全文获取类型
收费全文 | 2366篇 |
免费 | 87篇 |
专业分类
电工技术 | 17篇 |
化学工业 | 596篇 |
金属工艺 | 36篇 |
机械仪表 | 77篇 |
建筑科学 | 62篇 |
矿业工程 | 2篇 |
能源动力 | 50篇 |
轻工业 | 222篇 |
水利工程 | 26篇 |
石油天然气 | 4篇 |
无线电 | 189篇 |
一般工业技术 | 349篇 |
冶金工业 | 531篇 |
原子能技术 | 25篇 |
自动化技术 | 267篇 |
出版年
2023年 | 41篇 |
2022年 | 153篇 |
2021年 | 151篇 |
2020年 | 48篇 |
2019年 | 49篇 |
2018年 | 61篇 |
2017年 | 59篇 |
2016年 | 70篇 |
2015年 | 43篇 |
2014年 | 65篇 |
2013年 | 129篇 |
2012年 | 88篇 |
2011年 | 125篇 |
2010年 | 84篇 |
2009年 | 101篇 |
2008年 | 83篇 |
2007年 | 73篇 |
2006年 | 55篇 |
2005年 | 54篇 |
2004年 | 40篇 |
2003年 | 49篇 |
2002年 | 32篇 |
2001年 | 23篇 |
2000年 | 27篇 |
1999年 | 35篇 |
1998年 | 188篇 |
1997年 | 111篇 |
1996年 | 91篇 |
1995年 | 40篇 |
1994年 | 46篇 |
1993年 | 44篇 |
1992年 | 16篇 |
1991年 | 12篇 |
1990年 | 9篇 |
1989年 | 21篇 |
1988年 | 11篇 |
1987年 | 6篇 |
1986年 | 12篇 |
1985年 | 15篇 |
1984年 | 6篇 |
1983年 | 8篇 |
1982年 | 8篇 |
1981年 | 12篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1977年 | 7篇 |
1976年 | 15篇 |
1974年 | 3篇 |
1969年 | 3篇 |
1967年 | 7篇 |
排序方式: 共有2453条查询结果,搜索用时 15 毫秒
21.
22.
M A Rossi S Zucoloto J E Dutra de Oliveira P F Becker J S Oliveira 《Archivos latinoamericanos de nutrición》1978,28(1):29-40
A study of the effect of long-term alcohol consumption on the liver of well-nourished rats is described. Rats fed for 16 weeks on a semipurified diet supplemented with high levels of vitamins and lipotropic factors and alcohol corresponding to 35% of the total caloric intake developed marked fatty changes of the liver. Mild fatty changes were observed in pair-fed controls receiving as isoenergetic equivalent of sucrose instead of alcohol. Intracellular hyaline bodies, corresponding ultrastructurally to giant mitochondria were abundantly found in the hepatocytes of alcoholic rats, while in the controls they were not seen. Te findings in this investigation are postulated to provide further evidence that the long-term intake of alcohol exerts a direct causative role in the pathogenesis of liver damage. 相似文献
23.
Different particulate solids such as glass powder, various types of activated carbon and bentonite suspended in Thiobacillus ferrooxidans cultures produce very different effects on the oxidizing activity of the microorganism. The atmospheric oxygen uptake by Thiobacillus ferrooxidans in Warburg respirometer flasks containing 9K medium with ferrous sulfate as energy source and suspended bentonite is 2.8 times that in the absence of solids. The dissolution rate of pure pyrite in 250 cm3 shake flasks containing 9K medium and bentonite is considerably enhanced over that where the only solid phase is pyrite. Conversely, the oxidizing ability of the microorganism seems to be inhibited by all the activated carbons tested. The effect of ground glass seems to be related to its particle size distribution. Implications for the bioleaching of sulfide ores and coal pyrite are discussed in the light of current knowledge on the adsorption of Thiobacillus ferrooxidans cells on solid surfaces. 相似文献
24.
Francesca Rossi 《Constraints》2014,19(2):186-194
Collective decision making is an area of increasingly growing interest, mainly due to the rise of many IT-enabled environments where people connect and share information with others. We believe that constraint reasoning can have a major impact in this field, by providing general and flexible frameworks to model agents’ preferences over the alternative decisions, efficient algorithms to compute the best individual and collective decisions, and innovative approaches to deal with missing information. However, in order to do this, we claim that constraint reasoning should increase its efforts to open up to other research areas, such as voting and game theory, multi-agent systems, machine learning, and reasoning under uncertainty. 相似文献
25.
The enzymic activity of the GTP-dependent acyl-CoA synthase isolated from rat liver mitochondria is affected by removal and
addition of lecithin (3). Purified preparations of this enzyme contain bound lecithin. In this presentation the nature of
the lecithin-protein interaction is examined. From binding measurements at different temperatures it is possible to postulate
which type of secondary valence bonds is holding the protein and lecithin together.
Presented at AOCS Meeting, Chicago, October 1967. 相似文献
26.
M. Rossi G. Vitali D. Karpuzov M. Kalitzova H. Budinov 《Journal of Materials Science》1991,26(12):3337-3342
GaAs 100 wafers were implanted and later annealed by using three different techniques: furnace thermal annealing (FTA), flash lamp (RTA) and low-power laser annealing (LPLA). The resulting modifications of the structure were studied by RHEED. The RHEED pattern analysis indicates that: (a) A well annealed structure is observed after thermal treatment in furnace at 850 °C for 30 min; (b) the particular RTA employed leads to some texturing, but is not sufficient to provide good structural effects; (c) best annealing under our conditions is obtained by the LPLA technique, especially for low ion doses (less than 1013 cm–2); (d) variable-glancing-angle RHEED is an effective and convenient method to investigate the ion induced disorder in crystals at small depths. 相似文献
27.
28.
Felisari L Grillo V Jabeen F Rubini S Menozzi C Rossi F Martelli F 《Ultramicroscopy》2011,111(8):1018-1028
A dedicated specimen holder has been designed to perform low-voltage scanning transmission electron microscopy in dark field mode. Different test samples, namely InGaAs/GaAs quantum wells, InGaAs nanowires and thick InGaAs layers, have been analysed to test the reliability of the model based on the proportionality to the specimen mass-thickness, generally used for image intensity interpretation of scattering contrast processes. We found that size of the probe, absorption and channelling must be taken into account to give a quantitative interpretation of image intensity. We develop a simple procedure to evaluate the probe-size effect and to obtain a quantitative indication of the absorption coefficient. Possible artefacts induced by channelling are pointed out. With the developed procedure, the low voltage approach can be successfully applied for quantitative compositional analysis. The method is then applied to the estimation of the In content in the core of InGaAs/GaAs core-shell nanowires. 相似文献
29.
Jeanbourquin D Sage D Nguyen L Schaeli B Kayal S Barry DA Rossi L 《Water science and technology》2011,64(5):1108-1114
Discharges of combined sewer overflows (CSOs) and stormwater are recognized as an important source of environmental contamination. However, the harsh sewer environment and particular hydraulic conditions during rain events reduce the reliability of traditional flow measurement probes. An in situ system for sewer water flow monitoring based on video images was evaluated. Algorithms to determine water velocities were developed based on image-processing techniques. The image-based water velocity algorithm identifies surface features and measures their positions with respect to real world coordinates. A web-based user interface and a three-tier system architecture enable remote configuration of the cameras and the image-processing algorithms in order to calculate automatically flow velocity on-line. Results of investigations conducted in a CSO are presented. The system was found to measure reliably water velocities, thereby providing the means to understand particular hydraulic behaviors. 相似文献
30.
Rossi L Rumley L Ort C Minkkinen P Barry DA Chèvre N 《Water science and technology》2011,63(12):2975-2982
Sampling is a key step in the analysis of chemical compounds. It is particularly important in the environmental field, for example for wastewater effluents, wet-weather discharges or streams in which the flows and concentrations vary greatly over time. In contrast to the improvements that have occurred in analytical measurement, developments in the field of sampling are less active. However, sampling errors may exceed by an order of magnitude those related to analytical processes. We proposed an Internet-based application based on a sampling theory to identify and quantify the errors in the process of taking samples. This general theory of sampling, already applied to different areas, helps to answer questions related to the number of samples, their volume, their representativeness, etc. The use of the internet to host this application facilitates use of theoretical tools and raise awareness of the uncertainties related to sampling. An example is presented, which highlights the importance of the sampling step in the quality of analytical results. 相似文献