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   18628篇
  免费   1615篇
  国内免费   873篇
电工技术   3193篇
技术理论   1篇
综合类   1226篇
化学工业   1150篇
金属工艺   840篇
机械仪表   2112篇
建筑科学   845篇
矿业工程   1225篇
能源动力   515篇
轻工业   521篇
水利工程   314篇
石油天然气   725篇
武器工业   493篇
无线电   3335篇
一般工业技术   1322篇
冶金工业   785篇
原子能技术   231篇
自动化技术   2283篇
  2024年   75篇
  2023年   186篇
  2022年   381篇
  2021年   501篇
  2020年   572篇
  2019年   380篇
  2018年   317篇
  2017年   513篇
  2016年   634篇
  2015年   711篇
  2014年   1393篇
  2013年   1067篇
  2012年   1556篇
  2011年   1483篇
  2010年   1095篇
  2009年   1106篇
  2008年   876篇
  2007年   1212篇
  2006年   1063篇
  2005年   1005篇
  2004年   804篇
  2003年   805篇
  2002年   633篇
  2001年   540篇
  2000年   464篇
  1999年   381篇
  1998年   276篇
  1997年   213篇
  1996年   193篇
  1995年   155篇
  1994年   121篇
  1993年   94篇
  1992年   88篇
  1991年   63篇
  1990年   41篇
  1989年   36篇
  1988年   38篇
  1987年   8篇
  1986年   10篇
  1985年   5篇
  1984年   4篇
  1983年   4篇
  1982年   3篇
  1977年   1篇
  1975年   1篇
  1973年   1篇
  1962年   2篇
  1959年   2篇
  1957年   1篇
  1955年   2篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
介绍用线阵电荷耦合器件(CCD)技术设计的型材在线实时测量系统。采用粗测和精测相结合的方法,解决了较大长度范围内精确测量问题。详细介绍动态在线非接触式测控系统的基本工作原理及软硬件组成。实测结果表明其测量精度高、效果好,能满足快速流水线的现场检测。  相似文献   
92.
本文通过对液压夹轨装置结构和机理分析,指出原设计夹轨装置预留压紧量(Smax-S)不足是导致夹轨装置锁不紧的主要原因,并对相应间隙和零件进行了调整和改造,解决了拖车的锁紧问题。  相似文献   
93.
在分析PLC优缺点的基础上,提出一种利用在线可编程逻辑控制代替PLC的新技术。此外,给出了用在线可编程器件CPLD/FPGA组成的、VHDL语言实现的工件取放设备控制电路设计和程序。  相似文献   
94.
In recent years, numerous analytical and experimental researches have been performed on the prediction of thermal stresses in mass concrete structures. However, due to the difficulty of the problem, limitations still exist for both analytical and experimental methods of measuring thermal stresses in mass concrete. In this research, a new experimental device measuring thermal stresses directly in a laboratory setting is developed. The equipment is located in a temperature chamber that follows the temperature history, which has been previously obtained from temperature distribution analyses. Thermal forces are measured continuously by two load cells in the device. The results show that the thermal stresses estimated by the newly developed device agree well with general stress variations in actual structures.  相似文献   
95.
分析了橡胶制品硫化成型的对象特性,选择了硫化成型过程控制策略,研究了控制算法及其工程应用。研究结果表明,选择仿人智能控制作为硫化成型过程的控制策略时,可实现速度快、精度高的控制,且具有极强的鲁棒性。  相似文献   
96.
对化工槽车自动化洗涤装置失效及其原因进行了分析,指出洗槽机的冲洗和抽水不匹配、洗涤工艺不满足设计要求、硬件出现故障及化学品性质的影响是导致洗涤失效的主要原因,提出了完善现场流程、优化工艺操作、使用自动化控制技术、加强设备维护和保养等解决失效的措施。  相似文献   
97.
李军林 《大氮肥》1995,18(4):307-310
简要介绍模拟培训器的应用及其优越性,重点介绍渭河化肥厂模拟培训器的结构,功能,特点及应用情况,并且对培训器中存在问题进行了分析。  相似文献   
98.

Background and objective

The degeneration of the balance control system in the elderly and in many pathologies requires measuring the equilibrium conditions very often. In clinical practice, equilibrium control is commonly evaluated by using a force platform (stabilometric platform) in a clinical environment.In this paper, we demonstrate how a simple movement analysis system, based on a 3D video camera and a 3D real time model reconstruction of the human body, can be used to collect information usually recorded by a physical stabilometric platform.

Methods

The algorithm used to reconstruct the human body model as a set of spheres is described and discussed. Moreover, experimental measurements and comparisons with data collected by a physical stabilometric platform are also reported. The measurements were collected on a set of 6 healthy subjects to whom a change in equilibrium condition was stimulated by performing an equilibrium task.

Results

The experimental results showed that more than 95% of data collected by the proposed method were not significantly different from those collected by the classic platform, thus confirming the usefulness of the proposed system.

Conclusions

The proposed virtual balance assessment system can be implemented at low cost (about 500$) and, for this reason, can be considered a home use medical device. On the contrary, astabilometric platform has a cost of about 10,000$ and requires periodical calibration. The proposed system does not require periodical calibration, as is necessary for stabilometric force platforms, and it is easy to use. In future, the proposed system with little integration can be used, besides being an emulator of a stabilometric platform, also to recognize and track, in real time, head, legs, arms and trunk, that is to collect information actually obtained by sophisticated optoelectronic systems.  相似文献   
99.
Experiences applying standards in personal health devices (PHDs) show an inherent trade-off between interoperability and costs (in terms of processing load and development time). Therefore, reducing hardware and software costs as well as time-to-market is crucial for standards adoption. The ISO/IEEE11073 PHD family of standards (also referred to as X73PHD) provides interoperable communication between PHDs and aggregators. Nevertheless, the responsibility of achieving inexpensive implementations of X73PHD in limited resource microcontrollers falls directly on the developer. Hence, the authors previously presented a methodology based on patterns to implement X73-compliant PHDs into devices with low-voltage low-power constraints. That version was based on multitasking, which required additional features and resources. This paper therefore presents an event-driven evolution of the patterns-based methodology for cost-effective development of standardized PHDs. The results of comparing between the two versions showed that the mean values of decrease in memory consumption and cycles of latency are 11.59% and 45.95%, respectively. In addition, several enhancements in terms of cost-effectiveness and development time can be derived from the new version of the methodology. Therefore, the new approach could help in producing cost-effective X73-compliant PHDs, which in turn could foster the adoption of standards.  相似文献   
100.
介绍某公司引进的离子膜制碱装置采用国产DCS系统的原由,系统的结构及特点。详细论述ECS-100 DCS在装置的特殊控制、顺序控制、联锁等方面的应用情况。  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