全文获取类型
收费全文 | 1281篇 |
免费 | 79篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 14篇 |
综合类 | 1篇 |
化学工业 | 297篇 |
金属工艺 | 34篇 |
机械仪表 | 27篇 |
建筑科学 | 44篇 |
矿业工程 | 1篇 |
能源动力 | 57篇 |
轻工业 | 90篇 |
水利工程 | 8篇 |
石油天然气 | 2篇 |
无线电 | 119篇 |
一般工业技术 | 262篇 |
冶金工业 | 141篇 |
原子能技术 | 12篇 |
自动化技术 | 252篇 |
出版年
2024年 | 3篇 |
2023年 | 18篇 |
2022年 | 36篇 |
2021年 | 50篇 |
2020年 | 26篇 |
2019年 | 48篇 |
2018年 | 44篇 |
2017年 | 34篇 |
2016年 | 48篇 |
2015年 | 44篇 |
2014年 | 60篇 |
2013年 | 93篇 |
2012年 | 88篇 |
2011年 | 134篇 |
2010年 | 83篇 |
2009年 | 76篇 |
2008年 | 86篇 |
2007年 | 55篇 |
2006年 | 62篇 |
2005年 | 40篇 |
2004年 | 25篇 |
2003年 | 26篇 |
2002年 | 19篇 |
2001年 | 7篇 |
2000年 | 8篇 |
1999年 | 6篇 |
1998年 | 18篇 |
1997年 | 15篇 |
1996年 | 15篇 |
1995年 | 10篇 |
1994年 | 8篇 |
1993年 | 9篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1958年 | 2篇 |
1954年 | 3篇 |
1948年 | 2篇 |
1947年 | 2篇 |
1946年 | 2篇 |
排序方式: 共有1361条查询结果,搜索用时 15 毫秒
101.
Multichannel AR parameter estimation from noisy observations as an errors-in-variables issue 总被引:1,自引:0,他引:1
Julien Petitjean Eric Grivel William Bobillet Patrick Roussilhe 《Signal, Image and Video Processing》2010,4(2):209-220
In various applications from radar processing to mobile communication systems based on CDMA or OFDM, M-AR multichannel processes are often considered and may be combined with Kalman filtering. However, the estimations of the M-AR parameter matrices and the autocorrelation matrices of the additive noise and the driving process from noisy observations are key problems to be addressed. In this paper, we suggest solving them as an errors-in-variables issue. In that case, the noisy-observation autocorrelation matrix compensated by a specific diagonal block matrix and whose kernel is defined by the M-AR parameter matrices must be positive semi-definite. Hence, the parameter estimation consists in searching every diagonal block matrix that satisfies this property, in reiterating this search for a higher model order and then in extracting the solution that belongs to both sets. A comparative study is then carried out with existing methods including those based on the Extended Kalman Filter (EKF) and the Sigma-Point Kalman Filters (SPKF). It illustrates the relevance and advantages of the proposed approaches. 相似文献
102.
M. Kope¢ A. Yamada G. Kobayashi S. Nishimura R. Kanno A. Mauger F. Gendron C.M. Julien 《Journal of power sources》2009
A series of LiMnyFe1−yPO4 samples have been prepared in the whole range 0 ≤ y ≤ 1. Chemical delithiation could be achieved to obtain MnyFe1−yPO4 in the range 0 ≤ y ≤ 0.8, keeping the same crystal phase (olivine structure, space group Pnma). The composition y = 0.8 is the limit where the delithiated phase is still crystallized, but abruptly suffers strains at the molecular scale evidenced by both optical spectroscopy and X-ray diffraction. The analysis of the magnetic properties shows that in all the samples the concentration of impurities is negligible. The concentration of polarons, either holes associated to Li vacancies in LiMnyFe1−yPO4 or electrons associated to the existence of Li left in the matrix of MnyFe1−yPO4, is found to be small (≤1%) in all the samples. For y ≤ 0.6, all the Mn3+ ions MnyFe1−yPO4 are in the high-spin state (S = 2). At larger manganese concentration, however, the Mn3+ ions in excess of the critical concentration yc = 0.6 undergo a transition to the low-spin state (S = 1). As a consequence, and in contrast with prior works, we find that Mn0.8Fe0.2PO4 has magnetic interactions that are much smaller, and no antiferromagnetic ordering in this compound is detected, at least above 20 K. Antiferromagnetic ordering that had been reported so far for MnyFe1−yPO4 at large y-composition might come from incomplete delithiation. The spin-transition of Mn3+ in concentration (y–yc) to the low-spin state is at the origin of the strain fields at the molecular scale that increase with y for y > 0.6, and ultimately prevents the full delithiation for y > 0.8. This result sheds light on the reason for the degradation of cathode properties in Mn-rich compounds of the heterosite–purpurite series, while the electrochemical properties are good in the range y ≤ 0.6 but only at slow rates, due to the very small hopping mobility of the small polaron. 相似文献
103.
Etienne Prulière Julien Férec Francisco Chinesta Amine Ammar 《International Journal of Material Forming》2010,3(2):1339-1350
An efficient simulation of thermal and mechanical models involved in thermosetting composites forming needs to overcome some numerical difficulties related to: (i) the multi-scale behaviour; (ii) the complex geometries involved needing too many degrees of freedom; (iii) the large time intervals where the solution has to be computed; (iv) the non-linearity of the involved evolution equations; (v) the numerous couplings… In this work, an efficient strategy based on a separated representation is proposed. This method enables to avoid the use of an incremental strategy and can lead to impressive computing time savings especially when the model involves fine meshes and very small time steps. The local non-linear chemical kinetics and its coupling with the global heat balance equation are naturally introduced in the separated representation algorithm. Moreover, the dependence of the thermal conductivity and the specific heat on the temperature and on the reaction advancement degree are also taken into account. Knowing the history of the temperature field, the separated representation is again used to solve the thermo-mechanical problem in order to determine the residual stresses. 相似文献
104.
Julien Fatisson Sania Mansouri Daniel Yacoub Yahye Merhi Maryam Tabrizian 《Journal of the Royal Society Interface》2011,8(60):988-997
Platelet adhesion and activation rates are frequently used to assess the thrombogenicity of biomaterials, which is a crucial step for the development of blood-contacting devices. Until now, electron and confocal microscopes have been used to investigate platelet activation but they failed to characterize this activation quantitatively and in real time. In order to overcome these limitations, quartz crystal microbalance with dissipation (QCM-D) was employed and an explicit time scale introduced in the dissipation versus frequency plots (Df–t) provided us with quantitative data at different stages of platelet activation. The QCM-D chips were coated with thrombogenic and non-thrombogenic model proteins to develop the methodology, further extended to investigate polymer thrombogenicity. Electron microscopy and immunofluorescence labelling were used to validate the QCM-D data and confirmed the relevance of Df–t plots to discriminate the activation rate among protein-modified surfaces. The responses showed the predominant role of surface hydrophobicity and roughness towards platelet activation and thereby towards polymer thrombogenicity. Modelling experimental data obtained with QCM-D with a Matlab code allowed us to define the rate at which mass change occurs (A/B), to obtain an A/B value for each polymer and correlate this value with polymer thrombogenicity. 相似文献
105.
106.
Julien Schaeffer Jean-Claude Le Saux Monica Lora Robert L. Atmar Françoise S. Le Guyader 《International journal of food microbiology》2013
Contaminated shellfish have been implicated in gastroenteritis outbreaks in different countries. As no regulation has been set up yet regarding viral contamination of food, very few data are available on the prevalence of contaminated products on the market. This study presents data obtained from oysters collected on the French market in one producing area over a 16 month period of time. Noroviruses were detected in 9% of samples with a seasonal impact and influence of climatic events. Contamination levels were low and, surprisingly, oysters sampled directly from the producer were found to have less contamination than oysters from supermarkets. 相似文献
107.
Julien Jumel Michal K. Budzik Martin E.R. Shanahan 《Engineering Fracture Mechanics》2011,78(18):3253-3269
A first order correction is proposed taking into account both interface elasticity and transverse anticlastic curvature of flexible substrate(s) in the DCB (and related tests). Adherends are represented by Kirchhoff–Love plates, and the interface by a Winkler-type elastic foundation. Two functions are introduced, representing evolution of beam deflection along the sample midline and anticlastic curvature along the plate. A method of virtual work is used to find the associated equilibrium equation. The two-dimensional sample deformation is determined semi-analytically. Sample rigidity and energy release rate are computed for various geometrical configurations and compared to more common models. 相似文献
108.
This paper reports the first stage of work being undertaken to understand the factors that have impacted on the current state of food safety in the UK food manufacturing sector. The paper first explores developments in international food safety regulation in general and in particular, the UK. Using a survey and case study methodology, the paper examines the response of food manufacturing enterprises to food safety regulation, and uses statistical techniques to investigate the effects of enterprise size on the drivers for, benefits of, and challenges to compliance. Further, the factors that influence the successful implementation of an integrated food safety management system are also examined. The results show a great deal of both statutory and private regulation that has incentivised enterprises. In response, enterprises have implemented integrated food safety management systems to proactively deal with the risks associated with food safety, however, enterprises claim that statutory regulations are biased towards consumers, without adequate impact assessments on all stakeholders within the chain, and hence causing industry to incur significant costs that could otherwise be avoided. Even though compliance with food safety regulation is burdensome, the cost of non-compliance will also be significant to enterprises. The findings also show that there is no significant effect of size of enterprise on the drivers, benefits and challenges to compliance with food safety regulation. 相似文献
109.
110.
The learning of complex relationships can be decomposed into several neural networks. The modular organization is determined
by prior knowledge of the problem that permits to split the processing into tasks of small dimensionality. The sub-tasks can
be implemented with neural networks, although the learning examples cannot be used anymore to supervise directly each of the
networks. This article addresses the problem of learning in a modular context, developing in particular additive compositions. A simple rule allows defining efficient training, and combining, for example, several Supervised-SOM networks. This technique
is important because it introduces interesting generalizations in many modular compositions, permitting data fusion or sequential
combinations of neural networks.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献