全文获取类型
收费全文 | 6481篇 |
免费 | 459篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 48篇 |
综合类 | 7篇 |
化学工业 | 1493篇 |
金属工艺 | 90篇 |
机械仪表 | 137篇 |
建筑科学 | 269篇 |
矿业工程 | 20篇 |
能源动力 | 210篇 |
轻工业 | 960篇 |
水利工程 | 66篇 |
石油天然气 | 13篇 |
无线电 | 563篇 |
一般工业技术 | 1136篇 |
冶金工业 | 464篇 |
原子能技术 | 42篇 |
自动化技术 | 1429篇 |
出版年
2024年 | 11篇 |
2023年 | 88篇 |
2022年 | 164篇 |
2021年 | 264篇 |
2020年 | 166篇 |
2019年 | 184篇 |
2018年 | 263篇 |
2017年 | 286篇 |
2016年 | 318篇 |
2015年 | 217篇 |
2014年 | 340篇 |
2013年 | 584篇 |
2012年 | 513篇 |
2011年 | 463篇 |
2010年 | 393篇 |
2009年 | 375篇 |
2008年 | 342篇 |
2007年 | 296篇 |
2006年 | 196篇 |
2005年 | 188篇 |
2004年 | 138篇 |
2003年 | 151篇 |
2002年 | 132篇 |
2001年 | 61篇 |
2000年 | 51篇 |
1999年 | 66篇 |
1998年 | 116篇 |
1997年 | 91篇 |
1996年 | 63篇 |
1995年 | 57篇 |
1994年 | 49篇 |
1993年 | 40篇 |
1992年 | 24篇 |
1991年 | 13篇 |
1990年 | 17篇 |
1989年 | 17篇 |
1988年 | 18篇 |
1987年 | 17篇 |
1986年 | 18篇 |
1985年 | 16篇 |
1984年 | 9篇 |
1983年 | 10篇 |
1982年 | 14篇 |
1981年 | 9篇 |
1980年 | 10篇 |
1979年 | 8篇 |
1978年 | 10篇 |
1976年 | 12篇 |
1974年 | 6篇 |
1973年 | 8篇 |
排序方式: 共有6947条查询结果,搜索用时 15 毫秒
1.
Zia Muhammad Yousuf Irfan Otero Pablo Siddiqui Atif Poncela Javier 《Wireless Personal Communications》2021,116(2):1171-1193
Wireless Personal Communications - Underwater Wireless Sensor Networks (UWSNs) are playing a vital role in exploring the unseen underwater (UW) natural resources. However, performance evaluation of... 相似文献
2.
Lucas Portela Oliveira Camila Cristina de Foggi Bruna Natália Alves da Silva Pimentel Marcelo Assis Juan Andrés Elson Longo Carlos Eduardo Vergani 《Ceramics International》2021,47(16):22604-22614
The present study reports for the first time the performance of silver phosphate (Ag3PO4) microcrystals as photocatalyst (degradation of Rodamine B-RhB) and antifungal agent (against Candida albicans–C. albicans) under visible-light irradiation (455 nm). Ag3PO4 microcrystals were synthesized by a simple co-precipitation (CP) method at room temperature. The structural and electronic properties of the as-synthetized Ag3PO4 have been investigated before and after 4 cycles of RhB degradation under visible light using X-ray diffraction (XRD), micro-Raman spectroscopy, UV–Vis spectrophotometer and field emission scanning electron microscopy (FE-SEM) images. The antifungal activity was analyzed in planktonic cells and 48h-biofilm of C. albicans by colony forming units (CFU) counting, confocal laser and FE-SE microscopies. Statistical analysis was carried out using SPSS software. Morphological and structural modifications of Ag3PO4 were observed upon recycling. After 4 recycles, the material maintained its photodegradation property; an eightfold increase in the efficiency of Ag3PO4 was observed in planktonic cells and a two fold increase in biofilm when irradiated under visible light. Thus, higher antifungal effectiveness against C. albicans was obtained when associated with visible-light irradiation. 相似文献
3.
4.
5.
6.
7.
Fabíola Azanha de Carvalho Amanda Aleixo Moreira André Luiz Martinez de Oliveira Fabio Yamashita 《应用聚合物科学杂志》2021,138(28):50667
Neat poly (lactic acid) (PLA) and PLA/cassava bagasse (CB) composites were used to produce seedling tubes by extrusion and injection molding. The tubes were buried in simulated soil, and their biodegradation was investigated by weight loss, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). After 180 days, the composites' biodegradation was higher than neat PLA material, and the higher the CB content, the higher the biodegradation, which caused fissures and voids in the material. The biodegradation of PLA/CB composites increased the phosphorus content in the soil after 180 days. Composites of PLA with CB, an abundant agro-industrial residue in Brazil, are promising because they can reduce the environmental impact due to CB's proper destination, and the composites' costs and biodegradation are faster than pure PLA material. Both the faster biodegradation of the tube and the higher P content are advantageous for seedling tubes. 相似文献
8.
Andrés Mario Zervigón 《History of Photography》2019,43(2):130-143
For decades now, Douglas Crimp’s landmark 1980 essay ‘The Photographic Activity of Postmodernism’ has shaped our understanding of modernism’s aftermath, at least as it unfolded in North America and Western Europe. Less remembered, however, is the degree to which the procedures of disjunction, copying, appropriation, and outright theft that he highlighted were epitomised not just by contemporary photography, but by photomontage in particular. This article recovers the debates that led critics such as Crimp, Abigail Solomon-Godeau, Christopher Phillips, Benjamin Buchloh and others to turn to photomontage as one of their principal objects of concern in what became known as the postmodern critique of photography. Why was montage tasked to perform this critical function, particularly by people around the journal October who had not otherwise devoted the balance of their writing to photography’s history? The article suggests that these men and women, along with the contemporary artists they foregrounded, manifested what Mary Anne Doane has called a ‘desire for signification’, a reaction in the late 1970s against the mute theatricality of minimalist and conceptual art. Photomontage reintroduced representation to contemporary art and to the canon of art history. But unlike the reemerging illusionism in painting that also manifested this desire, montage guarded against an uncomplicated realism by highlighting and critiquing operations of representation in a manner that painting no longer could. 相似文献
9.
10.
Bill Robert Fleck Martin Troya Javier Mayerhofer Tanja Wimmer Manuel 《Software and Systems Modeling》2019,18(2):1017-1046
Software and Systems Modeling - Many model transformation scenarios require flexible execution strategies as they should produce models with the highest possible quality. At the same time,... 相似文献