首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   666篇
  免费   38篇
  国内免费   1篇
电工技术   3篇
综合类   2篇
化学工业   179篇
金属工艺   13篇
机械仪表   16篇
建筑科学   20篇
矿业工程   1篇
能源动力   19篇
轻工业   23篇
水利工程   4篇
无线电   60篇
一般工业技术   133篇
冶金工业   24篇
原子能技术   6篇
自动化技术   202篇
  2023年   8篇
  2022年   10篇
  2021年   19篇
  2020年   9篇
  2019年   10篇
  2018年   26篇
  2017年   10篇
  2016年   28篇
  2015年   22篇
  2014年   31篇
  2013年   28篇
  2012年   51篇
  2011年   66篇
  2010年   41篇
  2009年   42篇
  2008年   38篇
  2007年   32篇
  2006年   25篇
  2005年   15篇
  2004年   21篇
  2003年   22篇
  2002年   23篇
  2001年   10篇
  2000年   10篇
  1999年   9篇
  1998年   10篇
  1997年   8篇
  1995年   6篇
  1994年   2篇
  1993年   5篇
  1992年   4篇
  1991年   5篇
  1990年   4篇
  1989年   5篇
  1988年   3篇
  1987年   2篇
  1985年   2篇
  1984年   3篇
  1970年   2篇
  1965年   1篇
  1963年   1篇
  1962年   3篇
  1961年   2篇
  1960年   2篇
  1958年   1篇
  1957年   2篇
  1956年   4篇
  1955年   3篇
  1954年   2篇
  1953年   2篇
排序方式: 共有705条查询结果,搜索用时 15 毫秒
101.
In the last decade, many papers have been published to present sequential connected component labeling (CCL) algorithms. As modern processors are multi-core and tend to many cores, designing a CCL algorithm should address parallelism and multithreading. After a review of sequential CCL algorithms and a study of their variations, this paper presents the parallel version of the Light Speed Labeling for connected component analysis (CCA) and compares it to our parallelized implementations of State-of-the-Art sequential algorithms. We provide some benchmarks that help to figure out the intrinsic differences between these parallel algorithms. We show that thanks to its run-based processing, the LSL is intrinsically more efficient and faster than all pixel-based algorithms. We show also, that all the pixel-based are memory-bound on multi-socket machines and so are inefficient and do not scale, whereas LSL, thanks to its RLE compression can scale on such high-end machines. On a 4 × 15-core machine, and for 8192 × 8192 images, LSL outperforms its best competitor by a factor ×10.8 and achieves a throughput of 42.4 gigapixel labeled per second.  相似文献   
102.
Extraction of soybean flakes with 90, 95, 98 and 100% ethanol resulted in more rapid lipid and less rapid non-lipid removal with the increasing ethanol concentrations. There was little difference in the quality of the oil produced by the different solvents. Protein content of the residual meal averaged 52.1%.  相似文献   
103.
Summary Specific gravity-concentration data have been determined for wheat germ oil, milkweed seed oil, and cottonseed oil miscellas where trichloroethylene is used as a solvent. Extraction rate data at two temperatures and pilot plant runs on wheat germs, cottonseed, cottonseed meats, and milkweed seeds indicate increasing extraction time in the order given.  相似文献   
104.
The structural role of V in 28Li2O–72SiO2 (in mol%) lithium silicate glass doped with 0.5 mol% V2O5 was assessed using 29Si and 51V Nuclear Magnetic Resonance (NMR), Fourier-transform infrared (FTIR), and X-ray photoelectron (XPS) spectroscopy techniques. Despite the low amount of V2O5 used, the structural information obtained or deduced from the statistical analysis of the NMR data could explain the evolution of glass properties after V2O5 addition. The XPS results indicated that all vanadium exists in 5+ oxidation state. Both the 29Si NMR and FTIR data point toward an increase in the polymerization of the silicate network, caused by the V2O5 acting as network former, capable to form various tetrahedral units (for n = 0, 1, and 2) in the glasses. These units, which are similar to phosphate units, scavenge the Li+ ions and cause the silicate network to polymerize. However, in an overall balance, the entire glass network is depolymerized due to the additional nonbridging oxygens contributed by the vanadium polyhedra. The addition of vanadium causes the network to expand and increases the ionic conductivity.  相似文献   
105.
The areal energy density of on‐chip micro‐supercapacitors should be improved in order to obtain autonomous smart miniaturized sensors. To reach this goal, high surface capacitance electrode (>100 mF cm?2) has to be produced while keeping low the footprint area. For carbide‐derived carbon (CDC) micro‐supercapacitors, the properties of the metal carbide precursor have to be fine‐tuned to fabricate thick electrodes. The ad‐atoms diffusion process and atomic peening effect occurring during the titanium carbide sputtering process are shown to be the key parameters to produce low stress, highly conductive, and thick TiC films. The sputtered TiC at 10?3 mbar exhibits a high stress level, limiting the thickness of the TiC‐CDC electrode to 1.5 µm with an areal capacitance that is less than 55 mF cm?2 in aqueous electrolyte. The pressure increase up to 10?2 mbar induces a clear reduction of the stress level while the layer thickness increases without any degradation of the TiC electronic conductivity. The volumetric capacitance of the TiC‐CDC electrodes is equal to 350 F cm?3 regardless of the level of pressure. High values of areal capacitance (>100 mF cm?2) are achieved, whereas the TiC layer is relatively thick, which paves the way toward high‐performance micro‐supercapacitors.  相似文献   
106.
This paper presents a new technique for optimized energy harvesting using piezoelectric microgenerators called double synchronized switch harvesting (DSSH). This technique consists of a nonlinear treatment of the output voltage of the piezoelectric element. It also integrates an intermediate switching stage that ensures an optimal harvested power whatever the load connected to the microgenerator. Theoretical developments are presented considering either constant vibration magnitude, constant driving force, or independent extraction. Then experimental measurements are carried out to validate the theoretical predictions. This technique exhibits a constant output power for a wide range of load connected to the microgenerator. In addition, the extracted power obtained using such a technique allows a gain up to 500% in terms of maximal power output compared with the standard energy harvesting method. It is also shown that such a technique allows a fine-tuning of the trade-off between vibration damping and energy harvesting.  相似文献   
107.
“Africans believe in something that is difficult to render in English. We call it ubuntu or botho. It means the essence of being human. You know when it is there and when it is absent. It speaks about humanness, gentleness, hospitality, putting yourself out on behalf of others, being vulnerable. It embraces compassion and roughness. It recognizes that my humanity is bound up in yours, for we can only be human together” (Desmond Tutu)  相似文献   
108.
109.
Polarization shift keying (PolSK) is a digital modulation technique using the state of polarization of an electromagnetic wave as the signalling quantity. PolSK comes from fibre communications, where the channel offers two orthogonal states of polarization. This article develops on the idea to adapt this technology to satellite communications, where similar channel conditions exist. For this purpose, a digital PolSK modem was implemented on a programmable logic board. A proposal for constellation design as well as thoughts on synchronization of PolSK over satellite is presented. The modem was used to demonstrate a 16‐state Polarization Shift Keying link over a commercial satellite in Ku band. Measurements have been conducted in a back‐to‐back setup on intermediate frequency and on a Ku band transponder simulator to assess the impact of path‐length differences, carrier recovery and non‐linearity. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
110.
The synthesis of a novel group of quinacridine-based ligands (MMQs) is described along with an evaluation of their G-quadruplex binding properties. A set of biophysical assays was applied to characterize their interaction with DNA quadruplexes: FRET-melting experiments and equilibrium microdialysis were used to evaluate their quadruplex affinity and their ability to discriminate quadruplexes across a broad panel of DNA structures. All data collected support the proposed model of interaction of these compounds with G-quadruplexes, which is furthermore confirmed by a solution structure determined by 2D NMR experiments. Finally, the activity of the MMQ series against tumor cell growth is reported, and the data support the potential of quadruplex-interactive compounds for use in anticancer approaches.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号