全文获取类型
收费全文 | 742篇 |
免费 | 23篇 |
专业分类
电工技术 | 2篇 |
综合类 | 3篇 |
化学工业 | 247篇 |
金属工艺 | 16篇 |
机械仪表 | 13篇 |
建筑科学 | 47篇 |
矿业工程 | 2篇 |
能源动力 | 11篇 |
轻工业 | 78篇 |
水利工程 | 1篇 |
无线电 | 39篇 |
一般工业技术 | 147篇 |
冶金工业 | 47篇 |
原子能技术 | 6篇 |
自动化技术 | 106篇 |
出版年
2023年 | 4篇 |
2022年 | 9篇 |
2021年 | 21篇 |
2020年 | 12篇 |
2019年 | 20篇 |
2018年 | 14篇 |
2017年 | 16篇 |
2016年 | 21篇 |
2015年 | 19篇 |
2014年 | 24篇 |
2013年 | 41篇 |
2012年 | 42篇 |
2011年 | 42篇 |
2010年 | 39篇 |
2009年 | 38篇 |
2008年 | 35篇 |
2007年 | 32篇 |
2006年 | 24篇 |
2005年 | 27篇 |
2004年 | 27篇 |
2003年 | 14篇 |
2002年 | 14篇 |
2001年 | 12篇 |
2000年 | 15篇 |
1999年 | 14篇 |
1998年 | 13篇 |
1997年 | 17篇 |
1996年 | 14篇 |
1995年 | 15篇 |
1994年 | 8篇 |
1993年 | 9篇 |
1992年 | 7篇 |
1991年 | 9篇 |
1990年 | 7篇 |
1989年 | 6篇 |
1988年 | 13篇 |
1987年 | 8篇 |
1985年 | 6篇 |
1984年 | 2篇 |
1983年 | 9篇 |
1982年 | 5篇 |
1981年 | 8篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1972年 | 4篇 |
1970年 | 5篇 |
1969年 | 2篇 |
排序方式: 共有765条查询结果,搜索用时 0 毫秒
121.
For the assembly of hybrid microsystems a high accuracy in the range of a few micrometers is required. The combination of a parallel robot with an integrated 3D vision sensor uses positioning marks on the objects for object recognition. Within the assembly process, relative positioning accuracies in the submicrometer range have been obtained. Therefore, it is necessary to use a calibration strategy for matching the coordinate system of the 3D vision sensor with the coordinate system of the robot. The construction of the system, the calibration applied and the positioning accuracy achieved by the robot will be discussed. 相似文献
122.
Stian Svelle Morten Bjørgen Stein Kolboe Dietmar Kuck Matthias Letzel Unni Olsbye Osamu Sekiguchi Einar Uggerud 《Catalysis Letters》2006,109(1-2):25-35
In order to reach a deeper insight into the reaction mechanism of the zeolite catalyzed methanol to hydrocarbons reaction
(MTH), the proposed reaction intermediates, i.e., a series of multiply methyl-substituted benzenium ions has been generated
in the gas phase by chemical ionization. The fragmentations of the corresponding long-lived (metastable) ions have been investigated.
While expulsion of H2 dominates for the lower homologues, elimination of methane dominates for the higher homologues, accompanied by increasing
amounts CH3·. Loss of larger fragments relevant to the MTH-reaction, in particular ethene, propene and even butene, is also observed in
minor amounts. This latter finding is consistent with a proposed reaction cycle in the MTH reaction known as the paring mechanism, and the feasibility of this mechanism has thus been demonstrated. The metastable gas-phase ions studied here are considerably
more energetic than those residing in a zeolite catalyst, but they were found to decompose with markedly higher selectivity
towards alkenes as compared to those activated by collision-induced dissociation (CID). 相似文献
123.
Cell suspensions of Escherichia coli as a model for bacterial populations in wastewaters were treated with ozone as a disinfectant in a continuously operated pilot plant with a plug flow reactor. Suspensions with an initial number of CFU (colony forming units) of 108 mL?1 were ozonized with ozone concentrations up to 12 mg/L. Metabolic activities and membrane functions break down with increasing ozone concentrations. The fluorochromization using 3′,6′-diacetylfluorescein (FDA) proved to be a suitable method for the detection of an alteration in permeability of the cell membranes and an inactivation of metabolic activity. By fluorescence microscopic and photometric investigations it could be clearly demonstrated that, in the case of disinfection with ozone, inactivation of the cells includes first of all a damage of the cell membranes. In contrast to the determination of the number of CFU, fluorochromization allows the detection of alteration in metabolic activities. 相似文献
124.
125.
126.
Influence of growth conditions on biofilm development and mass transfer at the bulk/biofilm interface 总被引:8,自引:0,他引:8
In a long-term study on heterotrophic biofilms in tube reactors, this investigation focused on mass transfer at the bulk/biofilm interface, biofilm density and substrate conversion rates. Several biofilms were cultivated under different substrate and hydrodynamic conditions. Oxygen concentration profiles were measured with microelectrodes in the biofilm and in the boundary layer directly in the biofilm tube reactors. The thickness of the concentration boundary layer was found to depend on the surface structure of the biofilm. The hydrodynamic conditions and the substrate load during the growth phase of the biofilm in biofilm systems are two key parameters that influence the biofilm growth, particularly the structure, density and thickness. The measured substrate conversion rates, biofilm densities and the boundary layer thickness were used to formulate an equation for the mass transfer in biofilm tube reactors. 相似文献
127.
Energy policy scenarios to reach challenging climate protection targets in the German electricity sector until 2050 总被引:1,自引:0,他引:1
Stephan Nagl Michaela Fürsch Moritz Paulus Jan Richter Johannes Trüby Dietmar Lindenberger 《Utilities Policy》2011,19(3):185-192
In this article we demonstrate how challenging greenhouse gas reduction targets of up to 95% until 2050 can be achieved in the German electricity sector. In the analysis, we focus on the main requirements to reach such challenging targets. To account for interdependencies between the electricity market and the rest of the economy, different models were used to account for feedback loops with all other sectors. We include scenarios with different runtimes and retrofit costs for existing nuclear plants to determine the effects of a prolongation of nuclear power plants in Germany. Key findings for the electricity sector include the importance of a European-wide coordinated electricity grid extension and the exploitation of regional comparative cost effects for renewable sites. Due to political restrictions, nuclear energy will not be available in Germany in 2050. However, the nuclear life-time extension has a positive impact on end consumer electricity prices as well as economic growth in the medium term, if retrofit costs do not exceed certain limits. 相似文献
128.
129.
130.