全文获取类型
收费全文 | 357823篇 |
免费 | 27966篇 |
国内免费 | 15771篇 |
专业分类
电工技术 | 20898篇 |
技术理论 | 46篇 |
综合类 | 25426篇 |
化学工业 | 59721篇 |
金属工艺 | 20823篇 |
机械仪表 | 22484篇 |
建筑科学 | 27792篇 |
矿业工程 | 11687篇 |
能源动力 | 9708篇 |
轻工业 | 24053篇 |
水利工程 | 6769篇 |
石油天然气 | 23464篇 |
武器工业 | 2810篇 |
无线电 | 38807篇 |
一般工业技术 | 39398篇 |
冶金工业 | 18552篇 |
原子能技术 | 3638篇 |
自动化技术 | 45484篇 |
出版年
2024年 | 1466篇 |
2023年 | 5576篇 |
2022年 | 9891篇 |
2021年 | 13916篇 |
2020年 | 10464篇 |
2019年 | 8570篇 |
2018年 | 9865篇 |
2017年 | 11074篇 |
2016年 | 10142篇 |
2015年 | 13882篇 |
2014年 | 17472篇 |
2013年 | 20930篇 |
2012年 | 22717篇 |
2011年 | 25198篇 |
2010年 | 22265篇 |
2009年 | 21091篇 |
2008年 | 20683篇 |
2007年 | 19723篇 |
2006年 | 20084篇 |
2005年 | 17673篇 |
2004年 | 11978篇 |
2003年 | 10713篇 |
2002年 | 9906篇 |
2001年 | 8824篇 |
2000年 | 8780篇 |
1999年 | 9409篇 |
1998年 | 7194篇 |
1997年 | 6150篇 |
1996年 | 5817篇 |
1995年 | 4799篇 |
1994年 | 3892篇 |
1993年 | 2626篇 |
1992年 | 2081篇 |
1991年 | 1576篇 |
1990年 | 1242篇 |
1989年 | 1001篇 |
1988年 | 835篇 |
1987年 | 525篇 |
1986年 | 411篇 |
1985年 | 260篇 |
1984年 | 207篇 |
1983年 | 165篇 |
1982年 | 128篇 |
1981年 | 76篇 |
1980年 | 96篇 |
1979年 | 43篇 |
1978年 | 17篇 |
1977年 | 23篇 |
1976年 | 28篇 |
1973年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
关于粒子加速器人身辐射安全联锁系统设计原则的建议 总被引:2,自引:2,他引:0
本文讨论了在粒子加速器上的联锁系统设计中应遵循的一些原则,其中建立隔离区、“失效导致安全(Fail-safe)”,使用“硬件”、“多重联锁”、设置急停开关等是最重要的。 相似文献
12.
13.
14.
Medard M. Lumetta S. Liuyang Li 《Selected Areas in Communications, IEEE Journal on》2002,20(4):822-833
We describe an architecture for an optical local area network (LAN) or metropolitan area network (MAN) access. The architecture allows for bandwidth sharing within a wavelength and is robust to both link and node failures. The architecture can be utilized with an arbitrary, link-redundant mesh network (node-redundancy is necessary only to handle all node failures), and assumes neither the use of a star topology nor the ability to embed such a topology within the physical mesh. Reservation of, bandwidth is performed in a centralized fashion at a (replicated) head end node, simplifying the implementation of complex sharing policies relative to implementation on a distributed set of routers. Unlike a router, however, the head end does not take any action on individual packets and, in particular, does not buffer packets. The architecture thus avoids the difficulties of processing packets in the optical domain while allowing for packetized shared access of wavelengths. We describe the route construction scheme and prove its ability to recover from single link and single node failures, outline a flexible medium access protocol and discuss the implications for implementing specific policies, and propose a simple implementation of the recovery protocol in terms of state machines for per-link devices 相似文献
15.
16.
17.
18.
前言 近20年来,随着改革开放和国民经济的飞速发展,我国建筑卫生陶瓷行业也得到快速发展,产量连年增长,成为世界上建筑卫生陶瓷的最大生产国和消费国,也是出口大国.2007年全国卫生陶瓷的产量达到15 000万件,占世界产量的40%,出口量达到5 525万件,占产量的40%. 相似文献
19.
The cooling and solidification of melted drops during their movement in an immiscible cooling medium is widely employed for granulation in the chemical industry, and a study of these processes to provides a basis for the design of the granulation tower height and the temperature of the cooling medium is reported. A physical model of the cooling and solidification of the drop is established and the numerical calculation is performed. The influences of the key factors in the solidification, i.e., Bi number, drop diameter, temperature of the cooling medium, etc. are presented. The cooling and solidification during wax granulation in a water‐cooling tower and during urea granulation in an air‐cooling tower (spraying tower) are described in detail. Characteristics of the solidification and temperature distribution within the particle at different times are shown. The model and calculations can be used for structure design of the granulation tower and optimization of the operation parameters. 相似文献
20.
Xiang‐Dan Li Zhen‐Xin Zhong Sang‐Hoon Han Seung Hee Lee Myong‐Hoon Lee 《Polymer International》2005,54(2):406-411
From chloromethylated polyimide, a useful starting material for modification of aromatic polyimides, a thermocurable transparent polyimide having acrylate side groups was prepared. In the presence of 1,8‐diazabicyclo[5,4,0]undec‐7‐ene, chloromethylated polyimide was esterified with acrylic acid to synthesize poly(imide methylene acrylate). The polymer was soluble in organic solvent, which makes it possible to prepare a planar film by spin coating. The polymer film became insoluble after thermal treatment at 230 °C for 30 min. Optical transparency of the film at 400 nm (for 1 µm thickness) was higher than 98 % and not affected by further heating at 230 °C for 250 min. Adhesion properties measured by the ASTM D3359‐B method ranged from 4B to 5B. Preliminary results of planarization testing showed a high degree of planarization (DOP) value (>0.53). These properties demonstrate that poly(imide methylene acrylate) could be utilized as a thermocurable transparent material in fabricating display devices such as TFT‐LCD. Copyright © 2004 Society of Chemical Industry 相似文献