全文获取类型
收费全文 | 1917篇 |
免费 | 94篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 25篇 |
综合类 | 16篇 |
化学工业 | 579篇 |
金属工艺 | 31篇 |
机械仪表 | 34篇 |
建筑科学 | 140篇 |
矿业工程 | 3篇 |
能源动力 | 28篇 |
轻工业 | 181篇 |
水利工程 | 12篇 |
石油天然气 | 4篇 |
无线电 | 121篇 |
一般工业技术 | 382篇 |
冶金工业 | 93篇 |
原子能技术 | 16篇 |
自动化技术 | 351篇 |
出版年
2023年 | 28篇 |
2022年 | 51篇 |
2021年 | 67篇 |
2020年 | 38篇 |
2019年 | 47篇 |
2018年 | 46篇 |
2017年 | 44篇 |
2016年 | 53篇 |
2015年 | 47篇 |
2014年 | 74篇 |
2013年 | 101篇 |
2012年 | 92篇 |
2011年 | 159篇 |
2010年 | 103篇 |
2009年 | 114篇 |
2008年 | 104篇 |
2007年 | 84篇 |
2006年 | 88篇 |
2005年 | 75篇 |
2004年 | 69篇 |
2003年 | 54篇 |
2002年 | 54篇 |
2001年 | 45篇 |
2000年 | 45篇 |
1999年 | 42篇 |
1998年 | 28篇 |
1997年 | 30篇 |
1996年 | 20篇 |
1995年 | 20篇 |
1994年 | 29篇 |
1993年 | 15篇 |
1992年 | 12篇 |
1991年 | 24篇 |
1990年 | 14篇 |
1989年 | 17篇 |
1988年 | 10篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 6篇 |
1984年 | 11篇 |
1983年 | 8篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1978年 | 7篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1967年 | 2篇 |
1931年 | 3篇 |
排序方式: 共有2016条查询结果,搜索用时 8 毫秒
151.
Effect of Ca and B incorporation into silicon oxycarbide on its microstructure and phase composition
Fangtong Xie Isabel Gonzalo-Juan Hergen Breitzke Claudia Fasel Maximilian Trapp Gerd Buntkowsky Hans-Joachim Kleebe Ralf Riedel Aldo R. Boccaccini Emanuel Ionescu 《Journal of the American Ceramic Society》2019,102(12):7645-7655
Ca- and/or B-modified silicon oxycarbides were synthesized via pyrolysis of suitable polysilsesquioxane-based single-source precursors. Their polymer-to-ceramic transformation was investigated with thermogravimetric analysis, coupled with in situ evolved gas analysis. The prepared silicon oxycarbides were investigated with respect to their crystallization behavior, network architecture, and chemical compositions. The network connectivity in silicon oxycarbides can be affected/tuned upon using two different “tools”: (a) first, the use of network modifiers, such as Ca in our study, leads to a slight depolymerization of the network via generation of a small amount of Q3 sites; (b) second, the modification of silicon oxycarbide with B/Ca leads to a decrease of the carbon content in the network and thus to a significant decrease of its connectivity. Using these two different effects, the network connectivity in silicon oxycarbides can be finely tuned. 相似文献
152.
153.
Imide‐containing ladder polyphenylsilsesquioxanes with high thermal stability and thermoplastic properties 下载免费PDF全文
This work reports for the first time the synthesis of ladder polyphenylsilsesquioxanes containing imide building blocks as parts of the main parallel chains. The ladder structure of the synthesized polymers was documented by means of small angle X‐ray scattering (SAXS) measurements. The obtained ladder polymers exhibit stability with respect to decomposition up to temperatures as high as 460°C; additionally, they have melting points far below their decomposition temperatures, which make them interesting candidate materials for thermoplastic processing. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40085. 相似文献
154.
155.
156.
Harald Grssing Ewald Fauster Markus Weninger Ralf Schledjewski 《Polymer Composites》2016,37(6):1854-1863
Material parameters such as the permeability of dry reinforcing textiles are key variables for modern composite production using liquid composite molding (LCM) technique. Nowadays numerical filling simulations are required for predicting the mold filling behavior. Inaccurate predictions can lead to a high risk of air inclusion and corresponding need for cost‐intense revision of the mold design. Permeability values of the textiles used in the process are basic requirements for a numerical filling simulation, since the permeability is directly linked to the filling behavior. Nevertheless, the permeability values of non‐crimped fabrics (NCF) which are used for aerospace and automotive structures are rare. In this study the influence of textile parameters of NCF on the in‐plane permeability has been investigated using a capacitive in‐plane permeability measurement technology. The results show the influence of the roving filament number as well as the used stitch length on the in‐plane permeability. It is confirmed that the textile grammage is not affecting the in‐plane permeability of NCF reinforcements. The results of this study are valuable for textile selection with specific permeability data as well as for numerical filling simulations. POLYM. COMPOS., 37:1854–1863, 2016. © 2015 Society of Plastics Engineers 相似文献
157.
158.
Matthias Schulz Ute Pippardt Lutz Kiesel Katrin Ritter Ralf Kriegel 《American Institute of Chemical Engineers》2012,58(10):3195-3202
Ba0.5Sr0.5Co0.8Fe0.2O3‐δ tubes, capillaries, capillary modules, and asymmetric membranes were prepared and tested for oxygen permeation in a dead‐end vacuum operation mode at temperatures up to 850°C. The capillary module was built up by reactive air brazing using seven capillaries and a supply tube. Two machined discs were used as an end cap and as a connector plate. The oxygen permeation behaves according to Wagner at small driving forces, but significant negative deviations were observed for asymmetric membranes and single capillaries at higher ones. This is caused by pressure drops at the vacuum side for single capillaries. The highest oxygen flux was revealed for the capillary module with 175.5 mL(STP)/min at a low‐vacuum pressure of 0.042 bar at 850°C, but the asymmetric membrane showing a little bit higher flux at moderate vacuum pressures above 0.07 bar. © 2012 American Institute of Chemical Engineers AIChE J, 58: 3195–3202, 2012 相似文献
159.
160.
Ralf D. Brown 《Machine Translation》1989,4(2):129-147
A semantic and pragmatic interpreter that combines automatic and interactive disambiguation is described. This augmentor has an interactive disambiguation component that is called upon to aid automatic disambiguation when automated strategies prove inadequate. In addition to interactive disambiguation, the augmentor also provides the user interface for the KBMT-89 project. 相似文献