全文获取类型
收费全文 | 421篇 |
免费 | 50篇 |
国内免费 | 20篇 |
专业分类
电工技术 | 1篇 |
综合类 | 11篇 |
化学工业 | 99篇 |
金属工艺 | 5篇 |
机械仪表 | 15篇 |
建筑科学 | 12篇 |
矿业工程 | 5篇 |
能源动力 | 4篇 |
轻工业 | 2篇 |
石油天然气 | 3篇 |
武器工业 | 1篇 |
无线电 | 70篇 |
一般工业技术 | 145篇 |
冶金工业 | 4篇 |
原子能技术 | 1篇 |
自动化技术 | 113篇 |
出版年
2023年 | 7篇 |
2022年 | 3篇 |
2021年 | 9篇 |
2020年 | 6篇 |
2019年 | 14篇 |
2018年 | 6篇 |
2017年 | 17篇 |
2016年 | 18篇 |
2015年 | 20篇 |
2014年 | 32篇 |
2013年 | 35篇 |
2012年 | 38篇 |
2011年 | 31篇 |
2010年 | 35篇 |
2009年 | 36篇 |
2008年 | 24篇 |
2007年 | 32篇 |
2006年 | 31篇 |
2005年 | 10篇 |
2004年 | 26篇 |
2003年 | 21篇 |
2002年 | 7篇 |
2001年 | 4篇 |
1999年 | 10篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1973年 | 2篇 |
排序方式: 共有491条查询结果,搜索用时 34 毫秒
1.
《Ceramics International》2020,46(8):11499-11507
In this study, NiCo2O4 with different morphologies were fabricated using carriers by homogeneous coprecipitation combined with a sintering method. The phase and microstructure were characterized by XRD, SEM, EDS, TEM and BET, and the catalytic performances were investigated by NaBH4 hydrolysis experiments. These studies revealed that the deposition morphology of NiCo2O4 can be adjusted by using different kinds of carrier templates, and the supported NiCo2O4 samples presented the pine-needle-like, network-like, ball-cactus-like and dandelion-like morphologies respectively. The optimal catalytic activity, durability and stability make the network-like NiCo2O4 an appropriate catalyst for hydrogen generation of NaBH4 hydrolysis. It was found that the network-like NiCo2O4 is the most reusable and durable catalyst for ten consecutive cycles and 100% hydrogen generation conversion rate without obvious decrease among these morphologies. 相似文献
2.
Laterally Ordered Sub‐10 nm Features Obtained From Directed Self‐Assembly of Si‐Containing Block Copolymer Thin Films 下载免费PDF全文
3.
4.
《Journal of the European Ceramic Society》2014,34(6):1501-1509
Hybrid ceramics, polysiloxane-derived materials, feature adjustable surface characteristics and high specific surface areas, making the material promising for applications such as gas separation. For increased permeability in gas separation processes or accessibility of active sites, additional porosity on multiple length scales is desired. In this study, we demonstrate how water soluble templates can be utilized to obtain a controlled hierarchical porosity. KCl sieving fractions are used for adjusting the macroporosity and a polysiloxane precursor, aminopropyltriethoxysilane, to create mesopores. The generation of micro- and mesopores is characterized by nitrogen adsorption while the macroporosity is examined by scanning electron microscopy and mercury intrusion. Water and n-heptane vapor sorption experiments show the control of the surface characteristics of the material by the pyrolysis temperature. In summary, leaching of water soluble templates for meso- and macropores combined with micro pore generation by pyrolytic decomposition enables pore size control on three different length scales. 相似文献
5.
Porous templates were fabricated by hydrogen-etching metal organic chemical vapor deposited gallium nitride (GaN); these templates were used as substrates for the growth of GaN via hydride vapor phase epitaxy. The influence of annealing porous templates on GaN growth behavior was investigated. GaN epitaxied on the unannealing porous template followed the Volmer–Weber mode with the void preserved at the growth plane, whereas the GaN film on the annealed porous templates exhibited a layer-by-layer growth and filled the porous material. The GaN crystal quality was characterized by high-resolution XRD and CL, the results indicated that GaN grown with pores preserved at the template interface had a lower dislocation density than that grown with pores filled, and the best GaN film had a TD density of 104 cm−2. 相似文献
6.
Moving object tracking under complex scenes remains to be a challenging problem because the appearance of a target object can be drastically changed due to several factors, such as occlusions, illumination, pose, scale change and deformation. This study proposes an adaptive multi–feature fusion strategy, in which the target appearance is modeled based on timed motion history image with HSV color histogram features and edge orientation histogram features. The variances based on the similarities between the candidate patches and the target templates are used for adaptively adjusting the weight of each feature. Double templates matching, including online and offline template matching, is adopted to locate the target object in the next frame. Experimental evaluations on challenging sequences demonstrate the accuracy and robustness of the proposed algorithm in comparison with several state-of-the-art algorithms. 相似文献
7.
8.
Flake‐like polyaniline with various thicknesses was prepared by cationic emulsion polymerization of aniline monomer in the presence of cetyltrimethylammonium bromide (CTAB). The morphology of polyaniline with uniform and smooth flake‐like structure was observed using field‐emission scanning electron microscopy and transmission electron microscopy. The lamellar complex of (CTA)2S2O8, acting as a reactive soft template for the formation of polyaniline, was investigated using low‐angle X‐ray diffraction. The soft template provides an expanding space for the growth of polyaniline, in which the oxidization of aniline monomers can construct effectively a flake‐like structure. The concentration of CTAB plays an important role in adjusting the d‐spacing of the soft template. Crystallization and composition of polyaniline were characterized using X‐ray diffraction and Fourier transform infrared spectroscopy. The X‐ray diffraction pattern has a sharp peak at 2θ = 6.4° (d‐spacing = 13.7 Å), showing that polyaniline has a solid‐state ordering structure and high degree of crystallization. Doping and dispersive experiments were also included in the study. Copyright © 2012 Society of Chemical Industry 相似文献
9.
Elizabeth Elacqua Tomislav Friščić Leonard R. MacGillivray 《Israel journal of chemistry》2012,52(1-2):53-59
In this account, we review the synthesis of [2.2]paracyclophanes in the organic solid state. Reactions in crystalline solids provide a means to obtain molecules with high degrees of stereocontrol that can also be unattainable in solution. We show that [2.2]paracyclophanes form in the solid state stereospecifically and in quantitative yield via intermolecular [2+2] double photodimerization reactions. The double cycloaddition that affords a paracyclophane in the solid state does not readily occur in solution. Small molecules in the form of hydrogen-bond-donor templates can provide access to [2.2]paracyclophanes in a solid by design. A [2.2]paracyclophane obtained using a hydrogen-bond template is shown to exhibit attractive optical properties and has been employed as a building block of a metal-organic framework (MOF). 相似文献
10.
某地下游泳池顶板支模架高度、支模净空等达到了国家规定的危险性较大的分部分项工程标准,为确保安全施工并保证质量,对高大模板支撑体系进行专项设计并验算,采用扣件式钢管满堂支模架体系,确定了模板选型、支撑形式、间距、步距及节点做法,通过软件验算符合要求。 相似文献