全文获取类型
收费全文 | 14846篇 |
免费 | 1622篇 |
国内免费 | 1276篇 |
专业分类
电工技术 | 660篇 |
技术理论 | 2篇 |
综合类 | 1456篇 |
化学工业 | 829篇 |
金属工艺 | 1158篇 |
机械仪表 | 1941篇 |
建筑科学 | 1001篇 |
矿业工程 | 432篇 |
能源动力 | 402篇 |
轻工业 | 291篇 |
水利工程 | 207篇 |
石油天然气 | 450篇 |
武器工业 | 189篇 |
无线电 | 1440篇 |
一般工业技术 | 2311篇 |
冶金工业 | 463篇 |
原子能技术 | 95篇 |
自动化技术 | 4417篇 |
出版年
2024年 | 63篇 |
2023年 | 240篇 |
2022年 | 464篇 |
2021年 | 448篇 |
2020年 | 533篇 |
2019年 | 378篇 |
2018年 | 362篇 |
2017年 | 462篇 |
2016年 | 505篇 |
2015年 | 641篇 |
2014年 | 840篇 |
2013年 | 1017篇 |
2012年 | 1051篇 |
2011年 | 1203篇 |
2010年 | 946篇 |
2009年 | 936篇 |
2008年 | 911篇 |
2007年 | 985篇 |
2006年 | 928篇 |
2005年 | 789篇 |
2004年 | 611篇 |
2003年 | 635篇 |
2002年 | 472篇 |
2001年 | 353篇 |
2000年 | 313篇 |
1999年 | 302篇 |
1998年 | 273篇 |
1997年 | 223篇 |
1996年 | 191篇 |
1995年 | 160篇 |
1994年 | 113篇 |
1993年 | 80篇 |
1992年 | 60篇 |
1991年 | 56篇 |
1990年 | 50篇 |
1989年 | 42篇 |
1988年 | 29篇 |
1987年 | 10篇 |
1986年 | 17篇 |
1985年 | 11篇 |
1984年 | 15篇 |
1983年 | 6篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1975年 | 3篇 |
1957年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
151.
Experiments were performed in a shear cell device under four different solid fractions. The glass spheres with a mean diameter of 3 mm were used as granular materials. The motions of the granular materials were recorded by a high-speed camera. By using image processing technology and a particle tracking method, the average and fluctuation velocities in the streamwise and the transverse directions could be successfully measured and analyzed. Three bi-directional stress gages were used to measure the normal and shear stresses along the upper boundary. The effective viscosity of the granular material flow can be calculated. By tracking the movements of particles continually, the curves of the mean-square diffusive displacements versus time were plotted and were used to determine the self-diffusion coefficients from the slopes of the curves. The fluctuations and the self-diffusion coefficients in the streamwise direction were much higher than those in the transverse direction. The fluctuations were found to increase with the solid fraction, but the diffusion coefficients were greater in a more dilute flow system. 相似文献
152.
The prototyping of complex sheet metal parts using single point incremental forming (SPIF) requires the generation of optimal tool paths and/or tool path sequences that ensure that the formed part is within geometric design specifications. The presence of a multitude of features on complex parts leads to multiple inaccuracy inducing phenomena occurring simultaneously due to interactions between the features. This paper proposes a network analysis methodology using topological conceptual graphs to capture the effects of different phenomena on the final accuracy of a sheet metal part manufactured by SPIF. Using this framework optimized tool paths can be generated that compensate for the inaccuracy inducing behavior. Tool path generation algorithms to create partial tool paths that account for the accuracy of specific features in the part based on the proposed framework are also presented. Finally, the creation of integrated tool paths maintaining complementarity between tool paths and desired continuity behavior using non-uniform cubic B-splines is illustrated. A number of case studies demonstrating the applicability of the integrated framework are discussed, where the maximum deviations in the part are significantly reduced and the average absolute deviations for the complete part are brought down to less than 0.5 mm. 相似文献
153.
154.
155.
156.
This paper presents the trajectory tracking control of an autonomous underwater vehicle(AUV). To cope with parametric uncertainties owing to the hydrodynamic effect, an adaptive control law is developed for the AUV to track the desired trajectory. This desired state-dependent regressor matrix-based controller provides consistent results under hydrodynamic parametric uncertainties.Stability of the developed controller is verified using the Lyapunov s direct method. Numerical simulations are carried out to study the efficacy of the proposed adaptive controller. 相似文献
157.
158.
用无向网表示学校的平面图,设计了该平面图的存储结构,并应用最短路径算法实现了查询图中各景点的相关信息,以及查询图中任意两个景点间的最短路径的功能;应用克鲁斯卡尔算法构造该平面图的最小生成树,求出可以连通所有景点的最短路径。该系统为新生熟悉校园环境提供了方便。 相似文献
159.
针对移动机器人路径规划问题,提出一种基于QPSO算法的路径规划方法,并用概率论的方法分析了移动机器人路径规划的收敛性,阐明了该方法随均匀分布和正态分布的参数关系和收敛区间;然后根据移动机器人的运动特征提出一种改进的轨迹规划方法。移动机器人平台的实验结果表明了该方法在移动机器人路径规划中的有效性和可行性。 相似文献
160.