全文获取类型
收费全文 | 3225篇 |
免费 | 140篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 31篇 |
综合类 | 1篇 |
化学工业 | 840篇 |
金属工艺 | 81篇 |
机械仪表 | 45篇 |
建筑科学 | 108篇 |
矿业工程 | 4篇 |
能源动力 | 119篇 |
轻工业 | 258篇 |
水利工程 | 17篇 |
石油天然气 | 5篇 |
无线电 | 291篇 |
一般工业技术 | 699篇 |
冶金工业 | 203篇 |
原子能技术 | 36篇 |
自动化技术 | 629篇 |
出版年
2023年 | 17篇 |
2022年 | 60篇 |
2021年 | 59篇 |
2020年 | 52篇 |
2019年 | 47篇 |
2018年 | 82篇 |
2017年 | 85篇 |
2016年 | 108篇 |
2015年 | 72篇 |
2014年 | 129篇 |
2013年 | 179篇 |
2012年 | 169篇 |
2011年 | 251篇 |
2010年 | 186篇 |
2009年 | 212篇 |
2008年 | 184篇 |
2007年 | 170篇 |
2006年 | 167篇 |
2005年 | 131篇 |
2004年 | 120篇 |
2003年 | 87篇 |
2002年 | 96篇 |
2001年 | 49篇 |
2000年 | 57篇 |
1999年 | 52篇 |
1998年 | 64篇 |
1997年 | 56篇 |
1996年 | 43篇 |
1995年 | 39篇 |
1994年 | 39篇 |
1993年 | 30篇 |
1992年 | 27篇 |
1991年 | 19篇 |
1990年 | 14篇 |
1989年 | 15篇 |
1988年 | 15篇 |
1987年 | 11篇 |
1986年 | 10篇 |
1985年 | 16篇 |
1983年 | 8篇 |
1982年 | 9篇 |
1981年 | 13篇 |
1980年 | 7篇 |
1979年 | 8篇 |
1978年 | 9篇 |
1977年 | 12篇 |
1976年 | 12篇 |
1975年 | 7篇 |
1974年 | 9篇 |
1973年 | 7篇 |
排序方式: 共有3367条查询结果,搜索用时 0 毫秒
91.
Simoens François Meilhan Jérôme Nicolas Jean-Alain 《Journal of Infrared, Millimeter and Terahertz Waves》2015,36(10):961-985
Journal of Infrared, Millimeter, and Terahertz Waves - Sensitive and large-format terahertz focal plane arrays (FPAs) integrated in compact and hand-held cameras that deliver real-time terahertz... 相似文献
92.
Negar Naghavi Solange Temgoua Thibaud Hildebrandt Jean Franois Guillemoles Daniel Lincot 《Progress in Photovoltaics: Research and Applications》2015,23(12):1820-1827
The purpose of the present paper is to focus on the impact of oxygen gas partial pressure during the sputtering of i‐ZnO and ZnMgO on the transient behavior of Cu(In,Ga)Se2 (CIGSe) based solar cells parameters when a CBD‐Zn(S,O) buffer layer is used. Based on electrical characterization of cells, it is observed that the effect of light soaking is different on J–V characteristics depending on whether oxygen is or is not present during the first deposition time of the i‐ZnO or ZnMgO layers. In fact, when cells are prepared with standard i‐ZnO, the efficiencies are very low and a pronounced transient behavior is observed. However, when the first 10 nm of i‐ZnO or ZnMgO is formed by sputtered layer without adding oxygen during the process, depending on the thickness of the buffer layer, the transient effects strongly decreases. It is then possible to get stable cells reaching efficiencies quite similar to the CdS reference cells, especially with ZnMgO, without any post‐treatments. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
93.
Olivier Tingaud Ghislain Montavon Alain Denoirjean Jean-François Coudert Vincent Rat Pierre Fauchais 《Journal of Thermal Spray Technology》2010,19(1-2):207-218
Suspension plasma spraying (SPS) is an alternative to conventional atmospheric plasma spraying (APS) aiming at manufacturing thinner layers (i.e., 10-100 μm) due to the specific size of the feedstock particles, from a few tens of nanometers to a few micrometers. The staking of lamellae and particles, which present a diameter ranging from 0.1 to 2.0 μm and an average thickness from 20 to 300 nm, permits to manufacture finely structured layers. Moreover, it appears as a versatile process able to manufacture different coating architectures according to the operating parameters (suspension properties, injection configuration, plasma properties, spray distance, torch scan velocity, scanning step, etc.). However, the different parameters controlling the properties of the coating, and their interdependences, are not yet fully identified. Thus, the aim of this paper is, on the one hand, to better understand the influence of operating parameters on the coating manufacturing mechanisms (in particular, the plasma gas mixture effect) and, on the other hand, to produce Al2O3-ZrO2 finely structured layers with large varieties of architectures. For this purpose, a simple theoretical model was used to describe the plasma torch operating conditions at the nozzle exit, based on experimental data (mass enthalpy, arc current intensity, thermophysical properties of plasma forming gases, etc.) and the influences of the spray parameters were determined by mean of the study of sizes and shapes of spray beads. The results enabled then to reach a better understanding of involved phenomena and their interactions on the final coating architectures permitting to manufacture several types of microstructures. 相似文献
94.
Kaktcham Pierre Marie Zambou Ngoufack François Foko Kouam Edith Marius Oana Ciobotaru Florentina Matei Calina Petruta Cornea 《Food Biotechnology》2013,27(4):237-256
This study aims to evaluate the antifungal activity of lactic acid bacteria (LAB) from some Cameroonian food commodities against mycotoxigenic and spoilage molds. Following LAB isolation, the antifungal activity of the isolates was assessed. The organic acids were quantified using high-performance liquid chromatography and the ability of the LAB to reduce mold biomass and aflatoxin production was evaluated. The LAB were identified and the biopreservative potential of strain LO3 was evaluated on tomato paste. Nine percent of the strains isolated showed broad antifungal activity. The activity was due to the effect of organic acids comprising lactic, acetic, 4-hydroxy-3-phenyllactic and 3-phenyllactic acids. Lactobacillus plantarum LO3 exhibiting the highest and broadest antifungal activity was selected and showed the capacity to inhibit fungal growth and aflatoxin production in vitro. Moreover, this strain and its cell-free supernatant showed the ability to prevent aflatoxigenic mold growth in tomato paste without altering its physico-chemical and organoleptic properties. 相似文献
95.
Lenz M van Hullebusch ED Farges F Nikitenko S Corvini PF Lens PN 《Environmental science & technology》2011,45(3):1067-1073
In this study we evaluate the potential of anaerobic granular sludge as an inoculum for the bioremediation of selenium-contaminated waters using species-specific analytical methods. Solid species formed by microbial reduction were investigated using X-ray absorption near-edge structure (XANES) spectroscopy at the selenium K-edge. Furthermore, dissolved selenium species were specifically determined by ion chromatography (IC) and solid-phase microextraction gas chromatography-mass spectrometry (SPME-GC-MS). Least-squares linear combination of the XANES spectra for samples incubated with the highest selenate/selenite concentrations (10(-3) M) show the predominance of elemental selenium and a Se(-I) selenide, such as ferroselite, the thermodynamically most stable iron selenide. In contrast, elemental selenium and Se(-II) selenides are the main species detected at the lower selenate/selenite concentrations. In each repeated fed batch incubation, most aqueous selenite anions were converted into solid selenium species, regardless of the type of electron donor used (acetate or H(2)/CO(2)) and the selenium concentration applied. On the other hand, at higher concentrations of selenate (10(-4) and 10(-3) M), significant amounts of the oxyanion remained unconverted after consecutive incubations. SPME-GC-MS demonstrated selenium alkylation with both electron donors investigated, as dimethyl selenide (DMSe) and dimethyl diselenide (DMDSe). Selenite was even more alkylated in the presence of H(2)/CO(2) (maximum 2156 μg of Se/L of DMSe + DMDSe) as compared to acetate (maximum 50 μg of Se/L). In contrast, selenate was less alkylated using both electron donors (maximum 166 and 3 μg of Se/L, respectively). The high alkylation potential for selenite limits its bioremediation in selenium laden waters involving H(2)/CO(2) as the electron donor despite the fact that nontoxic elemental selenium and thermodynamically stable metal selenide species are formed. 相似文献
96.
97.
98.
Jean-Denis Mathias Pierre-Marie Geffroy Jean-François Silvain 《Applied Thermal Engineering》2009,29(11-12):2391-2395
The aim of this paper is to provide a methodical approach for architectural optimization of power microelectronic devices. Because critical parameters of electronic devices are linked with reliability, architectural optimization, selection of the geometrical parameters of device and optimization of these parameters by iteration method associated by numerical analysis of reliability have to be achieved. In this way, this paper discusses about a methodical and numerical approach for the optimization of reliability in electronic devices, in particular the influence of geometrical parameters on the device reliability. 相似文献
99.
Gwénaëlle Hourdin Alain Germain Claude Moreau François Fajula 《Catalysis Letters》2000,69(3-4):241-244
Ti‐BEA and Ti‐FAU, obtained by post‐synthesis treatment, and TS‐1, obtained by direct hydrothermal synthesis, have been tested
as catalysts for the Ruff oxidative degradation of calcium d‐gluconate to d‐arabinose using diluted hydrogen peroxide as oxidant.
Only large‐pore zeolites Ti‐BEA and Ti‐FAU were found to be active. It was shown, in particular, that a very rapid leaching
of titanium occurred and that the titanium species present in the solution were responsible for the catalytic activity observed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
100.
Ageing of aluminium hydroxide flocs 总被引:1,自引:0,他引:1
R.J. Franois 《Water research》1987,21(5)
The ageing processes of kaolinite suspensions flocculated with Al2(SO4)3 under a variety of different but well-controlled flocculation conditions were studied by measuring their average diameter, diameter distribution, strength and electrophoretic mobility.Three periods could be distinguished in the ageing process. Initially shrinkage of the flocs is mainly due to cementation-aggregation. In the first 6–8 h, dependent on the flocculation conditions, the average diameter reduces from 500 to 220 μm. During the following 4 days a shrinkage to 180 μm occurs, mainly due to condensation-polymerization and crystallization. In the third period, the average diameter increases because of Oswald ripening of the crystals.During each period the change of the diameter as a function of age can mathematically be described by: df,i = d∞ + d′· ti+i−ω. With d∞, d′ and ω constants dependent on the flocculation conditions.During ageing, the floc diameter distribution narrows. The shrinkage of the flocs during ageing is definitely not due to erosion of particles from the floc surface.The change of the electrophoretic mobility during ageing provides information on the thickness and homogeneity of the layer of insoluble hydroxides around the destabilized clay particles.The influence of a wide range of different flocculation process parameters on the floc ageing process is summarized, as is the influence of the ageing process on floc strength and floc density. The evolution of the effective floc density can be described by: .The constants Kp and a are functions of the ratio quantity of suspended solids vs coagulant dose. 相似文献