全文获取类型
收费全文 | 1960篇 |
免费 | 105篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 19篇 |
综合类 | 3篇 |
化学工业 | 495篇 |
金属工艺 | 40篇 |
机械仪表 | 46篇 |
建筑科学 | 47篇 |
矿业工程 | 4篇 |
能源动力 | 58篇 |
轻工业 | 369篇 |
水利工程 | 12篇 |
石油天然气 | 4篇 |
无线电 | 192篇 |
一般工业技术 | 297篇 |
冶金工业 | 187篇 |
原子能技术 | 14篇 |
自动化技术 | 281篇 |
出版年
2023年 | 19篇 |
2022年 | 57篇 |
2021年 | 59篇 |
2020年 | 45篇 |
2019年 | 31篇 |
2018年 | 61篇 |
2017年 | 65篇 |
2016年 | 74篇 |
2015年 | 56篇 |
2014年 | 73篇 |
2013年 | 130篇 |
2012年 | 123篇 |
2011年 | 118篇 |
2010年 | 94篇 |
2009年 | 87篇 |
2008年 | 101篇 |
2007年 | 85篇 |
2006年 | 77篇 |
2005年 | 45篇 |
2004年 | 36篇 |
2003年 | 62篇 |
2002年 | 53篇 |
2001年 | 36篇 |
2000年 | 30篇 |
1999年 | 30篇 |
1998年 | 68篇 |
1997年 | 57篇 |
1996年 | 32篇 |
1995年 | 31篇 |
1994年 | 21篇 |
1993年 | 27篇 |
1992年 | 18篇 |
1991年 | 13篇 |
1990年 | 18篇 |
1989年 | 15篇 |
1988年 | 11篇 |
1987年 | 6篇 |
1986年 | 10篇 |
1985年 | 11篇 |
1984年 | 5篇 |
1983年 | 8篇 |
1982年 | 7篇 |
1981年 | 11篇 |
1980年 | 10篇 |
1979年 | 5篇 |
1978年 | 8篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1973年 | 5篇 |
1966年 | 4篇 |
排序方式: 共有2068条查询结果,搜索用时 15 毫秒
81.
The effects of finishing time, (T0 = 0, T1 = 30 and T2 = 60 days), on Holstein–Friesian cull cows (n = 18) and post-mortem ageing, (1, 7, 14, 21, 35 and 42 days), under vacuum conditions of Longissimus thoracis (LT) muscles were investigated. The objective of this research was to study how finishing feeding (based on a commercial concentrate and corn silage), following a pasture period of 90 days, affected carcass and meat quality. Ageing time effect was also evaluated on the main quality attribute of added value pieces, such as “striploin of ox” from cull cows. Finishing treatment affected intramuscular fat content (IMF), moisture percentage, water-holding capacity (WHC), colour parameters and shear force of meat at 24 h post-mortem, whereas ageing time enhanced meat tenderness, when this was measured by two textural tests, Warner–Braztler (WB) and textural profile analysis (TPA). A minimum shear force was achieved at 7 and 14 days of ageing for T1 and T2, respectively. No differences (P > 0.05) could be found in colour parameters from 7 to 42 days. The results show that a finishing time of two months is very beneficial, due to the increase in meat fatness, improved overall carcass quality and luminosity (L*). Furthermore, 14 ageing days were sufficient to improved tenderness. Ageing time did not have an effect on lipid oxidation (P > 0.05) and this leads us to conclude that meat shelf life exceeded 42 days under vacuum conditions’. 相似文献
82.
Anodic oxides were grown on sputter-deposited Ta in different aqueous solutions. A photoelectrochemical investigation was performed in order to estimate the band gap of the films as a function of the anodizing bath composition and formation voltage, i.e. thickness. Photoelectrochemical results provided evidence of sub-band gap photocurrent for films formed in a bath containing ammonium ions at pH 9. Elemental depth profiles obtained by glow discharge optical emission spectroscopy revealed the presence of nitrogen species in the outer part of the anodic films, which is bonded to Ta according to XPS analysis. A mechanism of nitrogen incorporation is proposed in order to account for the pH dependence of film composition. 相似文献
83.
The starch granules remaining after enzymatic hydrolysis were analyzed. Enzymatic corrosion efficiency was related to granule diameter. The intrinsic viscosity of enzymatically treated cassava and corn starches was gradually lowered by hydrolysis. X-ray analysis and observation under a polarizing microscope suggested that enzymatic corrosion must occur in amorphous areas of the granules. Scanning electron microscopy showed that, for cassava granules, enzymatic corrosion occured mainly at the surface. Corn starch granules displayed considerable surface corrosion, as well as deep radial corrosion channels. 相似文献
84.
Sciacca E. Giudice A.C. Sanfilippo D. Zappa F. Lombardo S. Consentino R. Di Franco C. Ghioni M. Fallica G. Bonanno G. Cova S. Rimini E. 《Electron Devices, IEEE Transactions on》2003,50(4):918-925
Design and fabrication of single photon avalanche detector (SPAD) in planar technology is reported. Device design and critical issues in the technology are discussed. Experimental test procedures are described for dark-counting rate, afterpulsing probability, photon timing resolution, and quantum detection efficiency. Low-noise detectors are obtained, with dark counting rates down to 10 c/s for devices with 10 /spl mu/m diameter, down to 1 kc/s for 50 /spl mu/m diameter. The technology is suitable for monolithic integration of SPAD detectors and associated circuits. 相似文献
85.
Jinghua?LiEmail author Franco?Maloberti 《Analog Integrated Circuits and Signal Processing》2005,45(3):211-217
In this paper, we present a low power 12 bit 5 MSPS, successive approximation converter architecture using pipeline technique.
The converter consumes 4 mW at the Nyquist rate input with 1.8 V power supply. By combination of pipeline and successive architecture,
the entire circuit, simulated at the transistor level in a 0.18 μ CMOS process, achieves a FoM (Figure of Merit) of 0.19 pJ/conversion.
Jinghua Li was born in 1973. He received the MSEE and BSEE Degree from College of Electronics and information, Shanghai Jiaotong University
and Harbin Engineering University in 1997 and 1994 respectively. He is currently pursuing Ph.D degree in Department of Electrical
Engineering, Texas A&M University, College Station, TX, USA.
In 1997, he joined Bell Laboratory (China), Lucent Technologies as a member of technical staff. He worked on single-chip HDTV
decoder IC and Sonet/SDH SoC for various projects in Murray Hill, NJ, USA and Shanghai China. He also finished projects on
hardware implementation of Video conference/Phone based on H.263 standard as his master thesis. Since 2000, he has been a
research assistant in Analog Mixed Signal center, TAMU. Most currently his research interests are focused on low power analog
to digital conversion IC design, CMOS implementation of 10 G/2.5 G clock data recovery IC for high speed serial communications.
Franco Maloberti received the Laurea Degree in Physics (Summa cum Laude) from the University of Parma, Parma Italy, in 1968 and the Dr. Honoris
Causa degree in electronics from the Instituto Nacional de Astrofisica, Optica y Electronica (Inaoe), Puebla, Mexico in 1996.
In 1993 he was a Visiting Professor at ETH-PEL, Zurich. He was Professor of Microelectronics and Head of the Micro Integrated
Systems Group University of Pavia, Pavia, Italy and the TI/J.Kilby Analog Engineering Chair Professor at the Texas A&M University.
He is currently the Distinguished Microelectronic Chair Professor at University of Texas at Dallas and part-time Professor
at the University of Pavia, Italy.
His professional expertise is in the design, analysis and characterization of integrated circuits and analogue digital applications,
mainly in the areas of switched capacitor circuits, data converters, interfaces for telecommunication and sensor systems,
and CAD for analogue and mixed A-D design. He has written more than 250 published papers, three books and holds 15 patents.
He was in 1992 recipient of the XII Pedriali Prize for his technical and scientific contributions to national industrial production.
He was co-recipient of the 1996 Institute of Electrical Engineers (U.K.) Fleming Premium for the paper “CMOS Triode Transistor
Transconductor for high-frequency continuous time filters.” He has been responsible at both technical and management levels
for many research programs including ten ESPRIT projects and has served the European Commission as ESPRIT Projects' Evaluator,
Reviewer and as European Union expert in many European Initiatives. He served the Academy of Finland on the assessment of
electronic research in Academic institutions and on the research programs' evaluations.
Dr. Maloberti was Vice-President, Region 8, of the IEEE Circuit and Systems Society from 1995 to 1997 and an Associate Editor
of IEEE-Transaction on Circuit and System-II. He received the 1999 IEEE CAS Society Meritorious Service Award, the 2000 CAS
Society Golden Jubilee Medal, and the IEEE Millenium Medal. He is the President of the IEEE Sensor Council and member of the
Board of Governors of the IEEE CAS Society. He is a member of the Italian Electrothecnical and Electronic Society (AEI), the
Editorial Board of Analog Integrated Circuits and Signal Processing, and Fellow of IEEE. 相似文献
86.
Volker Franco Steier Christof Koplin Andreas Kailer 《Journal of Materials Science》2013,48(8):3239-3247
A method of manufacturing polymer-infiltrated ceramics (PICs) is to pre-infiltrate a porous ceramic with a liquid monomer and subsequently polymerize the organic component inside the ceramic structure. The volume reduction during polymerization leads to the formation of pores (defects), which has a detrimental effect on the mechanical properties of PICs. To avoid the generation of defects, a new polymerization method that uses pressure during polymerization was developed. To investigate the influences of pressure and heating rate on strength and microstructure, both parameters were varied. The influences of both parameters on the strength of PICs were studied using a biaxial test. The influence on the microstructure was investigated through microscopy. Fracture toughness and R-curve behavior of the manufactured PICs were determined with the SEVNB method. The process parameters have a strong influence on strength and microstructure of PICs. Defect-free PICs with improved strength could be manufactured using elevated pressure during polymerization. As expected, a distinct R-curve behavior and enhanced fracture toughness relative to composites manufactured using conventional methods was found. The developed manufacturing method leads to defectless PICs with increased mechanic behaviors. 相似文献
87.
88.
89.
90.
J.J. Ipus J.S. BlázquezV. Franco C.F. CondeA. Conde 《Journal of Alloys and Compounds》2011,509(5):1407-1410
The milling time evolution of magnetic anisotropy of ball milled powders can be described considering two regimes. First, for short milling times, the main factor affecting the magnetic behavior of the alloy is the accumulation of internal stresses. Second, for long milling times, magnetic anisotropy can be explained using three contributions: long-range magnetoelastic, averaged short-range magnetoelastic and averaged magnetocrystalline anisotropies. 相似文献