全文获取类型
收费全文 | 196篇 |
免费 | 9篇 |
专业分类
化学工业 | 27篇 |
金属工艺 | 23篇 |
机械仪表 | 8篇 |
建筑科学 | 6篇 |
能源动力 | 14篇 |
轻工业 | 24篇 |
石油天然气 | 3篇 |
无线电 | 33篇 |
一般工业技术 | 24篇 |
冶金工业 | 26篇 |
原子能技术 | 1篇 |
自动化技术 | 16篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 2篇 |
2020年 | 10篇 |
2019年 | 4篇 |
2018年 | 9篇 |
2017年 | 7篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2014年 | 10篇 |
2013年 | 16篇 |
2012年 | 8篇 |
2011年 | 16篇 |
2010年 | 15篇 |
2009年 | 12篇 |
2008年 | 9篇 |
2007年 | 5篇 |
2006年 | 7篇 |
2005年 | 12篇 |
2004年 | 6篇 |
2003年 | 6篇 |
2002年 | 2篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 5篇 |
1997年 | 8篇 |
1996年 | 2篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1991年 | 1篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1983年 | 1篇 |
1979年 | 2篇 |
排序方式: 共有205条查询结果,搜索用时 15 毫秒
11.
Amiodarone decreases plasma and tissue triiodothyronine (T3) and increases plasma cholesterol levels resembling changes seen during hypothyroidism. To elucidate the mechanism of amiodarone-induced hypercholesterolemia we investigated gene expression of three key proteins in cholesterol metabolism (cholesterol 7 alpha-hydroxylase, LDL receptor, HMG-CoA reductase) in livers of rats. Animals were treated with amiodarone or propylthiouracil (to induce mild hypothyroidism). The LDL receptor mRNA was downregulated (approximately 50%) in both amiodarone-treated and hypothyroid animals, while the other mRNA remained unchanged after 14-day treatment. The results suggest that amiodarone-induced hypercholesterolemia is associated with decreased LDL receptor mRNA levels. 相似文献
12.
Yucel Birol 《Journal of Materials Science》1989,24(6):2093-2098
The damage accumulation hypothesis is used to derive a fatigue crack growth rate equation. The fatigue life of a volume element
inside the plastic zone is evaluated by using low-cycle fatigue concepts. Crack growth rate is expressed as a function of
cyclic material parameters and plastic zone characteristics. For a given material, crack growth increment, is predicted to
be a fraction of the plastic zone size which can be expressed in terms of fracture mechanics parameters,K andJ. Hence, the proposed growth rate equation has a predictive capacity and is not limited to linear elastic conditions. 相似文献
13.
One hundred and fifty samples of raw calf/lamb meat samples (mince and chunks) and chicken parts (giblets, carcass) were analysed for the presence of Staphylococcus aureus. Eighty S. aureus strains were isolated and identified. Resistance of the strains to methicillin and other antibiotics was determined by the Kirby-Bauer disc diffusion test. The overall methicillin resistance rate for S. aureus was 67.5%. Of S. aureus strains, 87.5% were resistant to bacitracin. A high prevalence of penicillin G resistance was detected for S. aureus (53.8%). Few of the strains were resistant to erythromycin (7.5%). All strains were susceptible to vancomycin, sulbactam–ampicillin, ciprofloxacin and cefaperazone–sulbactam. This study confirmed the presence of S. aureus, especially antibiotic-resistant strains, in the foods examined, indicating poor sanitary conditions during processing which may create a health risk for consumers. 相似文献
14.
Ipek Akin Mikinori Hotta Filiz Cinar Sahin Onuralp Yucel Gultekin Goller Takashi Goto 《Journal of the European Ceramic Society》2009,29(11):2379-2385
ZrB2–SiC composites were prepared by spark plasma sintering (SPS) at temperatures of 1800–2100 °C for 180–300 s under a pressure of 20 MPa and at higher temperatures of above 2100 °C without a holding time under 10 MPa. Densification, microstructure and mechanical properties of ZrB2–SiC composites were investigated. Fully dense ZrB2–SiC composites containing 20–60 mass% SiC with a relative density of more than 99% were obtained at 2000 and 2100 °C for 180 s. Below 2120 °C, microstructures consisted of equiaxed ZrB2 grains with a size of 2–5 μm and α-SiC grains with a size of 2–4 μm. Morphological change from equiaxed to elongated α-SiC grains was observed at higher temperatures. Vickers hardness of ZrB2–SiC composites increased with increasing sintering temperature and SiC content up to 60 mass%, and ZrB2–SiC composite containing 60 mass% SiC sintered at 2100 °C for 180 s had the highest value of 26.8 GPa. The highest fracture toughness was observed for ZrB2–SiC composites containing 50 mass% SiC independent of sintering temperatures. 相似文献
15.
16.
Eigenface-domain super-resolution for face recognition 总被引:4,自引:0,他引:4
Gunturk B.K. Batur A.U. Altunbasak Y. Hayes M.H. III Mersereau R.M. 《IEEE transactions on image processing》2003,12(5):597-606
Face images that are captured by surveillance cameras usually have a very low resolution, which significantly limits the performance of face recognition systems. In the past, super-resolution techniques have been proposed to increase the resolution by combining information from multiple images. These techniques use super-resolution as a preprocessing step to obtain a high-resolution image that is later passed to a face recognition system. Considering that most state-of-the-art face recognition systems use an initial dimensionality reduction method, we propose to transfer the super-resolution reconstruction from pixel domain to a lower dimensional face space. Such an approach has the advantage of a significant decrease in the computational complexity of the super-resolution reconstruction. The reconstruction algorithm no longer tries to obtain a visually improved high-quality image, but instead constructs the information required by the recognition system directly in the low dimensional domain without any unnecessary overhead. In addition, we show that face-space super-resolution is more robust to registration errors and noise than pixel-domain super-resolution because of the addition of model-based constraints. 相似文献
17.
Closed-form connectivity-preserving solutions for motioncompensation using 2-D meshes 总被引:2,自引:0,他引:2
Motion compensation using two-dimensional (2-D) mesh models requires computation of the parameters of a spatial transformation for each mesh element (patch). It is well known that the parameters of an affine (bilinear or perspective) mapping can be uniquely estimated from three (four) point correspondences (at the vertices of a triangular or quadrilateral mesh element). On the other hand, overdetermined solutions using more than the required minimum number of point correspondences provide increased robustness against correspondence-estimation errors, however, this necessitates special consideration to preserve mesh-connectivity. This paper presents closed-form, overdetermined solutions for least squares estimation of affine motion parameters for a triangular mesh, which preserve mesh-connectivity using patch-based or node-based connectivity constraints. In particular, four new algorithms are presented: patch-constrained methods using point correspondences or spatio-temporal intensity gradients, and node-constrained methods using point correspondences or spatio-temporal intensity gradients. The methods using point correspondences can be viewed as postprocessing of a dense motion field for best representation in terms of a set of irregularly spaced samples. The methods that are based on spatio-temporal intensity gradients offer closed-form solutions for direct estimation of the best node-point motion vectors (equivalently the best transformation parameters). We show that the performance of the proposed closed-form solutions are comparable to those of the alternative search-based solutions at a fraction of the computational cost. 相似文献
18.
E. Yucel Cabir Terzioglu A. Varilci I. Belenli 《Journal of Materials Science: Materials in Electronics》2011,22(8):1143-1153
We have fabricated MgB2/Fe monofilament wires and tapes by a powder-in tube (PIT) technique, using an ex-situ process without any intermediate annealing.
MgB2/Fe monofilament tapes were annealed at 650–1,050°C for 60 min and 950°C for 30–240 min. We have investigated the effect of
annealing temperatures and times on the formation of MgB2 phase, activation energy, temperature dependence of irreversibility field H
irr(T) and upper critical field H
c2(T), transition temperature (T
c), lattice parameters (a and c), full width at half maximum, crystallinity, resistivity, residual resistivity ratio, active cross-sectional area fraction
and critical current densities. We observed that the activation energies of the MgB2/Fe monofilament samples increased with increasing annealing temperature up to 950°C and with increasing annealing time up
to 60 min while it decreased with increasing magnetic field. For the MgB2/Fe monofilament tape, the slope of the H
c2–T and H
irr–T curves decreased with increasing annealing temperature from 850 to 950°C as well as with increasing annealing time from 30
to 60 min. The transport and microstructure investigations show that T
c, J
c and microstructure properties are remarkably enhanced with increasing annealing temperature. The highest value of critical
current density is obtained for the sample annealed at 950°C for 60 min. The J
c and T
coffset values of the sample annealed at 950°C for 60 min were found to be 260.43 A/cm2 at 20 and 38.1 K, respectively. 相似文献
19.
A fast parametric motion estimation algorithm with illumination and lens distortion correction 总被引:5,自引:0,他引:5
Methods for estimating motion in video sequences that are based on the optical flow equation (OFE) assume that the scene illumination is uniform and that the imaging optics are ideal. When these assumptions are appropriate, these methods can be very accurate, but when they are not, the accuracy of the motion field drops off accordingly. This paper extends the models upon which the OFE methods are based to include irregular, time-varying illumination models and models for imperfect optics that introduce vignetting, gamma, and geometric warping, such as are likely to be found with inexpensive PC cameras. The resulting optimization framework estimates the motion parameters, illumination parameters, and camera parameters simultaneously. In some cases these models can lead to nonlinear equations which must be solved iteratively; in other cases, the resulting optimization problem is linear. For the former case an efficient, hierarchical, iterative framework is provided that can be used to implement the motion estimator. 相似文献
20.