全文获取类型
收费全文 | 1372篇 |
免费 | 71篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 19篇 |
化学工业 | 379篇 |
金属工艺 | 30篇 |
机械仪表 | 23篇 |
建筑科学 | 56篇 |
矿业工程 | 3篇 |
能源动力 | 39篇 |
轻工业 | 124篇 |
水利工程 | 10篇 |
无线电 | 126篇 |
一般工业技术 | 284篇 |
冶金工业 | 90篇 |
原子能技术 | 10篇 |
自动化技术 | 257篇 |
出版年
2024年 | 3篇 |
2023年 | 12篇 |
2022年 | 14篇 |
2021年 | 24篇 |
2020年 | 26篇 |
2019年 | 23篇 |
2018年 | 33篇 |
2017年 | 37篇 |
2016年 | 46篇 |
2015年 | 33篇 |
2014年 | 61篇 |
2013年 | 90篇 |
2012年 | 88篇 |
2011年 | 81篇 |
2010年 | 82篇 |
2009年 | 76篇 |
2008年 | 89篇 |
2007年 | 63篇 |
2006年 | 49篇 |
2005年 | 57篇 |
2004年 | 54篇 |
2003年 | 46篇 |
2002年 | 43篇 |
2001年 | 17篇 |
2000年 | 23篇 |
1999年 | 18篇 |
1998年 | 33篇 |
1997年 | 15篇 |
1996年 | 17篇 |
1995年 | 12篇 |
1994年 | 19篇 |
1993年 | 19篇 |
1992年 | 8篇 |
1991年 | 13篇 |
1990年 | 11篇 |
1989年 | 13篇 |
1988年 | 8篇 |
1987年 | 10篇 |
1986年 | 9篇 |
1985年 | 10篇 |
1984年 | 10篇 |
1983年 | 6篇 |
1982年 | 12篇 |
1981年 | 3篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1975年 | 5篇 |
1974年 | 3篇 |
排序方式: 共有1450条查询结果,搜索用时 15 毫秒
101.
Valentin Segouin Mathieu Domenjoud Yves Bernard Laurent Daniel 《Journal of the European Ceramic Society》2019,39(6):2091-2102
The strain response of a polarised PZT was characterised using Digital Image Correlation (DIC). The DIC algorithm is based on a global approach and regularises the displacement field using the balance equations of solid mechanics. The measurement error is reduced by correcting the displacements that are mechanically not admissible. A ferroelectric test showed that the standard deviations of strain fields remain mostly under 1.2 × 10?4 for an element size of 64 px. The standard deviation on the average value is 3 × 10?6. The strain field is homogeneous and its average value is consistent with the strain obtained from a CCD laser measurement device. The longitudinal strain, transverse strain and polarisation response of the PZT were measured for bipolar and unipolar loadings ranging from 50 to 5000 V/mm. Material properties were extracted from these measurements. This work shows the advantages of a novel 2D-DIC algorithm for piezoelectric strain characterisation. 相似文献
102.
The electrical contact resistance between isolated pairs of micron-sized gold particles has been measured as a function of their separation using apparatus constructed in house. When incorporated into a percolation model for current transport in a conducting particle filled insulator, the results of such measurements have been shown to be consistent with the observed variation of conductivity with filler content beyond the percolation threshold in gold filled epoxies. This has been tested further by using adsorbed alkanethiol monolayers to control the interparticle spacing in the composites, demonstrating the importance of the contact resistance for the macroscopic current transport properties. Received: 22 September 1997/Revised version: 30 October 1997/Accepted: 31 October 1997 相似文献
103.
Generating a Condensed Representation for Association Rules 总被引:1,自引:0,他引:1
Nicolas?PasquierEmail author Rafik?Taouil Yves?Bastide Gerd?Stumme Lotfi?Lakhal 《Journal of Intelligent Information Systems》2005,24(1):29-60
Association rule extraction from operational datasets often produces several tens of thousands, and even millions, of association rules. Moreover, many of these rules are redundant and thus useless. Using a semantic based on the closure of the Galois connection, we define a condensed representation for association rules. This representation is characterized by frequent closed itemsets and their generators. It contains the non-redundant association rules having minimal antecedent and maximal consequent, called min-max association rules. We think that these rules are the most relevant since they are the most general non-redundant association rules. Furthermore, this representation is a basis, i.e., a generating set for all association rules, their supports and their confidences, and all of them can be retrieved needless accessing the data. We introduce algorithms for extracting this basis and for reconstructing all association rules. Results of experiments carried out on real datasets show the usefulness of this approach. In order to generate this basis when an algorithm for extracting frequent itemsets—such as Apriori for instance—is used, we also present an algorithm for deriving frequent closed itemsets and their generators from frequent itemsets without using the dataset. 相似文献
104.
Nikolay Djourelov Benoît Marchand Hristo Marinov Nathalie Moncoffre Yves Pipon Patrick Nédélec Nelly Toulhoat Daniel Sillou 《Journal of Nuclear Materials》2013,432(1-3):287-293
Doppler broadening of annihilation gamma-line combined with a slow positron beam was used to measure the momentum density distribution of annihilating pair in a set of sintered UO2 samples. The influence of surface polishing, of implantation with 800-keV 136Xe2+ at fluences of 1 × 1015 and 1 × 1016 Xe cm?2, and of annealing were studied by following the changes of the momentum distribution shape by means of S and W parameters. The program used for this purpose was VEPFIT. At the two fluences in the stoichiometric as-implanted UO2, formation of Xe bubbles was not detected. The post-implantation annealing and over-stoichiometry in the as-implanted sample caused Xe precipitation and formation of Xe bubbles. 相似文献
105.
106.
A new measurement method is presented for determining when the impact ionisation (I-I) effect occurs in HEMTs. Until now the gate current or side gate current have been used as criteria, whereas in this Letter the noise factor is used. As will be described, this method is more accurate and less harmful to the devices 相似文献
107.
Mai Huong Ly-Chatain Mai Linh Le Mai Le Thanh Jean-Marc Belin Yves Waché 《Food research international (Ottawa, Ont.)》2010,43(6):1594-1602
Cell localisation in the matrix microstructure of fermented food is important for microbial activity and ripening. To evaluate the importance of physicochemical factors in these phenomena, the physicochemical behaviour of four strains of lactic acid bacteria were investigated after inoculation of raw milk or milk fractions. To discriminate between physicochemical and metabolic properties, media were (i) rapidly acidified to avoid cell division or (ii) bacteria were allowed to ferment milk. To evaluate the impact of milk components, cells were dispersed in protein or fatty globule fractions. From two Lactococcus lactis subsp. lactis biovar. diacetylactis strains selected from their different surface properties investigated in previous studies, after rapid acidification one was encountered in fatty globules and protein gels whereas the other was found in serum and on the surface of globules. After fermentation, the first one formed colonies in the lipid phase or next to it in the whey and the second formed colonies in the protein gel. Strains forming long chains (Lactobacillus bulgaricus and Streptococcus thermophilus) were always found in contact with fatty globules, where they developed. Our results suggest that localisation and subsequent spatial colonisation depend on the physicochemical properties of cell surfaces, on the structure in chains as well as on the metabolic ability to develop on proteins or lipids. 相似文献
108.
We present two detailed studies concerning thedmt and the multichannelhemt for power amplifications. Each work comprises a first theoretical part where the structure is optimized by simulating the device. Technological realizations are hence performed at the laboratory. The following measurements give results very encouraging and permit to foresee the superior performance relatively to that of GaAs powermesfet. 相似文献
109.
Yorick Reyjol Philippe Brodeur Yves Mailhot Marc Mingelbier Pierre Dumont 《Journal of Great Lakes research》2010
We evaluated whether or not the invasive round goby (Neogobius melanostomus) represents an important prey source for seven native fish predators in Lake St. Pierre (St. Lawrence River, Canada). The frequency of occurrence of round goby in the stomach contents of brown bullhead (Ameiurus nebulosus) and channel catfish (Ictalurus punctatus) was very low (< 5%), while for the five other predators, it varied between 22% (yellow perch; Perca flavescens) and 65% (sauger; Sander canadensis). Several competing models linking the probability of occurrence of round goby in stomach contents to variables related to space, physical habitat, biotic interactions and predator size were tested for the five species feeding on round goby. Results indicated that space variables influenced round goby occurrence in stomachs for all species. In addition, physical habitat variables had an influence for sauger and walleye (Sander vitreus); biotic variables had an influence for yellow perch, walleye and sauger; and size had an influence for northern pike (Esox lucius), smallmouth bass (Micropterus dolomieu) and walleye. These results are discussed in light of known biological features of the round goby and native predators studied here and have important implications in terms of understanding round goby invasion success in the Great Lakes–St. Lawrence system. 相似文献
110.