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   329755篇
  免费   24879篇
  国内免费   15099篇
电工技术   39459篇
技术理论   28篇
综合类   34675篇
化学工业   18689篇
金属工艺   12393篇
机械仪表   31136篇
建筑科学   45310篇
矿业工程   12286篇
能源动力   10686篇
轻工业   9424篇
水利工程   9684篇
石油天然气   10290篇
武器工业   5018篇
无线电   27903篇
一般工业技术   23310篇
冶金工业   9248篇
原子能技术   2858篇
自动化技术   67336篇
  2024年   534篇
  2023年   2958篇
  2022年   5286篇
  2021年   7104篇
  2020年   7698篇
  2019年   5733篇
  2018年   5387篇
  2017年   7426篇
  2016年   8800篇
  2015年   10123篇
  2014年   21784篇
  2013年   17958篇
  2012年   24033篇
  2011年   25769篇
  2010年   20396篇
  2009年   20710篇
  2008年   20157篇
  2007年   25285篇
  2006年   22204篇
  2005年   19816篇
  2004年   16105篇
  2003年   14754篇
  2002年   11345篇
  2001年   9513篇
  2000年   7766篇
  1999年   6185篇
  1998年   4731篇
  1997年   3875篇
  1996年   3434篇
  1995年   2878篇
  1994年   2369篇
  1993年   1614篇
  1992年   1330篇
  1991年   1005篇
  1990年   761篇
  1989年   671篇
  1988年   487篇
  1987年   306篇
  1986年   183篇
  1985年   207篇
  1984年   214篇
  1983年   164篇
  1982年   156篇
  1981年   92篇
  1980年   82篇
  1979年   63篇
  1978年   46篇
  1977年   37篇
  1976年   26篇
  1959年   30篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
92.
Solid oxide fuel cell (SOFC) systems with anode off-gas recirculation (AGR) and diesel pre-reforming are advantageous because they can operate with the current fuel infrastructure. In the SchIBZ-project, the prototype of such a SOFC system for maritime applications has already been commissioned. In this first paper, we model the system devices to conduct an exergy analysis of this real SOFC plant and validate them with experimental values from experiments in laboratory scale. The results of our simulation agree well with the experimental values. The calculations with the validated results may be closer to the real thermodynamic behavior of such system components than previous literature.  相似文献   
93.
绿色住区设计是建设宜居城市和实现节能减排目标的重要手段与方法。文章首先回顾绿色住区参数化优化设计方法及平台概况,在此基础上,重点介绍平面生成、噪声计算、通风计算、可视度计算等新增功能和天空遮挡算法升级,以及广州市的工程应用,最后展望平台研发与应用的未来发展方向。  相似文献   
94.
Abstract

In recent years, to prevent accidents and disaster are desired by implementing maintenance and management of facilities, such as conducting periodic inspections with appropriate frequency at plants. However, because the dangerous materials such as flammable gas and explosives is used in a plant, and there are many dangerous places in a plant such as high-temperature environment and high places and narrow spaces, it is desirable to use a remote-controlled robot for safety work and short inspections. Against this background, the Disaster Robotics Category-Plant Disaster Prevention Challenge was held in Japan at the World Robot Summit 2018. Our team was ranked 3rd in this competition, because our strategy of ‘inspection and investigation in cooperation with UGV and UAV’ was effective. In this paper, the competition contents of World Robot Summit 2018 and the robot inspection system that we are studying are explained. And what kind of strategy was challenged and result for these given competition tasks by using our robot system are introduced. And the lessons learned such as advantages and issues in UGV and UAV collaboration work at this competition are described for evaluate a robot investigation system for disaster response and inspection work at plants.  相似文献   
95.
96.
基于微电子机械系统(MEMS)工艺,提出一种多层圆片堆叠的THz硅微波导结构及其制作方法。为了验证该结构在制作THz无源器件中的优势,基于6层圆片堆叠的硅微波导结构,设计了一种中心频率365 GHz、带宽80 GHz的功率分配/合成结构,并对其进行了仿真。研究了制作该结构的工艺流程,攻克了工艺过程中的关键技术,包括硅深槽刻蚀技术和多层热压键合技术,并给出了工艺结果。最终实现了多层圆片堆叠功率分配/合成结构的工艺制作和测试。测试结果表明,尽管样品的插入损耗较仿真值增加3 dB左右,考虑到加工误差和夹具损耗等情况,样品主要技术指标与设计值较为一致。  相似文献   
97.
98.
Recent advances in the field of flow cytometry (FCM) have highlighted the importance of incorporating it as a basic analysis tool in laboratories. FCM not only allows the identification of cell subpopulations by detecting the expression of molecules in the cell membrane or cytoplasm, but it can also quantify and identify soluble molecules. The proper functioning of the FCM requires six fundamental systems, from those related to the transport of events to the systems dedicated to the analysis of information. In this review, we have identified the main considerations that every FCM user must know for an optimal antibody panel design, the quality systems that must govern the FCM protocols to guarantee reproducible results in research or clinical laboratories. Finally, we have introduced the current evidence that highlights the relevance of FCM in the investigation and clinical diagnosis of respiratory diseases, establishing important advances in the basic and clinical study of diseases as old as Tuberculosis along with the recent proposals for the monitoring and classification of patients infected with the new SARS-CoV2 virus.  相似文献   
99.
This paper proposes an adaptive super-twisting decoupled terminal sliding mode control technique for a class of fourth-order systems. The adaptive-tuning law eliminates the requirement of the knowledge about the upper bounds of external perturbations. Using the proposed control procedure, the state variables of cart-pole system are converged to decoupled terminal sliding surfaces and their equilibrium points in the finite time. Moreover, via the super-twisting algorithm, the chattering phenomenon is avoided without affecting the control performance. The numerical results demonstrate the high stabilization accuracy and lower performance indices values of the suggested method over the other ones. The simulation results on the cart-pole system as well as experimental validations demonstrate that the proposed control technique exhibits a reasonable performance in comparison with the other methods.  相似文献   
100.
Water hyacinth was the chosen alternative biomass for H2 production in this study. A batch and a continuous pilot plant systems are proposed. A batch system of 500?ml capacity was developed first for finding an appropriate biomass ratio which was found to be 2.5%wt. Results from the batch system was used to construct a kinetic model of water hyacinth hydrolysis. The same biomass and water ratio was used in the continuous system. Besides water hyacinth, glucose and cellulose?+?lignin biomasses were tested. During processing, temperature, pressure, and electric consumption of the system were recorded. The quality and quantity of gas products were analyzed by gas chromatography (GC). The water hyacinth biomass attained the highest rate of H2 production (providing energy of 11.43?kWh/mole of glucose). Comparing the batch and continuous pilot systems, the continuous system achieved 2.7 times more H2 mole% than the batch system did.  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