全文获取类型
收费全文 | 1981篇 |
免费 | 110篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 25篇 |
综合类 | 3篇 |
化学工业 | 486篇 |
金属工艺 | 41篇 |
机械仪表 | 48篇 |
建筑科学 | 47篇 |
矿业工程 | 4篇 |
能源动力 | 58篇 |
轻工业 | 370篇 |
水利工程 | 12篇 |
石油天然气 | 4篇 |
无线电 | 163篇 |
一般工业技术 | 312篇 |
冶金工业 | 214篇 |
原子能技术 | 14篇 |
自动化技术 | 293篇 |
出版年
2023年 | 17篇 |
2022年 | 42篇 |
2021年 | 64篇 |
2020年 | 43篇 |
2019年 | 36篇 |
2018年 | 62篇 |
2017年 | 66篇 |
2016年 | 72篇 |
2015年 | 54篇 |
2014年 | 74篇 |
2013年 | 134篇 |
2012年 | 121篇 |
2011年 | 125篇 |
2010年 | 94篇 |
2009年 | 91篇 |
2008年 | 105篇 |
2007年 | 88篇 |
2006年 | 78篇 |
2005年 | 53篇 |
2004年 | 37篇 |
2003年 | 63篇 |
2002年 | 54篇 |
2001年 | 37篇 |
2000年 | 34篇 |
1999年 | 29篇 |
1998年 | 73篇 |
1997年 | 61篇 |
1996年 | 34篇 |
1995年 | 31篇 |
1994年 | 17篇 |
1993年 | 29篇 |
1992年 | 15篇 |
1991年 | 11篇 |
1990年 | 20篇 |
1989年 | 15篇 |
1988年 | 13篇 |
1987年 | 5篇 |
1986年 | 10篇 |
1985年 | 10篇 |
1983年 | 8篇 |
1982年 | 4篇 |
1981年 | 10篇 |
1980年 | 9篇 |
1979年 | 5篇 |
1978年 | 8篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1973年 | 5篇 |
1971年 | 3篇 |
1966年 | 4篇 |
排序方式: 共有2094条查询结果,搜索用时 843 毫秒
51.
Franco Cataldo 《Fullerenes, Nanotubes and Carbon Nanostructures》2004,12(3):633-646
Since polyynes are easily accessible with the submerged electric arc synthesis between graphite electrodes, the chemical behavior of polyynes solutions in different solvents has been explored. It has been found that surprisingly the polyynes solutions, with polyynes having up to 16 carbon atoms arranged in a chain, are stable in air over 1 week time in the dark. These solutions react relatively slowly with ozone while add rapidly and completely bromine. The polyynes solutions are instead quite easily photolyzed under the action of UV radiation both in air and under N2. Two different light sources were used in the study: a low pressure mercury lamp emitting almost a monochromatic radiation at 254 nm and an high pressure mercury lamp emitting in a broad wavelength range in the ultraviolet. With the former monochromatic light source, it has been demonstrated the possibility to perform a selective photolysis of selected polyynes in a mixture of homologous series. 相似文献
52.
The hydrodynamic transport equations for charges in a semiconductor have been solved for a periodic excitation by means of a harmonic approach, in order to model microwave and millimetre-wave active devices. The solution is based on the expansion of physical variables in a Fourier series in the time domain, and on discretisation in the space domain. A waveform-balance technique in the TD is used to solve the nonlinear equations system. This approach allows for a longer time step with respect to standard TD solutions for most cases of interest, greatly reducing simulation time by at least two orders of magnitude in typical cases. © 2003 Wiley Periodicals, Inc. Int J RF and Microwave CAE 14: 36–48, 2004. 相似文献
53.
Jose Luis Fernandez-Marquez Giovanna Di Marzo Serugendo Sara Montagna Mirko Viroli Josep Lluis Arcos 《Natural computing》2013,12(1):43-67
In the last decade, bio-inspired self-organising mechanisms have been applied to different domains, achieving results beyond traditional approaches. However, researchers usually use these mechanisms in an ad-hoc manner. In this way, their interpretation, definition, boundary (i.e. when one mechanism stops, and when another starts), and implementation typically vary in the existing literature, thus preventing these mechanisms from being applied clearly and systematically to solve recurrent problems. To ease engineering of artificial bio-inspired systems, this paper describes a catalogue of bio-inspired mechanisms in terms of modular and reusable design patterns organised into different layers. This catalogue uniformly frames and classifies a variety of different patterns. Additionally, this paper places the design patterns inside existing self-organising methodologies and hints for selecting and using a design pattern. 相似文献
54.
The effect of processing protocol on physical stability and the microstructure of water‐in‐oil‐in‐water multiple emulsions containing a mixture of two amphiphilic copolymers with opposed hydrophilic‐lipophilic balance as emulsifiers and a green solvent, 2‐ethylhexyl lactate, as the dispersed phase, has been assessed. Emulsions were obtained in at least two steps: a homogenization step by using a rotor‐stator device, followed by one or two homogenization steps carried out in a high‐pressure device that used microfluidizer technology. To study the microstructure and physical stability of these emulsions, a combination of different techniques, such as transmitted‐light optical microscopy, globule size distribution, viscous flow tests, and multiple light scattering measurements, were performed. 相似文献
55.
Franco Cataldo 《Fullerenes, Nanotubes and Carbon Nanostructures》2013,21(2):289-295
Abstract Through a short review on pentalene chemistry, it is discussed the possibility to trap as organometallic complexes unstable fullerenes violating the isolated pentagons rule. 相似文献
56.
Shan He Chris Franco Wei Zhang 《International Journal of Food Science & Technology》2012,47(11):2397-2404
The aim of this study was to develop an enzymatic hydrolysis process of protein co‐products for two major commercial fish species in Australia: Atlantic salmon (AS) and Yellowtail kingfish (YTK). The outcomes are to produce high protein recovery of fish protein hydrolysates within controlled molecular weight ranges that display enhanced physicochemical properties of oil binding and emulsification. Three enzymes (Flavourzyme, Neutrase and Alcalase) were applied to processing co‐products. Protein recovery and physicochemical properties were evaluated with increasing hydrolysis time from 30 min to 180 min and ratio of enzyme to substrate (E/S) from 0.5% to 3.0%. In order to achieve a product with optimum emulsifying capacity (50 ± 0.6 m2 g?1), an E/S ratio of 0.6–1.3% Flavourzyme was applied for 30–111 min with a protein recovery of 55%; in order to achieve a product with optimum oil‐binding capacity (8.3 ± 0.3 g oil g hydrolysates?1), an E/S ratio of 2.3–3.0% Flavourzyme was applied for 25–64 min with a protein recovery of 70%. YTK protein hydrolysates were further membrane‐fractionated into five fractions (>100 kDa, 50–100 kDa, 30–50 kDa, 10–30 kDa and <10 kDa), and of these, the 10–30 kDa exhibited the best properties of oil binding (19 ± 0.3 g oil g hydrolysates?1) and emulsification (57 ± 0.7 m2 g?1). These results demonstrate the importance of enzymatic hydrolysis of seafood co‐products into high‐value ingredients for food products and processing. 相似文献
57.
Silvia Franco Elena Buratti Valentina Nigro Emanuela Zaccarelli Barbara Ruzicka Roberta Angelini 《International journal of molecular sciences》2021,22(8)
The phase behaviour of soft colloids has attracted great attention due to the large variety of new phenomenologies emerging from their ability to pack at very high volume fractions. Here we report rheological measurements on interpenetrated polymer network microgels composed of poly(N-isopropylacrylamide) (PNIPAM) and polyacrylic acid (PAAc) at fixed PAAc content as a function of weight concentration. We found three different rheological regimes characteristic of three different states: a Newtonian shear-thinning fluid, an attractive glass characterized by a yield stress, and a jamming state. We discuss the possible molecular mechanisms driving the formation of these states. 相似文献
58.
The membrane electric transport (MC) directly influences the performance of the polymer electrolyte fuel cells (PEMFC). The membrane conductivity is determined by a number of parameters such as: hydration technique, graphite cell geometry and pressure applied when the membrane electrode assembly (MEA) is joined. In addition, the membrane conductivity might be influenced by the electrode position due to the possibility of anisotropic electric conductivity. 相似文献
59.
Franco Cataldo Mihai V. Putz Ornella Ursini Giancarlo Angelini 《Fullerenes, Nanotubes and Carbon Nanostructures》2016,24(6):400-405
Two samples of activated carbon fabrics (ACF) with very high surface area (>1300 to >1800 m2/g) fully ozonized in the part 1 of this study were analyzed by thermogravimetric analysis (TGA) coupled both with differential thermal analysis (DTA) and FT-IR spectroscopy (TGA-FTIR). The adsorbed water and the amount of oxygenated functional groups were determined. The ozonized ACF shows an exothermal decomposition at about 181–189°C which may be due at least in part to the decomposition of ozonide and/or peroxide groups. The TGA-FTIR has revealed that the main products released from the thermal decomposition are CO2 followed by CO. Formic acid was detected only in correspondence to the exothermal transition at 181°C and was taken as a proof of the decomposition of secondary ozonides. 相似文献
60.