全文获取类型
收费全文 | 47066篇 |
免费 | 2970篇 |
国内免费 | 56篇 |
学科分类
工业技术 | 50092篇 |
出版年
2023年 | 415篇 |
2022年 | 424篇 |
2021年 | 1261篇 |
2020年 | 1008篇 |
2019年 | 1087篇 |
2018年 | 1793篇 |
2017年 | 1720篇 |
2016年 | 1839篇 |
2015年 | 1468篇 |
2014年 | 1767篇 |
2013年 | 3579篇 |
2012年 | 2840篇 |
2011年 | 2839篇 |
2010年 | 2198篇 |
2009年 | 1984篇 |
2008年 | 1991篇 |
2007年 | 1915篇 |
2006年 | 1337篇 |
2005年 | 1160篇 |
2004年 | 988篇 |
2003年 | 933篇 |
2002年 | 883篇 |
2001年 | 613篇 |
2000年 | 564篇 |
1999年 | 633篇 |
1998年 | 2571篇 |
1997年 | 1797篇 |
1996年 | 1200篇 |
1995年 | 791篇 |
1994年 | 617篇 |
1993年 | 705篇 |
1992年 | 320篇 |
1991年 | 272篇 |
1990年 | 268篇 |
1989年 | 267篇 |
1988年 | 236篇 |
1987年 | 227篇 |
1986年 | 216篇 |
1985年 | 238篇 |
1984年 | 211篇 |
1983年 | 172篇 |
1982年 | 224篇 |
1981年 | 233篇 |
1980年 | 224篇 |
1979年 | 147篇 |
1978年 | 141篇 |
1977年 | 351篇 |
1976年 | 684篇 |
1975年 | 95篇 |
1973年 | 96篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
Daniel Whittaker Andreas Geist Giuseppe Modolo Robin Taylor Mark Sarsfield Andreas Wilden 《溶剂提取与离子交换》2018,36(3):223-256
Over the last decade there has been much interest in the applications of diglycolamide (DGA) ligands for the extraction of the trivalent lanthanide and actinide ions from PUREX high active raffinates or dissolved spent nuclear fuel. Of the DGAs, the N,N,N’,N’-tetraoctyldiglycolamide (TODGA) is the best known and most widely studied. A number of new actinide separation processes have been proposed based on extraction with TODGA. This review covers TODGA-based processes and extraction data, specifically focusing on how phase modifiers have been used to increase metal loading and thus enhance the operating process envelopes. Effects of third phase formation and the organic phase speciation are reviewed in this context. Relevant aspects of the extraction chemistry of important solvents (TODGA-modifier-diluent combinations) are described and their performances demonstrated by a consideration of the published flowsheet tests. It is seen that modifiers are successfully enabling the use of TODGA in actinide separation processes but to date the identification and testing of suitable modifiers has been rather empirical. There is a growing understanding of the fundamental chemistry occurring in the organic phase and how that affects extractant speciation and metal loading capacity but studies are still needed if TODGA-based flowsheets are to become an industrially deployable option for minor actinide (MA) recovery processes. 相似文献
72.
Hierarchical micro-nanostructured albite-based glass-ceramic for high dielectric strength insulators
V. Fuertes M.J. Cabrera J. Seores D. Muñoz J.F. Fernández E. Enríquez 《Journal of the European Ceramic Society》2018,38(7):2759-2766
A novel glass-ceramic material based on albite type Na-rich feldspar has been synthesized by conventional ceramic process. High crystallinity, >94%?Vol.% is obtained by fast sintering which allows energy saving processing. Albite is the main crystalline phase and tetragonal SiO2 is a secondary phase. Electrical properties were examined by complex impedance, DC measurements, and dielectric breakdown test. Dielectric characterization shows a non-Debye type dielectric behavior with low dielectric constant, 4.6 at 1?MHz, low dielectric losses, (~10?3 at 1?MHz, and a large dielectric strength, ~60?kV/mm), that it is the largest value reported in ceramic insulators. Those dielectric properties are attained by the low glassy phase content in the samples and their unique micro-nanostructure. All these properties make this novel material a very promising candidate in the market of ceramic electrical insulator, highlighting for high-voltage applications. 相似文献
73.
Federico Cernuschi Paolo Bison Daniel E. Mack Marco Merlini Stefano Boldrini Stefano Marchionna Stefano Capelli Stefano Concari Alessia Famengo Alessandro Moscatelli Werner Stamm 《Journal of the European Ceramic Society》2018,38(11):3945-3961
In the perspective of fuelling the future generations of gas turbines by hydrogen rich syngas, the evaluation of the effect of a higher water vapour content into the flue gases on the TBC used, or potentially usable, is a need. For this purpose YPSZ APS TBC with two different microstructures have been exposed for 500?h at different temperatures in the range 1000?°C–1250?°C either in air and air +20% vol. H2O. The comparison between the different testing conditions has been performed in terms of sintering kinetics and phase stability, as evaluated by thermal diffusivity measurements and Synchrotron X-Rays diffraction, respectively. Furthermore the characterisation of thermal properties of two innovative TBCs (GZO-YPSZ and YAG) potentially able to withstand the CMAS attack and erosive environments, respectively, has been carried out.No clear evidence of a different behaviour of TBC has been observed, at least in the considered aging time and temperature range. 相似文献
74.
Crespo Juan-José Sánchez José L. Alfaro-Cortés Francisco J. Flich José Duato José 《The Journal of supercomputing》2021,77(11):12826-12856
The Journal of Supercomputing - Deadlock-free dynamic network reconfiguration process is usually studied from the routing algorithm restrictions and resource reservation perspective. The dynamic... 相似文献
75.
76.
77.
78.
Roberto C. Dante Pablo Martín-Ramos Pedro Chamorro-Posada Dario Rutto José Vázquez-Cabo Denisse G. Dante 《Fullerenes, Nanotubes and Carbon Nanostructures》2020,28(7):533-540
AbstractIn this work, a new g-C3N4-based Z-scheme with γ-Fe2O3 and β-Ag2Se both n-type semiconductors, and graphite to favor electron exchange is presented. The composite material was studied by XRD, FTIR, UV-Vis, TEM, XPS, TGA, DSC and TOF-SIMS, and the ability of this photocatalytic system to act as a photo-reductant was assessed using crystal violet (CV+) dye. Solar light driven photo-reduction of CV+ in the presence of tri-sodium citrate evidenced a synergistic enhancement of the activity of the composite toward reduction, with ~20 times higher conversion rates per unit of surface area than those of g-C3N4. Photo-oxidation experiments under Xe lamp irradiation in the presence of H2O2 also showed that the AgFeCN composite featured a higher activity (~8×) than g-C3N4. This Z-scheme may deserve further study as a photo-reductant to obtain hydrogen or hydrogenated compounds. Moreover, the use of CV+ may represent a facile procedure that can aid in the selection of new photocatalysts to be used in hydrogen production. 相似文献
79.
Juana Maria de Lourdes Medina-Contreras Patrick Mailloux-Salinas Juventino III Colado-Velazquez Norma Leticia Gomez Viquez Gómez-Viquez Rodrigo Velázquez-Espejel Ana del Carmen Susunaga-Notario David Julian Arias-Chávez Guadalupe Bravo 《Journal of the science of food and agriculture》2020,100(7):3212-3219
80.
Tsuchiya Letícia Diniz Braga Lucas Fiorini de Faria Oliveira Otávio de Bettio Raphael Winckler Greghi Juliana Galvani Freire André Pimenta 《Personal and Ubiquitous Computing》2021,25(2):281-295
Personal and Ubiquitous Computing - This article presents a study concerning the evaluation of a smart home control system for elderly people with a sample of 10 users in a city in the interior of... 相似文献