全文获取类型
收费全文 | 25377篇 |
免费 | 1037篇 |
国内免费 | 33篇 |
专业分类
电工技术 | 327篇 |
综合类 | 38篇 |
化学工业 | 5567篇 |
金属工艺 | 380篇 |
机械仪表 | 474篇 |
建筑科学 | 1308篇 |
矿业工程 | 100篇 |
能源动力 | 621篇 |
轻工业 | 1891篇 |
水利工程 | 232篇 |
石油天然气 | 71篇 |
无线电 | 1816篇 |
一般工业技术 | 4507篇 |
冶金工业 | 5374篇 |
原子能技术 | 196篇 |
自动化技术 | 3545篇 |
出版年
2023年 | 199篇 |
2022年 | 282篇 |
2021年 | 562篇 |
2020年 | 338篇 |
2019年 | 432篇 |
2018年 | 535篇 |
2017年 | 463篇 |
2016年 | 632篇 |
2015年 | 559篇 |
2014年 | 749篇 |
2013年 | 1420篇 |
2012年 | 1162篇 |
2011年 | 1510篇 |
2010年 | 1075篇 |
2009年 | 1014篇 |
2008年 | 1147篇 |
2007年 | 1085篇 |
2006年 | 944篇 |
2005年 | 762篇 |
2004年 | 745篇 |
2003年 | 660篇 |
2002年 | 563篇 |
2001年 | 428篇 |
2000年 | 362篇 |
1999年 | 416篇 |
1998年 | 1013篇 |
1997年 | 696篇 |
1996年 | 527篇 |
1995年 | 470篇 |
1994年 | 414篇 |
1993年 | 415篇 |
1992年 | 278篇 |
1991年 | 202篇 |
1990年 | 286篇 |
1989年 | 268篇 |
1988年 | 230篇 |
1987年 | 227篇 |
1986年 | 232篇 |
1985年 | 272篇 |
1984年 | 225篇 |
1983年 | 225篇 |
1982年 | 209篇 |
1981年 | 204篇 |
1980年 | 174篇 |
1979年 | 194篇 |
1978年 | 165篇 |
1977年 | 215篇 |
1976年 | 305篇 |
1975年 | 160篇 |
1974年 | 123篇 |
排序方式: 共有10000条查询结果,搜索用时 343 毫秒
991.
René Köppel Thomas Bucher Alain Meuwly Dominik Moor 《European Food Research and Technology》2014,239(2):347-355
According to the release of authorization, several new transgenic soy crops are expected to be present in the harvest of soy beans. In contrast to earlier times, methods for the detection of these transgenic crops are available already in advance. However, these methods are mainly still inefficient single real-time PCR methods. To increase the efficiency of product control, a multiplex quantitative real-time PCR system was developed and characterized for the four new transgenic soy traits DP-356043-5, DP-305423-1, MON 87701 and BPS-CV127-9. It showed amplification efficiency, correlation and sensitivity similar to the single PCR systems applied therein. To evaluate the robustness, an appropriate testing scheme was developed and applied for the first time on this multiplex real-time PCR system. It showed the robust amplification of all analytes also in case where conditions were varied. This system allows relative multiplex quantification and/or delta–delta Ct method quantification and proofed the applicability in routine. 相似文献
992.
Photonic Nanostructures Patterned by Thermal Nanoimprint Directly into Organo‐Metal Halide Perovskites 下载免费PDF全文
993.
994.
995.
Piotr Piela Jens Mitzel Erich Gülzow Jürgen Hunger Alexander Kabza Ludwig Jörissen Francesco Valle Alberto Pilenga Thomas Malkow Georgios Tsotridis 《International Journal of Hydrogen Energy》2017,42(31):20187-20200
The direct-search simplex method for function optimization has been adapted to performance optimization of polymer electrolyte membrane fuel cells (PEMFCs). The established method is strongly application oriented and uses only experimentally determined data for optimization. It is not restricted to discrete parameters optimums and does not require the use of third-party software or computational resources. Hence, it is easy to implement in fuel cell testing stations. The optimization consists of finding, for a given fuel cell load, an optimum set of values of the 7 fuel cell operating parameters: the fuel cell temperature, the reactants' stoichiometric ratios, the reactants' inlet relative humidity, and the reactants' outlet pressures, resulting in the highest fuel cell performance. The performance is measured using a scalar function of the operating parameters and the load and can be defined according to needs.Two PEMFC performance functions: the fuel cell voltage and the system-related fuel cell efficiency were optimized using the procedure for practically sized PEMFC stacks of two designs. With respect to the nominal operating conditions defined as optimal for each stack design by its manufacturer, the gains from the optimization procedure were up to over 12% and up to over 7% for the stack voltage and efficiency, respectively. The validation of the procedure involved 5 stack specimens and four laboratories and consistent results were obtained. 相似文献
996.
Traditional methods of Monte Carlo simulations of random rough surface scattering that use the finite element method involve the generation of multiple meshes for the purpose of taking ensemble averages. We propose a mesh reconfiguration scheme that instead uses a single master mesh. The main idea is to locally modify only the air–surface interface region in the mesh for each instance of a random rough surface. This method achieves a four fold improvement in computation time without any loss of accuracy. 相似文献
997.
Curing enhancement and network effects in multi‐walled carbon nanotube‐filled vulcanized natural rubber: evidence for solvent sensing 下载免费PDF全文
Deepalekshmi Ponnamma Konnanilkunnathil Thomas Varughese Mariam Al Ali Al‐Maadeed Sabu Thomas 《Polymer International》2017,66(6):931-938
Electrically and thermally conductive polymer composites offer great possibilities in various electronic fields because of their low weight and ease of processing. This paper addresses the curing behaviour and network properties of conducting multi‐walled carbon nanotube (MWCNT)‐reinforced natural rubber (NR) nanocomposites, emphasizing the sensing and diffusion performances. NR/MWCNT composites were prepared following a special master batch technique which allows the appropriate distribution of nanotubes within the elastomer. The sensing responses of the composites towards solvents were observed as variations in electrical resistance. Thermal resistance and glass transition behaviour were examined and correlated with the swelling measurements as evidence for solvent sensing. An optimum level of 3 phr of MWCNTs is understood to lead to the best properties for the NR/MWCNT composites. Finally, the structural morphology and interfacial interactions were found to have correlations with cure reactions, glass transition temperatures and sensing responses of all compositions. © 2017 Society of Chemical Industry 相似文献
998.
Ronit Bitton Lesley W. Chow R. Helen Zha Yuri S. Velichko E. Thomas Pashuck Samuel I. Stupp 《Small (Weinheim an der Bergstrasse, Germany)》2014,10(3):500-505
Self‐assembling peptide amphiphiles (PAs) can form hierarchically ordered membranes when brought in contact with aqueous polyelectrolytes of the opposite charge by rapidly creating a diffusion barrier composed of filamentous nanostructures parallel to the plane of the incipient membrane. Following this event, osmotic forces and charge complexation template nanofiber growth perpendicular to the plane of the membrane in a dynamic self‐assembly process. In this work, we show that this hierarchical structure requires massive interfacial aggregation of PA molecules, suggesting the importance of rapid diffusion barrier formation. Strong PA aggregation is induced here through the use of heparin‐binding PAs with heparin and also with polyelectrolytes of varying charge density. Small angle X‐ray scattering shows that in the case of weak PA‐polyelectrolyte interaction, membranes formed display a cubic phase ordering on the nanoscale that likely results from clusters of PA nanostructures surrounded by polyelectrolyte chains. 相似文献
999.
To further understand the needs of the growing population of elderly drivers and create solutions for safe mobility it is important to understand the driving scenarios and aspects in day to day traffic that may be of challenge for this group. More so, individual differences in how drivers perceive their own driving ability may have an effect on how individuals limit their mobility and/or increase their exposure to risk situations, with a potential negative effect on safety. 相似文献
1000.
P. Thomas J. L. Mansot A. Molza F. Begarin M. Dubois K. Guérin 《Tribology Letters》2014,56(2):259-271
The tribologic properties of graphitized carbon blacks and their fluorinated derivatives are investigated as a function of the fluorination rate. Very low intrinsic friction coefficients are obtained for highly fluorinated compounds. The correlation of the tribologic results and structural investigations of the initial compounds by TEM strongly suggests that the friction mechanisms involve surface effects in the early stage of friction. Long-term tribologic experiments and Raman analyses point out an evolution of the structure and composition of the tribofilms during the friction process leading to similar friction properties of the tribofilms. Wear studies revealed that highly fluorinated derivatives appear less efficient than pristine and weakly fluorinated compounds. 相似文献