全文获取类型
收费全文 | 530篇 |
免费 | 29篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 5篇 |
化学工业 | 127篇 |
金属工艺 | 39篇 |
机械仪表 | 21篇 |
建筑科学 | 18篇 |
矿业工程 | 4篇 |
能源动力 | 23篇 |
轻工业 | 30篇 |
水利工程 | 2篇 |
石油天然气 | 6篇 |
武器工业 | 8篇 |
无线电 | 49篇 |
一般工业技术 | 107篇 |
冶金工业 | 47篇 |
原子能技术 | 13篇 |
自动化技术 | 71篇 |
出版年
2023年 | 4篇 |
2022年 | 12篇 |
2021年 | 27篇 |
2020年 | 6篇 |
2019年 | 19篇 |
2018年 | 15篇 |
2017年 | 9篇 |
2016年 | 17篇 |
2015年 | 29篇 |
2014年 | 30篇 |
2013年 | 45篇 |
2012年 | 41篇 |
2011年 | 37篇 |
2010年 | 25篇 |
2009年 | 23篇 |
2008年 | 30篇 |
2007年 | 18篇 |
2006年 | 22篇 |
2005年 | 11篇 |
2004年 | 10篇 |
2003年 | 16篇 |
2002年 | 11篇 |
2001年 | 2篇 |
2000年 | 6篇 |
1999年 | 5篇 |
1998年 | 17篇 |
1997年 | 7篇 |
1996年 | 9篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1978年 | 3篇 |
1976年 | 4篇 |
1973年 | 6篇 |
1972年 | 4篇 |
1971年 | 3篇 |
1969年 | 8篇 |
1967年 | 1篇 |
1965年 | 2篇 |
1935年 | 2篇 |
排序方式: 共有570条查询结果,搜索用时 15 毫秒
1.
2.
Tomi Gominek Andrej Lubej Ciril Pohar 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(8):939-947
Precipitation of calcium sulfate dihydrate, gypsum, from (i) a pure sulfuric acid/lime suspension and (ii) a waste sulfuric acid/lime suspension in a continuous pilot plant in the temperature range from 40 °C to 80 °C was studied. It was observed that in the case of waste sulfuric acid with a high content of Mg2+ and Fe2+ ions, several hours after the beginning of the precipitation, partial dissolution of the product and modification of the crystals from needle‐ and plate‐like to agglomerated structures occurred. It is suggested that the secondary changes occur due to the increased concentration of Mg2+ and Fe2+ ions in the reactor. Below 60 °C, and above 70 °C plate‐like and needle‐like single crystals respectively were formed. The mean size (d50) of the crystals was found to increase with increasing temperature and decrease with the initial concentration of lime. Gypsum produced between 70 °C and 80 °C is suitable for further processing for construction plaster. In a precipitation process with pure sulfuric acid only single perfect needle‐like crystals occurred. Copyright © 2005 Society of Chemical Industry 相似文献
3.
J.L. Zeman 《International Journal of Pressure Vessels and Piping》1996,68(3):293-298
Progressive plastic deformation, or ratcheting, is a failure mechanism in ductile structures usually associated with non-proportional actions. In the case of cylindrical shell flat end connections, with or without opening, ratcheting may occur under the action of cyclically varying pressure from zero to a maximum value, i.e. for single action and, therefore, proportional loading. In this paper the ratcheting limits for this connection under this loading and for two different models are given, for an ideal-elastic ideal-plastic constitutive law, Mises' yield condition and associated flow law. The results are compared with each other and with the limits for global plastic deformation given in the literature. 相似文献
4.
Fast Recognition of Fibonacci Cubes 总被引:1,自引:0,他引:1
Fibonacci cubes are induced subgraphs of hypercubes based on Fibonacci strings. They were introduced to represent interconnection
networks as an alternative to the hypercube networks. We derive a characterization of Fibonacci cubes founded on the concept
of resonance graphs. The characterization is the basis for an algorithm which recognizes these graphs in O(mlog n) time.
A. Vesel supported by the Ministry of Science of Slovenia under the grant 0101-P-297. 相似文献
5.
6.
In this paper, we continue the research on formal treatment of attributes of information, based on the computational approach. In this scenario, the usefulness of advisory information is measured by the decrease in complexity of a problem we need to solve. We propose to model the time criticality via usefulness of a piece of information which is received during the computation. As a modeling tool, we use deterministic finite automata. 相似文献
7.
A. Zeman W. R. Eckert H. Scharmann 《European Journal of Lipid Science and Technology》1969,71(10):880-883
Elucidation of Structure of the Methyl Esters of Cyclic Fatty Acids V: Mass-Spectrometry of Isomeric Methyl Esters of Phenyl Undecanoic Acid Isomeric phenyl undecanoic acids obtained by the Friedel-Crafts reaction of benzene with 10-undecenoic acid were investigated as methyl esters using capillary gas-chromatography – mass spectrometry (GC-MS). The isomers could be identified as methyl esters of (5-), 6-, 7-, 8-, 9- and 10 phenyl undecanoic acids. The fragmentation due to electron bombardment is discussed. 相似文献
8.
Mass Spectrometric Fragmentation of Neopentylpolyolesters, Part III: Fatty Acid Diesters of Neopentylglycole The fragmentation of the homologous fatty acid diesters of neopentylglycole (C2 to C18) upon electron impact was investigated. Main fragments arise by M-RCOO and M-RCOOH. Cyclic acetal structures for these ions are postulated. Subsequent fragmentation was elucidated by DADI-measurements and high resolution measurements. The influence of the length of the fatty acid chain upon the fragmentation is discussed. Esters of branched fatty acids can be distinguished from esters of n-fatty acids by characteristic ions. 相似文献
9.
Mass Spectrometric Investigation of Dimeric Fatty Acids from Frying Fats Subjected to Thermal and Oxidative Action Methyl esters of dimers from peanut oil subjected to thermal and oxidative action in an industrial frying plant were isolated by column chromatography and investigated by mass spectrometry. Di-unsaturated bicyclic and tetra-unsaturated acyclic structures were found to be the main components of the dimers. Dimers of very similar composition were synthesized. The mechanism of dimer formation is discussed. 相似文献
10.
I. Zeman 《European Journal of Lipid Science and Technology》1983,85(5):207-212
Suitable operating conditions are shown for GC separation of linear alkylbenzene (AB) samples on capillary columns. Retention data on SE-30 of n-phenylalkanes C9-C16 were measured and separation factors for n-phenylalkanes isomers were calculated. For quantitative evaluation from peaks areas of n-phenylalkanes, correction coefficients were calculated. By statistical evaluation of errors, standard deviations and further statistical parameters were calculated, showing GC method as sufficiently accurate and reliable. From results of collaborative testing of the GC procedure for quantitative AB analysis, some recommendations followed, esp. for application of capillary columns with apolar thermostable stationary phase only, with advantage under temperature programming, applying reduced sample volume at limited FID attenuation. It must be pointed out, this method is strictly limited for linear AB. 相似文献