全文获取类型
收费全文 | 110266篇 |
免费 | 18437篇 |
国内免费 | 4026篇 |
学科分类
工业技术 | 132729篇 |
出版年
2024年 | 227篇 |
2023年 | 817篇 |
2022年 | 1525篇 |
2021年 | 2368篇 |
2020年 | 3021篇 |
2019年 | 4490篇 |
2018年 | 4561篇 |
2017年 | 5106篇 |
2016年 | 5519篇 |
2015年 | 6263篇 |
2014年 | 7101篇 |
2013年 | 8918篇 |
2012年 | 7556篇 |
2011年 | 7632篇 |
2010年 | 7520篇 |
2009年 | 7372篇 |
2008年 | 6933篇 |
2007年 | 6541篇 |
2006年 | 6227篇 |
2005年 | 5191篇 |
2004年 | 4505篇 |
2003年 | 4175篇 |
2002年 | 4680篇 |
2001年 | 4059篇 |
2000年 | 3077篇 |
1999年 | 1907篇 |
1998年 | 1016篇 |
1997年 | 851篇 |
1996年 | 746篇 |
1995年 | 647篇 |
1994年 | 475篇 |
1993年 | 354篇 |
1992年 | 286篇 |
1991年 | 223篇 |
1990年 | 184篇 |
1989年 | 119篇 |
1988年 | 110篇 |
1987年 | 85篇 |
1986年 | 44篇 |
1985年 | 60篇 |
1984年 | 44篇 |
1983年 | 36篇 |
1982年 | 20篇 |
1981年 | 21篇 |
1980年 | 22篇 |
1979年 | 14篇 |
1978年 | 9篇 |
1977年 | 14篇 |
1976年 | 15篇 |
1951年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
A route to synthesize ZSM‐5 crystals with a bimodal micro/mesoscopic pore system has been developed in this study; the successful incorporation of the mesopores within the ZSM‐5 structure was performed using tetrapropylammonium hydroxide (TPAOH)‐impregnated mesoporous materials containing carbon nanotubes in the pores, which were encapsulated in the ZSM‐5 crystals during a solid rearrangement process within the framework. Such mesoporous ZSM‐5 zeolites can be readily obtained as powders, thin films, or monoliths. 相似文献
23.
T. Choi J.‐H. Jang C.K. Ullal M.C. LeMieux V.V. Tsukruk E.L. Thomas 《Advanced functional materials》2006,16(10)
The probing of the micromechanical properties within a two‐dimensional polymer structure with sixfold symmetry fabricated via interference lithography reveals a nonuniform spatial distribution in the elastic modulus “imprinted” with an interference pattern in work reported by Tsukruk, Thomas, and co‐workers on p. 1324. The image prepared by M. Lemieux and T. Gorishnyy shows how the interference pattern is formed by three laser beams and is transferred to the solid polymer structure. The elastic and plastic properties within a two‐dimensional polymer (SU8) structure with sixfold symmetry fabricated via interference lithography are presented. There is a nonuniform spatial distribution in the elastic modulus, with a higher elastic modulus obtained for nodes (brightest regions in the laser interference pattern) and a lower elastic modulus for beams (darkest regions in the laser interference pattern) of the photopatterned films. We suggest that such a nonuniformity and unusual plastic behavior are related to the variable material properties “imprinted” by the interference pattern. 相似文献
24.
25.
关于我国钢铁工业发展战略的思考 总被引:2,自引:0,他引:2
21世纪初是世界经济发展的重大战略机遇期,如何抓住机遇加快发展,是中国钢铁行业应认真思考的问题。十一五我国钢铁工业的发展,靠什么来拉动,还能靠大规模的投资吗?目前我们还不能生产的双高产品怎么办,靠花钱能买来技术吗?靠市场能换来核心产品吗?值得深思。当今,我们思考的不仅应考虑个别企业的生存问题,而更应考虑的是钢铁行业整体的长远发展问题,即 相似文献
26.
27.
28.
电力系统谐波检测的现状与发展 总被引:7,自引:0,他引:7
准确、实时地对电力系统谐波进行检测有着重要的意义。本文根据电力系统谐波测量的基本方法,对近年来电力系统谐波检测的新方法进行了分析和评述。最后对电力系统的谐波测量进行了总结并提出了看法。 相似文献
29.
Polyaryloxydiphenylsilanes were prepared from phosphorus‐containing diols and diphenydichlorolsilane through solution polymerization. With a stoichiometric imbalance in feed monomers, the resulting polymers exhibited moderate melting points and good processing properties. The polymers prepared showed initial decomposition temperatures above 340 °C, excellent thermal stability, high char yields at 850 °C and very high limited oxygen index values of 56–59. The polymers' char yields and their (P + Si) contents showed linear relationships. © 2003 Society of Chemical Industry 相似文献
30.
L. Sheeney‐Haj‐Ichia S. Pogorelova Y. Gofer I. Willner 《Advanced functional materials》2004,14(5):416-424
Three different configurations of Au‐nanoparticle/CdS‐nanoparticle arrays are organized on Au/quartz electrodes for enhanced photocurrent generation. In one configuration, Au‐nanoparticles are covalently linked to the electrode and the CdS‐nanoparticles are covalently linked to the bare Au‐nanoparticle assembly. The resulting photocurrent, φ = 7.5 %, is ca. 9‐fold higher than the photocurrent originating from a CdS‐nanoparticle layer that lacks the Au‐nanoparticles, φ = 0.8 %. The enhanced photocurrent in the Au/CdS nanoparticle array is attributed to effective charge separation of the electron–hole pair by the injection of conduction‐band electrons from the CdS‐ to the Au‐nanoparticles. Two other configurations involving electrostatically stabilized bipyridinium‐crosslinked Au/CdS or CdS/Au nanoparticle arrays were assembled on the Au/quartz crystal. The photocurrent quantum yields in the two systems are φ = 10 % and φ = 5 %, respectively. The photocurrents in control systems that include electrostatically bridged Au/CdS or CdS/Au nanoparticles by oligocationic units that lack electron‐acceptor units are substantially lower than the values observed in the analogous bipyridinium‐bridged systems. The enhanced photocurrents in the bipyridinium‐crosslinked systems is attributed to the stepwise electron transfer of conduction‐band electrons to the Au‐nanoparticles by the bipyridinium relay bridge, a process that stabilizes the electron–hole pair against recombination and leads to effective charge separation. 相似文献