全文获取类型
收费全文 | 1543篇 |
免费 | 36篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 18篇 |
综合类 | 6篇 |
化学工业 | 352篇 |
金属工艺 | 19篇 |
机械仪表 | 39篇 |
建筑科学 | 73篇 |
矿业工程 | 8篇 |
能源动力 | 29篇 |
轻工业 | 222篇 |
水利工程 | 18篇 |
石油天然气 | 2篇 |
无线电 | 123篇 |
一般工业技术 | 226篇 |
冶金工业 | 263篇 |
原子能技术 | 17篇 |
自动化技术 | 165篇 |
出版年
2021年 | 18篇 |
2020年 | 18篇 |
2019年 | 11篇 |
2018年 | 17篇 |
2017年 | 19篇 |
2016年 | 33篇 |
2015年 | 16篇 |
2014年 | 35篇 |
2013年 | 72篇 |
2012年 | 44篇 |
2011年 | 65篇 |
2010年 | 58篇 |
2009年 | 52篇 |
2008年 | 65篇 |
2007年 | 57篇 |
2006年 | 45篇 |
2005年 | 28篇 |
2004年 | 30篇 |
2003年 | 38篇 |
2002年 | 27篇 |
2001年 | 33篇 |
2000年 | 28篇 |
1999年 | 26篇 |
1998年 | 86篇 |
1997年 | 60篇 |
1996年 | 44篇 |
1995年 | 35篇 |
1994年 | 47篇 |
1993年 | 34篇 |
1992年 | 24篇 |
1991年 | 16篇 |
1990年 | 15篇 |
1989年 | 24篇 |
1988年 | 10篇 |
1987年 | 16篇 |
1986年 | 16篇 |
1985年 | 15篇 |
1984年 | 17篇 |
1982年 | 9篇 |
1981年 | 14篇 |
1980年 | 13篇 |
1979年 | 11篇 |
1978年 | 20篇 |
1977年 | 16篇 |
1976年 | 34篇 |
1975年 | 12篇 |
1974年 | 17篇 |
1969年 | 9篇 |
1966年 | 9篇 |
1954年 | 9篇 |
排序方式: 共有1580条查询结果,搜索用时 15 毫秒
51.
Nanoporous gold bumps have been deposited on silicon wafers by electroplating a silver–gold alloy followed by etching the silver. An open-porous cellular structure of gold at meso-scale is left on top of the bumps. For flip chip bonding we found low temperature and low force bonding conditions. The porous interconnects have very promising properties, like compressibility and reduced stiffness, which should result in higher bond yield and extended reliability. 相似文献
52.
Christina Schwind Jürgen Buder Ulrike Cress Friedrich W. Hesse 《Computers & Education》2012,58(2):787-796
The Web is a perfect backdrop for opinion formation as a multitude of different opinions is publicly available. However, the different opinions often remain unexploited: Learners prefer preference-consistent over preference-inconsistent information, a phenomenon called confirmation bias. Two experiments were designed to test whether technologies such as recommender systems can be used to overcome this bias. The role of preference-inconsistent recommendations was explored by comparing their influence to a condition with preference-consistent recommendations and to a control condition without recommendations. In Study 1, preference-inconsistent recommendations led to a reduction of confirmation bias and to a more moderate view of the controversial topic of neuro-enhancement. In Study 2, we found that preference-inconsistent recommendations stimulated balanced recall and divergent thinking. Together these studies showed that preference-inconsistent recommendations are an effective approach for reducing confirmation bias and stimulating divergent thinking. In conclusion, future research and practical implications are discussed. 相似文献
53.
54.
Robert Sevenich Elke Kleinstueck Colin Crews Warwick Anderson Celine Pye Katerina Riddellova Jaromir Hradecky Eliska Moravcova Kai Reineke Dietrich Knorr 《Journal of food science》2014,79(2):M230-M237
The benefits that high‐pressure thermal sterilization offers as an emerging technology could be used to produce a better overall food quality. Due to shorter dwell times and lower thermal load applied to the product in comparison to the thermal retorting, lower numbers and quantities of unwanted food processing contaminants (FPCs), for example, furan, acrylamide, HMF, and MCPD‐esters could be formed. Two spore strains were used to test the technique; Geobacillus stearothermophilus and Bacillus amyloliquefaciens, over the temperature range 90 to 121 °C at 600 MPa. The treatments were carried out in baby food puree and ACES‐buffer. The treatments at 90 and 105 °C showed that G. stearothermophilus is more pressure‐sensitive than B. amyloliquefaciens. The formation of FPCs was monitored during the sterilization process and compared to the amounts found in retorted samples of the same food. The amounts of furan could be reduced between 81% to 96% in comparison to retorting for the tested temperature pressure combination even at sterilization conditions of F0‐value in 7 min. 相似文献
55.
Volkan Kumtepeli Yulong Zhao Maik Naumann Anshuman Tripathi Youyi Wang Andreas Jossen Holger Hesse 《国际能源研究杂志》2019,43(9):4127-4147
The rapid increase of renewable energy sources made coordinated control of the distributed and intermittent generation units a more demanded task. Matching demand and supply is particularly challenging in islanded microgrids. In this study, we have demonstrated a mixed‐integer quadratic programming (MIQP) method to achieve efficient use of sources within an islanded microgrid. A unique objective function involving fuel consumption of diesel generator, degradation in a lithium‐ion battery energy storage system, carbon emissions, load shifting, and curtailment of the renewable sources is constructed, and an optimal operating point is pursued using the MIQP approach. A systematic and extensive methodology for building the objective function is given in a sequential and explicit manner with an emphasis on a novel model‐based battery aging formulation. Performance of the designed system and a sensitivity analysis of resulting battery dispatch, diesel generator usage, and storage aging against a range of optimization parameters are presented by considering real‐world specifications of the Semakau Island, an island in the vicinity of Singapore. 相似文献
56.
The increasing demand for electric vehicles and thus lithium-ion batteries results in a multitude of challenges in production technology. The reproducibility and performance of large scale batteries for automotive applications are very high. At the same time the production processes are complex and involve many uncertainties. Two essential process steps are the electrode coating and electrode package assembly. The mass loading of anodes and cathodes are determined by the coating process, where deviations can be caused by different reasons. The selective assembly of the electrodes is a reasonable way to balance the production variances. The contribution shows extended algorithms and their benefits and drawbacks of matching electrodes in order to improve the subsequent electrode packaging process. Here, the aim is to reach higher cell capacities and optimized performance values by “optimally” balanced electrodes regarding the mass loading ratio, which is also related to the specific material capacity. 相似文献
57.
58.
Wolfram Witte Daniel Abou‐Ras Karsten Albe Gottfried H. Bauer Frank Bertram Christian Boit Rudolf Brüggemann Jürgen Christen Jens Dietrich Axel Eicke Dimitrios Hariskos Matthias Maiberg Roland Mainz Max Meessen Mathias Müller Oliver Neumann Thomas Orgis Stefan Paetel Johan Pohl Humberto Rodriguez‐Alvarez Roland Scheer Hans‐Werner Schock Thomas Unold Alfons Weber Michael Powalla 《Progress in Photovoltaics: Research and Applications》2015,23(6):717-733
The gallium gradient in Cu(In,Ga)Se2 (CIGS) layers, which forms during the two industrially relevant deposition routes, the sequential and co‐evaporation processes, plays a key role in the device performance of CIGS thin‐film modules. In this contribution, we present a comprehensive study on the formation, nature, and consequences of gallium gradients in CIGS solar cells. The formation of gallium gradients is analyzed in real time during a rapid selenization process by in situ X‐ray measurements. In addition, the gallium grading of a CIGS layer grown with an in‐line co‐evaporation process is analyzed by means of depth profiling with mass spectrometry. This gallium gradient of a real solar cell served as input data for device simulations. Depth‐dependent occurrence of lateral inhomogeneities on the µm scale in CIGS deposited by the co‐evaporation process was investigated by highly spatially resolved luminescence measurements on etched CIGS samples, which revealed a dependence of the optical bandgap, the quasi‐Fermi level splitting, transition levels, and the vertical gallium gradient. Transmission electron microscopy analyses of CIGS cross‐sections point to a difference in gallium content in the near surface region of neighboring grains. Migration barriers for a copper‐vacancy‐mediated indium and gallium diffusion in CuInSe2 and CuGaSe2 were calculated using density functional theory. The migration barrier for the InCu antisite in CuGaSe2 is significantly lower compared with the GaCu antisite in CuInSe2, which is in accordance with the experimentally observed Ga gradients in CIGS layers grown by co‐evaporation and selenization processes. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
59.
60.
The comparison of starch granule deformation and extent of starch gelatinization in a few common Indian unleavened flat breads (Chapati, Parontha and Poorie) was made. The starch granule swelling was evaluated by scanning electron as well as polarized light microscopy. The peak viscosity in Haake rotary viscosimeter and hydration capacity were used for comparing the extent of starch gelatinization in crust and crumb of these baked products. Although a few of the starch granules on the outside of crust, maintained a weak outline those in the crumb area gave only a matrix of gelatinized starch. The extent of starch gelatinization was reflected by the related increase in hydration capacity of these products. However, the peak viscosity values were found to be inversely related to the extent of starch gelatinization. As compared to crumb, a higher extent of browning was observed in the crust. Water absorption, type of cereal, mode and efficiency of heat transfer were found to control the extent of starch gelatinization in these baked products. 相似文献