全文获取类型
收费全文 | 2926篇 |
免费 | 89篇 |
国内免费 | 17篇 |
专业分类
电工技术 | 133篇 |
综合类 | 3篇 |
化学工业 | 380篇 |
金属工艺 | 65篇 |
机械仪表 | 53篇 |
建筑科学 | 160篇 |
矿业工程 | 10篇 |
能源动力 | 90篇 |
轻工业 | 270篇 |
水利工程 | 18篇 |
石油天然气 | 13篇 |
武器工业 | 1篇 |
无线电 | 322篇 |
一般工业技术 | 357篇 |
冶金工业 | 380篇 |
原子能技术 | 17篇 |
自动化技术 | 760篇 |
出版年
2023年 | 14篇 |
2022年 | 33篇 |
2021年 | 48篇 |
2020年 | 25篇 |
2019年 | 47篇 |
2018年 | 90篇 |
2017年 | 61篇 |
2016年 | 52篇 |
2015年 | 47篇 |
2014年 | 99篇 |
2013年 | 205篇 |
2012年 | 176篇 |
2011年 | 145篇 |
2010年 | 185篇 |
2009年 | 182篇 |
2008年 | 215篇 |
2007年 | 137篇 |
2006年 | 163篇 |
2005年 | 148篇 |
2004年 | 81篇 |
2003年 | 100篇 |
2002年 | 88篇 |
2001年 | 45篇 |
2000年 | 53篇 |
1999年 | 62篇 |
1998年 | 64篇 |
1997年 | 45篇 |
1996年 | 43篇 |
1995年 | 38篇 |
1994年 | 27篇 |
1993年 | 30篇 |
1992年 | 26篇 |
1991年 | 24篇 |
1990年 | 26篇 |
1989年 | 23篇 |
1988年 | 16篇 |
1987年 | 13篇 |
1986年 | 21篇 |
1985年 | 16篇 |
1984年 | 15篇 |
1983年 | 15篇 |
1982年 | 11篇 |
1981年 | 15篇 |
1980年 | 13篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 8篇 |
1974年 | 5篇 |
1971年 | 5篇 |
排序方式: 共有3032条查询结果,搜索用时 15 毫秒
1.
Steve Brightman 《今日电子》2008,(12)
采用WiMedia UWB标准的越来越多
WiMedia通用无线电平台是实现传输速率高达480Mb/s(更高的传输速率正在开发中)无线个人局域网(WPAN)的基础。这个平台并不局限于某一类应用,而是允许同时存在不同的协议适配层,如图1所示。WiMedia规范既规定了一些如无线USB之间相互通信的应用,也规定其他不相互通信的接口同时存在的应用。 相似文献
2.
3.
Document caching and connection caching are extensively studied problems. In document caching, one has to maintain caches
containing documents accessible in a network. In connection caching, one has to maintain a set of open network connections
that handle data transfer. Previous work investigated these two problems separately while in practice the problems occur together:
In order to load a document, one has to establish a connection between network nodes if the required connection is not already
open. In this paper we present the first study that integrates document and connection caching. We first consider a very basic
model in which all documents have the same size and the cost of loading a document or establishing a connection is equal to
1. We present deterministic and randomized online algorithms that achieve nearly optimal competitive ratios unless the size
of the connection cache is extremely small. We then consider general settings where documents have varying sizes. We investigate
a FAULT model in which the loading cost of a document is 1 as well as a BIT model in which the loading cost is equal to the
size of the document. 相似文献
4.
5.
Amit Chourasia Steve Cutchin Yifeng Cui Reagan W Moore Kim Olsen Steven M Day J Bernard Minster Philip Maechling Thomas H Jordan 《Computer Graphics and Applications, IEEE》2007,27(5):28-34
This study focuses on the visualization of a series of large earthquake simulations collectively called TeraShake. The simulation series aims to assess the impact of San Andreas Fault earthquake scenarios in Southern California. We discuss the role of visualization in gaining scientific insight and aiding unexpected discoveries. 相似文献
6.
Steve Lord 《Network Security》2003,2003(1):10-12
GSM is a series of standards defining various aspects of mobile voice and data communications. These standards provide a framework that looks set to underlie modern mobile business communications well into the 21st century. 相似文献
7.
This study explored strengths and limitations of table formatting choices by engaging twenty-eight participants in information searches in online tables, presented on a small-screen interface (Palm IIIc). Table length across conditions was held constant at three screens long (24 rows total) but varied from one to three screens wide (approximately 35, 70, and 105 characters per line). Target information was positioned in either the upper left, lower left, upper right, or lower right quadrants. Data collected were time on task, error rate, and level of participants' confidence in their answers. Experimenters found that increased horizontal scrolling imposed the heaviest burden on information search. This study supports restricting table widths to one screen on handheld computers. If necessary, however, tables can go to two screens wide without critical detriment to usability. While ruled line formatting is slightly better than interface character in providing visual support for the burden of horizontal scrolling, neither formatting option adequately compensates for the added burden. 相似文献
8.
According to enhanced interest for use of micro mechanical gear drives increased requirements occur for the transmittable
power output with at same time proceeding miniaturization. To meet these future necessities research trends lead to micro
technical parts from metal and ceramic materials. Using these materials the design of the parts has to meet restrictions of
several disciplines, predominantly manufacturing and moulding technologies.
Received: 10 August 2001/Accepted: 24 September 2001
This paper was presented at the Fourth International Workshop on High Aspect Ratio Microstructrue Technology HARMST 2001
in June 2001. 相似文献
9.
10.
This paper presents a 20-Gb/s 1:4-demultiplexer for future fiber-optic transmission systems. It uses an 0.4-μm emitter double polysilicon 21-GHz fT Si bipolar foundry process. This is the highest data rate of a 1:4-DEMUX reported so far in any technology. The 1:4-DEMUX features a tree-type architecture with one frequency divider and a channel switch circuit. The circuit design was carefully optimized to achieve high speed and moderate power dissipation. It consumes 1.4 W with a single -4.5-V supply 相似文献