全文获取类型
收费全文 | 80010篇 |
免费 | 6893篇 |
国内免费 | 3496篇 |
专业分类
电工技术 | 4809篇 |
技术理论 | 9篇 |
综合类 | 4996篇 |
化学工业 | 13748篇 |
金属工艺 | 4204篇 |
机械仪表 | 4559篇 |
建筑科学 | 5788篇 |
矿业工程 | 2078篇 |
能源动力 | 2605篇 |
轻工业 | 5074篇 |
水利工程 | 1434篇 |
石油天然气 | 4146篇 |
武器工业 | 759篇 |
无线电 | 9930篇 |
一般工业技术 | 9888篇 |
冶金工业 | 4316篇 |
原子能技术 | 1001篇 |
自动化技术 | 11055篇 |
出版年
2024年 | 335篇 |
2023年 | 1296篇 |
2022年 | 2474篇 |
2021年 | 3456篇 |
2020年 | 2512篇 |
2019年 | 2172篇 |
2018年 | 2355篇 |
2017年 | 2575篇 |
2016年 | 2358篇 |
2015年 | 3164篇 |
2014年 | 3894篇 |
2013年 | 4955篇 |
2012年 | 5101篇 |
2011年 | 5459篇 |
2010年 | 4680篇 |
2009年 | 4623篇 |
2008年 | 4407篇 |
2007年 | 4156篇 |
2006年 | 4287篇 |
2005年 | 3611篇 |
2004年 | 2678篇 |
2003年 | 2360篇 |
2002年 | 2413篇 |
2001年 | 2056篇 |
2000年 | 1829篇 |
1999年 | 1918篇 |
1998年 | 1722篇 |
1997年 | 1438篇 |
1996年 | 1239篇 |
1995年 | 1007篇 |
1994年 | 769篇 |
1993年 | 619篇 |
1992年 | 501篇 |
1991年 | 382篇 |
1990年 | 275篇 |
1989年 | 251篇 |
1988年 | 232篇 |
1987年 | 133篇 |
1986年 | 132篇 |
1985年 | 102篇 |
1984年 | 65篇 |
1983年 | 46篇 |
1982年 | 64篇 |
1981年 | 46篇 |
1980年 | 33篇 |
1979年 | 36篇 |
1977年 | 20篇 |
1976年 | 28篇 |
1975年 | 17篇 |
1973年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
Shape and size of the synthesized NiO nano-sheets were retained during transformation of sheet-like β-Ni(OH)2 to NiO at elevated temperatures via nano-sized zirconia coating on the surface of β-Ni(OH)2. The average grain size was 6.42 nm after 600 °C treatment and slightly increased to 10 nm after 1000 °C treatment, showing
effective sintering retardation between NiO nano-sheets. The excellent thermal stability revealed potential application at
elevated temperatures, especially for high temperature catalysts and solid-state electrochemical devices. 相似文献
52.
53.
通过细乳液聚合方法制备自交联型有机硅乳液 总被引:3,自引:0,他引:3
苯乙烯与甲基丙烯酸-3-三甲氧基硅丙酯(M PS)经细乳液聚合,制得了稳定的自交联型的水分散涂料,用透射电子显微镜(TEM)、动态光散射仪(DLS)和红外光谱(IR)表征了乳胶粒的形态和结构。发现与传统乳液聚合相比,细乳液聚合法可显著提高乳液的稳定性,且M PS加入量的增加会导致乳液稳定性降低。 相似文献
54.
55.
Summary A water insoluble azo-containing polyelectrolyte (PEAPB6P-AC) was successfully fabricated into multilayer films based on the layer-by-layer adsorption technique by using N, N-dimethylformamide (DMF) as the assembling media. The multilayer growth and structure were studied with UV-vis spectroscopy, and the multilayer surface were imaged with Atomic Force Microscopy and compared with that fabricated in water. The results show that assembling PEAPB6P-AC in DMF can effectively eliminate the hydrophobic aggregation of the azo units and consequently results in a much smoother multilayer surface than that fabricated in water. This improvement to the layer-by-layer adsorption technique, which can avoid some major difficulties faced when assembling hydrophobic polyelectrolytes in aqueous solutions, seems to be a versatile way to fabricate high quality multilayer films when using the hydrophobic even water-insoluble polyelectrolytes as assembling units. 相似文献
56.
57.
S. Perathoner P. Lanzafame R. Passalacqua G. Centi R. Schlgl D.S. Su 《Microporous and mesoporous materials》2006,90(1-3):347-361
SBA15–TiO2 samples prepared by introducing titanium with a grafting method and having TiO2 loadings below 15 wt.% have been characterized by XRF, XRD, IR, porosimetry, SEM, HRTEM, and UV–Visible diffuse reflectance. Differently from the samples reported in the literature characterized by a high TiO2 loading, no evidences have been found for the presence of titania particles inside or outside the mesopores of SBA-15. Three different titanium species were instead evidenced to be present. The first two derive from the reaction of titanium with silanol groups in the corona area of inner SBA-15 walls leading to the formation of either TiO4 tetrahedral sites (by reaction by hydroxyl nests of surface defect sites) and/or pseudo-octahedral surface sites anchored by two (or more) Si or Ti ions through bridging oxygens. The third species derives from the reaction of titanium in the regions with high sylanol density, e.g. in the micropores located in the corona of SBA-15 channels, leading to the formation of TiO2-like nanoareas (probably Si-doped) with dimensions of around 1–2 nm maximum. The potential interest of these materials as photocatalysts, for the presence of a TiO2-like nanoareas highly accessible by reactants, is discussed. 相似文献
58.
The preparation and properties of polyamide hot-melt adhesives derived from Koch C-19 diacid are described. They are comparable
to those of commercial C-36 dimer acid-based polyamides for bonding leather and metals and somewhat superior to those of polyamides
made from C-19 diacid derived from a hydroformylation process.
Presented at the AOCS annual meeting, Toronto, May 1982. 相似文献
59.
In this paper, the photocatalytic activity of industrial titanium dioxide (TiO2) based nacreous pigments was researched as functional building materials for photocatalytic NO remove. Three industrial TiO2 based nacreous pigments were selected to estimate the photocatalytic activity for NO remove. This study is a good proof that pearlescent pigments can eliminate NO, and its performance is positively correlated with its titanium dioxide content. And this research will widen the application of nacreous pigments in functional building materials, and provide a new way to eliminate in door nitric oxide pollution. 相似文献
60.
Chunnuan Ji Rongjun Qu Cheng Bo Cao Huo Chen Qiang Xu Changmei Sun Chunhua Wang Huafang Yuan Jun Zhou 《应用聚合物科学杂志》2006,102(6):6054-6059
A novel chelating resin containing sulfoxide and diethylene glycol, poly{4‐vinylbenzyl‐[2‐2‐(hydroxyethyl)ethoxyl]sulfoxide} (PVESO) was synthesized using chloromethylated polystyrene (PS‐Cl) as material. Its structure was characterized by elemental analysis, infrared spectra, and scanning electron microscopy (SEM). The adsorption capacities of the resin for Hg2+, Ag+, Cu2+, Zn2+, and Pb2+ at various pH values were determined. The maximum adsorption capacities for Hg2+ and Ag+ were 1.56 and 0.75 mmol g?1 respectively. The resin had high selectivity for Hg2+ and Ag+ over the pH range 1.0–7.0. The adsorption capacities for Hg2+ and Ag+ under competitive condition were also determined by batch experiment method. In addition, the adsorption kinetics of the resin towards Hg2+ at different temperatures was also investigated. The results showed that the adsorption rate was governed by film diffusion at 20°C and 25°C, by particle diffusion at 30°C and 35°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 6054–6059, 2006 相似文献