全文获取类型
收费全文 | 5882篇 |
免费 | 371篇 |
国内免费 | 20篇 |
专业分类
电工技术 | 91篇 |
综合类 | 13篇 |
化学工业 | 1290篇 |
金属工艺 | 132篇 |
机械仪表 | 129篇 |
建筑科学 | 226篇 |
矿业工程 | 10篇 |
能源动力 | 216篇 |
轻工业 | 351篇 |
水利工程 | 34篇 |
石油天然气 | 23篇 |
无线电 | 1051篇 |
一般工业技术 | 1115篇 |
冶金工业 | 498篇 |
原子能技术 | 30篇 |
自动化技术 | 1064篇 |
出版年
2024年 | 11篇 |
2023年 | 125篇 |
2022年 | 168篇 |
2021年 | 348篇 |
2020年 | 260篇 |
2019年 | 206篇 |
2018年 | 262篇 |
2017年 | 218篇 |
2016年 | 319篇 |
2015年 | 197篇 |
2014年 | 283篇 |
2013年 | 410篇 |
2012年 | 309篇 |
2011年 | 360篇 |
2010年 | 251篇 |
2009年 | 246篇 |
2008年 | 241篇 |
2007年 | 217篇 |
2006年 | 154篇 |
2005年 | 138篇 |
2004年 | 118篇 |
2003年 | 95篇 |
2002年 | 83篇 |
2001年 | 87篇 |
2000年 | 56篇 |
1999年 | 68篇 |
1998年 | 222篇 |
1997年 | 104篇 |
1996年 | 88篇 |
1995年 | 79篇 |
1994年 | 51篇 |
1993年 | 70篇 |
1992年 | 38篇 |
1991年 | 39篇 |
1990年 | 28篇 |
1989年 | 35篇 |
1988年 | 23篇 |
1987年 | 24篇 |
1986年 | 28篇 |
1985年 | 24篇 |
1984年 | 28篇 |
1983年 | 19篇 |
1982年 | 17篇 |
1981年 | 15篇 |
1980年 | 14篇 |
1979年 | 14篇 |
1978年 | 16篇 |
1977年 | 12篇 |
1975年 | 10篇 |
1973年 | 10篇 |
排序方式: 共有6273条查询结果,搜索用时 15 毫秒
1.
Quan Nguyen Minh Quoc Dat Lai Hoang Nguy Minh Minh Tu Tran Kieu Ngoc Lam Gia Uyen Le My Phung Hang Hoang Dung Nguyen Tran Diem Ai Chau Ngoc Thuc Trinh Doan 《International Journal of Food Science & Technology》2022,57(7):4507-4517
To prevent the adulteration of agricultural resources and provide a solution to enhance the green coffee bean supply chain, authentication using the near-infrared spectroscopy (NIRS) technique was investigated. Partial least square with discrimination analysis (PLS-DA) models combined with various preprocessing methods were built from NIR spectra of 153 Vietnamese green coffee samples. The model combined with the standard normal variate and the first order of derivative yielded excellent performance in predicting coffee species with the error cross-validation of 0.0261. PLS-DA model of mean centre and first-order derivative spectra also yielded good performance in verifying geographical indication of green coffee with the error of 0.0656. By contrast, the predicting abilities of post-harvest methods were poor. The overall results showed a high potential of the NIRS in online authentication practices. 相似文献
2.
ABSTRACT Contact tracing is widely considered as an effective procedure in the fight against epidemic diseases. However, one of the challenges for technology based contact tracing is the high number of false positives, questioning its trust-worthiness and efficiency amongst the wider population for mass adoption. To this end, this paper proposes a novel, yet practical smartphone-based contact tracing approach, employing WiFi and acoustic sound for relative distance estimate, in addition to the air pressure and the magnetic field for ambient environment matching. We present a model combining six smartphone sensors, prioritising some of them when certain conditions are met. We empirically verified our approach in various realistic environments to demonstrate an achievement of up to 95% fewer false positives, and 62% more accurate than Bluetooth-only system. To the best of our knowledge, this paper was one of the first work to propose a combination of smartphone sensors for contact tracing. 相似文献
3.
Hoang V. Le Phuong T. Pham Ly T. Le Anh D. Nguyen Ngoc Quang Tran Phong D. Tran 《International Journal of Hydrogen Energy》2021,46(44):22852-22863
WO3 is a potential material candidate for construction of photoanode for solar driven water splitting. In this work, μm-thick porous WO3 photoanode is prepared by depositing a stable ink made of WO3 nanoparticles and Aristoflex velvet polymer in water using the doctor blade technique, followed by a sintering in air. The nature of WO3 nanoparticles, its loading mass on F-doped tin oxide electrode as well as sintering temperature are examined in order to optimize the photocatalytic activity of the resultant WO3 photoanode. The operation of WO3 photoanode is investigated by varying the light illumination direction and light incident intensity as well as changing the nature of the electrolyte. Dissolved tungsten in electrolyte is quantified by ICP-MS providing insights into the influences of electrolyte nature and operating conditions to the corrosion of WO3. It is proposed that the H2O2 and OH. radical generated as by-products of the photo-driven water oxidation on the photoanode surface are harmful species that accelerate the dissolution of WO3. 相似文献
4.
Kooij Julian F. P. Flohr Fabian Pool Ewoud A. I. Gavrila Dariu M. 《International Journal of Computer Vision》2019,127(3):239-262
International Journal of Computer Vision - Anticipating future situations from streaming sensor data is a key perception challenge for mobile robotics and automated vehicles. We address the problem... 相似文献
5.
Anh Tuan Thanh Pham Oanh Kieu Truong Le Dung Van Hoang Truong Huu Nguyen Trang Huyen Cao Pham Phuong Thanh Ngoc Vo Thang Bach Phan Vinh Cao Tran 《Journal of the European Ceramic Society》2021,41(6):3493-3500
Structure modification has been found to tune significantly the transparent-conducting performance, especially mobility and conductivity of hydrogenated Ga-doped ZnO (HGZO) films. The strong correlation between film thickness and mobility of the films is revealed. The mobility increases quickly with increasing the thickness from 350 to 900 nm, and then tends to be saturated at further thicknesses. A higher mobility than 50 cm2/Vs can be achieved, which is an extra-high value for polycrystalline ZnO films deposited by using the sputtering technique. The thickness-dependent mobility originates from scatterings on grain boundaries and dislocation-induced defects controlled by thin-film growth. Based on the Volmer-Weber model, an expansion model is built up to describe the thickness-dependent crystal growth of the HGZO films, especially at the thick films. As a result, the 800 nm-thick HGZO film obtains the highest performance with high mobility of 51.5 cm2/Vs, low resistivity of 5.3 × 10?4 Ωcm, and good transmittance of 83.3 %. 相似文献
6.
7.
Annika Jahn Anton Hoffmann Luisa Blaesing Fabian Kunde Martin Bertau Martina Bremer Steffen Fischer 《化学,工程师,技术》2020,92(11):1733-1740
The enzymatic conversion of lignins, possibly in combination with electrochemical oxidation, makes aromatics such as syringol, guaiacol, vanillin and catechol available in the qualities required by the fragrance industry. The lignins were obtained by soda digestion from wheat straw and Miscanthus, characterized and then converted with laccases. The overall yield amounted up to 9 wt % with a product spectrum confined to four substances. Catechol was the major product, with a fraction of ≈75 %. It can easily be isolated by extraction with acetone. 相似文献
8.
Vu Hoa T. Nguyen Manh B. Vu Tan M. Le Giang H. Pham Trang T. T. Nguyen Trinh Duy Vu Tuan A. 《Topics in Catalysis》2020,63(11-14):1046-1055
Topics in Catalysis - Nano Fe-BTC/graphene oxide (GO) composites were successfully synthesized by hydrothermal treatment with a microwave-assisted method. Samples were characterized by X-ray... 相似文献
9.
Makrina A. Chairopoulou Fabian Kratzer Roland Gross Michael Herrmann Ulrich Teipel 《化学工程与技术》2020,43(5):904-912
Thermogravimetric analysis of a coccolith-containing biogenic broth showed a three-step degradation process. According to this system behavior, the biogenic broth was heated to specific temperatures and characterized in terms of its morphology, surface chemistry, and crystallinity. The elemental and organic composition of the treated samples was also evaluated and compared to the reference material. The presented results were acquired in an effort to exploit pretreatment scenarios for such a biogenic system that would improve and support a separation process. 相似文献
10.