全文获取类型
收费全文 | 7555篇 |
免费 | 705篇 |
国内免费 | 363篇 |
专业分类
电工技术 | 536篇 |
综合类 | 478篇 |
化学工业 | 1031篇 |
金属工艺 | 427篇 |
机械仪表 | 475篇 |
建筑科学 | 529篇 |
矿业工程 | 203篇 |
能源动力 | 215篇 |
轻工业 | 518篇 |
水利工程 | 150篇 |
石油天然气 | 510篇 |
武器工业 | 72篇 |
无线电 | 933篇 |
一般工业技术 | 888篇 |
冶金工业 | 395篇 |
原子能技术 | 60篇 |
自动化技术 | 1203篇 |
出版年
2024年 | 31篇 |
2023年 | 162篇 |
2022年 | 233篇 |
2021年 | 317篇 |
2020年 | 253篇 |
2019年 | 214篇 |
2018年 | 240篇 |
2017年 | 266篇 |
2016年 | 214篇 |
2015年 | 316篇 |
2014年 | 390篇 |
2013年 | 460篇 |
2012年 | 520篇 |
2011年 | 557篇 |
2010年 | 444篇 |
2009年 | 457篇 |
2008年 | 415篇 |
2007年 | 395篇 |
2006年 | 404篇 |
2005年 | 371篇 |
2004年 | 248篇 |
2003年 | 226篇 |
2002年 | 222篇 |
2001年 | 181篇 |
2000年 | 163篇 |
1999年 | 165篇 |
1998年 | 126篇 |
1997年 | 128篇 |
1996年 | 126篇 |
1995年 | 86篇 |
1994年 | 65篇 |
1993年 | 51篇 |
1992年 | 48篇 |
1991年 | 35篇 |
1990年 | 26篇 |
1989年 | 21篇 |
1988年 | 12篇 |
1987年 | 14篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1976年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有8623条查询结果,搜索用时 0 毫秒
1.
2.
3.
Haibo Zhang Guohua Geng Kang Li Cheng Liu Yuqing Hou 《Journal of Modern Optics》2018,65(20):2278-2289
Cone-beam X-ray luminescence computed tomography (CB-XLCT) is an attractive hybrid imaging modality, and it has the potential of monitoring the metabolic processes of nanophosphors-based drugs in vivo. However, the XLCT imaging suffers from a severe ill-posed problem. In this work, a sparse nonconvex Lp (0?p?1) regularization was utilized for the efficient reconstruction for early detection of small tumour in CB-XLCT imaging. Specifically, we transformed the non-convex optimization problem into an iteratively reweighted scheme based on the L1 regularization. Further, an iteratively reweighted split augmented lagrangian shrinkage algorithm (IRW_SALSA-Lp) was proposed to efficiently solve the non-convex Lp (0?p?1) model. We studied eight different non-convex p-values (1/16, 1/8, 1/4, 3/8, 1/2, 5/8, 3/4, 7/8) in both 3D digital mouse experiments and in vivo experiments. The results demonstrate that the proposed non-convex methods outperform L2 and L1 regularization in accurately recovering sparse targets in CB-XLCT. And among all the non-convex p-values, our Lp(1/4?p?1/2) methods give the best performance. 相似文献
4.
5.
针对国外变频器价格昂贵、调试周期和维修周期长等特点,我公司自主研发了可替代进口机的高性能钻机国产专用变频器。该变频器能够从零开始调速。当钻井卡钻时,能及时断开电动机,在低速提升时,能最大限度地发挥电动机的动力特性,提供220%的转矩输出。变频器具有易安装、调试、维护,性能稳定。应用中据实测数据显示,采用变频改造后,打1口井可节省柴油15t。 相似文献
6.
A distributed problem solving system can be characterized as a group of individual cooperating agents running to solve common problems. As dynamic application domains continue to grow in scale and complexity, it becomes more difficult to control the purposeful behavior of agents, especially when unexpected events may occur. This article presents an information and knowledge exchange framework to support distributed problem solving. From the application viewpoint the article concentrates on the stock trading domain; however, many presented solutions can be extended to other dynamic domains. It addresses two important issues: how individual agents should be interconnected so that their resources are efficiently used and their goals accomplished effectively; and how information and knowledge transfer should take place among the agents to allow them to respond successfully to user requests and unexpected external situations. The article introduces an architecture, the MASST system architecture, which supports dynamic information and knowledge exchange among the cooperating agents. The architecture uses a dynamic blackboard as an interagent communication paradigm to facilitate factual data, business rule, and command exchange between cooperating MASST agents. The critical components of the MASST architecture have been implemented and tested in the stock trading domain, and have proven to be a viable solution for distributed problem solving based on cooperating agents 相似文献
7.
基于体全息技术的WDM器件 总被引:2,自引:0,他引:2
利用体全息技术制作波分复用器件是一种新方法。本文介绍了此种方法的基本原理和器件的基本性能,并报道了国外对该项技术的研究进展。 相似文献
8.
9.
10.