全文获取类型
收费全文 | 1251篇 |
免费 | 47篇 |
专业分类
电工技术 | 28篇 |
综合类 | 2篇 |
化学工业 | 172篇 |
金属工艺 | 19篇 |
机械仪表 | 28篇 |
建筑科学 | 45篇 |
矿业工程 | 1篇 |
能源动力 | 39篇 |
轻工业 | 123篇 |
水利工程 | 12篇 |
石油天然气 | 1篇 |
无线电 | 111篇 |
一般工业技术 | 210篇 |
冶金工业 | 339篇 |
原子能技术 | 32篇 |
自动化技术 | 136篇 |
出版年
2023年 | 5篇 |
2022年 | 12篇 |
2021年 | 18篇 |
2020年 | 9篇 |
2019年 | 16篇 |
2018年 | 30篇 |
2017年 | 18篇 |
2016年 | 30篇 |
2015年 | 20篇 |
2014年 | 31篇 |
2013年 | 68篇 |
2012年 | 58篇 |
2011年 | 61篇 |
2010年 | 50篇 |
2009年 | 52篇 |
2008年 | 64篇 |
2007年 | 70篇 |
2006年 | 33篇 |
2005年 | 42篇 |
2004年 | 25篇 |
2003年 | 17篇 |
2002年 | 20篇 |
2001年 | 16篇 |
2000年 | 20篇 |
1999年 | 31篇 |
1998年 | 108篇 |
1997年 | 51篇 |
1996年 | 39篇 |
1995年 | 27篇 |
1994年 | 32篇 |
1993年 | 22篇 |
1992年 | 8篇 |
1991年 | 9篇 |
1990年 | 16篇 |
1989年 | 12篇 |
1988年 | 13篇 |
1987年 | 12篇 |
1986年 | 14篇 |
1985年 | 21篇 |
1984年 | 5篇 |
1983年 | 7篇 |
1982年 | 10篇 |
1981年 | 6篇 |
1980年 | 11篇 |
1978年 | 5篇 |
1977年 | 11篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1972年 | 3篇 |
1967年 | 3篇 |
排序方式: 共有1298条查询结果,搜索用时 15 毫秒
1.
Cogburn D.L. Mueller M. McKnight L. Klein H. Mathiason J. 《Communications Magazine, IEEE》2005,43(12):12-14
Who should control the Internet? A dozen years after the Internet became a mass medium, this issue has continued to grow in urgency, becoming white hot in fall 2005. At the September 2005 preparatory meeting for the UN World Summit on the Information Society (WSIS), a coalition of countries criticized the United States' unilateral control of the Internet's domain name system (DNS) and proposed the establishment of a multinational Council to supervise it. This proposal emerged from the Final Report of the UN Working Group on Internet Governance. Researchers from the Internet Governance Project, a university-based consortium for policy analysis, have concluded that the United States should internationalize governance of the Internet, but in a way that avoids intrusive, centralized control. 相似文献
2.
Tear cytokines and growth factors are likely to modulate the wound healing process following corneal epithelial injury. Hepatocyte growth factor (HGF) is a paracrine mediator of epithelial proliferation, motility, and differentiation that is produced by keratocytes and the lacrimal gland. Tear samples were collected preoperatively and one, two, and seven days postoperatively in eyes undergoing excimer laser surface ablation [photorefractive keratoplasty (PRK) or phototherapeutic keratoplasty (PTK)]. Tear HGF concentration was measured with a sensitive ELISA assay. Tear HGF production was calculated using the tear flow rate in the collection capillary and HGF concentration. Although the instantaneous concentration of HGF in tears decreased significantly in the days following PRK, a large increase in tear flow resulted in a marked increase in HGF bioavailability. The heparin-binding characteristics of HGF would result in increased binding to glycosaminoglycans and other heparin-like matrix components and, therefore, increased growth factor availability to the cognate recptor. This is the first report documenting changes in tear film HGF production. HGF may have an important function in maintenance and wound healing of the ocular surface epithelium since HGF is present in the normal tear film and the HGF secretion rate increases markedly in parallel with aqueous tear production following corneal surgical injury. 相似文献
3.
4.
Understanding how the structure of the unit-cell affects the cryogenic performance of a Si power Metal Oxide Semiconductor Field Effect Transistor (MOSFET) is an important step toward optimizing of the device for cryogenic operations. In this paper, numerical simulations of the Si power Double Diffused MOSFET’ (DMOS) are performed at room temperature and cryogenic temperatures. Physically based models for temperature dependent silicon properties are employed in the simulations. The performances of power DMOS’ with various unit-cell structures are compared at both room temperature and low temperatures. The effect of the cell structure on the on-resistance and breakdown voltage of the device are analyzed. The simulation results suggest that the device optimized for room temperature operation can be further optimized at cryogenic temperatures. 相似文献
5.
6.
Mueller C. Sullivan C. Chang W. Hall D. Zino J. Rice R. 《Quantum Electronics, IEEE Journal of》1980,16(3):363-372
Calculated butt coupling efficiency between a GaAlAs double heterostructure laser and a single-mode LiNbO3 Ti-diffused optical waveguide is presented in this paper as a function of the transverse displacement, the angular alignment, the longitudinal separation between the laser and the waveguide end surfaces, the radiation field of the laser diode and its dependence on the laser diode structure, and the mode profile of the waveguide and its dependence on experimental diffusion parameters. The maximum efficiency is less than 40 percent because of the mismatch between the waveguide mode and the laser radiation, caused primarily by the experimental limitations in their structures. The effect of the reflection of the waveguide end surface on the laser oscillation has also been estimated. 相似文献
7.
8.
9.
10.
Gogl D. Arndt C. Barwin J.C. Bette A. DeBrosse J. Gow E. Hoenigschmid H. Lammers S. Lamorey M. Yu Lu Maffitt T. Maloney K. Obermaier W. Sturm A. Viehmann H. Willmott D. Wood M. Gallagher W.J. Mueller G. Sitaram A.R. 《Solid-State Circuits, IEEE Journal of》2005,40(4):902-908
A 16-Mb magnetic random access memory (MRAM) is demonstrated in 0.18-/spl mu/m three-Cu-level CMOS with a three-level MRAM process adder. The chip, the highest density MRAM reported to date, utilizes a 1.42/spl mu/m/sup 2/ 1-transistor 1-magnetic tunnel junction (1T1MTJ) cell, measures 79 mm/sup 2/ and features a /spl times/16 asynchronous SRAM-like interface. The paper describes the cell, architecture, and circuit techniques unique to multi-Mb MRAM design, including a novel bootstrapped write driver circuit. Hardware results are presented. 相似文献