全文获取类型
收费全文 | 35269篇 |
免费 | 2645篇 |
国内免费 | 1905篇 |
专业分类
电工技术 | 1579篇 |
技术理论 | 1篇 |
综合类 | 1747篇 |
化学工业 | 8379篇 |
金属工艺 | 7373篇 |
机械仪表 | 1766篇 |
建筑科学 | 1612篇 |
矿业工程 | 693篇 |
能源动力 | 1666篇 |
轻工业 | 1842篇 |
水利工程 | 179篇 |
石油天然气 | 1123篇 |
武器工业 | 305篇 |
无线电 | 3102篇 |
一般工业技术 | 5351篇 |
冶金工业 | 1396篇 |
原子能技术 | 301篇 |
自动化技术 | 1404篇 |
出版年
2025年 | 18篇 |
2024年 | 759篇 |
2023年 | 832篇 |
2022年 | 1033篇 |
2021年 | 1196篇 |
2020年 | 1266篇 |
2019年 | 1128篇 |
2018年 | 1049篇 |
2017年 | 1268篇 |
2016年 | 1162篇 |
2015年 | 1182篇 |
2014年 | 1820篇 |
2013年 | 1863篇 |
2012年 | 2293篇 |
2011年 | 2603篇 |
2010年 | 2037篇 |
2009年 | 1974篇 |
2008年 | 1710篇 |
2007年 | 2075篇 |
2006年 | 2074篇 |
2005年 | 1709篇 |
2004年 | 1504篇 |
2003年 | 1265篇 |
2002年 | 1110篇 |
2001年 | 927篇 |
2000年 | 800篇 |
1999年 | 597篇 |
1998年 | 494篇 |
1997年 | 391篇 |
1996年 | 366篇 |
1995年 | 294篇 |
1994年 | 240篇 |
1993年 | 194篇 |
1992年 | 185篇 |
1991年 | 91篇 |
1990年 | 74篇 |
1989年 | 69篇 |
1988年 | 38篇 |
1987年 | 16篇 |
1986年 | 20篇 |
1985年 | 19篇 |
1984年 | 13篇 |
1983年 | 13篇 |
1982年 | 12篇 |
1981年 | 11篇 |
1980年 | 9篇 |
1979年 | 3篇 |
1975年 | 2篇 |
1959年 | 2篇 |
1951年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
23.
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
24.
ATO包裹硅酸锆的制备与应用 总被引:2,自引:0,他引:2
采用化学共沉淀技术制备了锑掺杂二氧化锡(ATO)包裹硅酸锆的导电粉体,对比了该导电粉体与ATO在防静电陶瓷中的应用效果。结果表明与掺纯ATO相比较,掺入ATO包裹硅酸锆的防静电陶瓷颜色比较浅,并且能明显减少氧化锡的用量,当陶瓷的表面电阻为107Ω/□量级时,用ATO包裹硅酸锆作为导电填料可以节省25%左右的ATO。 相似文献
25.
26.
转化乳剂的离子电导和光电导研究 总被引:1,自引:0,他引:1
本文研究了AgBrCl转化乳剂的离子电导和光电导。随着乳剂中溴含量的增高,其离子电导也随之升高,而光电子寿命则降低。AgBrCl乳剂的离子电导主要取决于其组成;AgBrCl转化乳剂的光电子寿命主要受隙间银子浓度的影响,隙间银离子浓度越大,光电子寿命越短。 相似文献
27.
Polypropylene/poly(methyl acrylate)‐grafted glass wool (PMA‐g‐GW) mixes were prepared. The polymerization process was carried out using potassium persulfate (PPS) and PPS/acetone sodium bisulfite (ASBS) as a redox‐pair initiation system at 60 and 70°C. The effect of using PPS or PPS/ASBS on the grafting percent and conversion percent reveals that the conversion percent values on using PPS as an initiator are higher than those of PPS/ASBS, while in the case of grafting, the inverse is true, that is, using PPS as an initiator gives grafting percent values lower than those that can be obtained using PPS/ASBS. The dielectric properties, thermal diffusivity, specific heat capacity, and thermal conductivity of PP loaded with modified glass wool as a function of different types and concentrations of initiators—used in the grafting polymerization process, namely, PPS and the redox initiating system—were also studied. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 723–732, 2003 相似文献
28.
V.V. Zyryanov N.F. Uvarov V.A. Sadykov Y.V. Frolova G.M. Alikina A.I. Lukashevich M.I. Ivanovskaya J.M. Criado S. Neophytides 《Catalysis Today》2005,104(2-4):114-119
Nanopowders of LaGaO3- and LaMnO3-based complex perovskites (P) and ceria-based fluorites (F) were prepared by mechanosynthesis. Compatible nanocomposites F + P and P + P with mixed ion and electron conducting (MIEC) properties were prepared and sintered at moderate temperatures up to dense ceramics. The obtained materials were studied by means of XRD, SEM, TEM, electrical conductivity measurements, temperature programmed (TP) reduction/oxidation and preliminary estimations of permeability were obtained. A new strategy based on the advantages of the mechanochemical ceramic approach is proposed to design multilayer ceramic membranes for CMR. Casting technology and one-step sintering were used for the production of thin film membranes with MIEC properties on porous substrates. The coarse fraction of as-milled powders from agglomerates with density 70% was used for the porous substrate, and fine fractions of aggregates with sizes <1 μm were used in preparation of composites for thin dense films. Ceria-based composites prepared by the Pechini route and/or mechanochemical method are proposed as materials for protecting thin films. 相似文献
29.
MENG Fan-Jun XU Bin-Shi ZHU Sheng MA Shi-Ming ZHANG Wei ZHU Zi-Xin National Key Laboratory for Remanufacturing Beijng China 《材料热处理学报》2004,(5)
Fe-Al intermetallics with remarkable high-temperatureintensity and excellent erosion,high-temperatureoxidation and sulfuration resistance are potential lowcost high-temperature structural material.ProducingFe-Al/WC composite coating by high velocity arcspraying(HVAS)on structural materials would notonly obviate the problems faced in fabrication of thesealloys into useful shapes,but also allow the effectiveuse of their outstanding high-temperature performance,which might thus promisingly mak… 相似文献
30.