全文获取类型
收费全文 | 13695篇 |
免费 | 1035篇 |
国内免费 | 424篇 |
专业分类
电工技术 | 1012篇 |
综合类 | 1041篇 |
化学工业 | 1503篇 |
金属工艺 | 917篇 |
机械仪表 | 438篇 |
建筑科学 | 2644篇 |
矿业工程 | 274篇 |
能源动力 | 2034篇 |
轻工业 | 935篇 |
水利工程 | 50篇 |
石油天然气 | 402篇 |
武器工业 | 58篇 |
无线电 | 635篇 |
一般工业技术 | 1195篇 |
冶金工业 | 1278篇 |
原子能技术 | 368篇 |
自动化技术 | 370篇 |
出版年
2024年 | 42篇 |
2023年 | 182篇 |
2022年 | 300篇 |
2021年 | 356篇 |
2020年 | 394篇 |
2019年 | 305篇 |
2018年 | 291篇 |
2017年 | 383篇 |
2016年 | 417篇 |
2015年 | 431篇 |
2014年 | 827篇 |
2013年 | 832篇 |
2012年 | 881篇 |
2011年 | 958篇 |
2010年 | 811篇 |
2009年 | 704篇 |
2008年 | 599篇 |
2007年 | 816篇 |
2006年 | 775篇 |
2005年 | 747篇 |
2004年 | 613篇 |
2003年 | 581篇 |
2002年 | 572篇 |
2001年 | 482篇 |
2000年 | 349篇 |
1999年 | 294篇 |
1998年 | 235篇 |
1997年 | 198篇 |
1996年 | 145篇 |
1995年 | 132篇 |
1994年 | 77篇 |
1993年 | 86篇 |
1992年 | 73篇 |
1991年 | 58篇 |
1990年 | 59篇 |
1989年 | 18篇 |
1988年 | 17篇 |
1987年 | 21篇 |
1986年 | 11篇 |
1985年 | 14篇 |
1984年 | 13篇 |
1983年 | 16篇 |
1982年 | 16篇 |
1981年 | 9篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1973年 | 1篇 |
1959年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
We investigated the resistive switching characteristics of a polystyrene:ZnO–graphene quantum dots system and its potential application in a one diode-one resistor architecture of an organic memory cell. The log–log I–V plot and the temperature-variable I–V measurements revealed that the switching mechanism in a low-current state is closely related to thermally activated transport. The turn-on process was induced by a space-charge-limited current mechanism resulted from the ZnO–graphene quantum dots acting as charge trap sites, and charge transfer through filamentary path. The memory device with a diode presented a ∼103 ION/IOFF ratio, stable endurance cycles (102 cycles) and retention times (104 s), and uniform cell-to-cell switching. The one diode-one resistor architecture can effectively reduce cross-talk issue and realize a cross bar array as large as ∼3 kbit in the readout margin estimation. Furthermore, a specific word was encoded using the standard ASCII character code. 相似文献
2.
3.
Jrgen Sjdin 《国际能源研究杂志》2002,26(6):475-494
Energy taxation in Sweden is complicated and strongly guides and governs district energy production. Consequently, there is a need for methods for accurate calculation and analysis of effects that different energy tax schemes may have on district energy utilities. Here, a practicable method to analyse influence of such governmental policy measures is demonstrated. The Swedish Government has for some years now been working on a reform of energy taxation, and during this process, several interest groups have expressed their own proposals for improving and developing the system of energy taxation. Together with the present system of taxation, four new alternatives, including the proposed directive of the European Commission, are outlined in the paper. In a case study, an analysis is made of how the different tax alternatives may influence the choice of profitable investments and use of energy carriers in a medium‐sized district‐heating utility. The calculations are made with a linear‐programming model framework. By calculating suitable types and sizes of new investments, if any, and the operation of existing and potential plants, total energy costs are minimized. Results of the analysis include the most profitable investments, which fuel should be used, roughly when during a year plants should be in operation, and at what output. In most scenarios, the most profitable measure is to invest in a waste incineration plant. However, a crucial assumption is, with reference to the new Swedish waste disposal act, a significant income from incinerating refuse. Without this income, different tax schemes result in different technical solutions being most profitable. An investment in cogeneration seems possible in only one scenario. It is also found that particular features of some alternatives seem to oppose both main governmental policy goals, and intentions of the district heating company. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
4.
5.
制备单根大重量喷涂钼丝的生产研究 总被引:3,自引:0,他引:3
全面系统地介绍了“大坯料轧制开坯-大加工率变形-长线拉伸”制造喷涂钼丝的工艺。重点阐述了Y370、Y250型三辊连轧机实现一火轧制开坯和长线拉伸增加在线碱洗工序对提高喷涂钼丝内部组织结构和外部表面质量的影响。分析了工艺中出现的问题,提出了相应的解决办法。 相似文献
6.
7.
建筑节能发展缓慢的原因及其对策 总被引:9,自引:0,他引:9
张旭 《徐州建筑职业技术学院学报》2005,5(1):55-57
我国实施建筑节能已近10年,但仍然只停留在试点、示范的层面上,尚未扩大到整体.分析了造成建筑节能发展缓慢的原因,并提出了推行和普及建筑节能的对策. 相似文献
8.
9.
介绍了综合应用新型无水冷技术和热管技术的轧钢加热炉高效运行的新模式,并结合首钢第一线材厂的实践,进一步阐明了该模式的实用性和给企业带来的良好效益。 相似文献
10.
介绍了新型环保钢制散热器的设计、结构特点及主要制造工艺和性能特点。通过实际运行 ,证明该新型环保钢制散热器在室内供暖方面具有广泛的应用推广价值 相似文献