全文获取类型
收费全文 | 1678篇 |
免费 | 96篇 |
专业分类
电工技术 | 5篇 |
化学工业 | 754篇 |
金属工艺 | 13篇 |
机械仪表 | 38篇 |
建筑科学 | 59篇 |
能源动力 | 47篇 |
轻工业 | 281篇 |
水利工程 | 13篇 |
石油天然气 | 3篇 |
无线电 | 48篇 |
一般工业技术 | 200篇 |
冶金工业 | 75篇 |
原子能技术 | 6篇 |
自动化技术 | 232篇 |
出版年
2024年 | 2篇 |
2023年 | 26篇 |
2022年 | 158篇 |
2021年 | 186篇 |
2020年 | 57篇 |
2019年 | 49篇 |
2018年 | 38篇 |
2017年 | 42篇 |
2016年 | 69篇 |
2015年 | 63篇 |
2014年 | 57篇 |
2013年 | 124篇 |
2012年 | 93篇 |
2011年 | 124篇 |
2010年 | 77篇 |
2009年 | 77篇 |
2008年 | 104篇 |
2007年 | 63篇 |
2006年 | 35篇 |
2005年 | 48篇 |
2004年 | 34篇 |
2003年 | 37篇 |
2002年 | 31篇 |
2001年 | 15篇 |
2000年 | 15篇 |
1999年 | 19篇 |
1998年 | 19篇 |
1997年 | 20篇 |
1996年 | 13篇 |
1995年 | 11篇 |
1994年 | 12篇 |
1993年 | 11篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 1篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有1774条查询结果,搜索用时 15 毫秒
31.
Paola Scarfato Elvira Avallone Pio Iannelli Vincenzo De Feo Domenico Acierno 《应用聚合物科学杂志》2007,105(6):3568-3577
In this paper we report on the preparation and characterization of polyurea‐based microencapsulated systems, containing essential oils as core materials, for potential applications in controlled‐release formulations of agrochemicals. Microcapsules were synthesized by interfacial polymerization in o/w emulsion between polyfunctional isocyanates and diamines, to investigate the effect of the monomer kind on the morphology and properties of the produced samples. The synthetic conditions that gave the best results were used to microencapsulate four essential oils, able to interfere with the seed germination and radicle elongation of some test plants. The produced samples were characterized, with the aim to analyze their morphology and to verify the effectiveness of essential oil microencapsulation. Moreover, preliminary bioassay based on seed germination and subsequent radical growth were carried out to study the effects of the microencapsulated essential oils. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献
32.
Paola Fabbri Massimo Messori Monica Montecchi Francesco Pilati Rosa Taurino Claudio Tonelli Maurizio Toselli 《应用聚合物科学杂志》2006,102(2):1483-1488
A commercial perfluoropolyether containing alkoxysilane functionalities was employed to prepare organic–inorganic hybrid coatings by using the sol‐gel process in the presence of tetraethoxysilane. Contact angle analysis revealed a strong hydrophobic and oleophobic character of the coatings almost independently from the molecular weight of the starting fluorinated oligomer. Surface tension values were in the range of 14–16 mN/m, suggesting a preferential segregation of fluorinated segments onto the surface of the coating. Atomic force microscopy showed the presence very smooth surfaces permitting to neglect the contribution of the surface roughness to wettability. Friction coefficient values were markedly lower with respect to the value of uncoated glass substrate. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1483–1488, 2006 相似文献
33.
The adsorption equilibrium data of pentachlorophenol (PCP) onto activated carbon fiber (ACF) in felt form were obtained in a batch adsorber at T = 25 °C and pH 12 and the Langmuir isotherm fitted reasonably well with the experimental data. The rate of adsorption of PCP on ACF was investigated in this work and the experimental concentration decay data were obtained in a differential column batch adsorber. The overall rate of adsorption of PCP was interpreted by a diffusional model that takes into account the external mass transport and intrafiber diffusion. The experimental concentration decay can be described quite well with the diffusional model if the overall rate of adsorption is mainly controlled by intrafiber diffusion and the external mass transport is not important to the overall rate of adsorption. Moreover, intrafiber diffusion was significantly affected by restricted diffusion since the molecular diameter of the PCP was closed to 55% of the average pore diameter. The effect of restricted diffusion was estimated using correlations reported in the literature. The molecules of PCP adsorbed on the surface of the pore also hindered the diffusion of PCP molecules inside the pores. 相似文献
34.
Bob Fields Paola Amaldi William Wong Satinder Gill 《International journal of human-computer interaction》2013,29(4):359-360
This study used protocol analyses and user drawings of their models of the system to investigate the “getting lost” problem in hypertext navigation. The “getting lost” problem is viewed as occurring when routine expectations of naive users, concerning appropriate linear sequences, are violated. Several ways in which users persistently attempt to work within a linear model, despite its inapplicability, are examined. The transition to more hierarchical user models is described. 相似文献
35.
Fault detection for discrete event systems using Petri nets with unobservable transitions 总被引:1,自引:0,他引:1
Maria Paola Cabasino Author Vitae Alessandro Giua Author Vitae Author Vitae 《Automatica》2010,46(9):1531-1539
In this paper we present a fault detection approach for discrete event systems using Petri nets. We assume that some of the transitions of the net are unobservable, including all those transitions that model faulty behaviors. Our diagnosis approach is based on the notions of basis marking and justification, that allow us to characterize the set of markings that are consistent with the actual observation, and the set of unobservable transitions whose firing enable it. This approach applies to all net systems whose unobservable subnet is acyclic. If the net system is also bounded the proposed approach may be significantly simplified by moving the most burdensome part of the procedure off-line, thanks to the construction of a graph, called the basis reachability graph. 相似文献
36.
In this paper a new nonlinear feedback control law for continuous stirred tank reactors, obtained by exact Input/Output (I/O) linearization and Sontag's input‐to‐state stability feedback control redesign methods, is studied. By the new feedback control law, a significant attenuation of the disturbance effect is guaranteed, with evident improvement with respect to control laws obtained by the exact I/O linearization method. The performed simulations validate the theoretical results. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
37.
38.
Circular splicing systems are a formal model of a generative mechanism of circular words, inspired by a recombinant behaviour of circular DNA. Some unanswered questions are related to the computational power of such systems, and finding a characterization of the class of circular languages generated by circular splicing systems is still an open problem. In this paper we solve this problem for monotone complete systems, which are finite circular splicing systems with rules of a simpler form. We show that a circular language L is generated by a monotone complete system if and only if the set Lin(L) of all words corresponding to L is a pure unitary language generated by a set closed under the conjugacy relation. The class of pure unitary languages was introduced by A. Ehrenfeucht, D. Haussler, G. Rozenberg in 1983, as a subclass of the class of context-free languages, together with a characterization of regular pure unitary languages by means of a decidable property. As a direct consequence, we characterize (regular) circular languages generated by monotone complete systems. We can also decide whether the language generated by a monotone complete system is regular. Finally, we point out that monotone complete systems have the same computational power as finite simple systems, an easy type of circular splicing system defined in the literature from the very beginning, when only one rule of a specific type is allowed. From our results on monotone complete systems, it follows that finite simple systems generate a class of languages containing non-regular languages, showing the incorrectness of a longstanding result on simple systems. 相似文献
39.
SNPs are positions of the DNA sequences where the differences among individuals are embedded. The knowledge of such SNPs is crucial for disease association studies, but even if the number of such positions is low (about 1% of the entire sequence), the cost to extract the complete information is actually very high. Recent studies have shown that DNA sequences are structured into blocks of positions, that are conserved during evolution, where there is strong correlation among values (alleles) of different loci. To reduce the cost of extracting SNPs information, the block structure of the DNA has suggested to limit the process to a subset of SNPs, the so-called Tag SNPs, that are able to maintain the most of the information contained in the whole sequence. In this paper, we apply a technique for feature selection based on integer programming to the problem of Tag SNP selection. Moreover, to test the quality of our approach, we consider also the problem of SNPs reconstruction, i.e. the problem of deriving unknown SNPs from the value of Tag SNPs and propose two reconstruction methods, one based on a majority vote and the other on a machine learning approach. We test our algorithm on two public data sets of different nature, providing results that are, when comparable, in line with the related literature. One of the interesting aspects of the proposed method is to be found in its capability to deal simultaneously with very large SNPs sets, and, in addition, to provide highly informative reconstruction rules in the form of logic formulas. 相似文献
40.
Donato Di Paola David Naso Biagio Turchiano Grazia Cicirelli Arcangelo Distante 《Journal of Intelligent and Robotic Systems》2009,56(5):513-541
This paper focuses on the control system for an autonomous robot for the surveillance of indoor environments. Our approach
proposes a matrix-based formalism which allows us to merge in a single framework discrete-event supervisory control, conflict
resolution and reactive control. As a consequence, the robot is able to autonomously handle high level tasks as well as low-level
behaviors, solving control and decision-making issues simultaneously. Moreover, the matrix-based controller is modular and
can be easily reconfigured if mission characteristics or robot hardware configuration change. An illustrative example and
a report on experimental investigations are provided to illustrate the main features of the proposed approach. 相似文献