全文获取类型
收费全文 | 4252篇 |
免费 | 408篇 |
国内免费 | 175篇 |
专业分类
电工技术 | 718篇 |
综合类 | 468篇 |
化学工业 | 313篇 |
金属工艺 | 110篇 |
机械仪表 | 299篇 |
建筑科学 | 338篇 |
矿业工程 | 120篇 |
能源动力 | 138篇 |
轻工业 | 184篇 |
水利工程 | 77篇 |
石油天然气 | 143篇 |
武器工业 | 166篇 |
无线电 | 434篇 |
一般工业技术 | 622篇 |
冶金工业 | 108篇 |
原子能技术 | 36篇 |
自动化技术 | 561篇 |
出版年
2024年 | 21篇 |
2023年 | 53篇 |
2022年 | 65篇 |
2021年 | 95篇 |
2020年 | 126篇 |
2019年 | 98篇 |
2018年 | 106篇 |
2017年 | 111篇 |
2016年 | 130篇 |
2015年 | 128篇 |
2014年 | 206篇 |
2013年 | 243篇 |
2012年 | 285篇 |
2011年 | 344篇 |
2010年 | 288篇 |
2009年 | 310篇 |
2008年 | 326篇 |
2007年 | 418篇 |
2006年 | 334篇 |
2005年 | 273篇 |
2004年 | 232篇 |
2003年 | 142篇 |
2002年 | 133篇 |
2001年 | 81篇 |
2000年 | 53篇 |
1999年 | 54篇 |
1998年 | 32篇 |
1997年 | 35篇 |
1996年 | 28篇 |
1995年 | 22篇 |
1994年 | 18篇 |
1993年 | 10篇 |
1992年 | 8篇 |
1991年 | 9篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1985年 | 1篇 |
1984年 | 2篇 |
排序方式: 共有4835条查询结果,搜索用时 0 毫秒
1.
《Ceramics International》2022,48(6):8325-8330
In this work, we propose a facile approach to fabricate Ti4+-doped Li3V2(PO4)3/C (abbreviated as C-LVTP) nanofibers using an electrospinning route followed by a high temperature treatment. In this designed nanocomposite, the ultrafine LVTP dots are homogeneously dispersed into one-dimensional carbon nanofibers and the Ti4+ doping does not destroy the crystal structure of monoclinic Li3V2(PO4)3. Compared to the undoped Li3V2(PO4)3/C (abbreviated as C-LVP), the as-fabricated C-LVTP fibers present higher reversible capacity, superior high-rate capability as well as better cyclic property. Especially, the C-LVT7%P cathode delivers not only high capacities of 187.2 and 160.3 mAh g?1 at 0.5 and 10 C respectively, but also stable cyclic property with the reversible capacity of 135.8 mAh g?1 at 20 C following 500-cycle spans. The good battery characteristics of C-LVT7%P can be mainly ascribed to Ti4+ doping, which can increase the electrical conductivity and Li+ diffusion coefficient. 相似文献
2.
《Ceramics International》2022,48(14):20237-20244
Composite anode materials with a unique architecture of carbon nanotubes (CNTs)-chained spinel lithium titanate (Li4Ti5O12, LTO) nanoparticles are prepared for lithium ion capacitors (LICs). The CNTs networks derived from commercial conductive slurry not only bring out a steric hindrance effect to restrict the growth of Li4Ti5O12 particles but greatly enhance the electronic conductivity of the CNTs/LTO composites, both have contributed to the excellent rate capability and cycle stability. The capacity retention at 30 C (1 C = 175 mA g?1) is as high as 89.7% of that at 0.2 C with a CNTs content of 11 wt%. Meanwhile, there is not any capacity degradation after 500 cycles at 5 C. The LIC assembled with activated carbon (AC) cathode and such a CNTs/LTO composite anode displays excellent energy storage properties, including a high energy density of 35 Wh kg?1 at 7434 W kg?1, and a high capacity retention of 87.8% after 2200 cycles at 1 A g?1. These electrochemical performances outperform the reported data achieved on other LTO anode-based LICs. Considering the facile and scalable preparation process proposed herein, the CNTs/LTO composites can be very potential anode materials for hybrid capacitors towards high power-energy outputs. 相似文献
3.
4.
绝缘涂敷制件的加工工艺研究与应用 总被引:1,自引:0,他引:1
主要论述了电工绝缘粉末的性能及其在高压电器设备应用中的有关试验项目。 相似文献
5.
In this work, we study dynamic provisioning of multicast sessions in a wavelength-routed sparse splitting capable WDM network
with an arbitrary mesh topology where the network consists of nodes with full, partial, or no wavelength conversion capabilities
and a node can be a tap-and-continue (TaC) node or a splitting and delivery (SaD) node. The objectives are to minimize the
network resources in terms of wavelength-links used by each session and to reduce the multicast session blocking probability.
The problem is to route the multicast session from each source to the members of every multicast session, and to assign an
appropriate wavelength to each link used by the session. We propose an efficient online algorithm for dynamic multicast session
provisioning. To evaluate the proposed algorithm, we apply the integer linear programming (ILP) optimization tool on a per
multicast session basis to solve off-line the optimal routing and wavelength assignment given a multicast session and the
current network topology as well as its residual network resource information. We formulate the per session multicast routing
and wavelength assignment problem as an ILP. With this ILP formulation, the multicast session blocking probability or success
probability can then be estimated based on solving a series of ILPs off-line. We have evaluated the effectiveness of the proposed
online algorithm via simulation in terms of session blocking probability and network resources used by a session. Simulation
results indicate that our proposed computationally efficient online algorithm performs well even when a fraction of the nodes
are SaD nodes. 相似文献
6.
应用型机械本科专业教学体系改革研究与实践 总被引:4,自引:0,他引:4
根据当前高等教育改革与发展的指导思想,紧紧围绕国家实施制造业信息化建设工程为背景,积极配合打造浙江先进制造业基地建设,结合现代机械专业结构调整,本着交叉、复合、应用型人才的培养目标,塑造具有宽口径、厚基础和强创新意识的人才培养理念,以数字化设计制造为核心,以机械技术、电子技术、信息技术和管理学科结合为主线,突出知识综合与创新能力,强调专业实践与专业知识的有效结合,有的放矢实施机械专业教学改革与实践。 相似文献
7.
K. T. Yu S. H. Sheu K. S. Chen 《The International Journal of Advanced Manufacturing Technology》2007,34(5-6):421-429
Recently, studies associated with testing the quality and performance of each process for a product with multi-characteristics
are proposed more often. However, most studies are limited to discussing one single type of quality characteristic. Practically,
a multi-characteristic product is potentially composed of three types: smaller-the-better, larger-the-better, and nominal-the-best.
In this paper, we propose an integrated product capability index which considers these three different types of quality characteristics.
According to the theory of testing hypothesis, we develop a testing procedure for the product capability index to judge whether
the process capabilities of total quality characteristics meet the customers’ demands. In addition, the relationship between
the product capability index and the yield of the entire product will be introduced. Finally, an example is provided as a
practical application. 相似文献
8.
9.
介绍了地层测试器密封设计中常用的材料、影响密封性能的主要因素;定性地论述了井下工具密封设计中应遵循的原则及注意事项。 相似文献
10.