全文获取类型
收费全文 | 1404篇 |
免费 | 3篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 13篇 |
金属工艺 | 2篇 |
建筑科学 | 1篇 |
能源动力 | 1篇 |
轻工业 | 3篇 |
无线电 | 7篇 |
一般工业技术 | 13篇 |
冶金工业 | 1322篇 |
原子能技术 | 2篇 |
自动化技术 | 42篇 |
出版年
2023年 | 2篇 |
2021年 | 1篇 |
2019年 | 1篇 |
2018年 | 8篇 |
2017年 | 5篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 4篇 |
2013年 | 3篇 |
2012年 | 4篇 |
2011年 | 3篇 |
2010年 | 5篇 |
2009年 | 5篇 |
2008年 | 4篇 |
2007年 | 7篇 |
2006年 | 6篇 |
2005年 | 2篇 |
2004年 | 1篇 |
2003年 | 4篇 |
2002年 | 1篇 |
2001年 | 1篇 |
2000年 | 4篇 |
1999年 | 48篇 |
1998年 | 446篇 |
1997年 | 214篇 |
1996年 | 157篇 |
1995年 | 98篇 |
1994年 | 67篇 |
1993年 | 78篇 |
1992年 | 10篇 |
1991年 | 7篇 |
1990年 | 13篇 |
1989年 | 19篇 |
1988年 | 8篇 |
1987年 | 20篇 |
1986年 | 12篇 |
1985年 | 9篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 7篇 |
1980年 | 13篇 |
1978年 | 2篇 |
1977年 | 33篇 |
1976年 | 60篇 |
1975年 | 3篇 |
1973年 | 1篇 |
排序方式: 共有1407条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Overrepresentation and underrepresentation of African Americans and Latinos as lawbreakers on television news 总被引:3,自引:0,他引:3
We conducted a content analysis of a random sample of local television news programming in Los Angeles and Orange counties to assess representations of Blacks, Latinos, and Whites as lawbreakers and law defenders. 'Intergroup' comparisons of perpetrators (Black and Latino vs. White) revealed that Blacks and Latinos are significantly more likely than Whites to be portrayed as lawbreakers on television news. 'Interrole' comparisons (lawbreakers vs. law defenders) revealed that Blacks and Latinos are more likely to be portrayed as lawbreakers than as defenders, whereas Whites are significantly more likely to be portrayed as defenders than as lawbreakers. 'Interreality' comparisons of lawbreakers (television news vs. crime reports from the California Department of Justice) revealed that Blacks are overrepresented as lawbreakers, and Latinos and Whites are underrepresented as lawbreakers on television news compared to their respective crime rates obtained from the California Department of Justice for Los Angeles and Orange counties. Interreality comparisons of law defenders (television news vs. county employment records) revealed that Whites are overrepresented, Latinos are underrepresented, and Blacks are neither over- nor underrepresented as police officers on television news compared to employment reports. We speculate on the psychological effects of exposure to these intergroup, interrole, and interreality differentials on television news viewers. 相似文献
5.
O‐P. Kwon S.‐J. Kwon M. Jazbinsek A. Choubey V. Gramlich P. Günter 《Advanced functional materials》2007,17(11):1750-1756
A series of new nonlinear optical chromophores based on configurationally locked polyenes (CLPs) with chiral pyrrolidine donors are synthesized. All CLP derivatives exhibit high thermal stability with decomposition temperatures Td at least > 270 °C. Acentric single crystals of enantiopure D ‐ and L ‐prolinol‐based chromophores with a monoclinic space group P21 exhibit a macroscopic second‐order nonlinearity that is twice as large than that of analogous dimethylamino‐based crystal. This is attributed to a strong hydrogen‐bonded polar polymer‐like chain built by these molecules, which is aligned along the polar crystallographic b‐axis. Five α‐phase CLP crystals with different donors grown from solution exhibit a reversible or irreversible thermally induced structural phase transition to a β‐phase. These phase transitions are unusual, changing the crystal symmetry from higher to lower at increasing temperatures, for example, from centrosymmetric to non‐centrosymmetric, enhancing their macroscopic second‐order nonlinear optical properties. 相似文献
6.
7.
8.
D. Demange C.G. Alecu N. Bekris O. Borisevich B. Bornschein S. Fischer N. Gramlich Z. Köllö T.L. Le R. Michling F. Priester M. Röllig M. Schlösser S. Stämmler M. Sturm R. Wagner S. Welte 《Fusion Engineering and Design》2012,87(7-8):1206-1213
Safe, reliable, and efficient tritium management in the breeder blanket will have to face unprecedented technological challenges. Beside the efficiency for tritium recovery from the breeder blanket (Tritium Extraction (TES) and Coolant Purification Systems (CPS)), the accuracy for tritium tracking between the inner and the outer fuel cycle must also be demonstrated. This paper focuses on the recent R&D carried out at the Tritium Laboratory Karlsruhe to tackle these issues. For ITER, the recently consolidated TES and CPS designs comprise adsorption columns and getter beds operated in semi-continuous mode. Different approaches for the tritium accountancy stage (TAS) have been evaluated. Balancing static (batch-wise gas collection at the TBM outlets and the tritium plant) or dynamic (in/on-line) approaches with respect to the expected analytical performances and integration issues, the first conceptual design of the TAS for EU TBMs is presented. For DEMO, the overall strategy for tritium recovery and tracking has been revisited. The necessity for on-line real-time tritium accountancy and improved process efficiency suggest the use of continuous processes such as permeator and catalytic membrane reactor. The main benefits combining the PERMCAT process with advanced membranes is discussed with respect to process improvements and facilitated accountancy using spectroscopic methods. 相似文献
9.
Bernhard Kaiser Catharina Gramlich Marc Frster 《Reliability Engineering & System Safety》2007,92(11):1521-1537
Safety models for software-controlled systems should be intuitive, compositional and have the expressive power to model both software and hardware behaviour. Moreover, they should provide quantitative results for failure or hazard probabilities. Fault trees are an accepted and intuitive model for safety analysis, but they are incapable of expressing state dependencies or temporal order of events. We propose to combine fault trees with an explicit State/Event semantics, using a graphical notation that is similar to Statecharts. Our new model, named State/Event Fault Trees (SEFTs), subsumes both deterministic state machines suited to describe software behaviour, and Markov chains that model probabilistic failures, while keeping the visualisation of causal chains known from fault trees. We allow exponentially distributed probabilistic events, deterministic delays, and triggered events. The model provides a component concept, where components are connected by typed ports. Quantitative evaluation is achieved by translating the component models to Deterministic and Stochastic Petri Nets (DSPNs) and using an existing tool for analysis or simulation. This paper, which is an extended version of [Kaiser B, Gramlich C. State-Event-Fault-Trees—a safety analysis model for software controlled systems. Computer safety, reliability, and security. Proceedings of the 23rd international conference, SAFECOMP 2004, Potsdam, Germany, September 21st–24th. Lecture Notes in Computer Science, vol. 3219, 2004.p. 195–209], revisits the model elements and the analysis procedure and provides a small case study of a fire alarm system, completed by an outlook on our tool project ESSaRel. 相似文献
10.