全文获取类型
收费全文 | 543篇 |
免费 | 171篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 7篇 |
综合类 | 19篇 |
化学工业 | 595篇 |
金属工艺 | 3篇 |
机械仪表 | 1篇 |
矿业工程 | 4篇 |
能源动力 | 2篇 |
轻工业 | 12篇 |
石油天然气 | 1篇 |
无线电 | 35篇 |
一般工业技术 | 21篇 |
冶金工业 | 2篇 |
原子能技术 | 4篇 |
自动化技术 | 14篇 |
出版年
2023年 | 8篇 |
2022年 | 13篇 |
2021年 | 32篇 |
2020年 | 10篇 |
2019年 | 6篇 |
2018年 | 20篇 |
2017年 | 8篇 |
2016年 | 14篇 |
2015年 | 9篇 |
2014年 | 31篇 |
2013年 | 28篇 |
2012年 | 28篇 |
2011年 | 39篇 |
2010年 | 40篇 |
2009年 | 66篇 |
2008年 | 28篇 |
2007年 | 52篇 |
2006年 | 55篇 |
2005年 | 23篇 |
2004年 | 22篇 |
2003年 | 25篇 |
2002年 | 40篇 |
2001年 | 24篇 |
2000年 | 18篇 |
1999年 | 13篇 |
1998年 | 19篇 |
1997年 | 12篇 |
1996年 | 4篇 |
1995年 | 12篇 |
1994年 | 14篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1990年 | 2篇 |
排序方式: 共有720条查询结果,搜索用时 15 毫秒
31.
间苯二酚六次甲基四胺络合物(PY)对白炭黑补强天然胶的影响 总被引:2,自引:0,他引:2
采用平衡溶胀法、力学性能以及老化性能,表征PY对白炭黑补强天然胶的影响。结果表明PY加强了橡胶-白炭黑界面的相互作用,使体系综合力学性能显著提高,加入了PY的硫化胶耐老化性也得到改善。 相似文献
32.
33.
研究了新型复合型防老剂LF 60对NR胶料的硫化特性、自由状态和应力状态下的热氧老化的防护性能。试验结果表明 :防老剂LF 60对NR胶料的硫化特性的影响较小 ,其胶料硫化诱导期比防老剂A、D和 40 1 0NA长 ;对NR胶料热氧老化防护性能和氧化起始温度均高于防老剂A和D ,与防老剂 40 1 0NA相近 ;在NR胶料中防老剂LF 60的用量以 1 1 .5份为宜。 相似文献
34.
No-reference (NR)/blind image quality assessment (IQA) metrics play an important role in the area of image processing. Natural scene statistics (NSS) model assumes that natural images possess certain regular statistical properties and is widely used in NR IQA metrics. Most existing NSS-based NR algorithms are achieved by measuring the variation of image statistics, which are characterized by the fitting parameters of NSS model, across different distortions. However, distortions not only change the image statistics, but also disturb the statistical regularity held by natural images. As a result, the distribution of distorted images can not well follow the NSS model. There exists fitting error between the real distribution of the distorted image and the fitted one under certain NSS model. In this paper, the statistical distributions of the distorted images are discussed in detail. We suggest to take the fitting errors into account as well as the fitting parameters for feature extraction, and propose a novel NR IQA algorithm. Experimental results on several image databases demonstrate that the proposed metric performs highly consistent with human visual perception. 相似文献
35.
In this paper, we put forward an effective and efficient no reference image blurriness assessment metric on the basis of local binary pattern (LBP) features. In this proposal, we reveal that part of the LBP histogram bins present monotonously with the degree of blurriness. The proposed method contains the following steps. Firstly, the LBP maps of an input image are extracted with multiple radiuses. And then, the frequency of pattern histogram is analyzed before part of bins are chosen as the features. In addition, we also take the entropy of these bins as another feature. Finally, we learn the extracted features to predict the image blurriness score. Validation of the proposed method is conducted on the blurred images of LIVE-II, CSIQ, TID2008, TID2013, LIVE3D IQA Phase I and LIVE3D IQA Phase II. Experimental results demonstrate that compared with the state-of-the-art image quality assessment (IQA) methods, the proposed algorithm has notable advantage in correlation with subjective perception and computational complexity. 相似文献
36.
With the wide propagation of cloud and mobile computing, screen content images (SCIs) have become more indispensable in our daily lives. Compared to natural scene images (NSIs), SCIs possess many particular characteristics, like mixed contents, extremely sharp edges, and text graphics. Consequently, more challenges occur in the feature extraction, which is used to reflect the distortion, during the quality assessment of SCIs. Recently, some convolutional neural network (CNN) models have been designed by automatically learning feature to evaluate the quality. In this paper, we develop a novel blind quality assessment method for SCIs via the CNN. First, compared with existing CNN-based methods, the proposed method avoids the disadvantage of training with image patches, and it is the pioneering attempt that takes the entire image as inputs. Second, instead of the image gray value, the original image is decomposed into two portions, i.e., the predicted and unpredicted portions, according to the internal generative mechanism (IGM) theory as the input of CNN. Through the CNN, all features of the image are learned automatically from beginning to end, and the network finally outputs the predicted score. Since existing SCI database is too small, to fully train the network, we collected 30000 SCIs and employed a high-accuracy full-reference quality assessment metric of SCI to compute scores as the training labels. Experimental results on SIQAD database demonstrate that the proposed method is comparable to reference-based SCI quality assessment metrics and is superior to the state-of-the-art NSI quality assessment metrics. 相似文献
37.
《Drug development and industrial pharmacy》2013,39(1):102-107
Purpose: The effect of surface-mannose modification on aerosolized liposomal delivery to alveolar macrophages (AMs) was evaluated in vitro and in vivo. Method: 4-Aminophenyl-α-D-mannopyranoside (Man) was used for surface-mannose modification, and mannosylated liposomes with various mannosylation rates (particle size: 1000 nm) were prepared. Results: In the in vitro uptake experiments, the uptake of mannosylated liposomes by AMs was increased with the increase in the mannosylation rate over the range 2.4–9.1 mol% Man and became constant at over 9.1%. Thus, the most efficient mannosylation rate was 9.1 mol% Man. Furthermore, free mannose inhibited the uptake of mannosylated liposomes by AMs. This indicates that the uptake mechanism of mannosylated liposomes by AMs is mannose receptor-mediated endocytosis. In the in vivo animal experiments, the mannosylated liposomes (mannosylation rate, 9.1 mol% Man) were more efficiently delivered to AMs after pulmonary aerosolization to rats than nonmodified liposomes and did not harm lung tissues. Conclusion: These results indicate that surface-mannose modification is useful for efficient aerosolized liposomal delivery to AMs. 相似文献
38.
The influence of the concentration of paraffin wax on the penetration rate, P, and the average diffusion coefficient, D, of kerosene in an SBR–NR composite and also on the coefficient of viscosity were investigated. All decreased with the addition of wax. Also, the effect of the concentration of paraffin wax on both the current–voltage characteristics and the temperature dependence of the dc electrical conductivity were studied. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3169–3177, 2001 相似文献
39.
40.