全文获取类型
收费全文 | 182篇 |
免费 | 18篇 |
专业分类
化学工业 | 18篇 |
金属工艺 | 2篇 |
机械仪表 | 11篇 |
建筑科学 | 6篇 |
矿业工程 | 2篇 |
能源动力 | 1篇 |
轻工业 | 39篇 |
水利工程 | 5篇 |
石油天然气 | 3篇 |
无线电 | 14篇 |
一般工业技术 | 52篇 |
冶金工业 | 36篇 |
原子能技术 | 1篇 |
自动化技术 | 10篇 |
出版年
2022年 | 2篇 |
2021年 | 5篇 |
2020年 | 5篇 |
2019年 | 2篇 |
2018年 | 8篇 |
2017年 | 13篇 |
2016年 | 8篇 |
2015年 | 5篇 |
2014年 | 1篇 |
2013年 | 13篇 |
2012年 | 7篇 |
2011年 | 14篇 |
2010年 | 6篇 |
2009年 | 7篇 |
2008年 | 7篇 |
2007年 | 3篇 |
2006年 | 5篇 |
2005年 | 3篇 |
2004年 | 10篇 |
2003年 | 6篇 |
2002年 | 7篇 |
2001年 | 2篇 |
2000年 | 5篇 |
1999年 | 3篇 |
1998年 | 13篇 |
1997年 | 8篇 |
1996年 | 5篇 |
1995年 | 10篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1989年 | 2篇 |
1986年 | 1篇 |
1982年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1972年 | 2篇 |
1968年 | 1篇 |
排序方式: 共有200条查询结果,搜索用时 406 毫秒
1.
2.
3.
Cortés Porto Rodrigo Genius Daniela Apvrille Ludovic 《Software and Systems Modeling》2021,20(3):667-683
Software and Systems Modeling - Cyber physical systems are built upon digital and analog circuits, making it necessary to handle different models of computation during their design and verification... 相似文献
4.
S.C.J. Kingsley G. Lawes A. Golov K. Matsumoto J.V. Porto E.N. Smith N. Mulders M.H.W. Chan J.M. Parpia 《Journal of Low Temperature Physics》1998,113(3-4):357-361
We have used a torsional oscillator to measure the superfluid density and dissipation near the superfluid transition of
3
He in aerogel of 99.5% porosity. We used a new cell (constructed at Penn State) for which the aerogel was grown in the pores of a 100 m silver sinter. The cell was tested with
4
He and showed no signs of the second-sound resonances that have interfered with previous torsional oscillator measurements. The measurements with
3
He, presented here, were taken at pressures of 1.34 and 4.13 bars. We observed values of
s
/ in the T 0 limit of 0.05 and 0.14 respectively. Our measurements show an increase in the dissipation on warming through T
c
. This series of measurements is ongoing and temperature sweeps at various pressures are planned. 相似文献
5.
We have examined the superfluidity of
3
He in 98.2% porous silica aerogel with up to 34% 4
He at 21.6 bar. The mixture is phase-separated for
4
He fractions between 11% and 34%. The
4
He-rich, phase preferentially occupies the regions of highest silica density in the aerogel, thus modifying the distribution of the correlated disorder seen by superftuid
3
He. The
3
He T
c
increases slightly with
4
He content while the superfluid fraction decreases rapidly. This behavior is inconsistent with that of
3
He in a homogeneously scattering medium and is analogous to that of a granular superconductor. 相似文献
6.
E. P. Muniz J. R. C. Proveti R. D. Pereira B. Segatto P. S. S. Porto V. P. Nascimento M. A. Schettino E. C. Passamani 《Journal of Materials Science》2013,48(4):1543-1554
The kinetics of formation of NiFe2O4 nanoparticles were investigated where the nanoparticles were produced by the proteic-sol–gel method using coconut water followed by annealing in (i) air, (ii) air in the presence of boron nitride (BN), or (iii) nitrogen. The sample dried at 473 K for 5.5 h was composed of small disordered NiFe2O4 nanoparticles in a superparamagnetic state as determined from Mössbauer spectroscopy. In general, heat treatment at high temperature leads to a nanocomposite rich in NiFe2O4. In air, annealing at 1173 K for 8 h favored the formation of the magnetically ordered NiFe2O4 inverse spinel structure, with bulk characteristics and average crystal sizes of approximately 66 nm. In a nitrogen atmosphere and in compacted BN powder under air atmosphere, the NiFe2O4 spinel structure stabilized for temperatures up to 873 and 773 K, respectively, however, decomposition of the NiFe2O4 phase into other undesired structures was observed above 873 K. 相似文献
7.
Heavy gas oil biodesulfurization by Rhodococcus erythropolis ATCC 4277: optimized culture medium composition and evaluation of low‐cost alternative media
下载免费PDF全文
![点击此处可从《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
8.
Sixty compounds of Lavandula angustifolia L. cultivated in Friuli Venezia Giulia (North-East Italy) were identified and quantified by GC-MS and GC-FID from essential oils obtained by means of hydrodistillation, and from extracts obtained by supercritical CO2 extraction (SFE) and ultrasound-assisted extraction (US). Using absolute calibration, a true quantification of 1-8 cineol, camphor, linalool, linalyl acetate and β-caryophyllene was carried out. The best extracts, in terms of amount of isolated compounds, flavour quality and stability were those obtained with SFE. Sonication performed at low amplitude for 5 min offered respect to high amplitude a promising alternative to hydrodistillation as a source of lavender flavouring ready to use for alcoholic beverages or/and confectionery products. 相似文献
9.
Porto JV Rolston S Laburthe Tolra B Williams CJ Phillips WD 《Philosophical transactions. Series A, Mathematical, physical, and engineering sciences》2003,361(1808):1417-1427
One of the essential features of a quantum computer is a quantum 'register' of well-characterized qubits. Neutral atoms in optical lattices are a natural candidate for such a register. We have demonstrated a patterned-loading technique that can be used to load atoms into large arrays of tightly confined but optically resolvable lattice sites. We have also seen preliminary indications of the Mott-insulator transition, which provides a route for single-atom initialization of the individual sites. Combining the two experiments should allow for large arrays of individually addressable single atoms, a system which provides a starting point for further quantum computation studies. 相似文献
10.
Fracture toughness of the interface between Ni–Cr/ceramic,alumina/ceramic and zirconia/ceramic systems
下载免费PDF全文
![点击此处可从《Fatigue & Fracture of Engineering Materials & Structures》网站下载免费的PDF全文](/ch/ext_images/free.gif)
C. P. S. Porto M. P. L. Parente R. M. N. Jorge L. C. Pereira S. Griza 《Fatigue & Fracture of Engineering Materials & Structures》2016,39(7):817-829
Few studies have focused on the interface fracture performance of bi‐layered structures, which have an important role in dental restorations, using ceramic materials. The purpose of this study is to evaluate the fracture mechanics performance of the Ni–Cr/ceramic, alumina/ceramic and zirconia/ceramic interfaces by investigating the propagation of an interfacial crack under a wide range of mode mixities. The effect of the mechanical properties of the base materials and the interface, on the crack initiation and crack path, will also be studied. The finite element method (FEM) was used to calibrate the production of the experimental specimens, allowing to obtain the minimum dimensions and amounts of material needed to correctly characterize the fracture event. The specimens were tested until failure using a three‐point bending test machine. The interface fracture parameters were obtained using the FEM. For all specimens, the cracks propagated into the ceramic. The results suggest that, in Ni–Cr/ceramic, alumina/ceramic and zirconia/ceramic bi‐layered structures, the ceramic is weaker than the interface, which can be used to explain the clinical phenomenon that the ceramic chipping rate is larger than interface delamination rate. Consequently, a ceramic material with a larger fracture toughness is needed to decrease the failure rate of ceramic restorations. 相似文献