全文获取类型
收费全文 | 632篇 |
免费 | 6篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 89篇 |
金属工艺 | 22篇 |
机械仪表 | 10篇 |
建筑科学 | 30篇 |
矿业工程 | 1篇 |
能源动力 | 9篇 |
轻工业 | 83篇 |
水利工程 | 2篇 |
石油天然气 | 2篇 |
无线电 | 47篇 |
一般工业技术 | 100篇 |
冶金工业 | 181篇 |
原子能技术 | 11篇 |
自动化技术 | 49篇 |
出版年
2021年 | 4篇 |
2019年 | 9篇 |
2018年 | 8篇 |
2017年 | 7篇 |
2016年 | 8篇 |
2015年 | 9篇 |
2014年 | 7篇 |
2013年 | 37篇 |
2012年 | 17篇 |
2011年 | 19篇 |
2010年 | 22篇 |
2009年 | 26篇 |
2008年 | 20篇 |
2007年 | 23篇 |
2006年 | 19篇 |
2005年 | 18篇 |
2004年 | 13篇 |
2003年 | 19篇 |
2002年 | 14篇 |
2001年 | 10篇 |
2000年 | 8篇 |
1999年 | 8篇 |
1998年 | 46篇 |
1997年 | 29篇 |
1996年 | 20篇 |
1995年 | 11篇 |
1994年 | 23篇 |
1993年 | 11篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 9篇 |
1984年 | 8篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 14篇 |
1980年 | 10篇 |
1978年 | 9篇 |
1977年 | 10篇 |
1976年 | 13篇 |
1975年 | 4篇 |
1974年 | 5篇 |
1973年 | 7篇 |
1970年 | 4篇 |
1967年 | 3篇 |
1958年 | 4篇 |
1956年 | 5篇 |
排序方式: 共有640条查询结果,搜索用时 31 毫秒
1.
Souchet Alexis D. Philippe Stphanie Lvque Aurlien Ober Floriane Leroy Laure 《Virtual Reality》2022,26(2):583-600
Virtual Reality - Do apparatuses and eyestrain have effects on learning performances and quality of experience? Materials and Methods: 42 participants played a serious game simulating a job... 相似文献
2.
Flexible and hydrophobic biobased films were obtained using zein esterified with methanol and para-toluene (p-toluene) sulfonic acid, cutin from tomato peels and ethanol. Esterification was confirmed by proton nuclear magnetic resonance and attenuated total reflectance–Fourier transform infrared spectroscopy (ATR-FTIR). Non-modified zein films were brittle and hydrophilic. ATR-FTIR demonstrated that zein esterification increased zein hydrophobicity. Without cutin, esterified zein films were hydrophobic but brittle. Addition of cutin yielded films that were flexible and hydrophobic, as demonstrated by contact angle measurements. Principal component analysis (PCA) of ATR-FTIR data showed that intensities at 3195 cm−1 and 3490 cm−1 were correlated to the relative hydrophobicity of zein films. PCA also showed that films of esterified zein and cutin were more hydrophobic than their counterparts (non-modified zein without cutin). Optical and scanning electron microscopy demonstrated that esterified zein was compatible with cutin and yielded cohesive films, which did not fracture upon bending. 相似文献
3.
Empirical models of regional adjustment often control for aggregate effects when estimating the impact of region-specific shocks on local economies. It is, however, difficult to filter out the effects of aggregate shocks—such as oil shocks, uncertainty shocks, or national recessions—because the incidence of these shocks varies across space and time. We propose an improved econometric method to control for this form of spatiotemporal heterogeneity, thereby yielding more accurate estimation of the effects of local shocks on regional economies. Applying the method to US states, we find that labour demand shocks are mostly absorbed through changes in participation; the migration response to these shocks is limited; and recoveries are highly protracted 相似文献
4.
5.
Fault management and security of computer networks present new challenges of increasing complexity. Decision procedures for fault diagnosis, security-related threats, and follow-up actions must, however, be evaluated on the basis of sound theoretical foundations and economic costs of various strategies. This paper presents a minimum expected cost solution for fault diagnosis and corrective actions. Several notions new to fault management are introduced. The methodology is applicable to both non-malicious and malicious faults. As a novel security-related application, the problem of choosing between two strategies for containing the spread of network worms is discussed. 相似文献
6.
Dr. Youness Touati-Jallabe Dr. Thibault Tintillier Dr. Elodie Mauchauffée Dr. Jean-Luc Boucher Jérémy Leroy Booma Ramassamy Dr. Abdallah Hamzé Dr. Karima Mezghenna Amine Bouzekrini Claudia Verna Jean Martinez Dr. Anne-Dominique Lajoix Dr. Jean-François Hernandez 《ChemMedChem》2020,15(6):517-531
More than 160 arginine analogues modified on the C-terminus via either an amide bond or a heterocyclic moiety (1,2,4-oxadiazole, 1,3,4-oxadiazole and 1,2,4-triazole) were prepared as potential inhibitors of NO synthases (NOS). A methodology involving formation of a thiocitrulline intermediate linked through its side-chain on a solid support followed by modification of its carboxylate group was developed. Finally, the side-chain thiourea group was either let unchanged, S-alkylated (Me, Et) or guanidinylated (Me, Et) to yield respectively after TFA treatment the corresponding thiocitrulline, S-Me/Et-isothiocitrulline and N-Me/Et-arginine substrate analogues. They all were tested against three recombinant NOS isoforms. Several compounds containing a S-Et- or a S-Me-Itc moiety and mainly belonging to both the dipeptide-like and 1,2,4-oxadiazole series were shown to inhibit nNOS and iNOS with IC50 in the 1–50 μM range. Spectral studies confirmed that these new compounds interacted at the heme active site. The more active compounds were found to inhibit intra-cellular iNOS expressed in RAW264.7 and INS-1 cells with similar efficiency than the reference compounds L-NIL and SEIT. 相似文献
7.
Jeremy R. Schwartzbord Jef L. Leroy Linda Severe Dan L. Brown 《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2016,33(6):1036-1042
Aflatoxins (AFs) are hepatocarcinogenic mycotoxins that can contaminate grains and oil seeds in tropical and sub-tropical areas and have been detected in maize and peanut products of Haiti. The first objective was to assess human exposure to AFs among Haitians at an urban hospital (GHESKIO) and a rural health centre (HCBH). The second objective was to test the association between AF exposure and reported dietary intake of potentially contaminated foods, such as maize, peanut products and milk. Measurement of urinary AFM1 by HPLC revealed that among 367 participants 14% and 22% at GHESKIO and HCBH, respectively, had detectable AFM1. The maximum and median AFM1 concentrations for all detected samples were 700 pg AFM1 ml–1 and 11.7 pg ml–1, respectively. Detection of AFM1 was significantly associated with peanut consumption (p < 0.05). Controlling for diet and age group in a logit model, patients who reported peanut consumption the day of the survey and patients from HCBH had greater log odds of excreting detectable AFM1 (p < 0.001 and 0.002, respectively); females had lower log odds (p = 0.020). Recalled frequency of consuming non-dairy animal-sourced foods, an indicator of diet quality, approached significance (p = 0.056) as an inverse predictor of urinary AFM1 detection. The findings augur the need for interventions that will improve food safety in Haiti and limit exposure to AFs, particularly among rural communities. 相似文献
8.
C. Ramadas Krishnan Balasubramaniam Avinash Hood Makarand Joshi C.V. Krishnamurthy 《Composite Structures》2011
In this study, the Lamb mode attenuation constants were derived in terms of the attenuation coefficient, group velocity and central frequency of excitation of the Lamb mode, using the Rayleigh damping model. Attenuation of Lamb waves, both fundamental symmetric and anti-symmetric modes, propagating through viscoelastic media (cross-ply glass/epoxy laminate) was modelled using the Finite Element Method. Numerically simulated attenuation of Lamb waves using Lamb mode attenuation constants was found to be in good agreement with the assumed attenuation. Experiments were performed on a quasi-isotropic laminate, employing air-coupled ultrasonic transducers, to measure the attenuation coefficient. Lamb mode attenuation constants, computed using the attenuation coefficient, were used to model the attenuation of the Lamb mode in quasi-isotropic laminates. Numerically simulated amplitude variation was found to be in good agreement with that computed from experiments. 相似文献
9.
Jan Gmys Rudi Leroy Mohand Mezmaz Nouredine Melab Daniel Tuyttens 《Concurrency and Computation》2016,28(18):4463-4484
In this paper, the focus is put on multi‐core branch‐and‐bound algorithms for solving large‐scale permutation‐based optimization problems. We investigate five work stealing (WS) strategies with a new data structure called integer–vector–matrix (IVM). In these strategies, each thread has a private IVM allowing the local management of a set of subproblems enumerated using a factorial system. The WS strategies differ in the way the victim thread is selected and the granularity of stolen work units (intervals of factoradics). To assess the efficiency of the private IVM‐based WS approach, the five WS strategies have been extensively experimented on the flowshop scheduling permutation problem and compared with their conventional linked‐list‐based counterparts. The obtained results demonstrate that the IVM‐based WS outperforms the linked‐list‐based one in terms of CPU time, memory usage and number of performed WS operations. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
10.
Jinhua Li Nicolas Menguy Christophe Gatel Victor Boureau Etienne Snoeck Gilles Patriarche Eric Leroy Yongxin Pan 《Journal of the Royal Society Interface》2015,12(103)
Magnetotactic bacteria (MTB) are known to produce single-domain magnetite or greigite crystals within intracellular membrane organelles and to navigate along the Earth''s magnetic field lines. MTB have been suggested as being one of the most ancient biomineralizing metabolisms on the Earth and they represent a fundamental model of intracellular biomineralization. Moreover, the determination of their specific crystallographic signature (e.g. structure and morphology) is essential for palaeoenvironmental and ancient-life studies. Yet, the mechanisms of MTB biomineralization remain poorly understood, although this process has been extensively studied in several cultured MTB strains in the Proteobacteria phylum. Here, we show a comprehensive transmission electron microscopy (TEM) study of magnetic and structural properties down to atomic scales on bullet-shaped magnetites produced by the uncultured strain MYR-1 belonging to the Nitrospirae phylum, a deeply branching phylogenetic MTB group. We observed a multiple-step crystal growth of MYR-1 magnetite: initial isotropic growth forming cubo-octahedral particles (less than approx. 40 nm), subsequent anisotropic growth and a systematic final elongation along [001] direction. During the crystal growth, one major {111} face is well developed and preserved at the larger basal end of the crystal. The basal {111} face appears to be terminated by a tetrahedral–octahedral-mixed iron surface, suggesting dimensional advantages for binding protein(s), which may template the crystallization of magnetite. This study offers new insights for understanding magnetite biomineralization within the Nitrospirae phylum. 相似文献