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131.
以柔性材料和高精度六面体作为惯性传感器的安装载体和基准,设计了一种免装配、安装误差小、体积小、功耗低且便于标定的微惯性测量单元。给出了安装误差小角度前提下的传感器的测量方程和标定方法;利用微控制器的并行工作机制,提出了一种快速有效的基于均值滤波和FIR滤波的组合滤波方案。实验结果表明:MIMU可以100 Hz的频率更新测量输出,加速度测量噪声小于2.5 mg、测量误差小于0.8 mg,旋转角速度测量噪声小于0.15 o/s、测量误差小于0.2 o/s,可满足微小型惯性导航系统的功耗、体积、测量精度和响应速度的应用需求。  相似文献   
132.
研究了一种紧耦合INS/视觉相对位姿测量方法在无人机自主空中加油中的应用。该方法直接将特征点的图像坐标作为滤波器输入,避免了求解复杂的非线性位姿方程,尤其是特征点提取不全时,该方法具有较强的鲁棒性。引入相对惯导误差建立了增广状态模型,根据杆臂效应详细推导了紧、松两种耦合模式的量测方程。采用扩展卡尔曼滤波算法估计误差状态,并校正惯导输出获取精确的相对位姿信息。仿真结果表明,与松耦合模式相比,紧耦合在提高系统实时性的同时可获得更高的测量精度,位置误差小于0.1 m,姿态角误差小于3'。  相似文献   
133.
低成本车载导航仪的组合导航算法设计   总被引:2,自引:0,他引:2  
针对GPS信号间歇性受阻而无法持续导航的问题,提出了一种由GPS、微惯性导航系统,以及电子罗盘构建车载组合导航系统的方案。以GPS位置信息是否有效为判断条件,设计了组合策略。当GPS信息有效时,采用以位置误差作为观测量的组合导航算法;当GPS信息无效时,引入速度约束辅助导航算法。试验表明,该组合策略能够在GPS有效时提供高精度的姿态、速度和位置信息,在GPS失效时,使位置误差得到有效抑制,从而保证了车载导航仪的导航精度和导航信息的持续性。  相似文献   
134.
For homogeneous isotropic turbulence study, the acquisition of band-pass filtered velocity increments (FVI) in a non-forced turbulent box is still a challenge both experimentally and numerically. Turbulence and associated physical processes, at a given instant, are permanently contaminated by a forcing process which can seldom be universal. The situation tends to be the origin of intermittency and the non-Gaussian probability density distribution for acceleration and velocity gradients. To reveal implied mechanism, grid turbulence is adapted to observe non-perturbed homogeneous isotropic turbulence. The velocity increments (VI) can be obtained following Comte-Bellot and Corrsin (GCBC) by means of two point-two time shifted velocity measurements. It is difficult to obtain decaying turbulence (DT) at large turbulent Reynolds number without pollution coming from walls. Nevertheless it is also significant to investigate DT in low Reynolds number regimes to determine non-polluted tendencies. The similarity of DT between particle image velocimetry (PIV) and hot wire anemometry measurements by GCBC are presented. Here we focus our tendency on VI and FVI probability density function (PDF) shapes in this letter. In conclusion, the tendency to Gaussian shape in inertial zone wavenumbers, demonstrates that there will be no intermittency if turbulent cascade is not perturbed.  相似文献   
135.
A novel rapid transfer alignment algorithm for laser strapdown inertial navigation system (SINS) is studied. Transfer alignment have typically relied on velocity measurements from the master SINS as the source of alignment information, but lever arm error must be compensated accurately while velocity information is utilized, all most every quaternion based error model is nonlinear, so nonlinear filtering algorithms are need, suffering from computational complex and large error. Aim at these problems, a novel improved rapid transfer alignment algorithm formulation is presented, applying quaternion to built the process and measurement models, the improvement employs a special manipulation of the measurement equation results in a linear pseudo-measurement equation, thus the classical linear Kalman filter is employed to estimate the state, need not lever arm error compensation, results in the reduce of computational burden. Observability analysis of this new transfer alignment algorithm has been done based on the piece-wise constant system (PWCS) method, results show that the presented algorithm can accomplish the initial alignment task perfectly. A transfer alignment simulation system is also developed for the evaluation and analysis of the presented algorithm, simulation results are confirmed with the theoretical conclusion, which can achieve the transfer alignment accuracy about 1 mrad within 10 s.  相似文献   
136.
双筒粘度计中牛顿流体的振荡解   总被引:5,自引:1,他引:4  
  相似文献   
137.
This is the first of a couple of papers in which the peculiar capabilities of the Hamiltonian approach to general relativity are exploited to get both new results concerning specific technical issues, and new insights about old foundational problems of the theory. The first paper includes: (1) a critical analysis of the various concepts of symmetry related to the Einstein-Hilbert Lagrangian viewpoint on the one hand, and to the Hamiltonian viewpoint, on the other. This analysis leads, in particular, to a re-interpretation of active diffeomorphisms as passive and metric-dependent dynamical symmetries of Einstein's equations, a re-interpretation which enables to disclose the (not widely known)) connection of a subgroup of them to Hamiltonian gauge transformations on-shell; (2) a re-visitation of the canonical reduction of the ADM formulation of general relativity, with particular emphasis on the geometro-dynamical effects of the gauge-fixing procedure, which amounts to the definition of a global non-inertial, space-time laboratory. This analysis discloses the peculiar dynamical nature that the traditional definition of distant simultaneity and clock-synchronization assume in general relativity, as well as the gauge relatedness of the “conventions” which generalize the classical Einstein's convention. (3) a clarification of the physical role of Dirac and gauge variables, as their being related to tidal-like and generalized inertial effects, respectively. This clarification is mainly due to the fact that, unlike the standard formulations of the equivalence principle, the Hamiltonian formalism allows to define a generalized notion of “force” in general relativity in a natural way.  相似文献   
138.
139.
行车时间估计和最优路径选择是智能交通系统中的研究热点,特别是对于车辆导航系统更具有深远的意义.首先以传统的交通流理论为基础,采用间接模型和动力学模型进行行车时间估计,通过仿真实验比较了两模型的优劣,并使用实测数据分析得到的车流量信息对动力学模型进行改进.然后使用Dijkstra算法寻找出静态状态下的最优路径,再结合前面建立的时间估计模型,给出了适用于动态随机状态下的路径寻优算法,用于解决路段行车时间期望随出发时刻动态变化的问题.最后指出了交通实时信息对解决动态随机最优路线问题的重要性,并结合卡尔曼滤波算法对路段相关的情况作了进一步讨论.  相似文献   
140.
嵌入式实时操作系统VxWorks在惯性导航系统中的应用   总被引:3,自引:0,他引:3  
详细介绍了嵌入式实时操作系统VxWorks的性能特点,叙述了基于VxWorks操作系统的开发过程和在导航接口机中的应用实例,提出了现行惯导系统软件从汇编语言到OS,高级语言的必要性和可能性,从而在提升软件的可维护性,可测试性和可靠性的同时,充分的发挥导航计算机的性能,以适应日益复杂的导航计算要求。  相似文献   
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