全文获取类型
收费全文 | 1635篇 |
免费 | 106篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 23篇 |
综合类 | 2篇 |
化学工业 | 462篇 |
金属工艺 | 34篇 |
机械仪表 | 20篇 |
建筑科学 | 69篇 |
矿业工程 | 6篇 |
能源动力 | 45篇 |
轻工业 | 217篇 |
水利工程 | 11篇 |
石油天然气 | 2篇 |
无线电 | 101篇 |
一般工业技术 | 272篇 |
冶金工业 | 132篇 |
原子能技术 | 6篇 |
自动化技术 | 341篇 |
出版年
2024年 | 5篇 |
2023年 | 20篇 |
2022年 | 44篇 |
2021年 | 63篇 |
2020年 | 36篇 |
2019年 | 57篇 |
2018年 | 64篇 |
2017年 | 62篇 |
2016年 | 66篇 |
2015年 | 56篇 |
2014年 | 90篇 |
2013年 | 115篇 |
2012年 | 126篇 |
2011年 | 109篇 |
2010年 | 99篇 |
2009年 | 96篇 |
2008年 | 93篇 |
2007年 | 82篇 |
2006年 | 63篇 |
2005年 | 44篇 |
2004年 | 42篇 |
2003年 | 32篇 |
2002年 | 49篇 |
2001年 | 21篇 |
2000年 | 28篇 |
1999年 | 15篇 |
1998年 | 22篇 |
1997年 | 17篇 |
1996年 | 17篇 |
1995年 | 17篇 |
1994年 | 8篇 |
1993年 | 14篇 |
1992年 | 13篇 |
1991年 | 11篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1970年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有1743条查询结果,搜索用时 15 毫秒
101.
102.
Giovanni Forzieri Gabriele Moser Enrique R. Vivoni Fabio Castelli Francesco Canovaro 《Canadian Metallurgical Quarterly》2010,136(11):855-867
For detailed hydraulic modeling, accurate spatial information of riparian vegetation patterns needs to be derived in automatic fashion. We propose a supervised classification for heterogeneous riparian corridors with a low number of spectrally separate classes using data fusion of a Quickbird image and LIDAR data. The approach considers nine land cover classes including three woody riparian species, brush, cultivated areas, grassland, urban infrastructures, bare soil and water. The classical “stacked vector” approach is adopted for data fusion, while the nonparametric weighted feature-extraction method and the pixel-oriented maximum likelihood algorithm are used for feature-reduction and classification purposes, respectively. We test the approach over a 14-km stretch of the Sieve River (Tuscany Region, Italy). A one-dimensional river modeling is applied over the study reach comparing the results of a classification-derived hydraulic roughness map and a traditional ground-based approach. Despite the complex study reach, the classification method produced encouraging accuracies (OKS = 0.77) and represents a useful tool to delineate application domains of flow resistance models suited to different hydrodynamic patterns (e.g., stiff/flexible vegetation). Hydraulic modeling results showed that the remotely derived floodplain roughness parameterization captures the equivalent Manning coefficient over 20 test cross sections with uncertainty distributions described by low mean and standard deviation values. 相似文献
103.
Wenceslao T. Medina Sophie Laurent Enrique Brandan José M. Aguilera 《Journal of food science》2010,75(3):E194-E200
ABSTRACT: Surface liquid adhesion (SLA) and liquid absorption (LA) of tritiated liquids, including water and skim, low-fat, whole, and fat-enriched milks, by cornflakes (CF) and frosted flakes (FF) were determined by scintillation counting using water-[3H] at 0.5 μCi/mL. SLA or the liquid adhering to individual flakes after a short immersion period was the same for CF and FF in the case of water (approximately 0.011 μL mm−2 of flake) but were always higher for CF than for FF and increased as the fat content in milks augmented. LA of individual flakes, followed for 300 s of soaking, increased with time and was always higher for CF than for FF (for the same liquid), however, data did not follow a regular pattern. Flakes showed quite compact outer surfaces and an internal porous matrix composed of air cells of various sizes separated by dense walls of different thicknesses. This heterogeneous microstructure of individual flakes may be the cause of the lack of a simple kinetics during the soaking process. Previous results obtained by soaking a mass of flakes overestimated the uptake of fluid by individual because they included the liquid occluded between the flakes. 相似文献
104.
The 12-month pre-Ph.D. ICTP Diploma Courses in the fields of Condensed Matter Physics, High Energy Physics, Mathematics, Earth System Physics and Basics Physics have been recorded using the automated, low cost recording system called EyA developed in-house. We discuss the technical details on how these recordings were implemented, together with some web usage statistics and students feedback. As yet, no similar endeavor has been made to put on-line a complete high-level Diploma Programme, due to the high costs involved when using alternative recording solutions. These recordings are freely available on the website www.ictp.tv. 相似文献
105.
Combined effects of lactic acid and nisin solution in reducing levels of microbiological contamination in red meat carcasses 总被引:1,自引:0,他引:1
Changes in bacterial counts on beef carcasses at specific points during slaughter and fabrication were determined, and the effectiveness of nisin, lactic acid, and a combination of the lactic acid and nisin in reducing levels of microbiological contamination was assessed. Swab samples were obtained from the surfaces of randomly selected beef carcasses. Carcasses were swabbed from the neck, brisket, and renal site after skinning, splitting, and washing. Treatments involving lactic acid (1.5%), nisin (500 IU/ml), or a mixture of nisin and lactic acid were applied after the neck area was washed. A control group was not sprayed. Results indicated that the highest prevalence of aerobic plate counts (APCs), total coliforms, and Escherichia coli was found in the neck site after splitting, and the lowest level of microbial contamination was found after skinning. Washing with water did not significantly reduce the bacterial load. The largest reduction in APCs, total coliforms, and E. coli occurred on carcasses treated with a mixture of nisin and lactic acid. A mixture of nisin and lactic acid can be applied to beef carcasses through spray washing and can reduce bacterial populations by 2 log units. 相似文献
106.
A general equivalent circuit for the modeling of a system of magnetically coupled coils including the losses is presented.
This equivalent circuit includes two parts: a subsystem of primary branches whose terminals correspond with those of the real
coils, and a secondary network which allows the representation of frequency-dependent inductances and resistances. An analysis
of the equations of the proposed circuit is carried out and an expression of the frequency-dependent impedance matrix as seen
by the primary coils is determined. The properties of the mathematical expression are analyzed. The proposed equivalent circuit
allows representing the dependence of inductances and resistances on the frequency. The expression of the impedance is the
starting point for the synthesis of an equivalent circuit, which is carried out in a separate article.
Received: 25 May 2001/Accepted: 25 June 2001 相似文献
107.
Manoj Gupta Farghalli Mohamed Enrique Lavernia 《Metallurgical and Materials Transactions A》1992,23(3):845-850
In the present study, the mechanisms governing the evolution of microstructure during spray atomization and codeposition of
metal matrix composites (MMCs) were investigated, with particular emphasis on the effects of the ceramic phase on the resulting
microstructure during solidstate cooling. The grain size refinement that is commonly observed when a distribution of ceramic
particulates is coinjected into a metallic spray during spray atomization and deposition processing was rationalized in terms
of three distinct effects: (a) solidification effects, (b) heattransfer effects, and (c) solid-state cooling effects. The
solidification and heat-transfer effects were discussed in Part I. [1] Regarding solid-state cooling effects, the present
results show that the presence of a dispersion of ceramic particulates in the aluminum matrix effectively reduces the rate
of grain growth during solid-state cooling. Experimental support to this suggestion was provided by the results of an investigation
on the changes in grain size following isochronal thermal anneals. 相似文献
108.
Supply Estimation Using Coevolutionary Genetic Algorithms in the Spanish Electrical Market 总被引:1,自引:0,他引:1
The price of electrical energy in Spain has not been regulated by the government since 1998, but determined by the supply from the generators in a competitive market, the so-called electrical pool. A genetic method for analyzing data from this new market is presented in this paper. The eventual objective is to determine the individual supply curves of the competitive agents. Adopting the point of view of the game theory, different genetic algorithm configurations using coevolutionary and non-coevolutionary strategies combined with scalar and multi-objective fitness are compared. The results obtained are the first step toward solving the induction of the optimal individual strategies into the Spanish electrical market from data in terms of perfect oligopolistic behavior. 相似文献
109.
The analogy between free-space propagation of optical beams and light-pulse reflection from linearly chirped fiber gratings is used to analyze the Lau effect in the temporal domain. The coherence conditions that are satisfied in the spatial domain for obtaining, at certain fixed locations, periodic fringes patterns are reformulated for guided light propagation. In this analogy, spatial periodic irradiance distributions are transformed in periodic sequences of light pulses. An optical setup is proposed to produce sharp pulse trains, with minimal distortion effects, that have repetition frequencies that are different from those associated with the input periodic optical signal. Some numerical results are given to illustrate this approach. 相似文献
110.
Ezequiel?López-RubioEmail author José?Mu?oz-Pérez José Antonio?Gómez-Ruiz Enrique?Domínguez-Merino 《Neural computing & applications》2003,12(2):109-118
The ASSOM is a self-organising neural network with the capability of adapting to linear subspaces. Here we propose two new methods to train the ASSOM network. A nonlinear system of equations is derived for network training. This system can be solved by a gradient-based approach or by the Levenberg–Marquardt method. Each of these two approaches gives a different learning rule. A comparison is carried out among the original Kohonens method and the proposed learning rules. Experimental results are reported, including a convergence speed experiment and a speech processing application, which show that the new learning rules have better performance than the original one. 相似文献