全文获取类型
收费全文 | 22022篇 |
免费 | 1914篇 |
国内免费 | 576篇 |
专业分类
电工技术 | 935篇 |
综合类 | 983篇 |
化学工业 | 4445篇 |
金属工艺 | 1046篇 |
机械仪表 | 1227篇 |
建筑科学 | 1065篇 |
矿业工程 | 333篇 |
能源动力 | 831篇 |
轻工业 | 2110篇 |
水利工程 | 252篇 |
石油天然气 | 598篇 |
武器工业 | 91篇 |
无线电 | 2929篇 |
一般工业技术 | 3814篇 |
冶金工业 | 1158篇 |
原子能技术 | 245篇 |
自动化技术 | 2450篇 |
出版年
2024年 | 50篇 |
2023年 | 295篇 |
2022年 | 539篇 |
2021年 | 765篇 |
2020年 | 577篇 |
2019年 | 577篇 |
2018年 | 653篇 |
2017年 | 711篇 |
2016年 | 792篇 |
2015年 | 799篇 |
2014年 | 1093篇 |
2013年 | 1408篇 |
2012年 | 1477篇 |
2011年 | 1780篇 |
2010年 | 1431篇 |
2009年 | 1277篇 |
2008年 | 1195篇 |
2007年 | 1098篇 |
2006年 | 906篇 |
2005年 | 847篇 |
2004年 | 765篇 |
2003年 | 789篇 |
2002年 | 900篇 |
2001年 | 773篇 |
2000年 | 526篇 |
1999年 | 438篇 |
1998年 | 437篇 |
1997年 | 317篇 |
1996年 | 244篇 |
1995年 | 201篇 |
1994年 | 177篇 |
1993年 | 113篇 |
1992年 | 100篇 |
1991年 | 66篇 |
1990年 | 54篇 |
1989年 | 60篇 |
1988年 | 33篇 |
1987年 | 18篇 |
1986年 | 22篇 |
1985年 | 12篇 |
1984年 | 21篇 |
1983年 | 21篇 |
1982年 | 14篇 |
1981年 | 19篇 |
1980年 | 12篇 |
1979年 | 11篇 |
1976年 | 12篇 |
1974年 | 9篇 |
1973年 | 10篇 |
1970年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
92.
93.
The employment of the Zn(Se,Te) pseudo-graded contacting scheme to p-type ZnSe-based alloys contributes directly to the recent
demonstration of room temperature continuous-wave operation of II– VI green-blue laser diodes. Contact ohmicity is maintained
down to cryogenic temperatures which enabled the investigation of electrical transport properties associated with the p-type
nitrogen-doped ZnSe, Zn(S,Se), and (Zn,Mg)(S,Se). The observation of both persistent photoconductivity and a metastable population
of holes which are in thermodynamic equilibrium with hydrogenic acceptors having reduced activation energy suggests the presence
of a DX-like behavior for holes in p-type (Zn,Mg)(S,Se). 相似文献
94.
Kazuko Satake Ai Katayama Hideki Ohkoshi Takeshi Nakahara Takashi Takeuchi 《Sensors and actuators. B, Chemical》1994,20(2-3):111-117
Oxide semiconductors have been examined to develop NOx sensors for exhaust monitoring. Titania doped with trivalent elements, such as Al3+, Sc3+, Ga3+ or In3+, has a good sensitivity and selectivity to NO between 450 and 550 °C, and shows rapid response. A sensor probe for monitoring exhaust NOx has been fabricated. Many kinds of interference gases, such as C3H6, CO and SO2, have been found to have only a slight influence on the sensor response to NO. The influence of O2 and H2O is also negligible, except for the cases of 0% H2O and fuel-rich conditions. In accordance with these results, the sensor probe operates satisfactority in the exhaust gas of various combustion conditions without interference from the various kinds of gas species in the exhaust gases. 相似文献
95.
96.
97.
Jung Nam Bae Jin Young Kim Geon Kim Yong Tae Lee Jae Sang Cha 《Multimedia Tools and Applications》2012,57(2):359-372
Recently, watermarking based data transmission techniques using terrestrial digital TV signal have been proposed since they
are also cost-free and can overcome the limitations of GPS. However, in the previous watermarking based methods, the detection
accuracy is low and additional data rate is too low. Thus, we propose the throughput enhancement method by employing the TZCD-MBOK
watermarking technique in T-DMB system. By applying the proposed scheme to T-DMB, it allows additional data transmission for
disaster broadcasting and improves efficiency of data transmission in shadow region and indoor to mobile environment through
watermarking spread code. From the simulation results, we confirm the proposed watermarking scheme affected on the existing
T-DMB signal. Moreover, it was also confirmed that the system capacity increases as the power of additional watermarking signal
rose. The results of the paper can be applied to wireless multimedia digital broadcasting systems. 相似文献
98.
99.
100.