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   155597篇
  免费   15351篇
  国内免费   9225篇
电工技术   12156篇
技术理论   3篇
综合类   12340篇
化学工业   22587篇
金属工艺   9941篇
机械仪表   10805篇
建筑科学   12245篇
矿业工程   5105篇
能源动力   4489篇
轻工业   10291篇
水利工程   3656篇
石油天然气   7766篇
武器工业   1877篇
无线电   18542篇
一般工业技术   16388篇
冶金工业   6881篇
原子能技术   1888篇
自动化技术   23213篇
  2024年   637篇
  2023年   2025篇
  2022年   4361篇
  2021年   6092篇
  2020年   4579篇
  2019年   3657篇
  2018年   4073篇
  2017年   4825篇
  2016年   4516篇
  2015年   6630篇
  2014年   8223篇
  2013年   9695篇
  2012年   11622篇
  2011年   12281篇
  2010年   11569篇
  2009年   11281篇
  2008年   10925篇
  2007年   10468篇
  2006年   9593篇
  2005年   8067篇
  2004年   5800篇
  2003年   5089篇
  2002年   5081篇
  2001年   4454篇
  2000年   3178篇
  1999年   2678篇
  1998年   1656篇
  1997年   1475篇
  1996年   1263篇
  1995年   1005篇
  1994年   810篇
  1993年   579篇
  1992年   437篇
  1991年   349篇
  1990年   287篇
  1989年   239篇
  1988年   175篇
  1987年   121篇
  1986年   99篇
  1985年   41篇
  1984年   46篇
  1983年   26篇
  1982年   33篇
  1981年   24篇
  1980年   28篇
  1979年   13篇
  1978年   10篇
  1976年   7篇
  1959年   10篇
  1951年   16篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
时尚与传统交织的当下,我们已经迎来12年一遇的传统农历新年--金猪年的到来,环顾大街小巷,到处都充满了喜气祥和的节日气氛,采购礼品也被提上了日程.  相似文献   
62.
StructureandMagneticPropertiesofLaCo_(13-X)M_XIntermetallicCompoundsWUJianMin;LIFeng;TAILiChiandZHEMGQunStructureandMagneticP...  相似文献   
63.
Centralized and distributed automated guided vehicle system (AGVS) models for materials handling, and the model for part processing are integrated into a single coherent model. This formulation can be used to collectively schedule and control the entire flexible manufacturing system (FMS) as opposed to the traditional separate scheduling of part processing and material handling. The two AGVS models are based on Petri nets and can be directly used in the scheduling method that uses Petri nets for formulation and heuristic search for solution. This method employs a global search to seek the optimal operation of an entire FMS. Scheduling examples are presented and the method compares favorably with the results simulated using heuristic dispatch rules  相似文献   
64.
Two new methods are proposed to implement the exclusive-OR and exclusive-NOR functions on the transistor level. The first method uses non-complementary signal inputs and the least number of transistors. The other one improves the performance of the prior method but two more transistors are utilized. Both of them have been fully simulated by HSPICE on a SUN SPARC 2 workstation  相似文献   
65.
A powerful concept to cope with resource limitations and information redundancy in wireless sensor networks is the use of collaboration groups to distill information within the network and suppress unnecessary activities. When the phenomena to be monitored have large geographical extents, it is not obvious how to define these collaboration groups. This article presents the application of geometric duality to form such groups for sensor selection and non-local phenomena tracking. Using a dual-space transformation, which maps a non-local phenomenon (e.g., the edge of a half-plane shadow) to a single point in the dual space and maps locations of distributed sensor nodes to a set of lines that partitions the dual space, one can turn off the majority of the sensors to achieve resource preservation without losing detection and tracking accuracy. Since the group so defined may consist of nodes that are far away in physical space, we propose a hierarchical architecture that uses a small number of computationally powerful nodes and a massive number of power constrained motes. By taking advantage of the continuity of physical phenomena and the duality principle, we can greatly reduce the power consumption in non-local phenomena tracking and extend the lifetime of the network.  相似文献   
66.
坐标旋转法的收敛性,误差估计及扩展   总被引:1,自引:0,他引:1  
本文通过推广正规序列的定义,得到一个不等式,由此证明了统一计算初等函数数值的坐标旋转法的收敛性,作了误差估计,并拓广了所计算的函数范围,成为快速计算所有初等函数的统一算法.  相似文献   
67.
Brambilla  G. Xu  F. Feng  X. 《Electronics letters》2006,42(9):517-519
It is demonstrated for the first time that long nanowires with radii as small as 30 nm can be manufactured with a conventional coupler fabrication rig. The temporal deterioration of nanowire optical properties has been studied and correlated with its mechanical behaviour. The original transmission properties have been restored by a post-fabrication treatment.  相似文献   
68.
潘峰 《中国煤炭》2006,32(4):70-70,73
介绍了平煤集团围绕以人为本的理念开展的提升理念、创新管理、加大投入和提高员工素质等一系列安全活动,为进一步抓好安全生产打下了坚实基础。  相似文献   
69.
70.
Parametric interpolation has many advantages over linear interpolation in machining curves. Real time parametric interpolation research so far has addressed achieving a uniform feed rate, confined chord errors and jerk limited trajectory planning. However, simultaneous consideration of confined chord errors that respect the acceleration and deceleration capabilities of the machine has not been attempted. In this paper, the offline detection of feed rate sensitive corners is proposed. The velocity profile in these zones is planned so that chord errors are satisfied while simultaneously accommodating the machine's acceleration and deceleration limits. Outside the zone of the feed rate sensitive corners, the feed rate is planned using the Taylor approximation. Simulation results indicate that the offline detection of feed rate sensitive corners improves parametric interpolation. For real time interpolation, the parametric curve information can be augmented with the detected feed rate sensitive corners that are stored in 2×2 matrices.  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