首页 | 官方网站   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   1216篇
  国内免费   40篇
  完全免费   204篇
工业技术   1460篇
  2020年   4篇
  2019年   9篇
  2018年   11篇
  2017年   18篇
  2016年   20篇
  2015年   39篇
  2014年   45篇
  2013年   44篇
  2012年   74篇
  2011年   89篇
  2010年   65篇
  2009年   88篇
  2008年   106篇
  2007年   115篇
  2006年   111篇
  2005年   105篇
  2004年   69篇
  2003年   63篇
  2002年   52篇
  2001年   56篇
  2000年   58篇
  1999年   32篇
  1998年   37篇
  1997年   27篇
  1996年   32篇
  1995年   17篇
  1994年   20篇
  1993年   6篇
  1992年   18篇
  1991年   6篇
  1990年   4篇
  1989年   7篇
  1988年   5篇
  1987年   4篇
  1986年   2篇
  1985年   1篇
  1979年   1篇
排序方式: 共有1460条查询结果,搜索用时 46 毫秒
1.
用非均匀B样条曲线优化设计凸轮廓线   总被引:1,自引:0,他引:1  
利用三次非均匀B样务曲线设计光顺凸轮廓线,使加速度曲线光滑,廓线便于控制和修正。对设计方法进行了推导,给出了设计实例。  相似文献   
2.
弧焊机器人空间焊缝定位系统的研究   总被引:3,自引:0,他引:3  
杨培  徐滨士  吴林 《应用激光》2005,25(5):319-321
建立了基于激光立体视觉的空间焊缝定位系统,使带有离线编程系统的弧焊机器人可以适应批量生产中每次焊缝位置的变化。利用激光视觉传感器获取空间焊缝特征点的机器人基坐标系坐标,用B样条曲线拟合测量点。可以快速实现空间焊缝的精确定位。  相似文献   
3.
用B样条函数对S形弯曲波导进行结构优化   总被引:2,自引:0,他引:2  
张冰娜  朱大庆  雷伟  曾四化 《中国激光》2004,31(11):312-1316
S形弯曲波导是集成光器件中不可缺少的部分。在光开关阵列、星形耦合器以及阵列波导光栅等器件中。以及将多个元件集成到一个芯片上时,都需要很多的S形弯曲波导来实现波导的侧向位移和连接。其尺寸和损耗直接影响整个器件的损耗以及集成密度。弯曲波导插入损耗(不包括由于结构缺陷而产生的光的散射损耗)由两部分组成:纯弯曲损耗和过渡损耗。从弯曲损耗产生的机理人手,提出用B样条泛函逼近理论实现任意边界条件下S形的优化方法,得到纯弯曲损耗尽可能小,并消除与直波导相连处过渡损耗的S形波导。且与正弦、余弦和双圆弧曲线得到的S形进行对比,用光束传播法验证。结果表明优化曲线插入损耗明显小于双圆弧和余弦曲线。  相似文献   
4.
无刷直流电机调速系统模糊神经网络控制新方法   总被引:8,自引:1,他引:7  
在分析无刷直流电机(BLDCM)数学模型的基础上建立控制系统的仿真模型,提出了用基本样条函数实现BLDCM模糊神经网络速度控制器设计的新方法。在dSPACE环境中构建了BLDCM控制系统硬件,进行了基本样条模糊神经网络调速系统的实时控制实验。结果表明,该方法响应快、超调小、鲁棒性强,动、静态特性均优于传统PI控制。  相似文献   
5.
Three-dimensional (3D) anthropometry based on the laser scanning technique not only provides one-dimensional measurements calculated in accordance with the landmarks which are pre-located on the human body surface manually, but also the 3D shape information between the landmarks. This new technique used in recent ergonomic research has brought new challenges to resolving the application problem that was generally avoided by anthropometric experts in their researches. The current research problem is concentrating on how to shift and develop one-dimensional measurements (1D landmarks) into three-dimensional measurements (3D land-surfaces). The main purpose of this paper is to test whether the function of B-splines can be used to fit 3D scanned human heads, and to for further study to develop a computer aided ergonomic design tool (CAED). The result shows that B-splines surfaces can effectively reconstruct 3D human heads based on the laser scanning technique.  相似文献   
6.
目的计算并分析机载短波天线激励机身表面近场的分布.方法用B样条方法进行飞机的整体计算机建模,并模拟其机载的短波天线,用时域有限差分法完成短波天线激励机身表面近场的分析计算.结果得到了位于机身表面样点的近场分布,以曲线及飞机轴向纵剖面的场分布灰度图的形式表示.结论在这种建模方法下,分析所得结果符合机载天线理论,它可为机载短波天线阻抗特性、远场方向图的研究,以及短波通信设备对其它机载电子设备干扰问题的分析提供基础及依据,这种研究对飞机的电磁兼容分析和设计有重要意义.  相似文献   
7.
Reverse engineering is an approach for constructing a CAD model from a physical part through dimensional measurement and surface model. For sheetmetal parts, when removed from dies after forming, are subject to springback due the resultant in-plane forces and moments throughout the sheet at the end of the forming processing. Therefore, springback should be compensated for integrating reverse engineering into the system of forming sheet metal with a complex surface. However, CAD modelling from measured points data is a roadblock to the automation of the duplication procedure. The difficulties here arise from surfaces fitting to measured points, which is well-known to be time-consuming. To avoid the roadblock, based on the convex hull property of B-spline, a new strategy for direct generation of die shapes from digitized points with springback compensation is presented in this paper. The proposed algorithm has been applied to a part of complicated geometry with good results.  相似文献   
8.
An algorithm of NURBS surface fitting for reverse engineering   总被引:3,自引:0,他引:3  
Reverse engineering is an approach for constructing a CAD model from a physical part through dimensional measurement and a surface model. Different from conventional methods, this paper develops a new algorithm by which a desired fitted surface is obtained with less computation. Let selected m×n measured points be control points to construct B-spline or NURBS surface, then modify this constructed surface by using all the measured points and least squares minimization. A new algorithm for parameterization for measured points is also presented in this paper. The effectiveness and efficiency of these proposed algorithms are demonstrated.  相似文献   
9.
This paper presents a non-uniform, periodic closed B-spline approximation algorithm for the fabrication of a medical pelvic model, based on rapid prototyping, and also gives the finite element evaluation of the pelvic model. Rapid prototyping (RP), when used in fabricating medical prosthesis, has a strict requirement for closeness and impermeability of STL files. Incorrect data structure in STL files will cause the subsequent slicing process not to proceed. The non-uniform periodic closed B-spline curve approximation method was applied to processing CT data. The precision and size of STL files was improved to optimize the RP model of the pelvis. Finally, the model of the pelvis was evaluated with the finite element method. Results suggest that a high similarity has been achieved in terms of shape, size and biomechanical properties of the pelvic model and the normal one, which validates our argument that rapid prototyping with non-uniform, periodic closed B-spline algorithm is suitable for the fabrication of a pelvic model, which will prove to be significant in the design of pelvic prostheses .  相似文献   
10.
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-23

京公网安备 11010802026262号