全文获取类型
收费全文 | 112117篇 |
免费 | 11332篇 |
国内免费 | 7192篇 |
专业分类
电工技术 | 8484篇 |
技术理论 | 3篇 |
综合类 | 9070篇 |
化学工业 | 16117篇 |
金属工艺 | 7226篇 |
机械仪表 | 7782篇 |
建筑科学 | 9192篇 |
矿业工程 | 3621篇 |
能源动力 | 3421篇 |
轻工业 | 7680篇 |
水利工程 | 2754篇 |
石油天然气 | 5523篇 |
武器工业 | 1354篇 |
无线电 | 13556篇 |
一般工业技术 | 12056篇 |
冶金工业 | 4536篇 |
原子能技术 | 1649篇 |
自动化技术 | 16617篇 |
出版年
2024年 | 502篇 |
2023年 | 1577篇 |
2022年 | 3002篇 |
2021年 | 4374篇 |
2020年 | 3293篇 |
2019年 | 2743篇 |
2018年 | 3007篇 |
2017年 | 3507篇 |
2016年 | 3295篇 |
2015年 | 4685篇 |
2014年 | 6016篇 |
2013年 | 6947篇 |
2012年 | 8232篇 |
2011年 | 9052篇 |
2010年 | 8396篇 |
2009年 | 8081篇 |
2008年 | 8162篇 |
2007年 | 7833篇 |
2006年 | 7401篇 |
2005年 | 5961篇 |
2004年 | 4376篇 |
2003年 | 3577篇 |
2002年 | 3477篇 |
2001年 | 2916篇 |
2000年 | 2377篇 |
1999年 | 1828篇 |
1998年 | 1164篇 |
1997年 | 1020篇 |
1996年 | 843篇 |
1995年 | 685篇 |
1994年 | 552篇 |
1993年 | 425篇 |
1992年 | 303篇 |
1991年 | 232篇 |
1990年 | 196篇 |
1989年 | 143篇 |
1988年 | 102篇 |
1987年 | 80篇 |
1986年 | 73篇 |
1985年 | 25篇 |
1984年 | 27篇 |
1983年 | 33篇 |
1982年 | 24篇 |
1981年 | 23篇 |
1980年 | 18篇 |
1979年 | 12篇 |
1977年 | 8篇 |
1976年 | 3篇 |
1959年 | 17篇 |
1951年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
191.
Chuxiang Li Jianhua Lu Jun Gu Ming L. Liou 《The Journal of VLSI Signal Processing》2003,33(3):277-285
In this paper, error-resilient schemes are proposed to support robust video transmission for digital terrestrial TV broadcasting (DTTB). In particular, a temporal error concealment incorporated with a low-complexity block-matching is developed, achieving an effective reception of predictive pictures in harsh terrestrial environment. Special algorithms are also designed for isolated I-pictures. Moreover, combined with an intra/inter case prediction, an adaptive error concealment scheme is further contrived to fit for different error conditions. Extensive simulations have been conducted under various DTTB channel conditions, even with a very high packet error rate, to verify the effectiveness of the proposed schemes. 相似文献
192.
193.
Demonstrates that although standard paraxial and wide-angle vector field propagation techniques lead to divergences for sufficiently small grid-point spacings and large refractive index differences, stability may be restored through either certain Pade approximates to the propagation operator or suitable boundary conditions. The authors also introduce a novel alternating directional implicit method applicable to less divergent discretizations of the vector wave equation 相似文献
194.
关于项目管理中施工进度控制的研究 总被引:5,自引:1,他引:4
阐述了项目管理中施工进度控制的地位与作用,分析了影响工程进度的因素,提出项目进度控制需做好的工作,以提高进度控制水平,确保合同工期的实现。 相似文献
195.
The low melting point metallic tin powder or alloy of tin and lead was blended with polypropy-lene. A kind of in situ composite has been prepared. The variations of torque were studied when the composites were mixed in Haake torque rheogeniometer. By way of capillary extrusion, effects upon rheology of the in situ com-posites of the low melting point metals (LMPM) and coupling agent for their different variety and content, were investigated. From flow curves, the results indicate that in situ composites mixed with the LMPM are a kind of pseudoplastic fluid. If the LMPM were melted, the higher the content of the LMPM , the lower apparent viscosity of composites. Meanwhile, when the coupling agent is added into composites, the viscosity of composite will go up first and drop then. This shows that the LMPM have a promoter flow action on the polypropylene. 相似文献
196.
介绍了养马岛大桥钢管拱肋支撑架的设计与施工,从设计方案的比选、施工技术等方面进行了论述,指出该桥使用此种支架施工,保证了质量,降低了成本。 相似文献
197.
198.
In this paper we report the fabrication of ferroelectric Pb(Zr0.52Ti0.48)O3 (PZT) thin films on Si-on-Insulator (SOI) substrates with and without an electrode by pulsed excimer laser deposition combined with rapid thermal annealing. Based on the structural and interfacial characteristics analysis by X-ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS), cross-sectional transmission electron microscopy (XTEM) and automatic spreading resistance measurement (ASR), the film structure and orientation were revealed to be dependent on the annealing time and annealing temperature as well as deposition temperature. From RBS spectra and XTEM observation it is shown that the PZT thin films did not interact with the top silicon layers of SOI and that the composition of the film was similar to the target. The ASR measurements showed that the electrical properties of PZT/SOI as well as PZT/Pt/SOI were abrupt, and that the electrical properties of the SOI substrates were still good after the PZT growth. 相似文献
199.
200.
钇铁石榴石薄膜材料的光吸收谱及Bi,Al掺入对谱的影响研究 总被引:2,自引:1,他引:1
采用单离子晶场跃迁模型,拟合出钇铁石榴石(YIG)薄膜材料的光吸收谱,与实验谱吻合得较好。从实验和理论上分析了(BIAI)YIG 薄膜材料的光吸收谱,结果表明,Al3+离子的作用如同稀释剂一样,减小了光吸收,Bi3+离子由于其强的自旋轨道耦合作用,增大了跃迁振子强度和跃迁线宽,从而增大了光吸收损耗,在此基础上所作的(BiAl)YIG的理论谱与实验谱符合得较好。 相似文献