全文获取类型
收费全文 | 2992篇 |
免费 | 346篇 |
国内免费 | 282篇 |
专业分类
电工技术 | 323篇 |
综合类 | 250篇 |
化学工业 | 97篇 |
金属工艺 | 39篇 |
机械仪表 | 191篇 |
建筑科学 | 81篇 |
矿业工程 | 19篇 |
能源动力 | 62篇 |
轻工业 | 8篇 |
水利工程 | 27篇 |
石油天然气 | 18篇 |
武器工业 | 21篇 |
无线电 | 176篇 |
一般工业技术 | 314篇 |
冶金工业 | 53篇 |
原子能技术 | 2篇 |
自动化技术 | 1939篇 |
出版年
2024年 | 6篇 |
2023年 | 80篇 |
2022年 | 67篇 |
2021年 | 96篇 |
2020年 | 126篇 |
2019年 | 115篇 |
2018年 | 87篇 |
2017年 | 105篇 |
2016年 | 133篇 |
2015年 | 120篇 |
2014年 | 191篇 |
2013年 | 243篇 |
2012年 | 191篇 |
2011年 | 195篇 |
2010年 | 165篇 |
2009年 | 182篇 |
2008年 | 197篇 |
2007年 | 173篇 |
2006年 | 182篇 |
2005年 | 163篇 |
2004年 | 126篇 |
2003年 | 125篇 |
2002年 | 116篇 |
2001年 | 79篇 |
2000年 | 61篇 |
1999年 | 49篇 |
1998年 | 38篇 |
1997年 | 39篇 |
1996年 | 19篇 |
1995年 | 33篇 |
1994年 | 18篇 |
1993年 | 15篇 |
1992年 | 12篇 |
1991年 | 16篇 |
1990年 | 12篇 |
1989年 | 10篇 |
1988年 | 6篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 8篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有3620条查询结果,搜索用时 250 毫秒
1.
ABSTRACT Incomplete pairwise comparison matrices offer a natural way of expressing preferences in decision-making processes. Although ordinal information is crucial, there is a bias in the literature: cardinal models dominate. Ordinal models usually yield nonunique solutions; therefore, an approach blending ordinal and cardinal information is needed. In this work, we consider two cascading problems: first, we compute ordinal preferences, maximizing an index that combines ordinal and cardinal information; then, we obtain a cardinal ranking by enforcing ordinal constraints. Notably, we provide a sufficient condition (that is likely to be satisfied in practical cases) for the first problem to admit a unique solution and we develop a provably polynomial-time algorithm to compute it. The effectiveness of the proposed method is analyzed and compared with respect to other approaches and criteria at the state of the art. 相似文献
2.
交通信号灯识别包括检测和状态识别,在智能交通系统中发挥重要作用。基于YOLOv3算法提出了一种交通信号灯检测与状态识别模型。针对交通信号灯相较于交通场景中其他目标具有尺度小的特性进行了算法的设计:降低骨干网络的下采样倍率以增加小尺度目标的特征描述能力;通过增大特征图的尺度来改进多尺度特征融合;引入广义交并比作为检测任务的损失函数来改进目标边界框的回归效果。同时,根据交通信号灯本身的特性,使用颜色和形状约束的方法对信号灯进行状态识别和类别验证。最后在公开的Bosch交通信号灯数据集上和实际的城区道路进行了实验验证。实验结果表明,所提出的算法能够提升交通信号灯识别的精度和召回率,识别准确率可以达到90%左右。 相似文献
3.
Graeme
Sabiston Il Yong Kim 《International journal for numerical methods in engineering》2020,121(19):4347-4373
A longstanding challenge in additive manufacturing (AM), the presence of void regions in additively manufactured components, causes two main issues: the enclosing of build material powder in powder bed fusion techniques and limiting tool access in critical post-processing operations to remove sacrificial support structures. As topology optimization has embraced and overcome many of the obstacles of incorporating AM constraints into the underlying numerical optimization statement, there exist few solutions that directly address this fundamental void region issue. By developing computationally efficient and effective solutions to this problem, the integration of these two advanced technologies can be fully realized. Drawing on inspiration from the principles of diffusion physics, a particle diffusion void restriction (PDVR) method is presented in this work that is capable of encouraging the optimization scheme to generate final designs that are fully accessible. Additionally, this method empowers the user to choose the type of post-processing method to clear support material (eg, three-axis or five-axis milling operations, number and orientation of part set-ups) and, therefore, quantify the level of costs associated with the post-processing operation. The PDVR optimization framework is demonstrated on multiple two- and three-dimensional test problems, with physically manufactured examples depicting the real-world benefits this method admits. 相似文献
4.
5.
Yuehui Ji Hailiang Zhou Qun Zong 《International Journal of Adaptive Control and Signal Processing》2019,33(5):829-842
An adaptive neural network (NN) command filtered backstepping control is proposed for the pure‐feedback system subjected to time‐varying output/stated constraints. By introducing a one‐to‐one nonlinear mapping, the obstacle caused by full stated constraints is conquered. The adaptive control law is constructed by command filtered backstepping technology and radial basis function NNs, where only one learning parameter needs to be updated online. The stability analysis via nonlinear small‐gain theorem shows that all the signals in closed‐loop system are semiglobal uniformly ultimately bounded. The simulation examples demonstrate the effectiveness of the proposed control scheme. 相似文献
6.
Jinglin Hu Xiuxia Sun Shuguang Liu Lei He 《International Journal of Adaptive Control and Signal Processing》2019,33(1):114-129
An adaptive finite‐time formation tracking control approach is proposed for multiple unmanned aerial vehicle (UAV) system with quantized input signals in this paper. The UAVs are described by nonholonomic kinematic model and autopilot model with uncertainties. An enhanced hysteretic quantizer is introduced to avoid chattering, and some restrictions are released by using a new quantization decomposition method. Based on backstepping technique and finite‐time Lyapunov stability theory, the adaptive finite‐time controller is designed for the trajectory tracking of the multi‐UAV formation. The nonholonomic constraints are solved by a transverse function. A transformation is introduced to the control input signals to eliminate the quantization effect. Stability analysis proves that the tracking errors can converge to a small neighborhood of the origin within finite time and all the closed‐loop signals are semiglobally finite‐time bounded. The effectiveness of the proposed control approach is validated by simulation and experiment. 相似文献
7.
8.
针对仿人机器人步行过程中存在的机器人关节角加速度约束影响控制性能的问题,提出一种考虑关节角加速度约束的仿人机器人偏摆力矩控制方法.该方法充分考虑了双臂在摆动过程中对偏摆力矩的影响,根据力矩平衡条件得到需要抵消的偏摆力矩的大小与方向,将偏摆力矩的控制问题转化为带约束条件的二次规划问题,并设计了一种在线变步长迭代算法计算得到优化后的双臂摆动轨迹.实验表明,该方法能有效抵消机器人步行中产生的偏摆力矩,避免控制过程中的"削峰"现象,有效提高机器人的步行稳定性. 相似文献
9.
ABSTRACTSocial networking technology has the potential to transform how organizations communicate, cooperate, and connect with key stakeholders. Our research explores how social networking technologies are deployed within organizations and how the use of these technologies is related to effectiveness in organizational communication and promotion. We also identify the facilitating factors and constraints around the use of social networking tools for communication. To examine these questions, we conducted interviews with 131 senior level executives across a broad range of organizations and employed both quantitative and qualitative methods of analysis. The executives were asked to rate numerically and then discuss in narrative form a series of questions about IT strategy and issues affecting social networking in their organization. We find important differences both in the types of tools used as well as how they are used and discuss the implications of our findings for companies seeking to more effectively harness social networking technologies. 相似文献
10.
Dennis K. J. Lin 《Quality Engineering》2019,31(1):49-59
AbstractThe study of order-of-addition (OofA) experiments is prevalent in many scientific and industrial areas. The statistical design of experiments (DOE) will considerably improve the efficiency of OofA experiments. Designing and modeling the OofA experiments have increasingly received a great deal of attention. In this article, we review the latest work on the design and model of OofA experiments, and introduce some new thoughts. We believe that this article will motivate fruitful applications in real OofA experiments as well as future developments in the methodology. 相似文献