全文获取类型
收费全文 | 2550篇 |
免费 | 62篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 22篇 |
综合类 | 3篇 |
化学工业 | 690篇 |
金属工艺 | 61篇 |
机械仪表 | 38篇 |
建筑科学 | 177篇 |
矿业工程 | 62篇 |
能源动力 | 43篇 |
轻工业 | 230篇 |
水利工程 | 55篇 |
石油天然气 | 1篇 |
无线电 | 183篇 |
一般工业技术 | 341篇 |
冶金工业 | 234篇 |
原子能技术 | 21篇 |
自动化技术 | 456篇 |
出版年
2021年 | 23篇 |
2019年 | 23篇 |
2018年 | 32篇 |
2017年 | 23篇 |
2016年 | 62篇 |
2015年 | 54篇 |
2014年 | 82篇 |
2013年 | 95篇 |
2012年 | 138篇 |
2011年 | 131篇 |
2010年 | 85篇 |
2009年 | 88篇 |
2008年 | 103篇 |
2007年 | 101篇 |
2006年 | 150篇 |
2005年 | 61篇 |
2004年 | 52篇 |
2003年 | 55篇 |
2002年 | 59篇 |
2001年 | 37篇 |
2000年 | 44篇 |
1999年 | 42篇 |
1998年 | 54篇 |
1997年 | 41篇 |
1996年 | 40篇 |
1995年 | 28篇 |
1994年 | 42篇 |
1993年 | 44篇 |
1992年 | 33篇 |
1991年 | 39篇 |
1990年 | 41篇 |
1989年 | 34篇 |
1988年 | 28篇 |
1987年 | 25篇 |
1986年 | 27篇 |
1985年 | 33篇 |
1984年 | 37篇 |
1983年 | 25篇 |
1982年 | 35篇 |
1981年 | 38篇 |
1980年 | 27篇 |
1979年 | 33篇 |
1978年 | 25篇 |
1977年 | 31篇 |
1976年 | 40篇 |
1975年 | 30篇 |
1974年 | 32篇 |
1973年 | 23篇 |
1971年 | 22篇 |
1970年 | 28篇 |
排序方式: 共有2617条查询结果,搜索用时 0 毫秒
51.
52.
53.
Blast furnace slags as functional fillers on rheological,thermal, and mechanical behavior of thermoplastics 下载免费PDF全文
Abdelhamid Mostafa Stephan Laske Gernot Pacher Clemens Holzer Helmut Flachberger Elke Krischey Bertram Fritz 《应用聚合物科学杂志》2016,133(8)
Blast furnace slags (BFS) is a secondary byproduct of iron industry, which has a combination of acidic and basic oxides and show a complex, multiphase structure. If appropriately tailored, BFS could be an effective functional filler, improving the property profile of thermoplastics such as polypropylene (PP) and polystyrene (PS). As a raw material, the proposed filler may introduce both economic and ecological advantages, as it is considered an inexpensive secondary product rather than a natural resource. The current study aims at investigating the effect of incorporating BFS as a micro‐sized filler on the rheological, thermal, and mechanical behavior of PP and PS. BFS types in this study are air‐cooled, crystalline, and amorphous, grounded types. Both types are ground into 71, 40, and 20 μm batches and introduced in 10, 20, and 30 weight fractions via melt kneading. Mixtures are then formed into 4‐mm and 2‐mm thick plates via compression molding. Slight increase in rheological factors is observed with increasing filler loading. BFS hinders the crystallization of PP, resulting in slight increase of crystallization temperatures (Tc) and lowering of crystallization enthalpy (ΔHc). No significant effect of filler on transition temperatures (Tg) is reported. Mechanically, BFS increases the tensile modulus of PP, but decreases its strength. For PS formulations, a modest toughening effect is observed by slag filler. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43021. 相似文献
54.
Helmut Mckel Gabriel Micard Kenneth Varner 《Progress in Photovoltaics: Research and Applications》2015,23(2):135-149
A theoretical analysis of the power loss and series resistance of the front side emitter in silicon solar cells is presented. Existing 1D models (infinitely long finger) and 2D models (including the effect of busbars) of emitter series resistance contribution are extended to the case of selective emitters. The general case of different current densities for both emitters in the selective emitter scheme is considered in these extensions. The resulting models depend on the individual sheet resistances and current densities in both emitters and the device's overall grid geometry. The models are corroborated by finite element simulation of the potential in the emitter. An excellent agreement is found between the analytical models, and the simulations for a wide range of sheet resistances typically encountered in silicon solar cells. Grid simulations using the 2D model are applied to solar cells with selective emitters, where the width of the low‐resistive emitter was varied. The simulations demonstrate that the 2D model can explain the absolute change in fill factor observed in these cells. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
55.
56.
57.
A Novel Technology for Natural Gas Conversion by Means of Integrated Oxidative Coupling and Dry Reforming of Methane 下载免费PDF全文
Dr. Joris W. Thybaut Prof. Guy B. Marin Dr. Claude Mirodatos Dr. Yves Schuurman Dr. Andre C. van Veen Prof. Vladislav A. Sadykov Dr. Helmut Pennemann Dr. Rainer Bellinghausen Prof. Leslaw Mleczko 《化学,工程师,技术》2014,86(11):1855-1870
A novel process concept for the oxidative coupling of methane followed by the oligomerization to liquids has been developed within the frame of the EU integrated project OCMOL. This technology is based on process intensification principles via cutting‐edge structured microreactor technology. It is also a fully integrated industrial process through the re‐use and the recycling of by‐products, in particular CO2, at every process stage. The focus of this contribution is on the reaction engineering aspects of the core steps, i.e., catalysts, kinetics and reactor design for the methane coupling and reforming. 相似文献
58.
Gerhard Heise Andreas Brner Marcel Dickmann Marina Englmaier Andreas Heiss Matthias Kemnitzer Jan Konrad Regina Moser Jrg Palm Helmut Vogt Heinz P. Huber 《Progress in Photovoltaics: Research and Applications》2015,23(10):1291-1304
In this paper, we present the selective structuring of all three patterns (P1, P2 and P3) of a monolithic interconnection of CIS (Cu(In,Ga)(S,Se)2) thin film solar cells by picosecond laser pulses at a wavelength of 1064 nm. We show results for single pulse ablation threshold values and line scribing of molybdenum films on glass (P1), CIS on molybdenum (P2) and zinc oxide on CIS (P3). The purposes of these processes are the p‐type isolation (P1), cell interconnect (P2) and n‐type isolation (P3), which are required for complete cell architecture. The half micron thick molybdenum back electrode can be structured with a process speed of more than 15 m/s at about 15 W average power without detectable residues and damage by direct induced laser ablation from the back side (P1). The CIS layer can be structured selectively down to the molybdenum at process speeds up to 1 m/s at about 15 W average power, due to the precision of direct laser ablation in the ultrashort pulse regime (P2). The ZnO front electrode layer is separated by clean trenches with straight side walls at process speeds of up to 15 m/s at about 10 W average power, as a result of indirect induced laser ablation (P3). A validation of functionality of all processes is demonstrated on CIS solar cell modules (30 × 30 cm2). By replacing one state‐of‐the‐art process by a picosecond laser process at a time, solar efficiencies could be increased for P1 and P2 and stayed on a similar level for P3. After an optimization of the patterning processes in the R&D pilot line of AVANCIS, we achieved a new record efficiency for an all‐laser‐patterned CIS solar module: 14.7% as best value for the aperture area efficiency of a 30 × 30 cm2 sized CIS module was reached. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
59.
Recent developments in the formulation of detergents have been driven by a strong consumer demand for natural and biodegradable products. Detergent manufacturers responded to this demand with corresponding products and advertising slogans such as “fully biodegradable”, “natural” or even “double natural” to oust their competitors. In a detergent formulation, starch- derived products can in principle be used for the following purposes: as the hydrophilic head group in surfactants, as the starting material for (poly)carboxylate co-builders and as the backbone of bleaching activators. Non-ionic classical surfactants can be replaced by alkylpolyglucosides (APGs), a class of products completely based on renewable resources such as glucose and fatty alcohols derived from natural fatty acids. Sodium tripolyphosphate (STPP), the product responsible for the eutrophication of surface waters, can be substituted by a combination of an inorganic zeolite and highly oxidised starch (dicarboxylic starch) or by citrate. Acetylated polyols derived from hydrogenated carbohydrates such as sorbitol can take over the function of the petrochemically-based tetraacetyl ethylene diamine (TAED) used as activator to allow perborate bleaching at lower washing temperatures. 相似文献
60.