全文获取类型
收费全文 | 6042篇 |
免费 | 240篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 62篇 |
综合类 | 7篇 |
化学工业 | 1256篇 |
金属工艺 | 141篇 |
机械仪表 | 155篇 |
建筑科学 | 210篇 |
矿业工程 | 16篇 |
能源动力 | 107篇 |
轻工业 | 598篇 |
水利工程 | 31篇 |
石油天然气 | 6篇 |
无线电 | 392篇 |
一般工业技术 | 1025篇 |
冶金工业 | 1569篇 |
原子能技术 | 44篇 |
自动化技术 | 672篇 |
出版年
2023年 | 44篇 |
2022年 | 77篇 |
2021年 | 127篇 |
2020年 | 97篇 |
2019年 | 78篇 |
2018年 | 170篇 |
2017年 | 162篇 |
2016年 | 180篇 |
2015年 | 140篇 |
2014年 | 159篇 |
2013年 | 374篇 |
2012年 | 313篇 |
2011年 | 336篇 |
2010年 | 240篇 |
2009年 | 225篇 |
2008年 | 282篇 |
2007年 | 216篇 |
2006年 | 199篇 |
2005年 | 185篇 |
2004年 | 165篇 |
2003年 | 175篇 |
2002年 | 122篇 |
2001年 | 92篇 |
2000年 | 114篇 |
1999年 | 94篇 |
1998年 | 502篇 |
1997年 | 297篇 |
1996年 | 196篇 |
1995年 | 114篇 |
1994年 | 99篇 |
1993年 | 109篇 |
1992年 | 25篇 |
1991年 | 37篇 |
1990年 | 23篇 |
1989年 | 41篇 |
1988年 | 35篇 |
1987年 | 28篇 |
1986年 | 22篇 |
1985年 | 33篇 |
1984年 | 25篇 |
1983年 | 20篇 |
1982年 | 31篇 |
1981年 | 40篇 |
1980年 | 23篇 |
1979年 | 16篇 |
1978年 | 26篇 |
1977年 | 43篇 |
1976年 | 46篇 |
1975年 | 20篇 |
1973年 | 12篇 |
排序方式: 共有6291条查询结果,搜索用时 15 毫秒
41.
42.
SF Brenière W Morochi MF Bosseno J Ordo?ez T Gutierrez F Vargas N Yaksic F Noireau 《Canadian Metallurgical Quarterly》1998,71(3):269-283
Triatoma sordida is the second species of Triatominae considered of epidemiological significance in Bolivia. Associated with Triatoma infestans in various regions, it is as yet the only triatomine species established in human dwellings in localities of Velasco province, Department of Santa Cruz. This domestication is considered as primary. Flagellate parasites were detected in 16.2% of domiciliary T. sordida and the kDNA-PCR confirmed the presence of Trypanosoma cruzi. Frequencies of T. cruzi clonets 20 and 39, common clonets in Bolivian domestic cycle (T. infestans), were established by their direct detection in feces using PCR and hybridization. These clonets present low frequencies in T. sordida and synanthropic mammals. Forty-six stocks were isolated and analysed by multilocus enzyme electrophoresis (MLEE). The MLEE showed a higher clonal diversity than in T. infestans domestic cycle and the genotypes were clustered in the two principal lineages of T. cruzi. Within each lineage, a broad variability was observed. Mixture of genotypes was mostly observed in mammals. The large diversity of T. cruzi in this cycle should be related to its sylvatic origin. Moreover, the current limited sample of stocks suggests a lineage association with specific hosts. 相似文献
43.
Yliès Falcone Jean-Claude Fernandez Laurent Mounier 《International Journal on Software Tools for Technology Transfer (STTT)》2012,14(3):349-382
The underlying property, its definition, and representation play a major role when monitoring a system. Having a suitable and convenient framework to express properties is thus a concern for runtime analysis. It is desirable to delineate in this framework the sets of properties for which runtime analysis approaches can be applied to. This paper presents a unified view of runtime verification and enforcement of properties in the Safety-Progress classification. First, we extend the Safety-Progress classification of properties in a runtime context. Second, we characterize the set of properties which can be verified (monitorable properties) and enforced (enforceable properties) at runtime. We propose in particular an alternative definition of ??property monitoring?? to the one classically used in this context. Finally, for the delineated sets of properties, we define specialized verification and enforcement monitors. 相似文献
44.
M. Jiménez-Melendo J. P. Riviére T. Suzuki H. Koizumi J. Castaing A. Domínguez-Rodríguez 《Journal of Materials Science》1992,27(13):3589-3593
NiO single crystals prepared by two crystal growth techniques (zone melting in an arc-image furnace and Verneuil crystallization have been deformed by compression along 001 at temperatures as low as 4.2 K, and the dislocation substructure observed by transmission electron microscopy. The Peierls mechanism has been suggested as the mechanism controlling the mechanical behaviour at the lower temperatures. The dislocations generated at cavities found in the zone-melted crystals may be responsible for the increase of the flow stress of these crystals compared with the Verneuil ones. 相似文献
45.
A new crystalline structure of poly 4-methylpentene-1 (P4MP1), modiification named modification V, is obtained from cyclopentane solutions and gels, for polymer volume fractions between 0.01 and 0.10. The effect of the thermal history imparted to the solution is analyzed. The relation between gelation, polymorphism and existence of helical conformations of P4MP1 in solution is discussed. Modification V is tentatively indexed on the basis of an hexagonal unit cell with dimensions a = 22.17 ± 0.14 Å and c = 6.69 ±0.02 Å. The crystal transforms into modification I at 130 ± 5°C, the heat of transition being + 15 ±2 J.g?1. 相似文献
46.
Zinc Coated Steel/Epoxy Adhesive Systems: Investigation of the Interfacial Zone by FTIR Spectroscopy
The present study takes advantage of the ability of Fourier Transform Infrared Spectroscopy (FTIR) for the analysis of ultrathin organic films on metals. FTIR in the reflection mode (IRRAS) is used in order to study the interaction of ultrathin films of dicyandiamide (hardener of most one-pack epoxy resins) with various substrates, model ones such as gold or zinc and industrial ones such as steel and zinc-coated steels.
Pure zinc surfaces and, to a lesser extent, zinc-coated steels are shown to react with dicyandiamide after heating at 180°C, as evidenced by the frequency shift of the absorption band (at about 2200 cm-1) characteristic for nitrile groups. As real systems consist of thick layers of a fully formulated adhesive cured onto a metallic substrate, the direct investigation of such a buried interphase is no longer possible by FTIR and by most of the known spectroscopies. Some mechanically tested specimens are then analysed, after failure, by FTIR microspectrometry. The spectra obtained, corresponding to the fracture initiation zone which is about 100 μm in diameter, advocate for the presence of an ultrathin layer of modified polymer still covering the substrate. 相似文献
Pure zinc surfaces and, to a lesser extent, zinc-coated steels are shown to react with dicyandiamide after heating at 180°C, as evidenced by the frequency shift of the absorption band (at about 2200 cm-1) characteristic for nitrile groups. As real systems consist of thick layers of a fully formulated adhesive cured onto a metallic substrate, the direct investigation of such a buried interphase is no longer possible by FTIR and by most of the known spectroscopies. Some mechanically tested specimens are then analysed, after failure, by FTIR microspectrometry. The spectra obtained, corresponding to the fracture initiation zone which is about 100 μm in diameter, advocate for the presence of an ultrathin layer of modified polymer still covering the substrate. 相似文献
47.
Information diffusion in large-scale networks has been studied to identify the users influence. The influence has been targeted as a key feature either to reach large populations or influencing public opinion. Through the use of micro-blogs, such as Twitter, global influencers have been identified and ranked based on message propagation (retweets). In this paper, a new application is presented, which allows to find first and classify then the local influence on Twitter: who have influenced you and who have been influenced by you. Until now, social structures of tweets’ original authors that have been either retweeted or marked as favourites are unobservable. Throughout this application, these structures can be discovered and they reveal the existence of communities formed by users of similar profile (that are connected among them) interrelated with other similar profile users’ communities. 相似文献
48.
Sun Zhuojin Wang Yong Gong Chen Laganiére Robert 《Multimedia Tools and Applications》2021,80(4):5351-5372
Multimedia Tools and Applications - Recently, there are lots of tracking methods proposed to improve the performance of visual tracking in videos with challenging situations, such as background... 相似文献
49.
Hélène?Mathis Clément?Cancès Edwige?Godlewski Nicolas?SeguinEmail author 《Journal of scientific computing》2015,63(3):820-861
In numerous industrial CFD applications, it is usual to use two (or more) different codes to solve a physical phenomenon: where the flow is a priori assumed to have a simple behavior, a code based on a coarse model is applied, while a code based on a fine model is used elsewhere. This leads to a complex coupling problem with fixed interfaces. The aim of the present work is to provide a numerical indicator to optimize to position of these coupling interfaces. In other words, thanks to this numerical indicator, one could verify if the use of the coarser model and of the resulting coupling does not introduce spurious effects. In order to validate this indicator, we use it in a dynamical multiscale method with moving coupling interfaces. The principle of this method is to use as much as possible a coarse model instead of the fine model in the computational domain, in order to obtain an accuracy which is comparable with the one provided by the fine model. We focus here on general hyperbolic systems with stiff relaxation source terms together with the corresponding hyperbolic equilibrium systems. Using a numerical Chapman–Enskog expansion and the distance to the equilibrium manifold, we construct the numerical indicator. Based on several works on the coupling of different hyperbolic models, an original numerical method of dynamic model adaptation is proposed. We prove that this multiscale method preserves invariant domains and that the entropy of the numerical solution decreases with respect to time. The reliability of the adaptation procedure is assessed on various 1D and 2D test cases coming from two-phase flow modeling. 相似文献
50.
Abdoul Bitar Stéphane Dauzère-Pérès Claude Yugma Renaud Roussel 《Journal of Scheduling》2016,19(4):367-376
In this paper, we propose a metaheuristic for solving an original scheduling problem with auxiliary resources in a photolithography workshop of a semiconductor plant. The photolithography workshop is often a bottleneck, and improving scheduling decisions in this workshop can help to improve indicators of the whole plant. Two optimization criteria are separately considered: the weighted flow time (to minimize) and the number of products that are processed (to maximize). After stating the problem and giving some properties on the solution space, we show how these properties help us to efficiently solve the problem with the proposed memetic algorithm, which has been implemented and tested on large generated instances. Numerical experiments show that good solutions are obtained within a reasonable computational time. 相似文献