全文获取类型
收费全文 | 5136篇 |
免费 | 342篇 |
国内免费 | 314篇 |
专业分类
电工技术 | 89篇 |
综合类 | 366篇 |
化学工业 | 479篇 |
金属工艺 | 973篇 |
机械仪表 | 1451篇 |
建筑科学 | 215篇 |
矿业工程 | 77篇 |
能源动力 | 156篇 |
轻工业 | 99篇 |
水利工程 | 238篇 |
石油天然气 | 43篇 |
武器工业 | 36篇 |
无线电 | 372篇 |
一般工业技术 | 820篇 |
冶金工业 | 168篇 |
原子能技术 | 35篇 |
自动化技术 | 175篇 |
出版年
2024年 | 34篇 |
2023年 | 107篇 |
2022年 | 156篇 |
2021年 | 156篇 |
2020年 | 221篇 |
2019年 | 181篇 |
2018年 | 206篇 |
2017年 | 257篇 |
2016年 | 233篇 |
2015年 | 215篇 |
2014年 | 255篇 |
2013年 | 316篇 |
2012年 | 299篇 |
2011年 | 336篇 |
2010年 | 224篇 |
2009年 | 279篇 |
2008年 | 287篇 |
2007年 | 352篇 |
2006年 | 294篇 |
2005年 | 208篇 |
2004年 | 195篇 |
2003年 | 149篇 |
2002年 | 154篇 |
2001年 | 109篇 |
2000年 | 103篇 |
1999年 | 68篇 |
1998年 | 61篇 |
1997年 | 58篇 |
1996年 | 72篇 |
1995年 | 31篇 |
1994年 | 19篇 |
1993年 | 36篇 |
1992年 | 18篇 |
1991年 | 19篇 |
1990年 | 16篇 |
1989年 | 11篇 |
1988年 | 16篇 |
1987年 | 7篇 |
1986年 | 6篇 |
1985年 | 3篇 |
1984年 | 13篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1980年 | 2篇 |
1979年 | 1篇 |
排序方式: 共有5792条查询结果,搜索用时 15 毫秒
11.
镀锌产品表面粗糙度影响因素的研究 总被引:1,自引:0,他引:1
以马钢第四钢轧总厂1#镀锌线的产品为研究对象,通过大量的数据检测,分析了热浸镀锌产品带钢表面粗糙度的影响因素,并得出变化规律。这些规律可以运用到实际生产中来对带钢表面的粗糙度进行计算和控制。 相似文献
12.
Experimental verification of the mathematical surface roughness model for sputtered silicon was performed. The beam shape and its significant level of intensity were determined first by measuring the topography of craters sputtered by focused ion beam (FIB). Then the beam function was generated for various combinations of beam parameters. The material function was developed both by theoretical and experimental analysis. These two functions were then used in the model to calculate the theoretical surface roughness. Microsurface analysis was formed by FIB sputtering of a (100) silicon wafer. The surface roughness at the bottom of the sputtered features was then measured using an atomic force microscope. The theoretical surface roughness was found to be within ±1 and ±5 nm of the measured surface roughness with the measurement uncertainty (standard deviation) of about ±0.36 and ±0.85 nm for Ra and Rt, respectively. 相似文献
13.
Meng Li Clara Seinsche Samuel Jansson Julio Hernandez Jadranka Rota Eric Warrant Mikkel Brydegaard 《Journal of the Royal Society Interface》2022,19(191)
There are hundreds of thousands of moth species with crucial ecological roles that are often obscured by their nocturnal lifestyles. The pigmentation and appearance of moths are dominated by cryptic diffuse shades of brown. In this study, 82 specimens representing 26 moth species were analysed using infrared polarimetric hyperspectral imaging in the range of 0.95–2.5 µm. Contrary to previous studies, we demonstrate that since infrared light does not resolve the surface roughness, wings appear glossy and specular at longer wavelengths. Such properties provide unique reflectance spectra between species. The reflectance of the majority of our species could be explained by comprehensive models, and a complete parametrization of the spectral, polarimetric and angular optical properties was reduced to just 11 parameters with physical units. These parameters are complementary and, compared with the within-species variation, were significantly distinct between species. Counterintuitively to the aperture-limited resolution criterion, we could deduce microscopic features along the surface from their infrared properties. These features were confirmed by electron microscopy. Finally, we show how our findings could greatly enhance opportunities for remote identification of free-flying moth species, and we hypothesize that such flat specular wing targets could be expected to be sensed over considerable distances. 相似文献
14.
15.
Robert BrowningMohammad Motaher Hossain Jiang LiScooter Jones Hung-Jue Sue 《Tribology International》2011,44(9):1024-1031
The physical aspect of mar behavior is studied by applying a standardized progressive sliding load methodology to smooth and textured automotive-grade thermoplastic olefins. It is shown that surface texture has a strong effect on light scattering and, hence, the propensity for mar visibility. It is also shown that digital imaging via a desktop scanner can be used to quantitatively and objectively assess mar resistance using contrast as a basis. Incorporation of slip agent definitively improves the mar resistance for both types of surfaces. Relationships between contrast, gloss and surface roughness in relation to mar visibility are discussed. 相似文献
16.
B. Degroote T. Vandeweyer N. Collaert W. Boullart E. Kunnen D. Shamiryan J. Wouters J. Van Puymbroeck A. Dixit M. Jurczak 《Microelectronic Engineering》2007,84(4):609-618
We present a method to obtain Si-fins with a critical dimension (CD) below 20 nm, separated by a minimum distance of 25 nm and connected by a common source/drain (S/D) pad. The method comprises of recursive spacer defined patterning to quadruple the line density of a 350 nm pitch resist pattern defined by 193 nm lithography. Spacer defined patterning is combined with resist based patterning to simultaneously define fins and S/D pads in a Silicon on Insulator (SOI) film. CD and Line Width Roughness (LWR) analysis was done on top down SEM images taken in a center die and in an edge die of a 200 mm wafer. The average CD is 17 nm in the center of the wafer and 18 nm at the edge. The LWR is 3 nm for both center and edge. Additional process steps to remove etch damage and round the top corner of the fin (i.e. oxidation followed by H2 anneal) further reduce the CD to 13 nm. 相似文献
17.
18.
Mohamed Lebbai Jang-Kyo Kim W. K. Szeto Matthew M. F. Yuen Pin Tong 《Journal of Electronic Materials》2003,32(6):558-563
Copper-oxide coating applied onto the copper substrate has emerged as an alternative to metallic coatings to improve adhesion
with polymeric adhesives and molding compounds. The interfacial-bond strengths between the black oxide-coated Cu substrate
and epoxy-based, glob-top resin were measured in button-shear tests, and the failure mechanisms were identified from the fracture-surface
examination. The emphasis was to establish the correlation between the coating thickness, the surface roughness, and the interfacial
adhesion with respect to treatment time. It was found that at the initial stage of treatment a thin layer of flat, cuprous
oxide developed, above which fibrillar-cupric oxide was formed with further treatment until saturation with densified fibrils
at about 150 sec. The interfacial-bond strength between the oxide-coated copper substrate and glob-top resin increased gradually
with increasing treatment time, until the bond strength reached a plateau constant after a treatment for about 150 sec. There
was a functional similarity between the oxide thickness, the surface roughness, and the interface-bond strength with respect
to treatment time. A treatment time of 150 sec is considered an optimal condition that can impart the highest interface adhesion. 相似文献
19.
粗化玻璃基板对OLED的影响 总被引:1,自引:0,他引:1
研究了粗化玻璃对有机电致发光器件的影响,分别在玻璃基板的平滑面及粗糙面上制作有机电致发光器件。所制备的器件结构为Al(15nm)/MoO3(60nm)/NPB(40nm)/Alq3∶C545T(2%,30nm)/Alq3(20nm)/LiF(1nm)/Al(100nm)。从电流密度-电压-亮度性能及光谱特性等方面对两种器件进行了对比分析。实验结果显示:当蒸镀面为平面时,电流密度及亮度均比粗面型高,其最高亮度达到24 410cd/m2。不同蒸镀面器件的相对光谱几乎没有变化,但粗面型器件存在黑斑,对其产生的原因进行了探讨。 相似文献
20.