全文获取类型
收费全文 | 184篇 |
免费 | 8篇 |
国内免费 | 13篇 |
专业分类
电工技术 | 7篇 |
综合类 | 6篇 |
化学工业 | 15篇 |
金属工艺 | 19篇 |
机械仪表 | 10篇 |
建筑科学 | 10篇 |
矿业工程 | 8篇 |
能源动力 | 9篇 |
轻工业 | 18篇 |
水利工程 | 9篇 |
石油天然气 | 6篇 |
无线电 | 17篇 |
一般工业技术 | 28篇 |
冶金工业 | 20篇 |
原子能技术 | 14篇 |
自动化技术 | 9篇 |
出版年
2024年 | 2篇 |
2023年 | 9篇 |
2022年 | 5篇 |
2021年 | 6篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 13篇 |
2017年 | 3篇 |
2016年 | 6篇 |
2015年 | 2篇 |
2014年 | 9篇 |
2013年 | 9篇 |
2012年 | 11篇 |
2011年 | 10篇 |
2010年 | 6篇 |
2009年 | 3篇 |
2008年 | 12篇 |
2007年 | 8篇 |
2006年 | 6篇 |
2005年 | 6篇 |
2004年 | 2篇 |
2003年 | 5篇 |
2002年 | 2篇 |
2001年 | 3篇 |
2000年 | 10篇 |
1999年 | 7篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 5篇 |
1993年 | 8篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1984年 | 1篇 |
1981年 | 2篇 |
排序方式: 共有205条查询结果,搜索用时 15 毫秒
11.
LI Gui-an SONG Jian-ping LI Xiu 《中国电子科技》2005,3(3):256-259
Synthesis of the optoelectronic storage material with structure for coating by nanosized metal and azo-dye was reported. The characterization of composites was made by using transmission electron microscope (TEM), ultraviolet-visible spectrometer (UV-Vis) and thermogravity analyzer (TGA). It is found that, due to the specific structure, in which azo-dye molecules are oriented and adsorbed on the spherical surface of nanosized metal, the absorption maximum of azo-dye methyl orange shift towards shorter wavelength band. The experimental results show that the proposed technique here wouM offer a promising way to synthesize short wavelength optoelectronic storage material by doping of metal nanoparticles coated with dyes in polymer. Furthermore, the composites based on the structure can present excellent thermal properties suitable for the requirements of optical storage. This new type of material is capable of matching semiconductor laser (GaN) in optoelectronic storage technology. 相似文献
12.
Kim J Hong AJ Kim SM Shin KS Song EB Hwang Y Xiu F Galatsis K Chui CO Candler RN Choi S Moon JT Wang KL 《Nanotechnology》2011,22(25):254006
We have demonstrated, for the first time, a novel three-dimensional (3D) memory chip architecture of stacked-memory-devices-on-logic (SMOL) achieving up to 95% of cell-area efficiency by directly building up memory devices on top of front-end CMOS devices. In order to realize the SMOL, a unique 3D Flash memory device and vertical integration structure have been successfully developed. The SMOL architecture has great potential to achieve tera-bit level memory density by stacking memory devices vertically and maximizing cell-area efficiency. Furthermore, various emerging devices could replace the 3D memory device to develop new 3D chip architectures. 相似文献
13.
GaAs nanowires (NWs) have been extensively explored for next generation electronics, photonics and photovoltaics due to their direct bandgap and excellent carrier mobility. Typically, these NWs are grown epitaxially on crystalline substrates, which could limit potential applications requiring high growth yield to be printable or transferable on amorphous and flexible substrates. Here, utilizing Ni as a catalytic seed, we successfully demonstrate the synthesis of highly crystalline, stoichiometric and dense GaAs NWs on amorphous SiO(2) substrates. Notably, the NWs are found to grow via the vapor-solid-solid (VSS) mechanism with non-spherical NiGa catalytic tips and low defect densities while exhibiting a narrow distribution of diameter (21.0 ± 3.9 nm) uniformly along the entire length of the NW (>10 μm). The NWs are then configured into field-effect transistors showing impressive electrical characteristics with I(ON)/I(OFF) > 10(3), which further demonstrates the purity and crystal quality of NWs obtained with this simple synthesis technique, compared to the conventional MBE or MOCVD grown GaAs NWs. 相似文献
14.
TheFeasibilityStudyoftheWasteHeatAir-ConditioningSystemforAutomobile¥Gui-pingLin;Xiu-ganYuan;Zhi-guangMei(Air-Conditioningand... 相似文献
15.
The correlation between Al metabolism and senile dementia in animal has been studied by AMS(accelerator mass spectrometry).Three groups of laboratory rats were fed with normal food.food with high Al content,and with enriched Ca and Mg together with high Al,respectively for six to eight months.Mapping test was made to recored th degree of wisdom degeneration.Half of the rats were sacrificed and Al contents in various organs were measured by atomic absorption spectroscopy.The rest were injected with ^26Al,killed after 5,10,15,25,and 35d and ^26Al contents measured by AMS.The distribution of Al as well as the correlation among the accumulation of ^26Al,and the existed Al content and dementia was studied. 相似文献
16.
本文介绍了美国近几年来内燃机油规格发展情况,并对新版 ILSAC GF-1级汽油机油建议规格及 CF-2和 CF 级柴油机油规格的试验方法作了介绍。 相似文献
17.
18.
Rate constants are important pharmacokinetic parameters and very useful in study of radiopharmaceuticals,nuclide therapy and internal radiation.In the situation of small numer of compartments,solution of rate constants is not too difficult.But with increasing compartment number,the calculation is tending to more complex,which makes solving rate constants very diffcult,Therefore,according to a general principle a series of formulae is established to simplify the process of solving rate constants. 相似文献
19.
Well-aligned, high-purity carbon nanotube (CNT) stacks of up to 10 layers fabricated in one batch process have been formed by water-assisted selective etching of carbon atoms. Etching takes place at the CNT caps as well as at the interface between CNTs and metal catalyst particles. This simple process generates high-purity CNTs and opens the CNT ends by removing the nanotube caps. High-resolution transmission electron microscopy indicates that the process does not damage CNT wall structures. A mechanism for stacked growth of CNT layers is proposed. 相似文献
20.
The Permian Chert Event is of great significance to understanding the geological evolution of the entire Permian; however, the origin of widespread chert formation is debated. We report new geochemical data from deep-marine siliceous rocks of the upper Permian Da-long Formation, Lower Yangtze region, southeastern China. Their geochemical results show that these thin-bedded siliceous rocks have a clear biologic origin, with rare to no evidence of hydrothermal influence. The values of Al/(Al + Fe + Mn) and Eu/Eu* are 0.60–0.84 (mean = 0.72) and 0.45–1.08 (mean = 0.77), respectively, and Mn/Ti ratios are relatively low (mean = 0.72). The correlations of LaN/ CeN, LaN/ YbN, and Fe2O3/ TiO2 with Al2O3/(Al2O3 + Fe2O3), along with the Ce anomaly, indicate that the Da-long siliceous rocks were deposited at a transitional zone between a continental margin and the open ocean; i.e., relatively close to terrestrial sediment input and far from hydrothermal activity. The accumulation of chert is related to its unique paleogeographic location in an equatorial setting with many submarine paleo-highlands. Intense upwelling and frequent local volcanism are the main factors that promoted the development of siliceous rocks in the studied area. Ocean acidification triggered by large-scale volcanism (Large Igneous Province) during the late Permian led to extensive silica precipitation and preservation. 相似文献