全文获取类型
收费全文 | 3823篇 |
免费 | 276篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 63篇 |
综合类 | 3篇 |
化学工业 | 1003篇 |
金属工艺 | 94篇 |
机械仪表 | 111篇 |
建筑科学 | 131篇 |
矿业工程 | 5篇 |
能源动力 | 157篇 |
轻工业 | 629篇 |
水利工程 | 28篇 |
石油天然气 | 20篇 |
无线电 | 277篇 |
一般工业技术 | 720篇 |
冶金工业 | 387篇 |
原子能技术 | 22篇 |
自动化技术 | 456篇 |
出版年
2024年 | 10篇 |
2023年 | 38篇 |
2022年 | 81篇 |
2021年 | 151篇 |
2020年 | 109篇 |
2019年 | 132篇 |
2018年 | 135篇 |
2017年 | 157篇 |
2016年 | 172篇 |
2015年 | 114篇 |
2014年 | 189篇 |
2013年 | 270篇 |
2012年 | 249篇 |
2011年 | 264篇 |
2010年 | 211篇 |
2009年 | 234篇 |
2008年 | 190篇 |
2007年 | 191篇 |
2006年 | 138篇 |
2005年 | 105篇 |
2004年 | 85篇 |
2003年 | 94篇 |
2002年 | 62篇 |
2001年 | 53篇 |
2000年 | 37篇 |
1999年 | 50篇 |
1998年 | 115篇 |
1997年 | 89篇 |
1996年 | 61篇 |
1995年 | 41篇 |
1994年 | 36篇 |
1993年 | 37篇 |
1992年 | 23篇 |
1991年 | 19篇 |
1990年 | 25篇 |
1989年 | 16篇 |
1988年 | 27篇 |
1987年 | 8篇 |
1986年 | 12篇 |
1985年 | 10篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1981年 | 11篇 |
1980年 | 5篇 |
1979年 | 5篇 |
1977年 | 9篇 |
1976年 | 8篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1972年 | 2篇 |
排序方式: 共有4106条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
6.
7.
P. Carrasqueira H. Rocha J. M. Dias T. Ventura B. C. Ferreira M. C. Lopes 《International Transactions in Operational Research》2023,30(1):206-223
Radiation therapy is a technology-driven cancer treatment modality that has experienced significant advances over the last decades, due to multidisciplinary contributions that include engineering and computing. Recent technological developments allow the use of noncoplanar volumetric modulated arc therapy (VMAT), one of the most recent photon treatment techniques, in clinical practice. In this work, an automated noncoplanar arc trajectory optimization framework designed in two modular phases is presented. First, a noncoplanar beam angle optimization algorithm is used to obtain a set of noncoplanar irradiation directions. Then, anchored in these directions, an optimization strategy is proposed to compute an optimal arc trajectory. The computational experiments considered a pool of twelve difficult head-and-neck tumor cases. It was possible to observe that, for some of these cases, the optimized noncoplanar arc trajectories led to significant treatment planning quality improvements, when compared with coplanar VMAT treatment plans. Although these experiments were done in a research environment treatment planning software (matRad), the conclusions can be of interest for a clinical setting: automated procedures can simplify the current treatment workflow, produce high-quality treatment plans, making better use of human resources and allowing for unbiased comparisons between different treatment techniques. 相似文献
8.
Chitosan microspheres containing bromocresol green, cresol red, and phenolphthalein for corrosion detection, through pH change, are synthesized in order to be used in protective coatings for aluminium alloys. Microspheres containing corrosion detection species are characterized morphologically (SEM) and physico‐chemically (FTIR, TGA). Release studies (UV–vis) are performed in corrosion‐promoting conditions (pH, NaCl), and detection studies by immersion in media associated with corrosion activity while microspheres' sensing activity is evaluated visually. Electrochemical characterization of AA2024 substrates in the presence of chitosan spheres is performed to understand material performance, and a color change is observed as a result of local pH increase in cathodic areas when corrosion takes place. These findings can be correlated with the results from release studies and seem a promising approach for corrosion sensing purposes, not only because pH increase is possible to detect due to corrosion, but also because chitosan is considered an environmentally friendly material. 相似文献
9.
Antoine Depoorter Carmen Kalalian Corinne Emmelin Chantal Lorentz Christian George 《Indoor air》2021,31(3):682-692
People spend approximately 80% of their time indoor, making the understanding of the indoor chemistry an important task for safety. The high surface-area-to-volume ratio characteristic of indoor environments leads the semi-volatile organic compounds (sVOCs) to deposit on the surfaces. Using a long path absorption photometer (LOPAP), this work investigates the formation of nitrous acid (HONO) through the photochemistry of adsorbed nitrate anions and its enhancement by the presence of furfural. Using a high-resolution proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF-MS), this work also investigates the surface emissions of VOCs from irradiated films of furfural and a mix of furfural and nitrate anions. Among the emitted VOCs, 2(5H)-furanone/2-Butenedial was observed at high concentrations, leading to maleic anhydride formation after UV irradiation. Moreover, the addition of potassium nitrate to the film formed NOx and HONO concentrations up to 10 ppb, which scales to ca. 4 ppb for realistic indoor conditions. This work helps to understand the high levels of HONO and NOx measured indoors. 相似文献
10.