全文获取类型
收费全文 | 364568篇 |
免费 | 10808篇 |
国内免费 | 5045篇 |
专业分类
电工技术 | 10315篇 |
技术理论 | 5篇 |
综合类 | 5999篇 |
化学工业 | 56274篇 |
金属工艺 | 18184篇 |
机械仪表 | 13514篇 |
建筑科学 | 14764篇 |
矿业工程 | 3197篇 |
能源动力 | 9688篇 |
轻工业 | 31230篇 |
水利工程 | 3702篇 |
石油天然气 | 7823篇 |
武器工业 | 686篇 |
无线电 | 43327篇 |
一般工业技术 | 62961篇 |
冶金工业 | 60691篇 |
原子能技术 | 5557篇 |
自动化技术 | 32504篇 |
出版年
2022年 | 3413篇 |
2021年 | 5140篇 |
2020年 | 3867篇 |
2019年 | 3856篇 |
2018年 | 5307篇 |
2017年 | 5533篇 |
2016年 | 5416篇 |
2015年 | 5528篇 |
2014年 | 7822篇 |
2013年 | 17571篇 |
2012年 | 11920篇 |
2011年 | 14982篇 |
2010年 | 12330篇 |
2009年 | 13146篇 |
2008年 | 13428篇 |
2007年 | 13442篇 |
2006年 | 12888篇 |
2005年 | 11685篇 |
2004年 | 9958篇 |
2003年 | 9513篇 |
2002年 | 9283篇 |
2001年 | 9194篇 |
2000年 | 8789篇 |
1999年 | 9834篇 |
1998年 | 20453篇 |
1997年 | 14716篇 |
1996年 | 11924篇 |
1995年 | 8949篇 |
1994年 | 7712篇 |
1993年 | 7230篇 |
1992年 | 5252篇 |
1991年 | 5032篇 |
1990年 | 4442篇 |
1989年 | 4264篇 |
1988年 | 4032篇 |
1987年 | 3449篇 |
1986年 | 3292篇 |
1985年 | 3842篇 |
1984年 | 3378篇 |
1983年 | 3053篇 |
1982年 | 2868篇 |
1981年 | 2882篇 |
1980年 | 2781篇 |
1979年 | 2598篇 |
1978年 | 2512篇 |
1977年 | 3193篇 |
1976年 | 4744篇 |
1975年 | 2198篇 |
1974年 | 2077篇 |
1973年 | 2085篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Wireless Personal Communications - The orthogonal frequency division multiplexing (OFDM) is the most encouraging multi-carrier modulation system chosen for the high data rates but the objective is... 相似文献
52.
53.
54.
55.
56.
Qingna Gong Songtao Cao Yu Zhou Ruixin Wang Weizhou Jiao 《International Journal of Hydrogen Energy》2021,46(41):21442-21453
Ni2P nanoparticles and CdS nanorods were grew together on a mesoporous g-C3N4 through a facile in-situ solvothermal approach. Under visible light (λ > 400 nm), the as-prepared ternary PCN–CdS-5% Ni2P composite displays a high H2 evolution rate with 2905.86 μmol g?1 h?1, which is about 14, 18 and 279 times that of PCN–CdS, PCN–Ni2P and PCN, respectively. The enhanced photocatalytic activity is mainly attributed to the improved separation efficiency of the photocarriers by the type II PCN–CdS heterojunction and the effective extraction of photogenerated electrons by Ni2P. Meanwhile, Ni2P acts as co-catalyst to provide the photocatalytic active site for hydrogen reduction. In addition, PCN–CdS-5% Ni2P composite exerts good stability in 12-h cycles. 相似文献
57.
Xiaoyan Qiu Yongqiang Zhang Haitao Wu Rui Yang Jun Yang Rongjuan Liu Yong Liu Zhiping Zhou Tongfan Hao Yijing Nie 《Polymer International》2019,68(2):218-224
The crystallization of capped ultrathin polymer films is closely dependent on film thickness and interfacial interaction. Using dynamic Monte Carlo simulations, the crystallization behaviors of polymer films confined between two substrates were investigated. The crystallization rate of confined polymers is reduced with high interfacial interactions. Above a critical strength of interfacial interaction, polymer crystallization in the thin film is inhibited within the simulation time scales. An increase in film thickness leads to a rise in critical interfacial interaction. In thicker films, the chains have more space to change conformation to form crystal stems. In addition, there are fewer absorbed segments in confined chains for the thicker films, and thus the chains have stronger ability to adjust their conformation. Therefore an increase in film thickness can cause a reduction in the entropic barrier required for the formation of crystals and thus an increase in the critical interfacial interaction. © 2018 Society of Chemical Industry 相似文献
58.
As a solid state joining process, ultrasonic spot welding has been proven to be a promising technique for joining copper alloys. However, challenges still remain in employing ultrasonic spot welding to join copper alloys. This article comprehensively reviews the current state of ultrasonic spot welding of copper alloys with a number of critical issues including materials flow, plastic deformation, temperature distribution, vibration, relative motion, vertical displacement, interface friction coefficient, online monitoring technique, coupled with the macrostructure and microstructure, the mechanical properties and electrical conductivity. In addition, the future trends in this field are provided. 相似文献
59.
Molecular structure and granule morphology of native and heat‐moisture‐treated pinhão starch
下载免费PDF全文
![点击此处可从《International Journal of Food Science & Technology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Vania Z. Pinto Khalid Moomand Nathan L. Vanier Rosana Colussi Franciene A. Villanova Elessandra R. Zavareze Loong‐Tak Lim Alvaro R. G. Dias 《International Journal of Food Science & Technology》2015,50(2):282-289
Pinhão seed is an unconventional source of starch and the pines grow up in native forests of southern Latin America. In this study, pinhão starch was adjusted at 15, 20 and 25% moisture content and heated to 100, 110 and 120 °C for 1 h. A decrease in λ max (starch/iodine complex) was observed as a result of increase in temperature and moisture content of HMT. The ratio of crystalline to amorphous phase in pinhão starch was determined via Fourier transform infra red by taking 1045/1022 band ratio. A decrease in crystallinity occurred as a result of HMT. Polarised light microscopy indicated a loss of birefringence of starch granules under 120 °C at 25% moisture content. Granule size distribution was further confirmed via scanning electron microscopy which showed the HMT effects. These results increased the understanding on molecular and structural properties of HMT pinhão starch and broadened its food and nonfood industrial applications. 相似文献
60.
Effects of different carbon sources and C/N values on nonvolatile taste components of Pleurotus eryngii
下载免费PDF全文
![点击此处可从《International Journal of Food Science & Technology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Wen Li Xiaobei Li Yan Yang Feng Zhou Yanfang Liu Shuai Zhou Hailong Yu 《International Journal of Food Science & Technology》2015,50(11):2360-2366
Pleurotus eryngii, the second largest industrial cultivation mushroom in China, is usually cultivated on substrates mainly consisting of sawdust and corncob. In this study, experiments were performed to determine the effects of different carbon sources and C/N values on nonvolatile taste components of P. eryngii. The effects of different carbon sources on nonvolatile taste components levels revealed that sawdust was beneficial to high levels of crude protein, amino acids, 5′‐nucleotides and equivalent umami concentration, while corncob was beneficial to high contents of carbohydrate, polysaccharides and trehalose. At the similar C/N values, relatively higher sawdust content was beneficial to umami amino acid production, while relatively higher corncob content was beneficial to high contents of carbohydrate, polysaccharides and mannitol. Higher C/N value was beneficial to high levels of crude protein, amino acids, 5′‐nucleotides and equivalent umami concentration, while lower C/N value was beneficial to high contents of carbohydrate, polysaccharides and trehalose. These results provided information for P. eryngii fruit body industrial cultivation to obtain specific nonvolatile taste components with high levels. 相似文献