全文获取类型
收费全文 | 2665篇 |
免费 | 100篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 52篇 |
综合类 | 4篇 |
化学工业 | 658篇 |
金属工艺 | 35篇 |
机械仪表 | 52篇 |
建筑科学 | 84篇 |
能源动力 | 73篇 |
轻工业 | 213篇 |
水利工程 | 10篇 |
石油天然气 | 9篇 |
无线电 | 256篇 |
一般工业技术 | 510篇 |
冶金工业 | 273篇 |
原子能技术 | 16篇 |
自动化技术 | 523篇 |
出版年
2024年 | 4篇 |
2023年 | 21篇 |
2022年 | 41篇 |
2021年 | 74篇 |
2020年 | 33篇 |
2019年 | 56篇 |
2018年 | 67篇 |
2017年 | 63篇 |
2016年 | 74篇 |
2015年 | 78篇 |
2014年 | 95篇 |
2013年 | 129篇 |
2012年 | 149篇 |
2011年 | 209篇 |
2010年 | 137篇 |
2009年 | 139篇 |
2008年 | 146篇 |
2007年 | 120篇 |
2006年 | 127篇 |
2005年 | 106篇 |
2004年 | 107篇 |
2003年 | 63篇 |
2002年 | 75篇 |
2001年 | 59篇 |
2000年 | 37篇 |
1999年 | 47篇 |
1998年 | 103篇 |
1997年 | 74篇 |
1996年 | 57篇 |
1995年 | 45篇 |
1994年 | 30篇 |
1993年 | 22篇 |
1992年 | 21篇 |
1991年 | 17篇 |
1990年 | 16篇 |
1989年 | 18篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 5篇 |
1985年 | 10篇 |
1984年 | 6篇 |
1982年 | 7篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 6篇 |
1976年 | 13篇 |
1974年 | 3篇 |
1970年 | 3篇 |
1968年 | 3篇 |
排序方式: 共有2768条查询结果,搜索用时 11 毫秒
71.
Eric Becker Véronique Favier Regis Bigot Pierre Cezard Laurent Langlois 《Journal of Materials Processing Technology》2010,210(11):1482-1492
Semi-solid forming is an effective near-net-shape forming process to produce components with complex geometry and in fewer forming steps. It benefits from the complex thixotropic behaviour of semi-solids. However, the consequences of such behaviour on the flow during thixoforming, is still neither completely characterized and nor fully understood, especially for high melting point alloys. The study described in this paper investigates thixoextrusion for C38 low carbon steel material using dies at temperatures much lower than the slug temperature. Four different process parameters were studied: the initial slug temperature, the die temperature, the ram speed and the presence of a ceramic layer at the tool/material interface. The extruded parts were found to have an exact shape and a good surface state only if the temperature was below a certain value. This critical temperature is not an intrinsic material property since its value depends on die temperature and the presence of the Ceraspray© layer. Two kinds of flow were highlighted: a homogeneous flow controlled by the behaviour of the solid skeleton characterized by a positive strain rate sensitivity, and a non homogeneous flow (macro liquid/solid phase separation) dominated by the flow of the free liquid. With decreasing ram speed, heat losses increase so that the overall consistency of the material improves, leading to apparent negative strain rate sensitivity. Finally, some ways to optimise thixoforming are proposed. 相似文献
72.
Carbon footprint as environmental performance indicator for the manufacturing industry 总被引:1,自引:0,他引:1
A. Laurent 《CIRP Annals》2010,59(1):37-40
With the current focus on our climate change impacts, the embodied CO2 emission or “Carbon footprint” is often used as an environmental performance indicator for our products or production activities. The ability of carbon footprint to represent other types of impact like human toxicity, and hence the overall environmental impact is investigated based on life cycle assessments of several materials of major relevance to manufacturing industries. The dependence of the carbon footprint on the assumed scenarios for generation of thermal and electrical energy in the life cycle of the materials is analyzed, and the appropriateness of carbon footprint as an overall indicator of the environmental performance is discussed. 相似文献
73.
74.
Zhijian Liu Laurent Babout Robert Banasiak Dominik Sankowski 《Flow Measurement and Instrumentation》2010,21(3):219-227
This paper presents a new design of rotatable sensor for ECT systems that can be mounted on a multi-phase flow installation. In order to attest how the performance of the sensor is affected by the rotatable frame, the effectiveness of the rotatable sensor is analyzed in terms of SNR (Signal-to-Noise Ratio) and image accuracy, which is dependent on the number of independent measurements, the image reconstruction strategy and the size of the mesh. The results confirm that with a sensor equipped with 16 electrodes, the optimum number of rotation steps is 3 in order to get the best compromise in terms of image accuracy and image reconstruction time. Results also show that this configuration achieves results similar to a classical sensor equipped with 32 electrodes. 相似文献
75.
Laurent Bédouet Florentina Pascale Michel Bonneau Alexandre Laurent 《Drug development and industrial pharmacy》2015,41(1):85-94
Intra-articular drug delivery systems (DDSs) are envisaged as interesting alternative to locally release non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen to reduce pain in patients with osteoarthritis. The present study examines the efficacy of S-(+)-ibuprofen on cartilage degradation as drug candidate for DDS loading. Humeral cartilage and joint capsule explants were collected from healthy sheep shoulder joints and they were cultured in mono- or in co-culture for 13?days with LPS in combination with S-(+)-ibuprofen at 50?µM and 1?mM. S-(+)-ibuprofen (50?µM) blocked prostaglandins production in LPS-activated explants but did not reduce cartilage degradation. By contrast, 1?mM S-(+)-ibuprofen treatment of cartilage explants reduced nitric oxide synthesis by 51% (p?=?0.0072), proteoglycans degradation by 35% (p?=?0.0114) and expression of serum amyloid protein – the main protein induced upon LPS challenge – by 44% (p?0.0001). On contrary, in presence of synovial membrane, the protective effects of S-(+)-ibuprofen on cartilage damages were significantly diminished. At 1mM, S-(+)-ibuprofen reduced the cell lysis during culture of cartilage and joint capsule either in mono- or in co-culture. This study performed on sheep explants shows that 1?mM S-(+)-ibuprofen inhibited cartilage degradation via a mechanism independent of cyclooxygenase inhibition. Reduction of prostaglandins synthesis at 50?µM in all treatment groups and reduction of cartilage degradation observed at 1?mM suggest that S-(+)-ibuprofen could be considered as a promising drug candidate for the loading of intra-articular DDS. 相似文献
76.
Antiferroelectric Thin Films: Giant Negative Electrocaloric Effect in Antiferroelectric La‐Doped Pb(ZrTi)O3 Thin Films Near Room Temperature (Adv. Mater. 20/2015) 下载免费PDF全文
77.
Free-living amoebae (FLA) are protozoa that can be found in water networks where they prey on bacteria within biofilms. Most bacteria are digested rapidly by phagocytosis, however some are able to survive within amoebae and some are even able to multiply, as it is the case for Legionella pneumophila. These resisting bacteria are a potential health problem as they could also resist to macrophage phagocytosis. Several publications already reported intra-amoebal bacteria but the methods of identification did not allow metagenomic analysis and are partly based on co-culture with one selected amoebal strain. The aim of our study was to conduct a rRNA-targeted metagenomic analysis on amoebae and intra-amoebal bacteria found in drinking water network, to provide the first FLA microbiome in environmental strains. Three sites of a water network were sampled during four months. Culturable FLA were isolated and total DNA was prepared, allowing purification of both amoebal and bacterial DNA. Metagenomic studies were then conducted through 18S or 16S amplicons sequencing. Hartmannella was by far the most represented genus of FLA. Regarding intra-amoebal bacteria, 54 genera were identified, among which 21 were newly described intra-amoebal bacteria, underlying the power of our approach. There were high differences in bacterial diversity between the three sites. Several genera were highly represented and/or found at least in two sites, underlying that these bacteria could be able to multiply within FLA. Our method is therefore useful to identify FLA microbiome and could be applied to other networks to have a more comprehensive view of intra-amoebal diversity. 相似文献
78.
Olivia M. Guillin Caroline Vindry Thophile Ohlmann Laurent Chavatte 《International journal of molecular sciences》2022,23(3)
The infection of CD4 T-lymphocytes with human immunodeficiency virus (HIV), the etiological agent of acquired immunodeficiency syndrome (AIDS), disrupts cellular homeostasis, increases oxidative stress and interferes with micronutrient metabolism. Viral replication simultaneously increases the demand for micronutrients and causes their loss, as for selenium (Se). In HIV-infected patients, selenium deficiency was associated with a lower CD4 T-cell count and a shorter life expectancy. Selenium has an important role in antioxidant defense, redox signaling and redox homeostasis, and most of these biological activities are mediated by its incorporation in an essential family of redox enzymes, namely the selenoproteins. Here, we have investigated how selenium and selenoproteins interplay with HIV infection in different cellular models of human CD4 T lymphocytes derived from established cell lines (Jurkat and SupT1) and isolated primary CD4 T cells. First, we characterized the expression of the selenoproteome in various human T-cell models and found it tightly regulated by the selenium level of the culture media, which was in agreement with reports from non-immune cells. Then, we showed that selenium had no significant effect on HIV-1 protein production nor on infectivity, but slightly reduced the percentage of infected cells in a Jurkat cell line and isolated primary CD4 T cells. Finally, in response to HIV-1 infection, the selenoproteome was slightly altered. 相似文献
79.
Cells of six strains of Cronobacter were subjected to dry stress and stored for 2.5 months at ambient temperature. The individual cell lag time distributions of recovered cells were characterized at 25 °C and 37 °C in non-selective broth. The individual cell lag times were deduced from the times taken by cultures from individual cells to reach an optical density threshold. In parallel, growth curves for each strain at high contamination levels were determined in the same growth conditions. In general, the extreme value type II distribution with a shape parameter fixed to 5 (EVIIb) was the most effective at describing the 12 observed distributions of individual cell lag times. Recently, a model for characterizing individual cell lag time distribution from population growth parameters was developed for other food-borne pathogenic bacteria such as Listeria monocytogenes. We confirmed this model’s applicability to Cronobacter by comparing the mean and the standard deviation of individual cell lag times to populational lag times observed with high initial concentration experiments. We also validated the model in realistic conditions by studying growth in powdered infant formula decimally diluted in Buffered Peptone Water, which represents the first enrichment step of the standard detection method for Cronobacter. Individual lag times and the pooling of samples significantly affect detection performances. 相似文献
80.
Agnès Princivalle Guilhem MartinCéline Viazzi Christian GuizardNicolas Grunbaum Laurent Dessemond 《Journal of power sources》2011,196(22):9238-9245
Ceramic powders of BaCe0.9Y0.1O2.95 (BCY10) have been prepared by the sol-gel method. Barium and yttrium acetate and cerium nitrate were used as ceramic precursors in a water solution. The reaction process studied by DTA-TG and XRD showed that calcination of the precursor powder at T ≥ 1000 °C produces a single perovskite phase. The densification behaviour of green compacts studied by constant heating rate dilatometry revealed that the shrinkage rate was maximal at 1430 °C. Sintered densities higher than 95% of the theoretical one were thus obtained below 1500 °C. The bulk and additional blocking effects were characterized by impedance spectroscopy in wet atmosphere between 150 and 600 °C. A proton conduction behaviour was clearly identified. The blocking effect can be related to a space-charge depletion layer of protons in the vicinity of grain boundaries. 相似文献