全文获取类型
收费全文 | 125353篇 |
免费 | 1482篇 |
国内免费 | 1195篇 |
专业分类
电工技术 | 1492篇 |
综合类 | 2367篇 |
化学工业 | 17681篇 |
金属工艺 | 7856篇 |
机械仪表 | 4393篇 |
建筑科学 | 3003篇 |
矿业工程 | 712篇 |
能源动力 | 2523篇 |
轻工业 | 5826篇 |
水利工程 | 1618篇 |
石油天然气 | 1725篇 |
无线电 | 13171篇 |
一般工业技术 | 26811篇 |
冶金工业 | 9824篇 |
原子能技术 | 1038篇 |
自动化技术 | 27990篇 |
出版年
2021年 | 342篇 |
2020年 | 278篇 |
2019年 | 376篇 |
2018年 | 15067篇 |
2017年 | 13993篇 |
2016年 | 10667篇 |
2015年 | 1136篇 |
2014年 | 1025篇 |
2013年 | 2567篇 |
2012年 | 4515篇 |
2011年 | 11230篇 |
2010年 | 9726篇 |
2009年 | 7293篇 |
2008年 | 8363篇 |
2007年 | 9492篇 |
2006年 | 1506篇 |
2005年 | 2420篇 |
2004年 | 2292篇 |
2003年 | 2236篇 |
2002年 | 1596篇 |
2001年 | 1209篇 |
2000年 | 1136篇 |
1999年 | 1053篇 |
1998年 | 2162篇 |
1997年 | 1683篇 |
1996年 | 1483篇 |
1995年 | 991篇 |
1994年 | 768篇 |
1993年 | 782篇 |
1992年 | 608篇 |
1991年 | 594篇 |
1990年 | 524篇 |
1989年 | 485篇 |
1988年 | 378篇 |
1987年 | 402篇 |
1986年 | 364篇 |
1985年 | 381篇 |
1984年 | 305篇 |
1983年 | 300篇 |
1982年 | 301篇 |
1981年 | 296篇 |
1980年 | 349篇 |
1979年 | 341篇 |
1978年 | 294篇 |
1977年 | 415篇 |
1976年 | 629篇 |
1975年 | 308篇 |
1974年 | 292篇 |
1973年 | 311篇 |
1972年 | 272篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Ferrite particles coated with biocompatible phases can be used for hyperthermia treatment of cancer. We have synthesized substituted
calcium hexaferrite, which is not stable on its own but is stabilized with small substitution of La. Hexaferrite of chemical
composition (CaO)0.75(La203)0.20(Fe2O3)6 was prepared using citrate gel method. Hydroxyapatite was prepared by precipitating it from aqueous solution of Ca(NO3)2 and (NH4)2HPO4 maintaining pH above 11. Four different methods were used for coating of hydroxyapatite on ferrite particles. SEM with EDX
and X-ray diffraction analysis shows clear evidence of coating of hydroxyapatite on ferrite particles. These coated ferrite
particles exhibited coercive field up to 2 kOe, which could be made useful for hysteresis heating in hyperthermia. Studies
by culturing BHK-21 cells and WBC over the samples show evidence of biocompatibility. SEM micrographs and cell counts give
clear indication of cell growth on the surface of the sample. Finally coated ferrite particle was implanted in Kasaulli mouse
to test its biocompatibility. The magnetic properties and biocompatibility studies show that these hydroxyapatite coated ferrites
could be useful for hyperthermia. 相似文献
2.
Chloride doped polyaniline conducting polymer films have been prepared in a protic acid medium (HCl) by potentiodynamic method
in an electrochemical cell and studied by cyclic voltammetry and FTIR techniques. The FTIR spectra confirmed Cl- ion doping in the polymers. The polymerization rate was found to increase with increasing concentration of aniline monomer.
But the films obtained at high monomer concentration were rough having a nonuniform flaky polyaniline distribution. Results
showed that the polymerization rate did not increase beyond a critical HCl concentration. Cyclic voltammetry suggested that,
the oxidation-reduction current increased with an increase in scan rate and that the undoped polyaniline films were not hygroscopic
whereas chloride doped polyaniline films were found to be highly hygroscopic. 相似文献
3.
4.
H. L. Du S. R. Rose Z. D. Xiang P. K. Datta X. Y. Li 《Materialwissenschaft und Werkstofftechnik》2003,34(4):421-426
The oxidation/sulphidation behaviour of a Ti‐46.7Al‐1.9W‐0.5Si alloy with a TiAl3 diffusion coating was studied in an environment of H2/H2S/H2O at 850oC. The kinetic results demonstrate that the TiAl3 coating significantly increased the high temperature corrosion resistance of Ti‐46.7Al‐1.9W‐0.5Si. The SEM, EDX, XRD and TEM analysis reveals that the formation of an Al2O3 scale on the surface of the TiAl3‐coated sample was responsible for the enhancement of the corroison resistance. The Ti‐46.7Al‐1.9W‐0.5Si alloy was also modified by Nb ion implantation. The Nb ion implanted and as received sampels were subjected to cyclic oxidation in an open air at 800oC. The Nb ion implantation not only increased the oxidation resistance but also substantially improved the adhesion of scale to the substrate. 相似文献
5.
6.
7.
8.
A.L. Pan H.G. ZhengZ.P. Yang F.X. Liu Z.J. Ding Y.T. Qian 《Materials Research Bulletin》2003,38(5):789-796
Small Ag particles or clusters dispersed mesoporous SiO2 composite films were prepared by a new method: First the matrix SiO2 films were prepared by sol-gel process combined with the dip-coating technique, then they were soaked in AgNO3 solutions followed by irradiation of γ-ray at room temperature and in ambient pressure. The structures of these films were examined by X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), and optical absorption spectroscopy. It has been shown that the Ag particles grown within the porous SiO2 films are very small, and they are isolated and dispersed from each other with very narrow size distributions. With increasing the soaking concentration and an additional annealing, an opposite peakshift effect of the surface plasmon resonance (SPR) was observed in the optical absorption measurements. 相似文献
9.
10.