全文获取类型
收费全文 | 1373篇 |
免费 | 84篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 32篇 |
综合类 | 6篇 |
化学工业 | 490篇 |
金属工艺 | 50篇 |
机械仪表 | 40篇 |
建筑科学 | 38篇 |
矿业工程 | 10篇 |
能源动力 | 41篇 |
轻工业 | 110篇 |
水利工程 | 3篇 |
石油天然气 | 2篇 |
无线电 | 117篇 |
一般工业技术 | 203篇 |
冶金工业 | 40篇 |
原子能技术 | 7篇 |
自动化技术 | 274篇 |
出版年
2024年 | 2篇 |
2023年 | 13篇 |
2022年 | 72篇 |
2021年 | 101篇 |
2020年 | 48篇 |
2019年 | 42篇 |
2018年 | 42篇 |
2017年 | 47篇 |
2016年 | 75篇 |
2015年 | 55篇 |
2014年 | 85篇 |
2013年 | 126篇 |
2012年 | 95篇 |
2011年 | 78篇 |
2010年 | 61篇 |
2009年 | 68篇 |
2008年 | 78篇 |
2007年 | 52篇 |
2006年 | 39篇 |
2005年 | 33篇 |
2004年 | 35篇 |
2003年 | 33篇 |
2002年 | 21篇 |
2001年 | 12篇 |
2000年 | 7篇 |
1999年 | 8篇 |
1998年 | 11篇 |
1997年 | 11篇 |
1996年 | 11篇 |
1995年 | 11篇 |
1994年 | 12篇 |
1993年 | 11篇 |
1992年 | 13篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 8篇 |
1982年 | 1篇 |
1981年 | 7篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1969年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有1463条查询结果,搜索用时 15 毫秒
91.
X-ray Photoelectron Spectroscopy (XPS) was used to study the influence of low energy Ar+ ion bombardment, electron bombardment and Pt deposition on the SrTiO3 (STO) single crystal electronic structure. Atomic composition changes were found and attributed to chemical reconstruction of the STO surface. A clear correlation between the presence of conducting, low Ti oxidation states in valence band and core level changes was detected. A strong effect caused by electron irradiation was ascribed to the electroreduction process. The influence of lanthanum doping on surface instability of STO was also discussed. The La doped sample (STO: 3,75% La) was found to be modified upon Pt metal deposition to a higher degree than pure STO crystal. 相似文献
92.
Two-component films of a non-amphiphilic azo dye and a liquid crystal with strongly polar –CN group were studied at an air–water interface on the basis of the surface potential–mean molecular area dependence recorded simultaneously with the surface pressure–mean molecular area isotherm. Additionally, the morphology of the films was monitored with the aid of Brewster angle microscope. A conventional Langmuir technique was used to form dye/liquid crystal films during reduction and expansion of an area occupied by the molecules. From the surface potential value, the effective dipole moment in the first monolayer formed on the water was calculated. Moreover, the number of molecules with dipole moments directed from the water to the air with respect to those directed towards water was estimated. The influence of the two components' miscibilities upon the surface potential after addition of the dye to the liquid crystal was determined. 相似文献
93.
94.
Lukasz A Kurgan Krzysztof J Cios Scott Dick 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》2006,36(1):32-53
Business intelligence and bioinformatics applications increasingly require the mining of datasets consisting of millions of data points, or crafting real-time enterprise-level decision support systems for large corporations and drug companies. In all cases, there needs to be an underlying data mining system, and this mining system must be highly scalable. To this end, we describe a new rule learner called DataSqueezer. The learner belongs to the family of inductive supervised rule extraction algorithms. DataSqueezer is a simple, greedy, rule builder that generates a set of production rules from labeled input data. In spite of its relative simplicity, DataSqueezer is a very effective learner. The rules generated by the algorithm are compact, comprehensible, and have accuracy comparable to rules generated by other state-of-the-art rule extraction algorithms. The main advantages of DataSqueezer are very high efficiency, and missing data resistance. DataSqueezer exhibits log-linear asymptotic complexity with the number of training examples, and it is faster than other state-of-the-art rule learners. The learner is also robust to large quantities of missing data, as verified by extensive experimental comparison with the other learners. DataSqueezer is thus well suited to modern data mining and business intelligence tasks, which commonly involve huge datasets with a large fraction of missing data. 相似文献
95.
96.
97.
Comparison of systematic search and database methods for constructing segments of protein structure 总被引:6,自引:0,他引:6
Fidelis Krzysztof; Stern Peter S.; Bacon David; Moult John 《Protein engineering, design & selection : PEDS》1994,7(8):953-960
Two principal methods of determining the conformation of shortpieces of polypeptide backbone in proteins have been developed:using a database of known structures and systematicallygeneratingall conformations. In this paper, we compare the effectivenessof these two techniques. The completeness of the database forsegments of different lengths is examined and it is found tocontain most conformations for segments seven residues long,but to deteriorate rapidly for longer regions. When the databasesegment is to be incorporated into the rest of a structure,at least seven residues are required to build four new residues,because of the need to positionthe segment relative to the restof the structure.It is found that such positioning using flankingresidues results in large errors in the inserted region. Weconclude that the database method is currently not effectivefor comparative modeling, even for short segments. The systematicsearchprocedure is found to generate almost all structures of shortsegments found in proteinsIn contrast to the database method,low root mean square error structures are obtained for a setof trial segments embedded in the rest of a protein structure.Thus, it should be considered the method of choice. 相似文献
98.
Fundamentals of controlled/“living” radical polymerization are given together with a discussion of selected initiating/catalytic systems which provide structural, compositional, and functionality control during radical polymerization. Four systems which enable the synthesis of polymers with low polydispersities (Mw/Mn< 1.2), relatively high molecular weights (Mn>10 000), and high degrees of functionality are: nitroxide-mediated polymerization of styrene and styrene copolymers; organometallic compounds used for polymerization of acrylates; atom transfer radical polymerization of various monomers; and the degenerative transfer process. Also important in this field are new structural features and potential applications of controlled radical polymerization. 相似文献
99.
Marek Berezowski Krzysztof Warmuziski 《Chemical Engineering and Processing: Process Intensification》1993,32(6):345-347
A method is proposed for increasing the dedusting efficiency of cyclones. The method, which is based on the introduction of the gas undergoing purification into a recycle loop, is of considerable practical importance as it enables the process to be controlled so as to maintain a constant efficiency of dust removal. 相似文献
100.