全文获取类型
收费全文 | 35260篇 |
免费 | 4576篇 |
国内免费 | 2522篇 |
专业分类
电工技术 | 10192篇 |
技术理论 | 1篇 |
综合类 | 3305篇 |
化学工业 | 1122篇 |
金属工艺 | 879篇 |
机械仪表 | 3451篇 |
建筑科学 | 1577篇 |
矿业工程 | 1208篇 |
能源动力 | 907篇 |
轻工业 | 491篇 |
水利工程 | 679篇 |
石油天然气 | 958篇 |
武器工业 | 517篇 |
无线电 | 6634篇 |
一般工业技术 | 2257篇 |
冶金工业 | 605篇 |
原子能技术 | 244篇 |
自动化技术 | 7331篇 |
出版年
2024年 | 154篇 |
2023年 | 430篇 |
2022年 | 862篇 |
2021年 | 1115篇 |
2020年 | 1243篇 |
2019年 | 935篇 |
2018年 | 963篇 |
2017年 | 1249篇 |
2016年 | 1346篇 |
2015年 | 1709篇 |
2014年 | 2578篇 |
2013年 | 2291篇 |
2012年 | 3155篇 |
2011年 | 3170篇 |
2010年 | 2347篇 |
2009年 | 2294篇 |
2008年 | 2230篇 |
2007年 | 2555篇 |
2006年 | 2121篇 |
2005年 | 1763篇 |
2004年 | 1435篇 |
2003年 | 1207篇 |
2002年 | 910篇 |
2001年 | 834篇 |
2000年 | 642篇 |
1999年 | 542篇 |
1998年 | 425篇 |
1997年 | 363篇 |
1996年 | 289篇 |
1995年 | 240篇 |
1994年 | 211篇 |
1993年 | 161篇 |
1992年 | 120篇 |
1991年 | 78篇 |
1990年 | 77篇 |
1989年 | 77篇 |
1988年 | 41篇 |
1987年 | 24篇 |
1986年 | 19篇 |
1985年 | 23篇 |
1984年 | 31篇 |
1983年 | 21篇 |
1982年 | 23篇 |
1981年 | 6篇 |
1980年 | 8篇 |
1979年 | 6篇 |
1978年 | 5篇 |
1965年 | 4篇 |
1964年 | 4篇 |
1961年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
TAN Zuo-wen 《通讯和计算机》2007,4(5):40-46
Signcryption is a public key or asymmetric cryptographic method that provides simultaneously both message confidentiality and integrity at a lower computational and communication cost. This paper presents a (t, n) threshold proxy signcryption scheme in which no less than t proxy agents in the proxy group can produce the signcryption cryptogram. combines the functionality of threshold proxy signing and encryption. The proposed scheme combines the functionality of both threshold proxy signing and encryption, and provides fair protection for the sender and the proxy agents. This scheme is secure against attack of public key substitution. It also satisfies security properties such as confidentiality and authenticity. 相似文献
22.
本文对白云鄂博主矿采场铁公路联合运输向公路运输转换位置是否确定为1638m水平以及运输工艺转换过程中相关问题进行分析论证,提出主矿采场铁路至少可向下延深一个水平,技术上可行,节约运费千万元以上。 相似文献
23.
Alexander Babich Konstantinos Mavrommatis Dieter Senk Heinrich Wilhelm Gudenau 《国际钢铁研究》2004,75(7):428-432
This contribution deals with advanced educational technologies needed to equip customers from higher education institutions, research and industry with efficient tools supporting their work and operating new skills‐training methods. The challenges are reducing the training costs, improving quality and increasing the number of graduates in engineering departments. The concept of a Virtual Lab based on the combination of various teaching methods and tools is presented. Principles of mathematisation in metallurgical education and training are discussed. An example of online course designed in the form of Virtual Lab is demonstrated. 相似文献
24.
厦门市气源转换的技术分析 总被引:3,自引:2,他引:1
分析了气源转换时原有输配系统的管道、调压设备、计量设备、用气设备与天然气系统相适应的问题,提出了相应的措施。 相似文献
25.
“To understand and protect our home planet, to explore the universe and search for life, and to inspire the next generation of explorers” is NASA's mission. The Systems Management Office at Johnson Space Center (JSC) is searching for methods to effectively manage the Center's resources to meet NASA's mission. D-Side is a group multi-criteria decision support system (GMDSS) developed to support facility decisions at JSC. D-Side uses a series of sequential and structured processes to plot facilities in a three-dimensional (3-D) graph on the basis of each facility's alignment with NASA's mission and goals, the extent to which other facilities are dependent on the facility, and the dollar value of capital investments that have been postponed at the facility relative to the facility's replacement value. A similarity factor rank orders facilities based on their Euclidean distance from Ideal and Nadir points. These similarity factors are then used to allocate capital improvement resources across facilities. We also present a parallel model that can be used to support decisions concerning allocation of human resources investments across workforce units. Finally, we present results from a pilot study where 12 experienced facility managers from NASA used D-Side and the organization's current approach to rank order and allocate funds for capital improvement across 20 facilities. Users evaluated D-Side favorably in terms of ease of use, the quality of the decision-making process, decision quality, and overall value-added. Their evaluations of D-Side were significantly more favorable than their evaluations of the current approach. 相似文献
26.
Bar-Anan Yoav; Liberman Nira; Trope Yaacov; Algom Daniel 《Canadian Metallurgical Quarterly》2007,136(4):610
A picture-word version of the Stroop task was used to test the automatic activation of psychological distance by words carrying various senses of psychological distance: temporal (tomorrow, in a year), social (friend, enemy), and hypotheticality (sure, maybe). The pictures implied depth, with the words appearing relatively close to or distant from the observer. The participants classified the spatial distance of words faster when the word's implicit psychological distance matched its spatial distance (e.g., a geographically close word was classified faster when it was "friend" than when it was "enemy"). The findings are consistent with the idea that psychological distance is accessed automatically, even when it is not directly related to people's current goals, and suggest that psychological distance is an important dimension of meaning, common to spatial distance, temporal distance, social distance, and hypotheticality. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
27.
管线用高强韧性宽厚钢板的开发 总被引:1,自引:0,他引:1
本文回顾了舞钢高强韧性管线用宽厚钢板的研制开发过程,并结合生产工艺,对钢板性能作了全面分析,指导了钢管线钢的生产。舞钢X70级管线钢有较高的断裂韧性、良好的可焊性以及抗SSCC、HIC性能。舞钢正在进行技术改造,以进一步改善组织,提高性能、满足西气东输要求。 相似文献
28.
29.
Johan Rönnblom 《Software》2007,37(10):1047-1059
A method for finding all matches in a pre‐processed dictionary for a query string q and with at most k differences is presented. A very fast constant‐time estimate using hashes is presented. A tree structure is used to minimize the number of estimates made. Practical tests are performed, showing that the estimate can filter out 99% of the full comparisons for 40% error rates and dictionaries of up to four million words. The tree is found to be efficient up to a 50% error rate. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
30.
介绍了管环缝射线透照方式,以及环缝单壁外透法和环缝双壁单影法100%射线透照检查一次透照长度及分段次数的计算。 相似文献