全文获取类型
收费全文 | 13824篇 |
免费 | 815篇 |
国内免费 | 539篇 |
专业分类
电工技术 | 228篇 |
综合类 | 652篇 |
化学工业 | 486篇 |
金属工艺 | 549篇 |
机械仪表 | 1081篇 |
建筑科学 | 1006篇 |
矿业工程 | 3157篇 |
能源动力 | 212篇 |
轻工业 | 108篇 |
水利工程 | 150篇 |
石油天然气 | 6151篇 |
武器工业 | 50篇 |
无线电 | 213篇 |
一般工业技术 | 439篇 |
冶金工业 | 242篇 |
原子能技术 | 5篇 |
自动化技术 | 449篇 |
出版年
2024年 | 35篇 |
2023年 | 215篇 |
2022年 | 287篇 |
2021年 | 377篇 |
2020年 | 394篇 |
2019年 | 270篇 |
2018年 | 268篇 |
2017年 | 360篇 |
2016年 | 466篇 |
2015年 | 501篇 |
2014年 | 872篇 |
2013年 | 772篇 |
2012年 | 1118篇 |
2011年 | 1222篇 |
2010年 | 781篇 |
2009年 | 742篇 |
2008年 | 649篇 |
2007年 | 762篇 |
2006年 | 762篇 |
2005年 | 690篇 |
2004年 | 579篇 |
2003年 | 516篇 |
2002年 | 453篇 |
2001年 | 396篇 |
2000年 | 358篇 |
1999年 | 287篇 |
1998年 | 217篇 |
1997年 | 147篇 |
1996年 | 204篇 |
1995年 | 173篇 |
1994年 | 113篇 |
1993年 | 38篇 |
1992年 | 36篇 |
1991年 | 36篇 |
1990年 | 23篇 |
1989年 | 15篇 |
1988年 | 11篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1964年 | 1篇 |
1962年 | 1篇 |
1958年 | 1篇 |
1957年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
1.
双玻光伏组件以其抗PID性强、防隐裂、防水汽透过、抗蜗牛纹、可靠性优异、轻量化等诸多优点,在晶硅太阳能组件市占比逐步提高。双玻光伏组件用背板玻璃一般需要预留出线孔,光伏背板玻璃的出线孔主要有两种打孔方式:金钢钻上下同步钻孔的模式和激光打孔。激光打孔以其易维护、可异形孔加工、效率高、生产成本低等优势得到各大玻璃厂的认可。通过分析在实际生产中激光打孔出现的打孔缺陷问题,提出了改善措施,有助于工厂的降本增效。 相似文献
2.
3.
4.
5.
《Ceramics International》2022,48(7):9658-9666
Polycrystalline Nd:YAG materials have wide applications in solid-state lasers. In this study, micro hole drilling experiments were performed on polycrystalline Nd:YAG using a polycrystalline diamond micro drill. The hole diameter, edge chipping, and hole wall surface quality were examined in detail. The results showed that the hole diameter was slightly larger than tool diameter. A diameter error of less than 5.5% was achieved. The edge chipping at the entry hole was formed by the encircled petal shape exfoliations, which were produced by the indentation and rotation movement in the drilling entry stage. Edge chipping at the exit hole was generated by an entire piece of exfoliation, which was produced by a circle of microcracks around the tool tip propagating to the bottom surface in the drilling exit stage. The edge chipping width at the entry hole was smaller than that at the exit hole. Based on different material removal modes, the hole surface morphology was classified into three types: ductile removal, coexisting ductile and brittle removal, and brittle removal. The hole surface quality mainly depended on the proportion of the brittle fracture to ductile removal surface. 相似文献
6.
7.
8.
Mohammad Hossein
Abbasi Laura Iapichino Sajad Naderi Lordejani Wil Schilders Nathan van de Wouw 《International journal for numerical methods in engineering》2020,121(23):5178-5199
To circumvent restrictions of conventional drilling methods, such as slow control actions and inability to drill depleted reservoirs, a drilling method called managed pressure drilling (MPD) has been developed. In MPD, single-phase flow processes can be modeled as a feedback interconnection of a high-order linear system and a low-order nonlinear system. These nonlinearities appear locally both inside and at the boundaries of the computational domain. To obtain a fast simulation platform for real-time purposes (eg, online model-based controller implementation), model order reduction is required for MPD. However, the local nonlinearities render applying model order reduction techniques challenging. In this study, a new approach is proposed to deal with such nonlinearities within the reduced basis (RB) context and it is successfully tested on a model for MPD. Contrary to the classical RB technique, the proposed approach not only does not generate nonphysical spikes at the locations of these local nonlinearities but also yields high speedup factors. The obtained reduced-order model can be used for efficient online simulation and controller design for drilling systems with MPD. 相似文献
9.
10.
甘蔗糖厂陆地运输的甘蔗卸至喂蔗台的主要形式有:桥式双梁吊车、旋臂桅杆卸蔗机、双臂式桅杆卸蔗机等。主要简述了目前常见的双臂式半自动挂钩桅杆卸蔗机的结构与工作原理,并介绍了在埃塞俄比亚OMO-KURAZ3糖厂改造中应用的固定双臂式半自动挂钩桅杆卸蔗机与喂蔗台的应用技术。 相似文献