全文获取类型
收费全文 | 690篇 |
免费 | 41篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 172篇 |
金属工艺 | 5篇 |
机械仪表 | 11篇 |
建筑科学 | 19篇 |
矿业工程 | 1篇 |
能源动力 | 19篇 |
轻工业 | 151篇 |
水利工程 | 3篇 |
石油天然气 | 1篇 |
无线电 | 46篇 |
一般工业技术 | 100篇 |
冶金工业 | 64篇 |
原子能技术 | 4篇 |
自动化技术 | 133篇 |
出版年
2024年 | 1篇 |
2023年 | 7篇 |
2022年 | 20篇 |
2021年 | 27篇 |
2020年 | 22篇 |
2019年 | 19篇 |
2018年 | 15篇 |
2017年 | 22篇 |
2016年 | 21篇 |
2015年 | 24篇 |
2014年 | 33篇 |
2013年 | 59篇 |
2012年 | 40篇 |
2011年 | 52篇 |
2010年 | 41篇 |
2009年 | 44篇 |
2008年 | 28篇 |
2007年 | 23篇 |
2006年 | 34篇 |
2005年 | 29篇 |
2004年 | 16篇 |
2003年 | 20篇 |
2002年 | 20篇 |
2001年 | 13篇 |
2000年 | 12篇 |
1999年 | 10篇 |
1998年 | 7篇 |
1997年 | 5篇 |
1996年 | 12篇 |
1995年 | 7篇 |
1994年 | 11篇 |
1993年 | 8篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 1篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有731条查询结果,搜索用时 15 毫秒
161.
In this paper, a systematic method based on mathematical programming is proposed for the design of environmentally conscious absorption cooling systems. The approach presented relies on the development of a multi-objective formulation that simultaneously accounts for the minimization of cost and environmental impact at the design stage. The latter criterion is measured by the Eco-indicator 99 methodology, which follows the principles of life cycle assessment (LCA). The design task is formulated as a bi-criteria nonlinear programming (NLP) problem, the solution of which is defined by a set of Pareto points that represent the optimal trade-off between the economic and environmental concerns considered in the analysis. These Pareto solutions can be obtained via standard techniques for multi-objective optimization. The main advantage of this approach is that it offers a set of alternative options for system design rather than a single solution. From these alternatives, the decision-maker can choose the best one according to his/her preferences and the applicable legislation. The capabilities of the proposed method are illustrated in a case study problem that addresses the design of a typical absorption cooling system. 相似文献
162.
Rodrigo del Pozo Victorino Diez Gonzalo Salazar Juan J Espinosa 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2006,81(3):282-288
This paper evaluates the performance of a laboratory‐scale anaerobic fixed‐film reactor (AFFR) with arranged media treating slaughterhouse wastewater. The reactor was operated at 20 °C, its organic loading rate was increased from 1.8 to 9.2 kg COD m?3 d?1, and it had a short hydraulic residence time (5–9 h). The influence of wastewater concentrations on its performance was studied by artificially increasing the blood content of the wastewater. The efficiency of the removal of organic matter decreased from 70% to 54% as the superficial velocity increased from 0.12 to 0.97 m h?1, due mainly to distribution defects, as had been confirmed experimentally by tracer tests. The kinetics of the anaerobic processes was limited by substrate availability, even at high COD concentrations (between 700 and 1100 mg dm?3) due to a high content of slowly biodegradable and inert compounds present in the wastewater from the slaughterhouse. It was observed that a large amount of the organic matter had accumulated inside the reactor instead of being removed by methanogenic digestion. Furthermore, the fraction of organic matter held inside the reactor varied significantly in relation to the blood content of the wastewater. Copyright © 2005 Society of Chemical Industry 相似文献
163.
It is sometimes argued that renewables are “expensive”. However, although it is generally true that the private costs of renewable electricity generation are certainly above those of conventional electricity, that statement fails to consider the social benefits provided by electricity from renewable energy sources (RES-E), including environmental and socioeconomic ones. This paper empirically analyses an additional albeit usually neglected benefit: the reduction in the wholesale price of electricity as a result of more RES-E generation being fed into the grid. The case of wind generation in Spain shows that this reduction is greater than the increase in the costs for the consumers arising from the RES-E support scheme (the feed-in tariffs), which are charged to the final consumer. Therefore, a net reduction in the retail electricity price results, which is positive from a consumer point of view. This provides an additional argument for RES-E support and contradicts one of the usual arguments against RES-E deployment: the excessive burden on the consumer. 相似文献
164.
Stability analysis of nonholonomic multiagent coordinate‐free formation control subject to communication delays 下载免费PDF全文
Antonio González Rosario Aragüés Gonzalo López‐Nicolás Carlos Sagüés 《国际强度与非线性控制杂志
》2018,28(14):4121-4138
》2018,28(14):4121-4138
This paper investigates the convergence of nonholonomic multiagent coordinate‐free formation control to a prescribed target formation subject to communication delays by means of Lyapunov‐Krasovskii approach and smooth state‐feedback control laws. As a result, an iterative algorithm based on linear matrix inequalities is provided to obtain the worst‐case point‐to‐point delay under which the multiagent system is guaranteed to be stable. It is worth mentioning that: (i) the given algorithm holds for any connected communication topology and (ii) the formation control is coordinate‐free, that is, a common frame is not required to be shared between agents. The effectiveness of the given method is illustrated through simulation results. 相似文献
165.
M Isabel Cambero Claudia I Pereira‐Lima Juan A Ordoez Gonzalo D García de Fernando 《Journal of the science of food and agriculture》2000,80(10):1510-1518
Of the range of preparation conditions studied here, the beef broths with the most favourable sensory characteristics (P ≤ 0.05) were those manufactured with minced meat in a 7.5 g l−1 NaCl solution in proportions of 1:2 (w/v), heated at 85 °C for 60 min (the beef broth flavour was clean, clear, without any off‐flavour). Our data indicate the importance of accurately determining the heat treatment, since intermediate treatments yielded beef broths of good quality, whereas less intense treatments produced broths with raw meat and bloody and metallic flavours, and intensely heated broths had a warmed‐over or sour and astringent flavour. At higher temperatures the cooking time required to obtain a good‐quality broth decreased. From the analysis of variance of the sensorial data, temperature plays a more important role than cooking time in the development of the sensory properties of beef broths. © 2000 Society of Chemical Industry 相似文献
166.
Compressed representations have become effective to store and access large Web and social graphs, in order to support various graph querying and mining tasks. The existing representations exploit various typical patterns in those networks and provide basic navigation support. In this paper, we obtain unprecedented results by finding “dense subgraph” patterns and combining them with techniques such as node orderings and compact data structures. On those representations, we support out-neighbor and out/in-neighbor queries, as well as mining queries based on the dense subgraphs. First, we propose a compression scheme for Web graphs that reduces edges by representing dense subgraphs with “virtual nodes”; over this scheme, we apply node orderings and other compression techniques. With this approach, we match the best current compression ratios that support out-neighbor queries (i.e., nodes pointed from a given node), using 1.0–1.8 bits per edge (bpe) on large Web graphs, and retrieving each neighbor of a node in 0.6–1.0 microseconds ( \(\upmu \) s). When supporting both out- and in-neighbor queries, instead, our technique generally offers the best time when using little space. If the reduced graph, instead, is represented with a compact data structure that supports bidirectional navigation, we obtain the most compact Web graph representations (0.9–1.5 bpe) that support out/in-neighbor navigation; yet, the time per neighbor extracted raises to around 5–20 \(\upmu \) s. We also propose a compact data structure that represents dense subgraphs without using virtual nodes. It allows us to recover out/in-neighbors and answer other more complex queries on the dense subgraphs identified. This structure is not competitive on Web graphs, but on social networks, it achieves 4–13 bpe and 8–12 \(\upmu \) s per out/in-neighbor retrieved, which improves upon all existing representations. 相似文献
167.
Mauricio P. Pinto Paula Sotomayor Gonzalo Carrasco-Avino Alejandro H. Corvalan Gareth I. Owen 《International journal of molecular sciences》2016,17(9)
Tumor angiogenesis is widely recognized as one of the “hallmarks of cancer”. Consequently, during the last decades the development and testing of commercial angiogenic inhibitors has been a central focus for both basic and clinical cancer research. While antiangiogenic drugs are now incorporated into standard clinical practice, as with all cancer therapies, tumors can eventually become resistant by employing a variety of strategies to receive nutrients and oxygen in the event of therapeutic assault. Herein, we concentrate and review in detail three of the principal mechanisms of antiangiogenic therapy escape: (1) upregulation of compensatory/alternative pathways for angiogenesis; (2) vasculogenic mimicry; and (3) vessel co-option. We suggest that an understanding of how a cancer cell adapts to antiangiogenic therapy may also parallel the mechanisms employed in the bourgeoning tumor and isolated metastatic cells delivering responsible for residual disease. Finally, we speculate on strategies to adapt antiangiogenic therapy for future clinical uses. 相似文献
168.
Juan A. Pajares Gonzalo Álvarez Fernando Ibeas Diego Gallego David R. Hall Dudley I. Farman 《Journal of chemical ecology》2010,36(6):570-583
The pine sawyer beetle, Monochamus galloprovincialis, is a pest of pine trees in Europe and North Africa. Previously considered a secondary pest of stressed and dying trees, it is now receiving considerable attention as a vector of the pine wood nematode, Bursaphelenchus xylophilus, the causal agent of a lethal wilting disease in susceptible species of pines. Adult beetles are attracted to traps baited with a kairomone blend consisting of a host volatile, α-pinene, and two bark beetle pheromone components, ipsenol and 2-methyl-3-buten-2-ol. More recently it has been shown that mature male M. galloprovincialis produce a pheromone that attracts mature females in a laboratory bioassay. Here, volatiles were collected from mature male and female M. galloprovincialis, and a compound produced specifically by mature males was identified as 2-undecyloxy-1-ethanol from its gas chromatographic retention times, its mass spectrum, and by comparison with synthetic standards. The naturally-derived and synthetic compounds elicited electroantennographic responses from both females and males. Sealed polyethylene vials and polyethylene sachets were shown to be effective dispensers with zero-order release, the latter giving a higher release rate than the former. In two field tests, multiple-funnel traps baited with synthetic 2-undecyloxy-1-ethanol caught both female and male M. galloprovincialis, with higher catches at the higher release rate. This compound also synergized the attractiveness of the kairomone blend, the combined mixture catching 80–140% more beetles than the sum of the catches to each bait separately and luring up to two beetles/trap/d in a moderate-density population. We conclude that 2-undecyloxy-1-ethanol is a male-produced aggregation pheromone of M. galloprovincialis. This is the first example of a sex-specific compound in the cerambycid subfamily Lamiinae with significant behavioral activity in the field at a range sufficient to make it a useful trap bait. The possible roles of this pheromone in the chemical ecology of M. galloprovincialis and its potential use in pine wilt disease management are discussed. 相似文献
169.
Junhua Ding Peter J. Clarke Gonzalo Argote-Garcia Xudong He 《Information and Software Technology》2009,51(11):1520-1533
High level Petri nets have been extensively used for modeling concurrent systems; however, their strong expressive power reduces their ability to be easily analyzed. Currently there are few effective formal analysis techniques to support the validation of high level Petri nets. The executable nature of high level Petri nets means that during validation they can be analyzed using test criteria defined on the net model. Recently, theoretical test adequacy coverage criteria for concurrent systems using high level Petri nets have been proposed. However, determining the applicability of these test adequacy criteria has not yet been undertaken. In this paper, we present an approach for evaluating the proposed test adequacy criteria for high level Petri nets through experimentation. In our experiments we use the simulation functionality of the model checker SPIN to analyze various test coverage criteria on high level Petri nets. 相似文献
170.
Raúl Ferrer‐Gallego Julián C Rivas‐Gonzalo M Teresa Escribano‐Bailón 《Journal of the science of food and agriculture》2013,93(4):967-972
BACKGROUND: Interest in high‐quality products with a clear geographical origin is increasing. For the wine industry and market sector, identity preservation is of fundamental importance owing to the large number of geographical classifications. Nowadays, there is a growing demand for analytical methods for tracing grapes and wines. In the oenological sector, infrared spectroscopy is becoming an attractive tool allowing simultaneous measurement of several analytical parameters and enabling real‐time decision making. RESULTS: Discriminant partial least squares, a supervised pattern recognition technique, was employed to discriminate between vineyards of origin using the near‐infrared spectra of intact grapes, skins or seeds. In order to compare the three sample presentations, a receiver operating characteristic curve was used. The best results were obtained using intact grape seeds, with prediction rates of samples correctly classified of about 95%, although the good results obtained with entire grapes (about 93% of samples correctly classified) and the simplicity of use of the fibre optic probe could advise using entire grape presentation for comprehensive studies. CONCLUSION: The procedure reported here seems to have excellent potential for a fast and reasonably inexpensive analysis of the origin of samples. It is noted that such classification can be made at any time of ripening. This paper provides information of interest to develop new and extensive models in the future. © 2012 Society of Chemical Industry 相似文献