystyrene solution were repeated for cone angles of 2, 4, and 6° (radius 15 mm) and showed no dependence on cone
angle. The Cox–Merz rule was not fulfilled for stresses beyond about 800 Pa. The tangential observation with a CCD camera
showed that the edge took a concave shape because of the second normal stress difference. Beyond 1,000 Pa, the concave edge
develops into a crevice, thus substantially reducing the effective cross-section. This leads to runaway in a constant torque
experiment. At p
21 = 800 Pa, head-on particle tracking confirms that the originally linear velocity profile takes a gooseneck shape, thus revealing
shear banding. When the creep stress is stepped down to 100 Pa, this velocity profile evolves back to a linear one. The conclusion
from this work is that even if nonlinear creep experiments are reproducible and a steady state is reached, this does not mean
that the flow field is homogeneous.
This paper was presented at Annual European Rheology Conference (AERC) held in Hersonisos, Crete, Greece, April 27–29, 2006. 相似文献
85.
86.
红外单站多目标跟踪算法研究 总被引:7,自引:7,他引:0
利用IRST(红外搜索与跟踪)系统所获取的各目标的角度及其红外光谱辐射功率和信息,通过对红外光谱辅射功率和的相关处理,运用选优的JPDA(联合概率数据关联)算法与IMM(交互多模型)算法实现了IRST系统的单站多目标跟踪,并通过两个仿真场景对算法性能进行了检验.仿真结果表明:在跟踪开始阶段,两个场景中的每个目标都能获得高精度的跟踪;当目标编队飞行时,算法能对各目标进行有效的跟踪,而且跟踪精确度也是令人满意的;当目标交叉飞行时,跟踪的误差明显加大,随着时间的延续,对远距离目标会失去跟踪能力,但对近距离目标仍能进行有效的跟踪. 相似文献
87.
88.
Fringe element reconstruction technique for tracking the free surface in three‐dimensional incompressible flow analysis was developed. The flow field was calculated by the mixed formulation based on a four‐node tetrahedral element with a bubble function at the centroid (P1+/P1). Since an Eulerian approach was employed in this study, the flow front interface was advected by the flow through a fixed mesh. For accurate modelling of interfacial movement, a fringe element reconstruction method developed can provide not only an accurate treatment of material discontinuity but also surface tension across the interface. The effect of surface tension was modelled by imposing tensile stress directly on the constructed surface elements at the flow front interface. To verify the numerical approach developed, the developed algorithm was applied to two examples whose solutions are available in references. Good agreement was obtained between the simulation results and these solutions. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
89.
模糊聚类分析的新算法 总被引:1,自引:0,他引:1
张兴华 《数学的实践与认识》2005,35(3):138-141
提出了一种模糊聚类分析的新算法——追踪法 ,解决了以往模糊聚类分析计算量过大以及难于编程实现的问题 .该方法尤其适用于大规模数据的模糊聚类分析 ,对于模糊聚类分析的推广使用有重要意义 . 相似文献
90.
由于子系统的时空耦合作用及参数的摄动性,实现参数摄动的耦合时空混沌的跟踪控制非常困难。然而模型未知的耦合时空混沌的每个子系统可由一系列模糊逻辑模型逼近,每个模糊逻辑模型代表子系统在特定运行点的局部线性化模型,同时考虑子系统状态的不可测性,采用模糊观测器来估计子系统的状态。基于模糊模型及状态观测器,计及混沌参数的摄动性,提出一种模糊跟踪控制方案,实现了参数摄动的耦合时空混沌的鲁棒跟踪控制,并将模糊跟踪控制表征为线性矩阵不等式问题,用线性矩阵不等式的凸优化方法求解控制器参数,确保系统的全局渐近稳定性。仿真验证了方案的有效性。 相似文献