全文获取类型
收费全文 | 4072篇 |
免费 | 225篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 37篇 |
综合类 | 2篇 |
化学工业 | 959篇 |
金属工艺 | 36篇 |
机械仪表 | 76篇 |
建筑科学 | 180篇 |
矿业工程 | 4篇 |
能源动力 | 126篇 |
轻工业 | 416篇 |
水利工程 | 37篇 |
石油天然气 | 3篇 |
无线电 | 390篇 |
一般工业技术 | 824篇 |
冶金工业 | 284篇 |
原子能技术 | 26篇 |
自动化技术 | 904篇 |
出版年
2024年 | 6篇 |
2023年 | 37篇 |
2022年 | 126篇 |
2021年 | 165篇 |
2020年 | 131篇 |
2019年 | 109篇 |
2018年 | 155篇 |
2017年 | 143篇 |
2016年 | 189篇 |
2015年 | 119篇 |
2014年 | 190篇 |
2013年 | 293篇 |
2012年 | 255篇 |
2011年 | 304篇 |
2010年 | 216篇 |
2009年 | 218篇 |
2008年 | 227篇 |
2007年 | 192篇 |
2006年 | 166篇 |
2005年 | 139篇 |
2004年 | 125篇 |
2003年 | 107篇 |
2002年 | 103篇 |
2001年 | 57篇 |
2000年 | 43篇 |
1999年 | 58篇 |
1998年 | 76篇 |
1997年 | 54篇 |
1996年 | 45篇 |
1995年 | 29篇 |
1994年 | 16篇 |
1993年 | 17篇 |
1992年 | 22篇 |
1991年 | 6篇 |
1990年 | 11篇 |
1989年 | 11篇 |
1988年 | 14篇 |
1987年 | 8篇 |
1986年 | 13篇 |
1985年 | 13篇 |
1984年 | 13篇 |
1983年 | 9篇 |
1982年 | 8篇 |
1981年 | 15篇 |
1980年 | 6篇 |
1977年 | 8篇 |
1976年 | 8篇 |
1975年 | 6篇 |
1971年 | 3篇 |
1970年 | 3篇 |
排序方式: 共有4304条查询结果,搜索用时 12 毫秒
1.
2.
Evaluation of the effect of processing on cocoa polyphenols: antiradical activity,anthocyanins and procyanidins profiling from raw beans to chocolate 下载免费PDF全文
Matteo Bordiga Monica Locatelli Fabiano Travaglia Jean Daniel Coïsson Giuseppe Mazza Marco Arlorio 《International Journal of Food Science & Technology》2015,50(3):840-848
The content and composition of anthocyanins and procyanidins in fermented cocoa beans (from different geographic origins: Ecuador, Cameroon, Ivory Coast, Ghana and Nigeria), roasted nibs, cocoa mass and chocolate were determined, beside the determination of the total antiradical capacity. Concerning geographic origin, cocoa beans and processed products from Ecuador showed the highest levels of anthocyanins, followed by Nigeria and Cameroon. Generally, as cocoa beans were further processed, the levels of anthocyanins and flavan‐3‐ols decreased. The largest observed losses of phenolics occurred during roasting. A progressive decreasing trend in polyphenol concentration was observed in the other processed samples as well. Despite the original content of polyphenols in raw cocoa beans, technological processes imply a significant impact on cocoa quality, confirming the need of specific optimisation to obtain high value chocolate. 相似文献
3.
4.
5.
The size effects on the mean values of the mechanical properties of condensed matter and on the related variances are analysed by means of a unified approach based on the multiscale character of energy dissipation. In particular, the scaling law for fragmentation energy density is obtained taking into account the self-similarity of fragments. It is based on a generalization of the three classical comminution laws that has been performed to evaluate the energy dissipation, computing volume and surface area of the particles for one- two- and three-dimensional fragmented objects. The result is general and can be applied to different fractal energy dissipation mechanisms, e.g., plasticity. Based on this approach, the scaling laws for mean and standard deviation values of the main mechanical properties of materials can be derived, like Young's and shear elastic moduli, ultimate normal and shear stresses and strains, fracture energy and toughness. 相似文献
6.
Bart Van der Bruggen 《Membrane Technology》2003,2003(2):6-9
As the requirement for fresh water increases worldwide, there is a need for more and more plants that are able to treat non-conventional water sources. Sea water has become an important source of fresh water in many arid regions. This feature provides an overview of recent process improvements in sea water desalination using reverse osmosis, multi-stage flash, multi-effect distillation and electrodialysis. Areas discussed include the use of alternative energy sources (wind energy, solar energy and nuclear energy) for reverse osmosis or distillation processes, and the impact of the different desalination process on the environment. Also covered are the implementation of hybrid processes in sea water desalination, and the pretreatment of desalination plants by pressure-driven membrane processes. 相似文献
7.
M. F. Sorokïna O. M. Kanunnikova F. Z. Gil'mutdinov V. I. Kozhevnikov 《Glass and Ceramics》1996,53(1-2):11-13
The method of x-ray electron spectroscopy is used to investigate lead silicatexPbO(1 -x) · SiO2 (x - 0.3, 0.4, 0.5, 0.55, 0.667) glasses. The concentration dependences of the spectra of inner Pb4f, Si2p, and Ols levels led to the conclusion that for low contents of PbO, lead is present in the glass in the form of modifying ions, whereas in high concentrations, it plays the role of glass former. Restructuring in the glass occurs for about 50% molar concentration of PbO. The Pb - O bond in the glass is more ionic than in PbO. With an increase in the PbO content in the glass, the Pb - O bond becomes closer to that of lead monoxide, i.e., is more covalent. 相似文献
8.
Farzaneh Fayazpour Bart Lucas Roosmarijn E. Vandenbroucke Stefaan Derveaux Jan Tavernier Sam Lievens Joseph Demeester Stefaan C. De Smedt 《Advanced functional materials》2008,18(18):2716-2723
To obtain more biologically relevant data there is a growing interest in the use of living cells for assaying the biological activity of unknown chemical compounds. Density ‘multiplex’ cell‐based assays, where different cell types are mixed in one well and simultaneously investigated upon exposure to a certain compound are beginning to emerge. To be able to identify the cells they should be attached to microscopic carriers that are encoded. This paper investigates how digitally encoded microparticles can be loaded with cells while keeping the digital code in the microcarriers readable. It turns out that coating the surface of the encoded microcarriers with polyelectrolytes using the layer‐by‐layer (LbL) approach provides the microcarriers with a ‘highly functional’ surface. The polyelectrolyte layer allows the growth of the cells, allows the orientation of the cell loaded microcarriers in a magnetic field, and does not hamper the reading of the code. It has further been shown that the cells growing on the polyelectrolyte layer can become transduced by adenoviral particles hosted by the polyelectrolyte layer. It is concluded that the digitally encoded microparticles are promising materials for use in biomedical and pharmaceutical in‐vitro research where cells are used as tools. 相似文献
9.
10.
Nguyen-Huy Dung Pardo Marie-Paule Dogguy.Smiri Leïla 《Materials Research Bulletin》1982,17(3):293-300
The Mn0.23Ga1.85S3 phase belongs to the solid solution , stable at low temperature in the Ga2S3MnS system. It is hexagonal superstructure of the wurtzite, with the Ga2S3α′ type (; Z = 6; space groupe P61 or P65). Its crystal structure has been refined by the least squares method to a final R = 0.06 with 323 independant reflections. This structure is closely related to Ga2S3 α described by Hahn and Frank, and differs only by the partial occupation of the vacant metal site of Ga2S3 by Mn atoms in statistical disorder. 相似文献