全文获取类型
收费全文 | 16069篇 |
免费 | 764篇 |
国内免费 | 381篇 |
专业分类
电工技术 | 108篇 |
技术理论 | 1篇 |
综合类 | 302篇 |
化学工业 | 6590篇 |
金属工艺 | 3420篇 |
机械仪表 | 829篇 |
建筑科学 | 307篇 |
矿业工程 | 251篇 |
能源动力 | 1148篇 |
轻工业 | 299篇 |
水利工程 | 25篇 |
石油天然气 | 85篇 |
武器工业 | 53篇 |
无线电 | 592篇 |
一般工业技术 | 2498篇 |
冶金工业 | 461篇 |
原子能技术 | 102篇 |
自动化技术 | 143篇 |
出版年
2024年 | 29篇 |
2023年 | 266篇 |
2022年 | 341篇 |
2021年 | 510篇 |
2020年 | 514篇 |
2019年 | 446篇 |
2018年 | 438篇 |
2017年 | 398篇 |
2016年 | 340篇 |
2015年 | 377篇 |
2014年 | 793篇 |
2013年 | 953篇 |
2012年 | 904篇 |
2011年 | 1265篇 |
2010年 | 1001篇 |
2009年 | 969篇 |
2008年 | 1004篇 |
2007年 | 997篇 |
2006年 | 1014篇 |
2005年 | 816篇 |
2004年 | 725篇 |
2003年 | 571篇 |
2002年 | 370篇 |
2001年 | 322篇 |
2000年 | 305篇 |
1999年 | 328篇 |
1998年 | 287篇 |
1997年 | 190篇 |
1996年 | 191篇 |
1995年 | 127篇 |
1994年 | 97篇 |
1993年 | 81篇 |
1992年 | 56篇 |
1991年 | 54篇 |
1990年 | 35篇 |
1989年 | 37篇 |
1988年 | 20篇 |
1987年 | 8篇 |
1986年 | 13篇 |
1985年 | 9篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
C. Lavoie F. M. d Heurle C. Detavernier C. Cabral Jr. 《Microelectronic Engineering》2003,70(2-4):144-157
In this paper, we review some of the advantages and disadvantages of nickel silicide as a material for the electrical contacts to the source, drain and gate of current and future CMOS devices. We first present some of the limitations imposed on the current cobalt silicide process because of the constant scaling, of the introduction of new substrate geometries (i.e. thin silicon on insulator) and of the modifications to the substrate material (i.e. SiGe). We then discuss the advantages of NiSi and for each of the CoSi2 limitations, we point out why Ni is believed to be superior from the point of view of material properties, miscibility of phases and formation mechanisms. Discussion follows on the expected limitations of NiSi and some of the possible solutions to palliate these limitations. 相似文献
32.
Effect of Stoichiometry on Properties of Rare-Earth-Based Hydrogen Storage Alloy for Nickel-Metal Hydride Secondary Battery 总被引:2,自引:0,他引:2
Effect of stoichiometry on microstructures, electrochemical properties and PCT characteristics of the alloys MI(Ni0.71Co0.15-Al0.06Mn0.08)x (MI=Lanthanum-rich Michmetal, x=4.6~5.2) have been investigated. The lattice constants a, c, and cellvolumes of non-stoichiometric alloys are bigger than those of the stoichiometric alloy. With the increasing stoichiometry x,the value of a decreases, and the value of c and cell volume increases except for those of the stoichiometric alloy; the plateaupressure of PCT curve, discharge capacity and cycling stability all increase. The alloy with x=5.2 shows the highest dischargecapacity and the best cycling stability among the studied alloys. 相似文献
33.
34.
ABSTRACT: Shellac and wax-based citrus coatings were applied to Fallglo, Robinson, Sunburst, Dancy and Murcott tangerines, Nova and Orlando tangelos, and Temple oranges. Flavor volatiles were measured before and after storage. Concentrations of ethyl acetate, ethyl butyrate, isopentanol and 2-methyl-3-buten-2-ol increased markedly for fruit with shellac-based coatings, and were highly correlated with ethanol content, but at different ratios for the different varieties. The concentration increases were relatively less for fruit coated with the wax-based coatings, and suggest that high-gloss shellac and resin-based coatings are not appropriate for tangerines. 相似文献
35.
本文运用一典型的人工神经网络模型─“反向传播”模型,对高氧化态(Ⅱ─Ⅳ)三核金属簇合物的构型分布进行了分析,得到了较好的分类、预报结果为化合物结构分析提供了新的工具。 相似文献
36.
37.
Two commercial Pt modified aluminide coatings (RT22 and MDC150L) on the same single crystal Ni-based superalloy (CMSX-4) were studied by: scanning electron microscopy; transmission electron microscopy; energy dispersive X-ray spectrometry; and gravimetry. The RT22 coating is an inward grown coating (high activity), while MDC150L is produced by outward growth (low activity). Samples were oxidised in still laboratory air at 1050 °C for various times up to 2000 h. It was found that the outward grown coating produced a slower growing oxide that was more spallation resistant. Several possible reasons for this were identified including: coating purity; coating surface topography; and ductile to brittle transition temperature. The microstructural differences between the two coatings in the as-coated condition were investigated and the development of their microstructure during heat treatment was described. A model for coating growth during heat treatment was proposed. 相似文献
39.
40.
采用自行开发研制的超音速电弧喷设备,在45钢表面制成了钛铝合金复合涂层。并利用金相显微镜、X射线衍射仪、扫描电镜、电子探针,对涂层的成分、相结构、显微组织及其结合强度、显微硬度进行了研究。结果表明,利用超音速电弧喷涂设备,可以在45钢表面形成 度高、孔隙率低,结合强度较好和硬度高的Ti-Al合金涂层。 相似文献