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   7809篇
  免费   601篇
  国内免费   249篇
电工技术   448篇
技术理论   1篇
综合类   509篇
化学工业   1301篇
金属工艺   331篇
机械仪表   411篇
建筑科学   523篇
矿业工程   210篇
能源动力   229篇
轻工业   713篇
水利工程   139篇
石油天然气   465篇
武器工业   58篇
无线电   697篇
一般工业技术   943篇
冶金工业   646篇
原子能技术   83篇
自动化技术   952篇
  2024年   33篇
  2023年   120篇
  2022年   199篇
  2021年   297篇
  2020年   216篇
  2019年   193篇
  2018年   243篇
  2017年   255篇
  2016年   232篇
  2015年   292篇
  2014年   393篇
  2013年   493篇
  2012年   488篇
  2011年   543篇
  2010年   440篇
  2009年   405篇
  2008年   426篇
  2007年   407篇
  2006年   419篇
  2005年   311篇
  2004年   235篇
  2003年   209篇
  2002年   191篇
  2001年   202篇
  2000年   169篇
  1999年   182篇
  1998年   260篇
  1997年   186篇
  1996年   127篇
  1995年   106篇
  1994年   90篇
  1993年   65篇
  1992年   38篇
  1991年   28篇
  1990年   19篇
  1989年   20篇
  1988年   21篇
  1987年   13篇
  1986年   10篇
  1985年   7篇
  1984年   3篇
  1983年   10篇
  1982年   9篇
  1980年   3篇
  1979年   6篇
  1978年   3篇
  1977年   10篇
  1976年   11篇
  1974年   3篇
  1959年   7篇
排序方式: 共有8659条查询结果,搜索用时 15 毫秒
71.
In this paper, the design of a low‐power 512‐bit synchronous EEPROM for a passive UHF RFID tag chip is presented. We apply low‐power schemes, such as dual power supply voltage (VDD=1.5 V and VDDP=2.5 V), clocked inverter sensing, voltage‐up converter, I/O interface, and Dickson charge pump using Schottky diode. An EEPROM is fabricated with the 0.25 μm EEPROM process. Power dissipation is 32.78 μW in the read cycle and 78.05 μW in the write cycle. The layout size is 449.3 μm × 480.67 μm.  相似文献   
72.
A video signal through a high‐density optical link has been demonstrated to show the reliability of optical link for high‐data‐rate transmission. To reduce optical point‐to‐point links, an electrical link has been utilized for control and clock signaling. The latency and flicker with background noise occurred during the transferring of data across the optical link due to electrical‐to‐optical with optical‐to‐electrical conversions. The proposed synchronization technology combined with a flicker and denoising algorithm has given good results and can be applied in high‐definition serial data interface (HD‐SDI), ultra‐HD‐SDI, and HD multimedia interface transmission system applications.  相似文献   
73.
This paper presents a detailed analysis of some classes of stable multivariate polynomials. The main aim of the analysis is to give conditions under which polynomials preserve stability when they are subjected to small coefficient variations. The maximal class of such polynomials is introduced. Some basic properties of polynomials from this class are obtained.  相似文献   
74.
针对当前分割方法不能兼顾可见光与近红外光谱的异质噪声虹膜图像的分割精度与效率问题,提出一种基于注意力机制与密集多尺度特征融合的编-解码网络.首先,引入基于深度可分离卷积的改进残差瓶颈单元,降低参数量与计算量的同时防止信息丢失与梯度混淆;其次,改进密集空洞空间金字塔模块的空洞率组合并放置于编码器后,以增强多尺度特征融合;...  相似文献   
75.
简述了在AVR单片机上移植的uCOS-II嵌入式操作系统中关于中断处理的一种方法。主要应用在对实时性要求非常之高的场合中,采用软件手段实现的嵌套可以保证关键中断得到及时的响应。  相似文献   
76.
某型导弹接收机在进行温度循环高温试验时发生故障,经过排查定位为所使用的机械滤波器失效,即滤波器高温时输出端绝缘电阻降低。该文通过对机械滤波器封装结构、工艺制造流程等方面进行分析,得出机械滤波器的失效原因,并通过有效措施控制该器件失效问题再次发生,有效提高了该器件质量的可靠性。  相似文献   
77.
随着互联网技术的迅猛发展,互联网金融应运而生,构成国家经济积极发展的重要组成部分,而互联网金融风险问题亟待解决。文章根据传统金融的风险特点,建立互联网金融风险二级指标,基于模糊层次分析法构建模型,对互联网金融风险进行定量分析评估。实证结果显示互联网金融信用风险和运营风险为主要风险,为未来风险防控和风险监管提供了参考依据。  相似文献   
78.
Organometal perovskite single crystals have been recognized as a promising platform for high-performance optoelectronic devices, featuring high crystallinity and stability. However, a high trap density and structural nonuniformity at the surface have been major barriers to the progress of single crystal-based optoelectronic devices. Here, the formation of a unique nanoisland structure is reported at the surface of the facet-controlled cuboid MAPbI3 (MA = CH3NH3+) single crystals through a cation interdiffusion process enabled by energetically vaporized CsI. The interdiffusion of mobile ions between the bulk and the surface is triggered by thermally activated CsI vapor, which reconstructs the surface that is rich in MA and CsI with reduced dangling bonds. Simultaneously, an array of Cs-Pb-rich nanoislands is constructed on the surface of the MAPbI3 single crystals. This newly reconstructed nanoisland surface enhances the light absorbance over 50% and increases the charge carrier mobility from 56 to 93 cm2 V−1 s−1. As confirmed by Kelvin probe force microscopy, the nanoislands form a gradient band bending that prevents recombination of excess carriers, and thus, enhances lateral carrier transport properties. This unique engineering of the single crystal surface provides a pathway towards developing high-quality perovskite single-crystal surface for optoelectronic applications.  相似文献   
79.
K-metal batteries have become one of the promising candidates for the large-scale energy storage owing to the virtually inexhaustible and widely potassium resources. The uneven K+ deposition and dendrite growth on the anode causes the batteries prematurely failure to limit the further application. An integrated K-metal anode is constructed by cold-rolling K metal with a potassiphilic porous interconnected mediator. Based on the experimental results and theoretical calculations, it demonstrates that the potassiphilic porous interconnected mediator boosts the mass transportation of K-metal anode by the K affinity enhancement, which decreases the concentration polarization and makes a dendrite-free K-metal anode interface. The interconnected porous structure mitigates the internal stress generated during repetitive deposition/stripping, enabling minimized the generation of electrode collapse. As a result, a durable K-metal anode with excellent cycling ability of exceed 1, 000 h at 1 mA cm−2/1 mAh cm−2 and lower polarization voltage in carbonate electrolyte is obtained. This proposed integrated anode with fast K+ kinetics fabricated by a repeated cold rolling and folding process provides a new avenue for constructing a high-performance dendrites-free anode for K-metal batteries.  相似文献   
80.
A method for measuring the frequency stability of tunable laser is proposed by using confocal Fabry-Perot(F-P)interferometer.The F-P interferometer is used to get the output frequency of the laser as a reference,and the method eliminates the need of an independent optical source as a frequency reference.Using this technique,the frequency stability of the tunable external-cavity diode laser(ECDL)is measured to be 2.26×10~(-9)with an integration time of 20 ms.  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