全文获取类型
收费全文 | 8795篇 |
免费 | 175篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 58篇 |
综合类 | 5篇 |
化学工业 | 1061篇 |
金属工艺 | 116篇 |
机械仪表 | 75篇 |
建筑科学 | 217篇 |
矿业工程 | 4篇 |
能源动力 | 89篇 |
轻工业 | 542篇 |
水利工程 | 31篇 |
石油天然气 | 8篇 |
武器工业 | 1篇 |
无线电 | 379篇 |
一般工业技术 | 908篇 |
冶金工业 | 4975篇 |
原子能技术 | 58篇 |
自动化技术 | 444篇 |
出版年
2022年 | 43篇 |
2021年 | 65篇 |
2020年 | 46篇 |
2019年 | 50篇 |
2018年 | 76篇 |
2017年 | 75篇 |
2016年 | 101篇 |
2015年 | 100篇 |
2014年 | 114篇 |
2013年 | 163篇 |
2012年 | 159篇 |
2011年 | 190篇 |
2010年 | 183篇 |
2009年 | 147篇 |
2008年 | 179篇 |
2007年 | 148篇 |
2006年 | 159篇 |
2005年 | 115篇 |
2004年 | 121篇 |
2003年 | 134篇 |
2002年 | 108篇 |
2001年 | 126篇 |
2000年 | 112篇 |
1999年 | 241篇 |
1998年 | 1613篇 |
1997年 | 977篇 |
1996年 | 646篇 |
1995年 | 340篇 |
1994年 | 259篇 |
1993年 | 315篇 |
1992年 | 78篇 |
1991年 | 93篇 |
1990年 | 105篇 |
1989年 | 96篇 |
1988年 | 81篇 |
1987年 | 74篇 |
1986年 | 83篇 |
1985年 | 65篇 |
1984年 | 37篇 |
1983年 | 47篇 |
1982年 | 56篇 |
1981年 | 53篇 |
1980年 | 68篇 |
1979年 | 48篇 |
1978年 | 45篇 |
1977年 | 156篇 |
1976年 | 273篇 |
1975年 | 39篇 |
1970年 | 27篇 |
1966年 | 26篇 |
排序方式: 共有8971条查询结果,搜索用时 15 毫秒
991.
992.
R. Schmidt 《工业材料与腐蚀》2006,57(2):203-203
993.
M. Benyoucef A. Rastelli O. G. Schmidt S. M. Ulrich P. Michler 《Nanoscale research letters》2006,1(2):172-176
We report on the experimental observation of bright photoluminescence emission at room temperature from single unstrained GaAs quantum dots (QDs). The linewidth of a single-QD ground-state emission (≈ 8.5 meV) is comparable to the ensemble inhomogeneous broadening (≈ 12.4 meV). At low temperature (T ≤ 40 K) photon correlation measurements under continuous wave excitation show nearly perfect single-photon emission from a single GaAs QD and reveal the single photon nature of the emitted light up to 77 K. The QD emission energies, homogeneous linewidths and the thermally activated behavior as a function of temperature are discussed. 相似文献
994.
Integrated hollow waveguides with arch-shaped cores 总被引:1,自引:0,他引:1
J.P. Barber E.J. Lunt Z.A. George Dongliang Yin H. Schmidt A.R. Hawkins 《Photonics Technology Letters, IEEE》2006,18(1):28-30
An optical waveguide is described that has a hollow arch-shaped core. Optical confinement for this structure is based on the antiresonant reflecting optical waveguide principle. The waveguides are built on a silicon substrate using a sacrificial etch technique with reflowed photoresist serving as the sacrificial material and producing the core's arch shape. Investigations of fabrication parameters are reported that allow for predicting a final arch-shaped geometry based on initial photoresist width and thickness. Optical mode guiding is demonstrated in an arch-shaped waveguide with a liquid core. 相似文献
995.
996.
997.
PC12 cells are known to express the prion protein, a normal cell surface glycoprotein. This protein is upregulated in PC12 cells differentiated with nerve growth factor. A neurotoxic prion protein peptide, PrP106-126, is not toxic to PC12 cells alone. PrP106-126 is toxic to PC12 cells co-cultured with microglia and more so to NGF-differentiated PC12 cells. PC12 cells selected for resistance to either copper toxicity or oxidative stress have higher levels of PrP(C) expression. Both PC12 variants are more sensitive to the toxicity of PrP106-126. This suggests that PC12 sensitivity to PrP106-126 toxicity is related to prion protein expression and not to a state of high differentiation induced by NGF. Variants of PC12 cells that are more resistant to copper toxicity have higher levels of anti-oxidant enzymes, superoxide dismutase and glutathione peroxidase. Our results suggest that cells expressing higher levels of PrP(C) have higher resistance to oxidative stress or copper toxicity but are more sensitive to PrP106-126 toxicity. Prion protein expression may be involved in both the metabolism of copper and resistance to oxidative stress. Increased cellular resistance to copper toxicity may be partly related to increased activity of anti-oxidant enzymes. 相似文献
998.
EB Blanchard ML Peters C Hermann SM Turner TC Buckley K Barton MP Dentinger 《Canadian Metallurgical Quarterly》1997,22(4):227-245
In order to test for the specific therapeutic effects of thermal biofeedback (TBF) for hand warming on vascular headache (HA), 70 patients with chronic vascular HA were randomly assigned to TBF for hand warming, TBF for hand cooling, TBF for stabilization of hand temperature, or biofeedback to suppress alpha in the EEG. Patients in each condition initially had high levels of expectation of therapeutic benefit and found the treatment rationales highly credible. Participants in each condition received 12 treatment sessions on a twice-per-week basis. Based on daily HA diary data gathered for 4 weeks prior to treatment and 4 weeks after treatment, HA Index was significantly (p = .003) reduced as was HA medication consumption. There were no differential reductions in HA Index or Medication Index among the four conditions. Global self-reports of improvement gathered at the end of the post-treatment monitoring period also did not differ among the four conditions. We were unable to demonstrate a specific effect of TBF for hand warming on vascular HA activity. 相似文献
999.
We outline a design of a highly scalable network monitoring, visualization, and control (NMVC) system with advanced algorithmic and human-in-the-loop capability. This capability allows network administrators to calibrate and fine-tune network and application parameters in real time according to observed traffic patterns. The goal of the NMVC system is to ensure adequate quality of service to network users, while maintaining high network resource utilization. The main components of our system are: a network probe and an endsystem probe which can probe gigabit/s links, software network management agents that provide extensible multi-attribute event filtering for highly scalable date/event collection, efficient online event ordering algorithms that can help synthesize and display a consistent view of network health, status, and performance and a View Choreographer that allows management applications and administrators to specify the mapping of network events to higher-level events and to visualization objects and updates 相似文献
1000.