全文获取类型
收费全文 | 333730篇 |
免费 | 25137篇 |
国内免费 | 12519篇 |
专业分类
电工技术 | 17883篇 |
技术理论 | 56篇 |
综合类 | 19688篇 |
化学工业 | 56543篇 |
金属工艺 | 18521篇 |
机械仪表 | 21176篇 |
建筑科学 | 25718篇 |
矿业工程 | 10959篇 |
能源动力 | 9762篇 |
轻工业 | 18629篇 |
水利工程 | 5254篇 |
石油天然气 | 22975篇 |
武器工业 | 2599篇 |
无线电 | 36629篇 |
一般工业技术 | 39775篇 |
冶金工业 | 20285篇 |
原子能技术 | 3215篇 |
自动化技术 | 41719篇 |
出版年
2024年 | 1288篇 |
2023年 | 5208篇 |
2022年 | 8869篇 |
2021年 | 12464篇 |
2020年 | 9815篇 |
2019年 | 8004篇 |
2018年 | 9199篇 |
2017年 | 10375篇 |
2016年 | 9278篇 |
2015年 | 12219篇 |
2014年 | 15868篇 |
2013年 | 19179篇 |
2012年 | 20166篇 |
2011年 | 22446篇 |
2010年 | 19199篇 |
2009年 | 18329篇 |
2008年 | 17974篇 |
2007年 | 17396篇 |
2006年 | 18276篇 |
2005年 | 16131篇 |
2004年 | 10344篇 |
2003年 | 9127篇 |
2002年 | 8133篇 |
2001年 | 7473篇 |
2000年 | 8006篇 |
1999年 | 9736篇 |
1998年 | 8707篇 |
1997年 | 7099篇 |
1996年 | 6561篇 |
1995年 | 5469篇 |
1994年 | 4488篇 |
1993年 | 3214篇 |
1992年 | 2503篇 |
1991年 | 1982篇 |
1990年 | 1522篇 |
1989年 | 1253篇 |
1988年 | 1052篇 |
1987年 | 702篇 |
1986年 | 550篇 |
1985年 | 366篇 |
1984年 | 243篇 |
1983年 | 207篇 |
1982年 | 203篇 |
1981年 | 141篇 |
1980年 | 146篇 |
1979年 | 69篇 |
1978年 | 39篇 |
1977年 | 88篇 |
1976年 | 175篇 |
1975年 | 22篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
In connection with the specific features of high velocity aerated flow generated by hydraulic engineering structures, the mathematical model is developed for high turbulence air-water two-phase flow with the use of twin flow theoretical model in this paper. Furthermore the numerical method is proposed to treat bubbled flows. In addition, on the basis of air-water stratified twin flow model, the new calculation methods and free surface tracking technique are proposed to describe complicated movements of the free surface. Finally, the proposed model is used to calculate artificial aerated flows. The computed results coincide quite well with experimental results. This means that the proposed method can provide solid basis for practical engineering design. 相似文献
992.
993.
Ma Weidong Liu Wen Wenmin Wang Luo Yong Bu Qinlian Xiouli Zhao Jiang Shan Li Wei 《Photonics Technology Letters, IEEE》2007,19(15):1115-1117
An athermal 40-channel dense wavelength-division-multiplexing multi/demultiplexer using a novel combination technology is proposed. It consists of one 1times4 100- to 400-GHz spacing interleaver filter and four sub-arrayed-waveguide gratings (AWGs). The temperature-dependent wavelength shift of the combined device is successfully suppressed to 0.058 nm in the -20degC to 70degC temperature range. Moreover, the combined device's adjacent crosstalk (typically -35 dB) is much better than conventional AWGs (typically -25 dB). 相似文献
994.
Li Yonghua Wang Chunbo Chen Hongwei 《Frontiers of Energy and Power Engineering in China》2007,1(1):96-100
Power plants in China have to burn blended coal instead of one specific coal for a variety of reasons. So it is of great necessity
to investigate the combustion of blended coals. Using a test rig with a capacity of 640 MJ/h with an absolute milling system
and flue gas online analysis system, characteristics such as burnout, slag, and pollution of some blended coals were investigated.
The ratio of coke and slag as a method of distinguishing coal slagging characteristic was introduced. The results show that
the blending of coal has some effect on NO
x
but there is no obvious rule. SO
x
emission can be reduced by blending low sulfur coal.
Translated from Proceedings of the CSEE, 2005, 25(18): 97–103 [译自: 中国电机工程学报] 相似文献
995.
996.
Haiying Wang 《Materials Research Bulletin》2005,40(6):911-919
Eu3+-doped Y2O3, YOF, La2O3, LaOF hollow spheres have been synthesized by a facile template route. Eu3+ were doped into the various host materials to make the hollow sphere red-luminescent. Difference in fluorescence spectra recorded on the hollow spheres were compared in detail and attributed to the different crystal symmetry of host materials. These phosphors might find applications in the fields such as light phosphor powders, advanced flat panel display, or biological labeling. 相似文献
997.
998.
999.
1000.
In order to conduct in vivo continuous monitoring of blood gas levels, very thin disposable pO/sub 2/, pCO/sub 2/, and pH sensors, which could be incorporated into a syringe needle or a catheter, were microfabricated. Electrode patterns were formed on a polyimide substrate and stacked with intervening polyimide insulating layers. An electrolyte layer was formed, which was covered with a silicone rubber gas-permeable membrane or a passivating layer. The most critical part of the sensor was a Ag-AgCl reference electrode with a pinhole structure. Because of the structure and novel operational mode of the reference electrode, its potential stabilized immediately, and reproducible responses were realized for the respective sensors. Performance characterization revealed clear responses and linear calibration plots in the ranges of partial pressures or pH of physiological levels. No significant damages or changes in the performance of the sensors were observed after ethylene oxide sterilization. 相似文献