全文获取类型
收费全文 | 5722篇 |
免费 | 660篇 |
国内免费 | 318篇 |
专业分类
电工技术 | 818篇 |
综合类 | 660篇 |
化学工业 | 354篇 |
金属工艺 | 147篇 |
机械仪表 | 508篇 |
建筑科学 | 529篇 |
矿业工程 | 173篇 |
能源动力 | 164篇 |
轻工业 | 208篇 |
水利工程 | 113篇 |
石油天然气 | 167篇 |
武器工业 | 200篇 |
无线电 | 550篇 |
一般工业技术 | 702篇 |
冶金工业 | 131篇 |
原子能技术 | 37篇 |
自动化技术 | 1239篇 |
出版年
2024年 | 37篇 |
2023年 | 102篇 |
2022年 | 148篇 |
2021年 | 165篇 |
2020年 | 206篇 |
2019年 | 155篇 |
2018年 | 154篇 |
2017年 | 159篇 |
2016年 | 199篇 |
2015年 | 214篇 |
2014年 | 322篇 |
2013年 | 338篇 |
2012年 | 414篇 |
2011年 | 455篇 |
2010年 | 370篇 |
2009年 | 404篇 |
2008年 | 379篇 |
2007年 | 525篇 |
2006年 | 427篇 |
2005年 | 357篇 |
2004年 | 287篇 |
2003年 | 196篇 |
2002年 | 166篇 |
2001年 | 109篇 |
2000年 | 82篇 |
1999年 | 71篇 |
1998年 | 50篇 |
1997年 | 49篇 |
1996年 | 38篇 |
1995年 | 34篇 |
1994年 | 26篇 |
1993年 | 13篇 |
1992年 | 10篇 |
1991年 | 12篇 |
1990年 | 5篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1966年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有6700条查询结果,搜索用时 15 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.
This paper provides a unified approach for the optimization of measurements placements employed for power system online monitoring through state estimation. The proposed methodology, which can be suitable for the mixed measure system, preserves state estimation observability and bad-data processing capability by employing numerical algorithms for observability checking, critical measurements and critical couple identification. First, node injection radix measurements and measurement categories are defined. According to the above definitions, the coefficient matrix can be solved. The analysis on the column vectors of the coefficient matrix can determine each measurement classification. Furthermore, the numbers of each measurement class contains can determine bad-data processing capability. The observability can be checked by the type number of measurements. The proposed method is illustrated with the IEEE39-bus system and the IEEE118-bus system. Results from the case studies are presented to demonstrate that the approach adequately fulfills the desired properties related to observability, bad-data processing, cost, and robustness. 相似文献
3.
《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
4.
5.
现代电子工业Cpk评价中的特殊问题 总被引:2,自引:0,他引:2
现代电子工业生产具有许多新的特点,如果不针对具体情况,均采用传统工业生产中广泛使用的常规方法计算其工序能力指数,评价生产工艺水平,将可能导致错误的结论。总结了电子工业生产中工艺参数的典型特点,并讨论了工序能力指数的正确计算方法。 相似文献
6.
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
7.
在分析Magoon和Dow对临界时刻研究的基础上 ,从事件持续时间的长短对油气最终生成的影响这一角度 ,通过对成油体系中各事件发生的过程进行分析 ,指出原成油体系事件分析图表的不合理之处 ;建立成油体系临界时刻分析模型 ,探索临界时刻定量评价的方法以及方法在油气潜力评估中的应用意义 相似文献
8.
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
9.
Liu Shi-he 《水动力学研究与进展(B辑)》1994,(4)
EFFECTOFSTREAMLINECURVATUREANDSOMEOTHERCONDITIONSONTHETURBULENTSTRUCTURESINTHEOTHERREGIONOFANOBSTACLELiuShi-he(WuhanUniversit... 相似文献
10.
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