全文获取类型
收费全文 | 619篇 |
免费 | 17篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 21篇 |
综合类 | 11篇 |
化学工业 | 193篇 |
金属工艺 | 22篇 |
机械仪表 | 123篇 |
建筑科学 | 12篇 |
矿业工程 | 8篇 |
能源动力 | 37篇 |
轻工业 | 77篇 |
石油天然气 | 76篇 |
无线电 | 11篇 |
一般工业技术 | 33篇 |
冶金工业 | 17篇 |
原子能技术 | 2篇 |
出版年
2023年 | 4篇 |
2022年 | 3篇 |
2021年 | 6篇 |
2020年 | 7篇 |
2019年 | 8篇 |
2018年 | 9篇 |
2017年 | 15篇 |
2016年 | 14篇 |
2015年 | 9篇 |
2014年 | 12篇 |
2013年 | 102篇 |
2012年 | 16篇 |
2011年 | 31篇 |
2010年 | 24篇 |
2009年 | 29篇 |
2008年 | 24篇 |
2007年 | 25篇 |
2006年 | 19篇 |
2005年 | 13篇 |
2004年 | 27篇 |
2003年 | 23篇 |
2002年 | 22篇 |
2001年 | 18篇 |
2000年 | 26篇 |
1999年 | 21篇 |
1998年 | 29篇 |
1997年 | 13篇 |
1996年 | 15篇 |
1995年 | 18篇 |
1994年 | 13篇 |
1993年 | 11篇 |
1992年 | 16篇 |
1991年 | 11篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
排序方式: 共有643条查询结果,搜索用时 15 毫秒
11.
This study determines the influences of siloxane flow agents’ migration on the outermost surface composition of clearcoats, before and after ethanol cleaning. This evaluation is undertaken to improve adhesion of pressure-sensitive adhesives (PSAs) on automotive paint systems. Most of the siloxane flow agents segregate from the bulk to the clearcoat outermost surface during curing. These additives can cover until 50% of the surface area but X-ray photoelectron spectroscopy (XPS) and time of flight-secondary ion mass spectrometry (ToF-SIMS) analyses indicate that they can be removed by ethanol cleaning. Composition of the cleaned clearcoats surfaces are similar as the composition of clearcoat formulated without siloxane additives: the polyester-(melamine)-polyurethane network is more detected than before cleaning. However, outermost surface analyses show that several aging weeks increase the siloxane additives segregation. This post-cleaning migration modifies the clearcoat surface composition and cancels the chemical modifications due to the ethanol cleaning. XPS analyses show that silicon concentrations after cleaning and aging are inversely proportional to the initial silicon concentrations measured after curing. It highlights that aging has to be controlled to improve adhesion of PSAs on clearcoats. A second ethanol cleaning on aged clearcoats is not effective to remove these new siloxane additives. Their formulation should be different from the flow agents and it could modify their solubility in ethanol. This result could also indicate that these new siloxane additives are not located on the last molecular layer of surface and they would not be soluble in ethanol. 相似文献
12.
添加物对氮化硼材料性能的影响 总被引:1,自引:1,他引:1
研究了引入锆英石和氧化铝等添加物的热压氮化硼材料的抗氧化性、热震稳定性及力学性能。结果表明,向氮化硼中引入锆英石和氧化铝后,虽然未能按预期设想生成莫来石,但却对提高氮化硼材料的抗氧化性、热震稳定性及力学性能有利。 相似文献
13.
煤矸石混合材对标准稠度影响的灰色关联分析 总被引:1,自引:0,他引:1
利用灰色关联分析的数学方法,对利用煤矸石作水泥混合材所产生的标准稠度用水量改变的影响,做了分析。论述了不同细度水泥条件下,煤矸石粒径分布范围对水泥需水量的影响。发现了在水泥较细时,在粒径范围<5 μm下的煤矸石颗粒,对标准稠度用水量影响最大;在水泥较粗时,粒径范围在5~10 μm下的煤矸石颗粒,对标准稠度用水量影响最大。 相似文献
14.
15.
16.
Copper deposition in the presence of an organic additive (3-mercaptopropionic acid, MPA) was studied by cyclic voltammetry and in situ scanning tunneling microscopy (STM) and the results are compared to those for additive-free solutions. It is shown that underpotential deposition (upd) of copper onto a fully MPA-covered electrode produces a defect-rich substrate, but the defects are blocked by the dense organic film for bulk deposition, resulting in a low number of nuclei. A grain-refining effect of MPA, however, was found, when Cu deposition was initiated shortly after addition of MPA to the solution, i.e., for a low-coverage MPA adlayer. 相似文献
17.
Miroslav Pastorek 《Materials and Manufacturing Processes》2018,33(15):1674-1680
Thermal annealing as an additional polymer processing step or post-treatment processing step enables the structural changes of amorphous parts into crystalline parts. This paper investigates the feasibility of thermal annealing at 100°C up to 90?min used as an additional processing step to modify the crystalline structure and the thermo-mechanical stability of poly(lactic acid) (PLA). Moreover, the crystallization ability of PLA has been amended by the addition of 3?wt% of wood flour and kaolin. The values of the degree of crystallinity and lamellar thickness determined by wide-angle-X-ray scattering showed that the thermal annealing of PLA samples modified with nucleating agents was an efficient processing step to increase the final crystallinity of PLA. Moreover, altered crystalline structure helped to improve the thermomechanical stability of PLA. 相似文献
18.
本文研究了在Al2 O3 陶瓷中引入Mg O、Cr2 O3 、V2 O5 、TiO2 、ZrO2 等不同添加剂对陶瓷结构和性能的影响, 并分析其作用机制。 相似文献
19.
20.
Properties of MoS2 coatings can be improved by the codeposition of a small amount of titanium (Ti). In this study, MoS2-based composite coatings, which consisted of Ti or titanium nitride (TiN) and molybdenum disulfide, are synthesized by unbalanced plasma plating. Two forms of MoS2-based composite coatings have been developed: TiN-MoS2/Ti and TiN-MoS2/TiN coatings. The effect of Ti or TiN and processing parameters on properties of such coatings are investigated. Scanning electron microscopy (SEM), dry drilling and turning tests are used to determine the structure, composition and tribological performance of MoS2-based coatings. Experimental results indicate that these MoS2-based composite coatings are considerably more wear-resistant and are less sensitive to atmospheric water vapor than pure MoS2 coatings. These coatings show excellent results when tested for a wide range of industrial turning and drilling applications. 相似文献