全文获取类型
收费全文 | 9466篇 |
免费 | 823篇 |
国内免费 | 10篇 |
学科分类
工业技术 | 10299篇 |
出版年
2024年 | 35篇 |
2023年 | 140篇 |
2022年 | 115篇 |
2021年 | 329篇 |
2020年 | 275篇 |
2019年 | 276篇 |
2018年 | 359篇 |
2017年 | 374篇 |
2016年 | 478篇 |
2015年 | 420篇 |
2014年 | 549篇 |
2013年 | 995篇 |
2012年 | 876篇 |
2011年 | 694篇 |
2010年 | 476篇 |
2009年 | 471篇 |
2008年 | 513篇 |
2007年 | 449篇 |
2006年 | 411篇 |
2005年 | 265篇 |
2004年 | 235篇 |
2003年 | 203篇 |
2002年 | 195篇 |
2001年 | 122篇 |
2000年 | 119篇 |
1999年 | 87篇 |
1998年 | 81篇 |
1997年 | 90篇 |
1996年 | 67篇 |
1995年 | 68篇 |
1994年 | 62篇 |
1993年 | 51篇 |
1992年 | 35篇 |
1991年 | 30篇 |
1990年 | 19篇 |
1989年 | 19篇 |
1988年 | 21篇 |
1987年 | 10篇 |
1986年 | 16篇 |
1985年 | 23篇 |
1984年 | 22篇 |
1983年 | 14篇 |
1982年 | 18篇 |
1981年 | 17篇 |
1980年 | 16篇 |
1979年 | 24篇 |
1978年 | 11篇 |
1977年 | 10篇 |
1976年 | 11篇 |
1973年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
A model for atmospheric pollutant transport is proposed considering an advection–diffusion–reaction equation. A splitting method is used to decouple the advection, diffusion and reaction parts. A scheme based on finite volume, finite difference and backward differentiation formula is used for solving an atmospheric transport-chemistry problem. 相似文献
62.
63.
André J. Torii Rafael H. Lopez Leandro F. F. Miguel 《Structural and Multidisciplinary Optimization》2016,54(2):289-299
Truss optimization based on the ground structure approach often leads to designs that are too complex for practical purposes. In this paper we present an approach for design complexity control in truss optimization. The approach is based on design complexity measures related to the number of bars (similar to Asadpoure et al. Struct Multidisc Optim 51(2):385–396 2015) and a novel complexity measure related to the number of nodes of the structure. Both complexity measures are continuously differentiable and thus can be used together with gradient based optimization algorithms. The numerical examples show that the proposed approach is able to reduce design complexity, leading to solutions that are more fit for engineering practice. Besides, the examples also indicate that in some cases it is possible to significantly reduce design complexity with little impact on structural performance. Since the complexity measures are non convex, a global gradient based optimization algorithm is employed. Finally, a detailed comparison to a classical approach is presented. 相似文献
64.
André M. Eberle 《International Journal of Parallel, Emergent and Distributed Systems》2016,31(5):405-419
Traditionally, computer programs have been developed using the sequential programming paradigm. With the advent of parallel computing systems, such as multicore processors and distributed environments, the sequential paradigm became a barrier to the utilisation of the available resources, since the program is restricted to a single processing unit. To address this issue, we propose a transparent automatic parallelisation tool with a binary rewriter. The steps of our approach are: the disassembly of the Intel x86 application, its transformation into an intermediary language; the analysis of this intermediary representation to obtain the flow and dependency graphs; the partitioning of the application into parallel units, using the obtained graphs; and, finally, the reassembly of the application back into the original Intel x86 architecture. By transforming the compiled application software, we aim at obtaining a program which can better explore the parallel resources, with no extra effort required from users or developers. 相似文献
65.
We have fabricated and characterized an n-doped InSb Faraday isolator in the mid-IR range (9.2 μm). A high isolation ratio (31(2) dB) and low insertion loss (1.9(3) dB) are obtained. Temperature dependance is analyzed. Further possible improvements are discussed, including the realization of a two-stage isolator. A similar design can be used to cover a wide wavelength range (λ ~ 7.5-30 μm). 相似文献
66.
This article addresses the output feedback control for discrete‐time Markov jump linear systems. With fully known transition probability, sufficient conditions for an internal model based controller design are obtained. For the case where the transition probabilities are uncertain and belong to a convex polytope with known vertices, we provide a sufficient LMI condition that guarantees the norm of the closed‐loop system is below a prescribed level. That condition can be improved through an iterative procedure. Additionally, we are able to deal with the case of cluster availability of the Markov mode, provided that some system matrices do not vary within a given cluster, an assumption that is suitable to deal with packet dropout models for networked control systems. A numerical example shows the applicability of the design and compares it with previous results. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
67.
Esteban J. Palomo Enrique Domínguez Rafael M. Luque-Baena José Muñoz 《Neural Processing Letters》2013,37(1):69-87
Both image compression based on color quantization and image segmentation are two typical tasks in the field of image processing. Several techniques based on splitting algorithms or cluster analyses have been proposed in the literature. Self-organizing maps have been also applied to these problems, although with some limitations due to the fixed network architecture and the lack of representation in hierarchical relations among data. In this paper, both problems are addressed using growing hierarchical self-organizing models. An advantage of these models is due to the hierarchical architecture, which is more flexible in the adaptation process to input data, reflecting inherent hierarchical relations among data. Comparative results are provided for image compression and image segmentation. Experimental results show that the proposed approach is promising for image processing, and the powerful of the hierarchical information provided by the proposed model. 相似文献
68.
Guérard S Chevalier Y Moreschi H Defontaine M Callé S Mitton D 《Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine》2011,225(11):1113-1117
For various applications, precision of the Young's modulus of cancellous bone specimens is needed. However, measurement variability is rarely given. The aim of this study was to assess the Young's modulus repeatability using a uniaxial cyclic compression protocol on embedded specimens of human cancellous bone. Twelve specimens from 12 human calcanei were considered. The specimens were first defatted and then 1 or 2 mm at the ends were embedded in an epoxy resin. The compression experiment consists in applying 20 compressive cycles between 0.2 per cent and 0.6 per cent strain with a 2 Hz loading frequency. The coefficient of variation of the current protocol was found to be 1.2 percent. This protocol showed variability similar to the end-cap technique (considered as a reference). It can be applied on porous specimen (especially human bone) and requires minimal bone length to limit end-artifact variability. The current method could be applied in association with noninvasive measurements (such as ultrasound) with full compatibility. This possibility opens the way for bone damage follow-up based on Young's modulus monitoring. 相似文献
69.
Padilla-Parra S Audugé N Coppey-Moisan M Tramier M 《Microscopy research and technique》2011,74(8):788-793
Dual-color fluorescence correlation spectroscopy is an interesting method to quantify protein interaction in living cells. But, when performing these experiments, one must compensate for a known spectral bleed through artifact that corrupts cross-correlation data. In this article, problems with crosstalk were overcome with an approach based on fluorescence lifetime correlation spectroscopy (FLCS). We show that FLCS applied to dual-color EGFP and mCherry cross-correlation allows the determination of protein-protein interactions in living cells without the need of spectral bleed through calibration. The methodology was validated by using EGFP-mCherry tandem in comparison with coexpressed EGFP and mCherry in live cell. The dual-color FLCS experimental procedure where the different laser intensities do not have to be controlled during experiment is really very helpful to study quantitatively protein interactions in live sample. 相似文献
70.