全文获取类型
收费全文 | 7706篇 |
免费 | 395篇 |
国内免费 | 26篇 |
专业分类
电工技术 | 113篇 |
综合类 | 19篇 |
化学工业 | 1433篇 |
金属工艺 | 131篇 |
机械仪表 | 186篇 |
建筑科学 | 333篇 |
矿业工程 | 9篇 |
能源动力 | 260篇 |
轻工业 | 477篇 |
水利工程 | 43篇 |
石油天然气 | 29篇 |
无线电 | 1343篇 |
一般工业技术 | 1394篇 |
冶金工业 | 861篇 |
原子能技术 | 47篇 |
自动化技术 | 1449篇 |
出版年
2023年 | 115篇 |
2022年 | 203篇 |
2021年 | 311篇 |
2020年 | 249篇 |
2019年 | 220篇 |
2018年 | 277篇 |
2017年 | 235篇 |
2016年 | 340篇 |
2015年 | 223篇 |
2014年 | 287篇 |
2013年 | 489篇 |
2012年 | 358篇 |
2011年 | 416篇 |
2010年 | 318篇 |
2009年 | 336篇 |
2008年 | 352篇 |
2007年 | 307篇 |
2006年 | 260篇 |
2005年 | 213篇 |
2004年 | 184篇 |
2003年 | 182篇 |
2002年 | 141篇 |
2001年 | 153篇 |
2000年 | 132篇 |
1999年 | 125篇 |
1998年 | 347篇 |
1997年 | 201篇 |
1996年 | 159篇 |
1995年 | 124篇 |
1994年 | 91篇 |
1993年 | 106篇 |
1992年 | 64篇 |
1991年 | 59篇 |
1990年 | 51篇 |
1989年 | 54篇 |
1988年 | 45篇 |
1987年 | 40篇 |
1986年 | 41篇 |
1985年 | 39篇 |
1984年 | 38篇 |
1983年 | 24篇 |
1982年 | 21篇 |
1981年 | 27篇 |
1980年 | 19篇 |
1979年 | 16篇 |
1978年 | 22篇 |
1977年 | 18篇 |
1976年 | 21篇 |
1975年 | 15篇 |
1973年 | 11篇 |
排序方式: 共有8127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.
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.
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
5.
6.
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
7.
Effect of Supports and Promoters on the Performance of Ni-Based Catalysts in Ethanol Steam Reforming
Thanh Khoa Phung Thong Le Minh Pham Anh-Nga T. Nguyen Khanh B. Vu Ha Ngoc Giang Tuan-Anh Nguyen Thanh Cong Huynh Hong Duc Pham 《化学工程与技术》2020,43(4):672-688
Ethanol steam reforming (ESR) is one of the potential processes to convert ethanol into valuable products. Hydrogen produced from ESR is considered as green energy for the future and can be an excellent alternative to fossil fuels with the aim of mitigating the greenhouse gas effect. The ESR process has been well studied, using transition metals as catalysts coupled with both acidic and basic oxides as supports. Among various reported transition metals, Ni is an inexpensive material with activity comparable to that of noble metals, showing promising ethanol conversion and hydrogen yields. Additionally, different promoters and supports were utilized to enhance the hydrogen yield and the catalyst stability. This review summarizes and discusses the influences of the supports and promoters of Ni-based catalysts on the ESR process. 相似文献
8.
Ajit Sharma Doan Van Thuan Thanh-Dong Pham Mai Hung Thanh Tung Nguyen Thi Thanh Truc Dai-Viet N. Vo 《化学工程与技术》2020,43(4):752-761
FeO-doped TiO2 nanoparticle photocatalysts were immobilized onto the surface of fibrous activated carbon (ACF) via a sol-gel process. As an adsorbent and photocatalyst, FeO-TiO2 on immobilized ACFs (FeO-TiO2/ACF) greatly improved the photocatalysis rate of hydrogen production as compared with pure TiO2 and ACF-TiO2 under UV irradiation and visible light. The addition of ACFs surface significantly reduced the photogenerated pairs of electrons-hole recombination, thereby promoting the photocatalysis action of doped photo-metal oxides of FeO-TiO2. Co-doping of FeO onto the lattice of the TiO2 approach can improve the absorption activity of visible light through photo-metal oxide of TiO2 and further enhance hydrogen production under visible light. The photocatalytic fabrics (FeO-TiO2/ACF) were effortlessly split out from the experimental solution for re-utilization and exhibited high stability even after five complete regeneration cycles. 相似文献
9.
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
10.
The extended quadratic residue code is the only (48,24,12) self-dual doubly-even code 总被引:3,自引:0,他引:3
Houghten S.K. Lam C.W.H. Thiel L.H. Parker J.A. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2003,49(1):53-59
An extremal self-dual doubly-even binary (n,k,d) code has a minimum weight d=4/spl lfloor/n/24/spl rfloor/+4. Of such codes with length divisible by 24, the Golay code is the only (24,12,8) code, the extended quadratic residue code is the only known (48,24,12) code, and there is no known (72,36,16) code. One may partition the search for a (48,24,12) self-dual doubly-even code into three cases. A previous search assuming one of the cases found only the extended quadratic residue code. We examine the remaining two cases. Separate searches assuming each of the remaining cases found no codes and thus the extended quadratic residue code is the only doubly-even self-dual (48,24,12) code. 相似文献