全文获取类型
收费全文 | 1917485篇 |
免费 | 53946篇 |
国内免费 | 22160篇 |
专业分类
电工技术 | 55194篇 |
技术理论 | 45篇 |
综合类 | 31238篇 |
化学工业 | 332063篇 |
金属工艺 | 84981篇 |
机械仪表 | 67049篇 |
建筑科学 | 74446篇 |
矿业工程 | 23252篇 |
能源动力 | 59512篇 |
轻工业 | 143059篇 |
水利工程 | 22774篇 |
石油天然气 | 59923篇 |
武器工业 | 2921篇 |
无线电 | 234693篇 |
一般工业技术 | 331140篇 |
冶金工业 | 216755篇 |
原子能技术 | 37876篇 |
自动化技术 | 216670篇 |
出版年
2022年 | 19880篇 |
2021年 | 29033篇 |
2020年 | 22033篇 |
2019年 | 22840篇 |
2018年 | 27410篇 |
2017年 | 28214篇 |
2016年 | 32129篇 |
2015年 | 31024篇 |
2014年 | 45690篇 |
2013年 | 107897篇 |
2012年 | 59397篇 |
2011年 | 75816篇 |
2010年 | 66211篇 |
2009年 | 72937篇 |
2008年 | 67280篇 |
2007年 | 64158篇 |
2006年 | 65020篇 |
2005年 | 58250篇 |
2004年 | 53897篇 |
2003年 | 52538篇 |
2002年 | 50607篇 |
2001年 | 46695篇 |
2000年 | 44865篇 |
1999年 | 45251篇 |
1998年 | 62738篇 |
1997年 | 51474篇 |
1996年 | 45043篇 |
1995年 | 37760篇 |
1994年 | 34370篇 |
1993年 | 33049篇 |
1992年 | 28582篇 |
1991年 | 25400篇 |
1990年 | 25416篇 |
1989年 | 24329篇 |
1988年 | 22746篇 |
1987年 | 20580篇 |
1986年 | 19894篇 |
1985年 | 23039篇 |
1984年 | 22864篇 |
1983年 | 20735篇 |
1982年 | 19628篇 |
1981年 | 19760篇 |
1980年 | 18389篇 |
1979年 | 18731篇 |
1978年 | 17995篇 |
1977年 | 18332篇 |
1976年 | 20175篇 |
1975年 | 16222篇 |
1974年 | 15631篇 |
1973年 | 15767篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Li Zhang Huiqun Yuan Sheng-Hung Chang Anthony Lam 《The International Journal of Advanced Manufacturing Technology》2020,107(3):1081-1089
With the continuous development of the Internet of Things technology and the proposal of “Made in China 2025”, the construction of IoT applicat 相似文献
992.
ABSTRACTThis paper proposes the multiple-hypotheses image segmentation and feed-forward neural network classifier for food recognition to improve the performance. Initially, the food or meal image is given as input. Then, the segmentation is applied to identify the regions, where a particular food item is located using salient region detection, multi-scale segmentation, and fast rejection. Then, the features of every food item are extracted by the global feature and local feature extraction. After the features are obtained, the classification is performed for each segmented region using a feed-forward neural network model. Finally, the calorie value is computed with the aid of (i) food volume and (ii) calorie and nutrition measure based on mass value. The experimental results and performance evaluation are validated. The outcome of the proposed method attains 0.947 for Macro Average Accuracy (MAA) and 0.959 for Standard Accuracy (SA), which provides better classification performance. 相似文献
993.
Radiochemistry - The study deals with separation of uranium, thorium, and yttrium with highest possible purity from El-Garaa El-Hamara sulfate leach liquor. From the latter, almost complete... 相似文献
994.
995.
996.
Li Jinghang Zhao Zhigang Zhang Shaohui Su Cheng 《Journal of Mechanical Science and Technology》2021,35(10):4727-4735
Journal of Mechanical Science and Technology - A multi-robot collaborative towing system fixed on floating base for high load marine work was established in this paper, and its dynamics and... 相似文献
997.
Locke Davenport Huyer Serena Mandla Yufeng Wang Scott B. Campbell Bess Yee Christian Euler Benjamin F. Lai A. Dawn Bannerman Dawn S. Y. Lin Miles Montgomery Kayla Nemr Timothy Bender Slava Epelman Radhakrishnan Mahadevan Milica Radisic 《Advanced functional materials》2021,31(6):2003341
Itaconate (ITA) is an emerging powerhouse of innate immunity with therapeutic potential that is limited in its ability to be administered in a soluble form. A library of polyester materials that incorporate ITA into polymer backbones resulting in materials with inherent immunoregulatory behavior is developed. Harnessing hydrolytic degradation release from polyester backbones, ITA polymers result in the mechanism specific immunoregulatory properties on macrophage polarization in vitro. In a functional assay, the polymer-released ITA inhibits bacterial growth on acetate. Translation to an in vivo model of biomaterial associated inflammation, intraperitoneal injection of ITA polymers demonstrate a rapid resolution of inflammation in comparison to a control polymer silicone, demonstrating the value of sustained biomimetic presentation of ITA. 相似文献
998.
Özge Seçmeler Özlem Güçlü Üstündağ 《International Journal of Food Science & Technology》2019,54(5):1609-1616
The partitioning of predominant lipophilic olive bioactives (squalene, β-sitosterol and α-tocopherol) in olive oil processing was studied for the first time using common integrated olive milling plant. 7% of the oil and 5% of the squalene present in the olives was lost in the last pomace. β-sitosterol and α-tocopherol, which are mainly concentrated in the seed of the olive fruit, was recovered in virgin olive oil to a lesser extent (66%, 67%) while 10% were lost in last pomace. Thus, the loss of β-sitosterol and α-tocopherol was higher than that of squalene and oil, due to nonrecovered bound forms. 19% of the α-tocopherol and 21% of the β-sitosterol loss was unaccounted for, which can be attributed to degradation of α-tocopherol and incomplete recovery of sterols from the olive and pomace matrices. This study provides a basis for process development studies. 相似文献
999.
Joshua C. Price Simon J. Levett Valentin Radu David A. Simpson Aina Mogas Barcons Christopher F. Adams Melissa L. Mather 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(22)
Fluorescent nanodiamonds (fNDs) containing nitrogen vacancy (NV) centers are promising candidates for quantum sensing in biological environments. This work describes the fabrication and implementation of electrospun poly lactic‐co‐glycolic acid (PLGA) nanofibers embedded with fNDs for optical quantum sensing in an environment, which recapitulates the nanoscale architecture and topography of the cell niche. A protocol that produces uniformly dispersed fNDs within electrospun nanofibers is demonstrated and the resulting fibers are characterized using fluorescent microscopy and scanning electron microscopy (SEM). Optically detected magnetic resonance (ODMR) and longitudinal spin relaxometry results for fNDs and embedded fNDs are compared. A new approach for fast detection of time varying magnetic fields external to the fND embedded nanofibers is demonstrated. ODMR spectra are successfully acquired from a culture of live differentiated neural stem cells functioning as a connected neural network grown on fND embedded nanofibers. This work advances the current state of the art in quantum sensing by providing a versatile sensing platform that can be tailored to produce physiological‐like cell niches to replicate biologically relevant growth environments and fast measurement protocols for the detection of co‐ordinated endogenous signals from clinically relevant populations of electrically active neuronal circuits. 相似文献
1000.
David J. Lawrence Brianna L. Smith Cameron D. Collard Keyton A. Elliott Kyle L. Fakhoury Jeffery D. Mangold Anna N. Soyka 《International Journal of Hydrogen Energy》2021,46(2):1642-1655
Monolithically-integrated tandem photoanodes were fabricated on substrates consisting of epitaxial n-GaAs1-xPx (x ? 0.32) grown on n+-GaAs wafers. A p+-n junction photovoltaic (PV) cell was first formed by zinc diffusion into the n-GaAs0.68P0.32 from a deposited ZnO coating. After diffusion the ZnO serves as a transparent electrical contact to the resulting p+-GaAs0.68P0.32 surface layer. Transparent, conducting SnO2:F provides chemical and mechanical protection for the ZnO and the underlying PV cell, and it electrically connects this cell to a top BiVO4 photocatalyst layer. In some photoanodes, a WO3 thin film was interposed between the SnO2:F and BiVO4. All oxide coatings were produced by ultrasonic spray pyrolysis except WO3, which was spin coated. Unassisted (unbiased) solar water splitting was achieved, with a solar-to-hydrogen efficiency approaching 2%, without addition of any co-catalyst to the BiVO4 surface. This work can provide insights to other researchers regarding scalable, low cost approaches for the planar monolithic integration of oxide photoanode materials with PV cells to create new tandem devices. 相似文献