全文获取类型
收费全文 | 55977篇 |
免费 | 4608篇 |
国内免费 | 2957篇 |
专业分类
电工技术 | 3601篇 |
技术理论 | 4篇 |
综合类 | 4849篇 |
化学工业 | 9020篇 |
金属工艺 | 3591篇 |
机械仪表 | 3614篇 |
建筑科学 | 3427篇 |
矿业工程 | 1565篇 |
能源动力 | 1530篇 |
轻工业 | 4806篇 |
水利工程 | 1300篇 |
石油天然气 | 2434篇 |
武器工业 | 536篇 |
无线电 | 5853篇 |
一般工业技术 | 6537篇 |
冶金工业 | 3155篇 |
原子能技术 | 700篇 |
自动化技术 | 7020篇 |
出版年
2024年 | 107篇 |
2023年 | 510篇 |
2022年 | 1135篇 |
2021年 | 1630篇 |
2020年 | 1229篇 |
2019年 | 1072篇 |
2018年 | 1300篇 |
2017年 | 1354篇 |
2016年 | 1308篇 |
2015年 | 1931篇 |
2014年 | 2467篇 |
2013年 | 3372篇 |
2012年 | 3836篇 |
2011年 | 4108篇 |
2010年 | 3937篇 |
2009年 | 3865篇 |
2008年 | 4077篇 |
2007年 | 4003篇 |
2006年 | 3735篇 |
2005年 | 3087篇 |
2004年 | 2377篇 |
2003年 | 1778篇 |
2002年 | 1642篇 |
2001年 | 1435篇 |
2000年 | 1261篇 |
1999年 | 969篇 |
1998年 | 803篇 |
1997年 | 697篇 |
1996年 | 599篇 |
1995年 | 508篇 |
1994年 | 473篇 |
1993年 | 345篇 |
1992年 | 292篇 |
1991年 | 242篇 |
1990年 | 161篇 |
1989年 | 179篇 |
1988年 | 157篇 |
1987年 | 135篇 |
1986年 | 109篇 |
1985年 | 130篇 |
1984年 | 127篇 |
1983年 | 138篇 |
1982年 | 101篇 |
1981年 | 102篇 |
1980年 | 89篇 |
1979年 | 89篇 |
1978年 | 75篇 |
1977年 | 66篇 |
1976年 | 73篇 |
1975年 | 60篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
采用ZG31Mn2Si替代ZGMn13生产拖拉机和推土机履带板.改进铸造工艺,可以生产出合格的铸件;经淬火、低温退火处理,其基体组织为马氏体,属强韧性钢种,能够切削加工. 相似文献
72.
A critical review of the current status of tungsten resources, of state-of-the-art processing technology and of product development
in India vis-a-vis the world scenario is presented. An attempt has been made to identify technology gap areas requiring attention. 相似文献
73.
74.
A transformational approach for proving termination of parallel logic programs such as GHC programs is proposed. A transformation
from GHC programs to term rewriting systems is developed; it exploits the fact that unifications in GHC-resolution correspond
to matchings. The termination of a GHC program for a class of queries is implied by the termination of the resulting rewrite
system. This approach facilitates the applicability of a wide range of termination techniques developed for rewrite systems
in proving termination of GHC programs. The method consists of three steps: (a) deriving moding information from a given GHC
program, (b) transforming the GHC program into a term rewriting system using the moding information, and finally (c) proving
termination of the resulting rewrite system. Using this method, the termination of many benchmark GHC programs such as quick-sort,
merge-sort, merge, split, fair-split and append, etc., can be proved.
This is a revised and extended version of Ref. 12). The work was partially supported by the NSF Indo-US grant INT-9416687
Kapur was partially supported by NSF Grant nos. CCR-8906678 and INT-9014074.
M. R. K. Krishna Rao, Ph.D.: He currently works as a senior research fellow at Griffith University, Brisbane, Australia. His current interests are in
the areas of logic programming, modular aspects and noncopying implementations of term rewriting, learning logic programs
from examples and conuterexamples and dynamics of mental states in rational agent architectures. He received his Ph.D in computer
science from Tata Institute of Fundamental Research (TIFR), Bombay in 1993 and worked at TIFR and Max Planck Institut für
Informatik, Saarbrücken until January 1997.
Deepak Kapur, Ph.D.: He currently works as a professor at the State University of New York at Albany. His research interests are in the areas
of automated reasoning, term rewriting, constraint solving, algebraic and geometric reasoning and its applications in computer
vision, symbolic computation, formal methods, specification and verification. He obtained his Ph.D. in Computer Science from
MIT in 1980. He worked at General Electric Corporate Research and Development until 1987. Prof. Kapur is the editor-in-chief
of the Journal of Automated Reasoning. He also serves on the editorial boards of Journal of Logic Programming, Journal on
Constraints, and Journal of Applicable Algebra in Engineering, Communication and Computer Science.
R. K. Shyamasundar, Ph.D.: He currently works as a professor at Tata Institute of Fundamental Research (TIFR), Bombay. His current intersts are in
the areas of logic programming, reactive and real time programming, constraint solving, formal methods, specification and
verification. He received his Ph.D in computer science from Indian Institute of Science, Bangalore in 1975 and has been a
faculty member at Tata Institute of Fundamental Research since then. He has been a visiting/regular faculty member at Technological
University of Eindhoven, University of Utrecht, IBM TJ Watson Research Centre, Pennsylvania State University, University of
Illinois at Urbana-Champaign, INRIA and ENSMP, France. He has served on (and chaired) Program Committees of many International
Conferences and has been on the Editorial Committees. 相似文献
75.
制作压力传感器时,在二氧化硅层上淀积多晶硅膜,既可利用优良的机械特性,又可保证压敏电阻与衬底间具有良好的绝缘性,由此可大大提高器件的温度特性。介绍了一种多晶硅压力传感器的原理和设计。实验结果表明,这类传感器具有灵敏度好,精度高等特点,电路工作范围为0-250℃,且具有良好的温度稳定性。 相似文献
76.
本文简述了以EVA为基质材料制备有机PTC特性材料的实验,实测了样品有关特性,并用非线性回归方法讨论了其导电机理.这对指导温度传感器的设计有一定帮助. 相似文献
77.
78.
现有的虚拟专用网(VPN)方案大多基于IP协议,这种结构的VPN在数据包转发速度、扩展性、服务质量等方面都存在欠缺,所以本文提出了基于多协议标记交换(MPLS)骨干网络的VPN解决方案.由于MPLS和IPSec在身份认证方面都没有定义,所以我们在方案中把认证中心(CA)的证书管理引入进来.该方案的核心思想是:利用MPLS在传输效率上的优势,通过CA进行身份认证、IKE协议[1]进行密钥协商以及IPSec协议[2]进行数据包加密,从而在MPLS骨干网络上建立一个安全高效的VPN.本文对实现MPLS VPN的每个关键部件都做了进一步的描述. 相似文献
79.
环境友好阻燃环氧树脂覆铜板研究进展 总被引:15,自引:0,他引:15
论述了环境友好阻燃环氧树脂覆铜板研究开发的意义。提出通过开发并使用含氮、磷或硅的非卤阻燃型环氧树脂,含磷、氮或磷-氮的功能性阻燃固化剂和在体系中添加有机磷阻燃剂、氢氧化铝等无机阻燃剂等途径来开发环境友好阻燃环氧树脂覆铜板。并对我国在今后该领域的研究作了展望。 相似文献
80.