首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   151135篇
  免费   20884篇
  国内免费   15720篇
电工技术   12892篇
技术理论   9篇
综合类   19251篇
化学工业   12539篇
金属工艺   5803篇
机械仪表   11902篇
建筑科学   14184篇
矿业工程   5506篇
能源动力   6733篇
轻工业   4725篇
水利工程   9356篇
石油天然气   9455篇
武器工业   2235篇
无线电   12237篇
一般工业技术   13343篇
冶金工业   5241篇
原子能技术   1403篇
自动化技术   40925篇
  2024年   695篇
  2023年   2540篇
  2022年   4867篇
  2021年   5624篇
  2020年   5852篇
  2019年   5030篇
  2018年   4735篇
  2017年   5808篇
  2016年   6670篇
  2015年   6963篇
  2014年   9321篇
  2013年   9776篇
  2012年   11084篇
  2011年   11967篇
  2010年   9321篇
  2009年   9706篇
  2008年   9701篇
  2007年   10956篇
  2006年   9513篇
  2005年   8261篇
  2004年   6741篇
  2003年   5856篇
  2002年   4664篇
  2001年   3882篇
  2000年   3315篇
  1999年   2578篇
  1998年   2162篇
  1997年   1812篇
  1996年   1685篇
  1995年   1427篇
  1994年   1165篇
  1993年   830篇
  1992年   689篇
  1991年   552篇
  1990年   433篇
  1989年   368篇
  1988年   237篇
  1987年   143篇
  1986年   116篇
  1985年   110篇
  1984年   121篇
  1983年   66篇
  1982年   84篇
  1981年   47篇
  1980年   58篇
  1979年   55篇
  1978年   19篇
  1962年   10篇
  1959年   20篇
  1951年   11篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
951.
952.
In early 2000,large domestic shipyards introduced shipbuilding 3D computer-aided design (CAD) to the hull production design process to define manufacturing and assembly information.The production design process accounts for most of the man-hours (M/H) of the entire design process and is closely connected to yard production because designs must take into account the production schedule of the shipyard,the current state of the dock needed to mount the ship’s block,and supply information.Therefore,many shipyards are investigating the complete automation of the production design process to reduce the M/H for designers.However,these problems are still currently unresolved,and a clear direction is needed for research on the automatic design base of manufacturing rules,batches reflecting changed building specifications,batch updates of boundary information for hull members,and management of the hull model change history to automate the production design process.In this study,a process was developed to aid production design engineers in designing a new ship’s hull block model from that of a similar ship previously built,based on AVEVA Marine.An automation system that uses the similar ship’s hull block model is proposed to reduce M/H and human errors by the production design engineer.First,scheme files holding important information were constructed in a database to automatically update hull block model modifications.Second,for batch updates,the database’s table,including building specifications and the referential integrity of a relational database were compared.In particular,this study focused on reflecting the frequent modification of building specifications and regeneration of boundary information of the adjacent panel due to changes in a specific panel.Third,the rollback function is proposed in which the database (DB) is used to return to the previously designed panels.  相似文献   
953.
954.
视觉伺服的乒乓球机器人系统作为典型的"手眼系统",是研究高速视觉感知和快速伺服运动的理想平台,其涉及的高速物体识别跟踪、快速精确轨迹预测及机械臂伺服准确回球等关键技术在工业、军事等领域有广泛的应用前景.本文提出了乒乓球机器人的高速视觉伺服系统实现方法,包括基于特征直方图统计和快速轮廓搜索的目标识别算法,基于模型参数学习和自适应模型调整的物体运动状态估计和轨迹预测算法,及基于轨迹预测的灵巧臂回球规划算法.通过实验验证了各算法的实时性和高效性,并在165cm高的仿人机器人"悟"和"空"上成功实现了双机器人对打和与人对打任务.  相似文献   
955.
介绍日照钢铁1580mm热轧带钢过程控制系统的应用,以及系统配置、网络结构、中间件和应用软件功能。  相似文献   
956.
957.
A current development trend in research on intelligent systems is to optimize a general intelligent prediction system into an individuation intelligent prediction system that is applied in specialized fields. Protein structure prediction is a challenging international issue. In this paper, we propose a new intelligent prediction system model, designed as a multi-layer compound pyramid model, for predicting secondary protein structure. The model comprises four independent intelligent interfaces and several knowledge discovery methods. The model penetrates throughout the domain knowledge, with the effective attributes chosen by Causal Cellular Automata. Furthermore, a high pure structure database is constructed for training. On the RS126 dataset, the overall state per-residue accuracy, Q3, reached 83.99%, while on the CB513 dataset, Q3 reached 85.58%. Meanwhile, on the CASP8 sequences, the results are superior to those produced by other methods, such as Psipred, Jpred, APSSP2 and BehairPred. These results confirm that our method has a strong generalization ability, and that it provides a model for the construction of other intelligent systems.  相似文献   
958.
We propose a model structure with a double-layer hidden Markov model (HMM) to recognise driving intention and predict driving behaviour. The upper-layer multi-dimensional discrete HMM (MDHMM) in the double-layer HMM represents driving intention in a combined working case, constructed according to the driving behaviours in certain single working cases in the lower-layer multi-dimensional Gaussian HMM (MGHMM). The driving behaviours are recognised by manoeuvring the signals of the driver and vehicle state information, and the recognised results are sent to the upper-layer HMM to recognise driving intentions. Also, driving behaviours in the near future are predicted using the likelihood-maximum method. A real-time driving simulator test on the combined working cases showed that the double-layer HMM can recognise driving intention and predict driving behaviour accurately and efficiently. As a result, the model provides the basis for pre-warning and intervention of danger and improving comfort performance.  相似文献   
959.
We present an iterative linear quadratic regulator(ILQR) method for trajectory tracking control of a wheeled mobile robot system.The proposed scheme involves a kinematic model linearization technique,a global trajectory generation algorithm,and trajectory tracking controller design.A lattice planner,which searches over a 3D(x,y,θ) configuration space,is adopted to generate the global trajectory.The ILQR method is used to design a local trajectory tracking controller.The effectiveness of the proposed method is demonstrated in simulation and experiment with a significantly asymmetric differential drive robot.The performance of the local controller is analyzed and compared with that of the existing linear quadratic regulator(LQR) method.According to the experiments,the new controller improves the control sequences(v,ω) iteratively and produces slightly better results.Specifically,two trajectories,’S’ and ’8’ courses,are followed with sufficient accuracy using the proposed controller.  相似文献   
960.
重症监护病房中的病人身体状况通常很不稳定,常出现各种需要医护人员介入治疗的紧急状况。由于医疗资源有限,医护人员可能无法及时发现并处理这些紧急状况,给病人的存活率带来严重的负面影响。如果可以预测这些紧急状况的发生,并及时通知相关医护人员,将大大提高病人的存活率。常见重症监护病房紧急状况包括突然死亡、败血症、肺部感染、急性低血压、以及器官衰竭等。紧急状况预警建模主要采用病人的长时间生命体征监测数据,预测在一定时间之后发生某种紧急状况的可能性。预警模型所采用的监测数据分为静态数据、事件数据和时间序列数据等三类。静态数据具有容易采集、但预测准确性偏低的特点。事件数据或时间序列数据、以及多种类型数据的混合数据对于紧急状况预警模型的预测性能的提高有重要作用,将会获得更广泛的应用。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号