全文获取类型
收费全文 | 12962篇 |
免费 | 1033篇 |
国内免费 | 310篇 |
专业分类
电工技术 | 57篇 |
技术理论 | 1篇 |
综合类 | 375篇 |
化学工业 | 6974篇 |
金属工艺 | 2492篇 |
机械仪表 | 365篇 |
建筑科学 | 170篇 |
矿业工程 | 70篇 |
能源动力 | 181篇 |
轻工业 | 825篇 |
水利工程 | 13篇 |
石油天然气 | 157篇 |
武器工业 | 37篇 |
无线电 | 444篇 |
一般工业技术 | 1762篇 |
冶金工业 | 307篇 |
原子能技术 | 48篇 |
自动化技术 | 27篇 |
出版年
2024年 | 43篇 |
2023年 | 299篇 |
2022年 | 250篇 |
2021年 | 432篇 |
2020年 | 437篇 |
2019年 | 404篇 |
2018年 | 399篇 |
2017年 | 375篇 |
2016年 | 359篇 |
2015年 | 350篇 |
2014年 | 651篇 |
2013年 | 748篇 |
2012年 | 856篇 |
2011年 | 973篇 |
2010年 | 815篇 |
2009年 | 728篇 |
2008年 | 729篇 |
2007年 | 847篇 |
2006年 | 860篇 |
2005年 | 716篇 |
2004年 | 646篇 |
2003年 | 444篇 |
2002年 | 311篇 |
2001年 | 248篇 |
2000年 | 245篇 |
1999年 | 244篇 |
1998年 | 219篇 |
1997年 | 151篇 |
1996年 | 110篇 |
1995年 | 70篇 |
1994年 | 74篇 |
1993年 | 52篇 |
1992年 | 44篇 |
1991年 | 42篇 |
1990年 | 27篇 |
1989年 | 30篇 |
1988年 | 19篇 |
1987年 | 10篇 |
1986年 | 12篇 |
1985年 | 3篇 |
1984年 | 15篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 21 毫秒
31.
高温润滑涂层设计的系统考虑 总被引:3,自引:0,他引:3
航天、航空、核能等尖端技术迫切要求使用耐高温润滑涂层,以保护金属构件的表面,增加发动机、推进器的工作效率和输出功率,80年代国际摩擦学界根据工业和国防的需要将高温润滑涂层和耐磨材料定为摩擦学学科发展的重要研究方向之一。本文对高温润滑涂层设计中遇到的典型环境、涉及到的关键问题、未来发展的途径等问题作了阐述。 相似文献
32.
33.
进行了PAA(PolyacrylicAcid)-PSF(Polysulfone)交联复合膜的制备,研究了交联剂、添加剂对膜性能的影响,并通过扫描电镜观察了膜的断面结构.研究了PAA-PSF交联复合膜对低浓度有机醇类水溶液反渗透分离性能.发现对于1000×10-6乙醇水溶液截留率达到66.2%,透过流束可达0.9×10-6(m3·m-2·s-1).随醇的分子量的增加,截留率不断上升,对戊醇的截留率达94.3%,而透过流束则保持相对稳定.对不同结构醇类的分离性能研究表明,截留率存在有:tert->sec->iso->n-的规律. 相似文献
34.
35.
Advanced high-energy plasma systems are being used to achieve the benefits of the high-velocity oxy-fuel (HVOF) system without
losing the inherent advantages of plasma for coating of gas turbine parts. MCrAlY coatings play a very important role in the
performance and reliability of gas turbine components. One of the important considerations for next generation of gas turbines,
which have more demanding conditions and need to withstand ever increasing operating temperatures, is that they should possess
very low oxygen content levels in the coating. Low oxygen content coatings are applied by the expensive low-pressure plasma
spray (LPPS)/vacuum plasma spray (VPS) technique for critical components in aero- and land-based gas turbines. This work deals
with the development of low-cost LPPS equivalent coatings (having low oxygen content) using the high-energy high-velocity
plasma spray (HEHVPS) gun and inert gas shroud. A comparison has also been made with CoNiCrAlY coatings by HVOF. 相似文献
36.
37.
The role of adhesion promoters, copper oxidation, and thermal aging in the adhesion mechanism of enamel on copper winding wires is investigated. Evidence is presented on the predominant role of the copper oxide at the interface in the wire–enamel adhesion phenomena. The oxidation process and the copper oxides stability at the interface are seen to strongly depend upon the thermal aging of the wire and the nature of both the enamel and the promoter. Atomic force and scanning electron microscopy analyses show that so‐called promoters act more efficiently as corrosion inhibitors than as adhesion enhancers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 952–958, 2003 相似文献
38.
In accord with the increasing concern about the global environmental issues, the absorption refrigeration heat-pump systems are currently being considered very promising and attractive. For the purpose of supporting the advanced R&D technology in this area, we have developed a novel correlation to represent the bubble-point pressures of LiBr H2O solutions. The developed correlation covers the most extensive range of validity ever proposed: 273–483 K for temperatures, 0.05 kPa to 1.0 MPa for pressures. and 29 76 wt% LiBr for concentrations.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994. Boulder, Colorado, U.S.A. 相似文献
39.
aneta Polkowska Jacek Namienik Jacek Czerwiski & Bogdan Zygmunt 《International Journal of Food Science & Technology》1996,31(5):387-395
Applicability of thin-layer headspace (TLHS) procedure giving an aqueous concentrate and also classical purge and trap (PT) in off-line mode to isolate and enrich volatile organohalogen compounds in common beverages was tested. Both enrichment tech-niques were used in combination with gas chromatography – electron capture detection (GC-ECD). TLHS, combined with direct aqueous injection (DAI)-GC-ECD, proved applicable in the determination of volatile organohalogen compounds in all studied beverages, while the PT in a version with no preliminary sample pre-treatment was of limited applicability. Detection limits of the TLHS-based procedure were in the order of 1 ppt. Content of volatile organohalogen compounds in a number of beverages available on the Polish market including mineral waters, beers, juices, carbonated and non-carbonated soft drinks, etc. was determined by means of TLHS-DAI-GC-ECD. 相似文献
40.
Statistical studies of branched ester latex and paint properties 总被引:3,自引:0,他引:3
R. A. Prior W. R. Hinson O. W. Smith D. R. Bassett 《Progress in Organic Coatings》1996,29(1-4):209-224
Vinyl versatate, butyl acrylate and 2-ethylhexyl acrylate were compared as comonomer, for colloid-stabilized vinyl acetate latex polymers to assess their impact on latex coating properties. Vinyl versatate afforded advantages in scrub resistance, gloss, hydrophobicity and higher glass transition temperatures. Butyl acrylate developed better wet adhesion efficiency, gel content and hiding efficiency. 2-Ethylhexyl acrylate offered performance comparable to butyl acrylate in hiding efficiency, lowering copolymer glass transition temperatures, and gloss development. Combinations of these monomers, in many instances, afforded a better balance of performance properties than individual monomers alone. In the subject study, a simplex-centroid design was utilized to statistically map polymer compositions for determining the effect of comonomer composition on latex and paint film properties. In addition to developing contour maps of polymer and paint properties as a function of composition, a technique for studying structure-property relationships is presented. 相似文献