全文获取类型
收费全文 | 15074篇 |
免费 | 1045篇 |
国内免费 | 15篇 |
专业分类
电工技术 | 104篇 |
综合类 | 7篇 |
化学工业 | 2818篇 |
金属工艺 | 191篇 |
机械仪表 | 366篇 |
建筑科学 | 472篇 |
矿业工程 | 25篇 |
能源动力 | 296篇 |
轻工业 | 2223篇 |
水利工程 | 88篇 |
石油天然气 | 40篇 |
无线电 | 918篇 |
一般工业技术 | 2179篇 |
冶金工业 | 4554篇 |
原子能技术 | 47篇 |
自动化技术 | 1806篇 |
出版年
2024年 | 35篇 |
2023年 | 155篇 |
2022年 | 147篇 |
2021年 | 357篇 |
2020年 | 308篇 |
2019年 | 319篇 |
2018年 | 421篇 |
2017年 | 416篇 |
2016年 | 532篇 |
2015年 | 471篇 |
2014年 | 623篇 |
2013年 | 1121篇 |
2012年 | 988篇 |
2011年 | 789篇 |
2010年 | 596篇 |
2009年 | 599篇 |
2008年 | 619篇 |
2007年 | 532篇 |
2006年 | 490篇 |
2005年 | 318篇 |
2004年 | 297篇 |
2003年 | 251篇 |
2002年 | 244篇 |
2001年 | 159篇 |
2000年 | 153篇 |
1999年 | 253篇 |
1998年 | 1416篇 |
1997年 | 869篇 |
1996年 | 588篇 |
1995年 | 347篇 |
1994年 | 256篇 |
1993年 | 295篇 |
1992年 | 64篇 |
1991年 | 87篇 |
1990年 | 66篇 |
1989年 | 80篇 |
1988年 | 76篇 |
1987年 | 51篇 |
1986年 | 59篇 |
1985年 | 62篇 |
1984年 | 27篇 |
1983年 | 25篇 |
1982年 | 34篇 |
1981年 | 34篇 |
1980年 | 52篇 |
1979年 | 30篇 |
1978年 | 20篇 |
1977年 | 87篇 |
1976年 | 191篇 |
1973年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Pablo Sevilla Clara Sandino Milena Arciniegas Jordi Martínez-Gomis Maria Peraire Francisco Javier Gil 《Materials science & engineering. C, Materials for biological applications》2010,30(1):14-19
Lately new biomedical grade yttria stabilized zirconia (YTZP) dental implants have appeared in the implantology market. This material has better aesthetical properties than conventional titanium used for implants but long term behaviour of these new implants is not yet well known. The aim of this paper is to quantify the mechanical response of YTZP dental implants previously degraded under different time conditions and compare the toughness and fatigue strength with titanium implants. Mechanical response has been studied by means of mechanical testing following the ISO 14801 for Standards for dental implants and by finite element analysis. Accelerated hydrothermal degradation has been achieved by means of water vapour and studied by X-ray diffraction and nanoindentation tests. The results show that the degradation suffered by YTZP dental implants will not have a significant effect on the mechanical behaviour. Otherwise the fracture toughness of YTZP ceramics is still insufficient in certain implantation conditions. 相似文献
992.
993.
José M. Contreras Antonia Jiménez-Morales José M. Torralba 《Journal of Materials Processing Technology》2009,209(15-16):5618-5625
The aim of this work is to fabricate bronze components by metal injection moulding (MIM) studying the possibility of changing partially or totally the gas atomised powder by water atomised ones that are cheaper than the former. In order to carry out this study, a bronze 90/10 gas atomised spherical powder (usual MIM powder <22 μm) and two water atomised irregular powders (particle size <35 μm and <140 μm) were mixed in different proportions. As received powders and their mixtures were used to fabricate feedstocks and processed by MIM to evaluate the influence of powder particle size and morphology on debinding and sintering stages. Finally, both mechanical properties hardness and maximum flexural stress were determined to characterize the sintered materials. The addition of irregular fine and coarse powders was found to affect the moulding process, although densities and mechanical properties close to values of gas atomised one were obtained after sintering. Therefore, the use of water atomised bronze powders could be a promising way to diminish production costs in this technology. 相似文献
994.
María José Hernández‐López José Antonio Prieto Francisca Randez‐Gil 《Yeast (Chichester, England)》2010,27(12):1061-1069
We cloned a genomic DNA fragment of the yeast Torulaspora delbrueckii by complementation of a Saccharomyces cerevisiae snf1Δ mutant strain. DNA sequence analysis revealed that the fragment contained a complete open reading frame (ORF), which shares a high similarity with the S. cerevisiae energy sensor protein kinase Snf1. The cloned TdSNF1 gene was able to restore growth of the S. cerevisiae snf1Δ mutant strain on media containing nonfermentable carbon sources. Furthermore, cells of the Tdsnf1Δ mutant were unable to proliferate under nonfermenting conditions. Finally, protein domain analysis showed that TdSnf1p contains a typical catalytic protein kinase domain (positions 41–293), which is also present in other Snf1p homologues. Within this region we identified a protein kinase ATP‐binding region (positions 48–71) and a consensus Ser/Thr protein kinase active site (positions 160–172). The GenBank Accession No. for the sequenced DNA fragment is HM131845. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
995.
996.
Arantxa Villanueva Gintautas Daunys Dan Witzner Hansen Martin Böhme Rafael Cabeza André Meyer Erhardt Barth 《Universal Access in the Information Society》2009,8(4):241-257
This paper presents a principled analysis of various combinations of image features to determine their suitability for remote
eye tracking. It begins by reviewing the basic theory underlying the connection between eye image and gaze direction. Then
a set of approaches is proposed based on different combinations of well-known features and their behaviour is evaluated, taking
into account various additional criteria such as free head movement, and minimum hardware and calibration requirements. The
paper proposes a final method based on multiple glints and the pupil centre; the method is evaluated experimentally. Future
trends in eye tracking technology are also discussed. 相似文献
997.
998.
999.
1000.
C. Pi?eiro J. Barros-Velázquez Carmen G. Sotelo José M. Gallardo 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1999,11(12):342-348
The water-soluble proteins of nine flat fish species of high commercial value, belonging to the Pleuronectidae, Scophtalmidae, and Soleidae families, were analyzed by two-dimensional (2D) electrophoresis, this being carried out by nondenaturing isoelectric focusing (IEF) in the 3.5–9.5 pH range and gradient SDS-PAGE in the 12–14% range. Most of the major proteins fell in the 3.5–6.9 pH range. From these, the most specific proteins were in the acidic fraction (pI<5.2; MW<16 kDa). Species-specific 2D protein patterns were observed in all the nine species, and more than 25 proteins could be individualized. The combination of nondenaturing IEF and gradient SDS-PAGE, both in the absence of urea, allowed detailed characterization of both the isoelectric points and molecular weights of the major water-soluble proteins and proved to be a valuable tool for the differential characterization of the flat fish species studied. 相似文献