全文获取类型
收费全文 | 6232篇 |
免费 | 585篇 |
国内免费 | 538篇 |
专业分类
电工技术 | 596篇 |
综合类 | 764篇 |
化学工业 | 67篇 |
金属工艺 | 147篇 |
机械仪表 | 530篇 |
建筑科学 | 139篇 |
矿业工程 | 100篇 |
能源动力 | 24篇 |
轻工业 | 40篇 |
水利工程 | 39篇 |
石油天然气 | 65篇 |
武器工业 | 53篇 |
无线电 | 1275篇 |
一般工业技术 | 274篇 |
冶金工业 | 69篇 |
原子能技术 | 55篇 |
自动化技术 | 3118篇 |
出版年
2024年 | 9篇 |
2023年 | 29篇 |
2022年 | 62篇 |
2021年 | 79篇 |
2020年 | 88篇 |
2019年 | 92篇 |
2018年 | 71篇 |
2017年 | 117篇 |
2016年 | 170篇 |
2015年 | 229篇 |
2014年 | 377篇 |
2013年 | 366篇 |
2012年 | 523篇 |
2011年 | 576篇 |
2010年 | 423篇 |
2009年 | 400篇 |
2008年 | 509篇 |
2007年 | 532篇 |
2006年 | 481篇 |
2005年 | 478篇 |
2004年 | 365篇 |
2003年 | 331篇 |
2002年 | 223篇 |
2001年 | 179篇 |
2000年 | 159篇 |
1999年 | 109篇 |
1998年 | 62篇 |
1997年 | 64篇 |
1996年 | 40篇 |
1995年 | 45篇 |
1994年 | 30篇 |
1993年 | 29篇 |
1992年 | 20篇 |
1991年 | 16篇 |
1990年 | 10篇 |
1989年 | 4篇 |
1988年 | 9篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 7篇 |
1980年 | 6篇 |
1977年 | 4篇 |
1975年 | 3篇 |
1973年 | 4篇 |
1961年 | 2篇 |
1960年 | 1篇 |
1958年 | 1篇 |
1955年 | 2篇 |
排序方式: 共有7355条查询结果,搜索用时 46 毫秒
1.
Train driving is a highly visual task. The visual capabilities of the train driver affects driving safety and driving performance. Understanding the effects of train speed and background image complexity on the visual behavior of the high-speed train driver is essential for optimizing performance and safety. This study investigated the role of the apparent image velocity and complexity on the dynamic visual field of drivers. Participants in a repeated-measures experiment drove a train at nine different speeds in a state-of-the-art high-speed train simulator. Eye movement analysis indicated that the effect of image velocity on the dynamic visual field of high-speed train driver was significant while image complexity had no effect on it. The fixation range was increasingly concentrated on the middle of the track as the speed increased, meanwhile there was a logarithmic decline in fixation range for areas surrounding the track. The extent of the visual search field decreased gradually, both vertically and horizontally, as the speed of train increased, and the rate of decrease was more rapid in the vertical direction. A model is proposed that predicts the extent of this tunnel vision phenomenon as a function of the train speed.Relevance to industryThis finding can be used as a basis for the design of high-speed railway system and as a foundation for improving the operational procedures of high-speed train driver for safety. 相似文献
2.
1-read/1-write (1R1W) register file (RF) is a popular memory configuration in modern feature rich SoCs requiring significant amount of embedded memory. A memory compiler is constructed using the 8T RF bitcell spanning a range of instances from 32 b to 72 Kb. An 8T low-leakage bitcell of 0.106 μm2 is used in a 14 nm FinFET technology with a 70 nm contacted gate pitch for high-density (HD) two-port (TP) RF memory compiler which achieves 5.66 Mb/mm2 array density for a 72 Kb array which is the highest reported density in 14 nm FinFET technology. The density improvement is achieved by using techniques such as leaf-cell optimization (eliminating transistors), better architectural planning, top level connectivity through leaf-cell abutment and minimizing the number of unique leaf-cells. These techniques are fully compatible with memory compiler usage over the required span. Leakage power is minimized by using power-switches without degrading the density mentioned above. Self-induced supply voltage collapse technique is applied for write and a four stack static keeper is used for read Vmin improvement. Fabricated test chips using 14 nm process have demonstrated 2.33 GHz performance at 1.1 V/25 °C operation. Overall Vmin of 550 mV is achieved with this design at 25 °C. The inbuilt power-switch improves leakage power by 12x in simulation. Approximately 8% die area of a leading 14 nm SoC in commercialization is occupied by these compiled RF instances. 相似文献
3.
文章针对使用USB存储设备造成的内部泄密问题,提出了一种USB存储设备访问控制方案,该方案对用户的身份认证基于安全强度很高的椭圆曲线数字签名算法,同时使用过滤器驱动程序实现了USB存储设备的读写控制,因而此方案具有较好的安全性、实用性和通用性。 相似文献
4.
介绍了Freescale公司嵌入式微处理器MCF5282的原理、特点,给出了该处理器在嵌入式操作系统uClinux下通过I2C硬件扩展数字输入的原理,以及I2C总线的驱动程序设计流程. 相似文献
5.
文章介绍了在windows2000环境下通过编写WDM(Windows Driver Model)设备驱动程序实现实时数据采集和控制的一种方法。采用研华数据采集卡PCL818L产生中断信号.通过编写WDM驱动程序实现了在windows2000环境下转台的位置控制。并在实验中调试通过。实验结果表明:在采样频率为1KHz的情况下。控制系统很好实现了输出对输入的跟踪,证明了采用方法的正确性。该方法解决了windows2000环境下的实时性问题,为在windows环境下实时控制系统的实现提供了有益的尝试。 相似文献
6.
在双光束激光直写系统中,衍射光变图像的光刻是逐像素点进行的.本文提出在该系统中采用狭缝获得光栅线来进行衍射图形的直写,利用一种改进的矢量文件格式,使平台沿着垂直光栅线的方向运动,获得连续的多光点同时直写,直写后的衍射光栅线是连续的,系统的运行效率是逐点光刻的几十倍.编写了与DXF文件的接口直写控制程序,给出了实验结果. 相似文献
7.
8.
本文中所设计的电荷泵将用于手机液晶显示驱动模块中.通过对Fibonacci型电荷泵上升时间的估算,对减小上升时间和动态功耗进行折中考虑,本文提出优化开关频率的方法.用1.2μm CMOS双阱工艺参数对所设计的电荷泵进行模拟,结果表明这个电荷泵具有较快的上升速度和较高的效率.通过提高VGS电平和保证开关管的衬底始终接在最高电位上,文中提出了一种新型Fibonacci电荷泵,它可以正常工作在从1.2V到5V变化的多种电源电压下. 相似文献
9.
Technology can take many forms from the development of sophisticated electronics to the application of basic procedural principles. Technology transfer can also take several forms, however, in this case, it is the transfer of technological principles between application domains that is of primary interest. This paper presents a framework (the Five ‘M’s framework) that can be used to consider the likely success of technology transfer. The framework is based upon a sociotechnical system approach. The framework is illustrated with an evaluation of the introduction of intelligent cruise control into motor vehicles. It is argued that this is a technological concept first developed as an aerospace application in the form of the autopilot. In this case, it is argued that the transfer of this technology in its current form may potentially compromise safety. 相似文献
10.
IR2520是自适应镇流器控制器与600V半桥驱动器单片IC ,可用来驱动半桥配置中的荧光灯。文中介绍了IR2520的主要特点和基本原理 ,给出了它的典型应用电路。 相似文献