全文获取类型
收费全文 | 38041篇 |
免费 | 2355篇 |
国内免费 | 31篇 |
专业分类
电工技术 | 259篇 |
综合类 | 19篇 |
化学工业 | 8664篇 |
金属工艺 | 718篇 |
机械仪表 | 786篇 |
建筑科学 | 1054篇 |
矿业工程 | 80篇 |
能源动力 | 806篇 |
轻工业 | 6371篇 |
水利工程 | 335篇 |
石油天然气 | 139篇 |
武器工业 | 5篇 |
无线电 | 1427篇 |
一般工业技术 | 6336篇 |
冶金工业 | 8204篇 |
原子能技术 | 150篇 |
自动化技术 | 5074篇 |
出版年
2024年 | 82篇 |
2023年 | 369篇 |
2022年 | 807篇 |
2021年 | 1188篇 |
2020年 | 817篇 |
2019年 | 929篇 |
2018年 | 1464篇 |
2017年 | 1440篇 |
2016年 | 1495篇 |
2015年 | 1153篇 |
2014年 | 1419篇 |
2013年 | 2870篇 |
2012年 | 2208篇 |
2011年 | 2138篇 |
2010年 | 1703篇 |
2009年 | 1575篇 |
2008年 | 1523篇 |
2007年 | 1380篇 |
2006年 | 981篇 |
2005年 | 859篇 |
2004年 | 771篇 |
2003年 | 681篇 |
2002年 | 669篇 |
2001年 | 500篇 |
2000年 | 454篇 |
1999年 | 515篇 |
1998年 | 2457篇 |
1997年 | 1680篇 |
1996年 | 1095篇 |
1995年 | 666篇 |
1994年 | 499篇 |
1993年 | 584篇 |
1992年 | 214篇 |
1991年 | 215篇 |
1990年 | 163篇 |
1989年 | 167篇 |
1988年 | 165篇 |
1987年 | 145篇 |
1986年 | 125篇 |
1985年 | 147篇 |
1984年 | 132篇 |
1983年 | 102篇 |
1982年 | 137篇 |
1981年 | 148篇 |
1980年 | 157篇 |
1979年 | 82篇 |
1978年 | 80篇 |
1977年 | 280篇 |
1976年 | 625篇 |
1973年 | 65篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Physical Stability of Octenyl Succinate–Modified Polysaccharides and Whey Proteins for Potential Use as Bioactive Carriers in Food Systems 下载免费PDF全文
The high cost and potential toxicity of biodegradable polymers like poly(lactic‐co‐glycolic)acid (PLGA) has increased the interest in natural and modified biopolymers as bioactive carriers. This study characterized the physical stability (water sorption and state transition behavior) of selected starch and proteins: octenyl succinate–modified depolymerized waxy corn starch (DWxCn), waxy rice starch (DWxRc), phytoglycogen, whey protein concentrate (80%, WPC), whey protein isolate (WPI), and α‐lactalbumin (α‐L) to determine their potential as carriers of bioactive compounds under different environmental conditions. After enzyme modification and particle size characterization, glass transition temperature and moisture isotherms were used to characterize the systems. DWxCn and DWxRc had increased water sorption compared to native starch. The level of octenyl succinate anhydrate (OSA) modification (3% and 7%) did not reduce the water sorption of the DWxCn and phytoglycogen samples. The Guggenheim–Andersen–de Boer model indicated that native waxy corn had significantly (P < 0.05) higher water monolayer capacity followed by 3%‐OSA‐modified DWxCn, WPI, 3%‐OSA‐modified DWxRc, α‐L, and native phytoglycogen. WPC had significantly lower water monolayer capacity. All Tg values matched with the solid‐like appearance of the biopolymers. Native polysaccharides and whey proteins had higher glass transition temperature (Tg) values. On the other hand, depolymerized waxy starches at 7%‐OSA modification had a “melted” appearance when exposed to environments with high relative humidity (above 70%) after 10 days at 23 °C. The use of depolymerized and OSA‐modified polysaccharides blended with proteins created more stable blends of biopolymers. Hence, this biopolymer would be suitable for materials exposed to high humidity environments in food applications. 相似文献
52.
53.
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
54.
55.
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
56.
57.
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
58.
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
59.
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
60.