全文获取类型
收费全文 | 219511篇 |
免费 | 18033篇 |
国内免费 | 12697篇 |
专业分类
电工技术 | 34610篇 |
技术理论 | 22篇 |
综合类 | 25052篇 |
化学工业 | 10590篇 |
金属工艺 | 7563篇 |
机械仪表 | 18541篇 |
建筑科学 | 18612篇 |
矿业工程 | 8955篇 |
能源动力 | 8258篇 |
轻工业 | 4859篇 |
水利工程 | 6466篇 |
石油天然气 | 6700篇 |
武器工业 | 3829篇 |
无线电 | 21789篇 |
一般工业技术 | 11473篇 |
冶金工业 | 6913篇 |
原子能技术 | 2289篇 |
自动化技术 | 53720篇 |
出版年
2024年 | 739篇 |
2023年 | 1949篇 |
2022年 | 3908篇 |
2021年 | 4944篇 |
2020年 | 5370篇 |
2019年 | 3867篇 |
2018年 | 3563篇 |
2017年 | 5079篇 |
2016年 | 6051篇 |
2015年 | 7124篇 |
2014年 | 13695篇 |
2013年 | 11636篇 |
2012年 | 16159篇 |
2011年 | 17181篇 |
2010年 | 13013篇 |
2009年 | 13101篇 |
2008年 | 13439篇 |
2007年 | 17209篇 |
2006年 | 15484篇 |
2005年 | 13874篇 |
2004年 | 11373篇 |
2003年 | 10266篇 |
2002年 | 7787篇 |
2001年 | 6537篇 |
2000年 | 5398篇 |
1999年 | 4380篇 |
1998年 | 3284篇 |
1997年 | 2672篇 |
1996年 | 2357篇 |
1995年 | 1998篇 |
1994年 | 1662篇 |
1993年 | 1122篇 |
1992年 | 949篇 |
1991年 | 683篇 |
1990年 | 553篇 |
1989年 | 459篇 |
1988年 | 326篇 |
1987年 | 188篇 |
1986年 | 114篇 |
1985年 | 120篇 |
1984年 | 102篇 |
1983年 | 92篇 |
1982年 | 71篇 |
1981年 | 64篇 |
1980年 | 51篇 |
1979年 | 45篇 |
1978年 | 34篇 |
1977年 | 28篇 |
1976年 | 23篇 |
1959年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 290 毫秒
991.
The layer reexcavation ratio is proposed to use for determination of overburden thickness in the combined conveying and direct-dumping systems of mining by draglines with haulage to goaf. It is established that this method ensures the decrease in costs of mining the horizontal and flat-dipping deposits. 相似文献
992.
993.
994.
995.
论企业竞争情报信息系统的构建与重要性 总被引:1,自引:0,他引:1
简要地述叙了现代企业构建竞争情报信息系统的必要性,介绍了竞争情报信息的构建与应用以及该系统在企业中所起的重要作用。 相似文献
996.
997.
This paper explains the manufacturing process of a composite train carbody with a sandwich composite structure for bodyshell and a stainless steel structure for the under frame. In addition, the structural behavior and safety of the composite carbody of the Korean tilting train was investigated by the static load tests. From the test results, the stiffness of the composite carbody met the specified design. In the aspect of strength, the maximum stress of the composite bodyshell was of 12.2% of strength of CF1263 carbon/epoxy. 相似文献
998.
Intelligent multisensor surveillance systems consist of several types of sensors, which are installed on fixed and mobile devices. These components provide a huge quantity of information that has to be contrasted, correlated and integrated in order to recognize and react on special situations. These systems work in highly dynamic environments, with severe security and robustness requirements. All these characteristics imply the need for distributed solutions. In these solutions, scattered components can decide and act with some degree of autonomy (for instance, if they become isolated), or cooperate and coordinate for a complete tracking of special situations. In order to cope with these requirements and to better structure the solution, we have decided to design surveillance system control as a multiagent system. This is done by applying an agent-orientated methodology, which is assessed with concrete scenarios. 相似文献
999.
Francesco Sarti Yaacov ArkinJean Chorowicz Arnon KarnieliTeresa Cunha 《Remote sensing of environment》2003,86(2):141-149
Differential radar interferometry, using archived ERS data over the region of the Dead Sea Transform, allows to detect ground movement (subsidence or uplift) in playas within the southern Arava Valley segment of the Dead Sea Rift. These measurements are consistent with a mean displacement rate of about 0.4 cm/month, in the direction of the radar beam, during the 8-month period preceding the Nuweiba earthquake of 22 November 1995. In the 3 years following the earthquake, the measured rate was smaller by a factor of 10. These movements are not related to salt diapirs or water pumping activities in the area. The exact location, along faults, suggests a possible correlation with pre-seismic and post-seismic fault deformation.A simple fault model consistent with the observed phenomena associates the observed subsidence/uplift to right and left stepping en-echelon fault patterns related to inter-seismic tensional accumulation along the faults. Further observations are necessary on this site and similar fault areas to corroborate the correlation between seismic activity and the observed phenomena. Monitoring of these sites should continue with differential Global positioning system (GPS) measurements and radar interferometric analysis using Envisat and Radarsat as well as archived data (including J-ERS). 相似文献
1000.
以某公司焦化厂焦化DCS控制系统为例,从DCS系统的选型、设计、实施等几方面。阐述焦化DCS控制系统的设计与实现。 相似文献