全文获取类型
收费全文 | 2288篇 |
免费 | 136篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 19篇 |
综合类 | 11篇 |
化学工业 | 553篇 |
金属工艺 | 63篇 |
机械仪表 | 48篇 |
建筑科学 | 139篇 |
矿业工程 | 24篇 |
能源动力 | 51篇 |
轻工业 | 133篇 |
水利工程 | 10篇 |
无线电 | 189篇 |
一般工业技术 | 479篇 |
冶金工业 | 123篇 |
原子能技术 | 21篇 |
自动化技术 | 567篇 |
出版年
2024年 | 2篇 |
2023年 | 30篇 |
2022年 | 43篇 |
2021年 | 69篇 |
2020年 | 68篇 |
2019年 | 55篇 |
2018年 | 69篇 |
2017年 | 54篇 |
2016年 | 83篇 |
2015年 | 83篇 |
2014年 | 84篇 |
2013年 | 199篇 |
2012年 | 163篇 |
2011年 | 178篇 |
2010年 | 147篇 |
2009年 | 151篇 |
2008年 | 149篇 |
2007年 | 133篇 |
2006年 | 112篇 |
2005年 | 86篇 |
2004年 | 65篇 |
2003年 | 65篇 |
2002年 | 50篇 |
2001年 | 29篇 |
2000年 | 24篇 |
1999年 | 36篇 |
1998年 | 24篇 |
1997年 | 17篇 |
1996年 | 19篇 |
1995年 | 16篇 |
1994年 | 12篇 |
1993年 | 15篇 |
1992年 | 17篇 |
1991年 | 8篇 |
1990年 | 11篇 |
1989年 | 10篇 |
1988年 | 7篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1970年 | 2篇 |
1960年 | 2篇 |
排序方式: 共有2430条查询结果,搜索用时 15 毫秒
41.
Design optimization of an enzymatic assay in an electrokinetically-driven microfluidic device 总被引:1,自引:1,他引:0
Y. T. Atalay P. Verboven S. Vermeir N. Vergauwe F. Delport B. M. Nicolaï J. Lammertyn 《Microfluidics and nanofluidics》2008,5(6):837-849
Microfluidic systems are increasingly popular for rapid and cheap determinations of enzyme assays and other biochemical analysis.
In this study reduced order models (ROM) were developed for the optimization of enzymatic assays performed in a microchip.
The model enzyme assay used was β-galactosidase (β-Gal) that catalyzes the conversion of Resorufin β-d-galactopyranoside (RBG) to a fluorescent product as previously reported by Hadd et al. (Anal Chem 69(17): 3407–3412, 1997). The assay was implemented in a microfluidic device as a continuous flow system controlled electrokinetically and with a
fluorescence detection device. The results from ROM agreed well with both computational fluid dynamic (CFD) simulations and
experimental values. While the CFD model allowed for assessment of local transport phenomena, the CPU time was significantly
reduced by the ROM approach. The operational parameters of the assay were optimized using the validated ROM to significantly
reduce the amount of reagents consumed and the total biochip assay time. After optimization the analysis time would be reduced
from 20 to 5.25 min which would also resulted in 50% reduction in reagent consumption. 相似文献
42.
Hoyer D Friedrich H Frank B Pompe B Baranowski R Zebrowski JJ Schmidt H 《Computer methods and programs in biomedicine》2006,81(3):246-255
Heart rate variability (HRV) represents the cardiovascular control mediated by the autonomic nervous system and other mechanisms. In the established task force HRV monitoring different cardiovascular control mechanisms can approximately be identified at typical frequencies of heart rate oscillations by power spectral analysis. HRV measures assessing complex and fractal behavior partly improved clinical risk stratification. However, their relationship to (patho-)physiology is not sufficiently explored. Objective of the present work is the introduction of complexity measures of different physiologically relevant time scales. This is achieved by a new concept of the autonomic information flow (AIF) analysis which was designed according to task force HRV. First applications show that different time scales of AIF improve the risk stratification of patients with multiple organ dysfunction syndrome and cardiac arrest patients in comparison to standard HRV. Each group's significant time scales correspond to their respective pathomechanisms. 相似文献
43.
In this paper we survey our research on smart meeting rooms and its relevance for augmented reality meeting support and virtual
reality generation of meetings in real time or off-line. The research reported here forms part of the European 5th and 6th
framework programme projects multi-modal meeting manager (M4) and augmented multi-party interaction (AMI). Both projects aim
at building a smart meeting environment that is able to collect multimodal captures of the activities and discussions in a
meeting room, with the aim to use this information as input to tools that allow real-time support, browsing, retrieval and
summarization of meetings. Our aim is to research (semantic) representations of what takes place during meetings in order
to allow generation, e.g. in virtual reality, of meeting activities (discussions, presentations, voting, etc.). Being able
to do so also allows us to look at tools that provide support during a meeting and at tools that allow those not able to be
physically present during a meeting to take part in a virtual way. This may lead to situations where the differences between
real meeting participants, human-controlled virtual participants and (semi-) autonomous virtual participants disappear.
相似文献
Dirk HeylenEmail: |
44.
Optimum tracking with evolution strategies 总被引:1,自引:0,他引:1
Evolutionary algorithms are frequently applied to dynamic optimization problems in which the objective varies with time. It is desirable to gain an improved understanding of the influence of different genetic operators and of the parameters of a strategy on its tracking performance. An approach that has proven useful in the past is to mathematically analyze the strategy's behavior in simple, idealized environments. The present paper investigates the performance of a multiparent evolution strategy that employs cumulative step length adaptation for an optimization task in which the target moves linearly with uniform speed. Scaling laws that quite accurately describe the behavior of the strategy and that greatly contribute to its understanding are derived. It is shown that in contrast to previously obtained results for a randomly moving target, cumulative step length adaptation fails to achieve optimal step lengths if the target moves in a linear fashion. Implications for the choice of population size parameters are discussed. 相似文献
45.
Gerben Klaas Dirk de Vries Maarten van Someren 《Expert systems with applications》2012,39(18):13426-13439
In this paper we present a machine learning framework to analyze moving object trajectories from maritime vessels. Within this framework we perform the tasks of clustering, classification and outlier detection with vessel trajectory data. First, we apply a piecewise linear segmentation method to the trajectories to compress them. We adapt an existing technique to better retain stop and move information and show the better performance of our method with experimental results. Second, we use a similarity based approach to perform the clustering, classification and outlier detection tasks using kernel methods. We present experiments that investigate different alignment kernels and the effect of piecewise linear segmentation in the three different tasks. The experimental results show that compression does not negatively impact task performance and greatly reduces computation time for the alignment kernels. Finally, the alignment kernels allow for easy integration of geographical domain knowledge. In experiments we show that this added domain knowledge enhances performance in the clustering and classification tasks. 相似文献
46.
Two dimensional simulations of non-cohesive granular matter in a biaxial shear tester are discussed. The effect of particle elasticity on the mechanical behavior is investigated using two complementary distinct element methods (DEM): Soft particle molecular dynamics simulations (Particle Flow Code, PFC) for elastic particles and contact dynamics simulations (CD) for the limit of perfectly rigid particles. As soon as the system dilates to form shear bands, it relaxes the elastic strains so that one finds the same stresses for rigid respectively elastic particles in steady state flow. The principal stresses in steady state flow are determined. They are proportional to each other, giving rise to an effective macroscopic friction coefficient which is about 10% smaller than the microscopic friction coefficient between the grains. 相似文献
47.
Dirk Veestraeten 《Computational Economics》2004,24(2):185-207
Models in economics and other fields often require a restricted Brownian motion because frequently implicit or explicit barriers restrict the domain. This paper contributes to the literature on reflected Brownian motion by deriving its conditional density function as a closed-form expression that consists of infinite sums of Gaussian densities. This solution is compared with an alternative, trigonometric expression derived earlier. Numerical analyses reveal that convergence properties of the expression derived in this paper are superior to those of the alternative representation for most practically relevant set-ups. Despite the complex appearance of the density formula, its use only requires fractions of a second on simple desktop computers such that, next to the theoretical appeal, also practicability is guaranteed. 相似文献
48.
49.
The scope of the article is to describe the automated production of a thixoformed steel part. The production plant was set up within a prototype initiative at the Institute of Metal Forming in cooperation with the Institute of Automatic Control of RWTH Aachen University and industrial partners. Preliminary experiments showed that the quality of the formed parts varied to a great extent due to changing production conditions since the handling of the billet was carried out manually. To eliminate the possible disturbances introduced by the manual handling of the billet, an automation concept has been elaborated in order to guarantee a defined production environment. An industrial robot (KUKA) fulfils the handling tasks like the feeding of the induction coil with the feedstock material and the placing of the heated billet into the hydraulic press. The removal of the formed part from the press is realised by a simple mechanical device in order to be able to use only one gripper. The design of the gripper ensures a minimal heat loss during handling. The induction coil, the gripper system and the cavity are flooded with inert gas in order to prevent scaling. The sequence control for the production of a part is realised on the controller of the robot which provides sufficient PLC functionality and can be easily equipped with the required I/O components to trigger the different automation components. 相似文献
50.
Joost P. A. Vogels Stephen I. Klink Roel Penterman Henk De Koning Edzer E. A. Huitema Dirk J. Broer 《Journal of the Society for Information Display》2004,12(4):411-416
Abstract— In this article, second‐generation liquid‐crystal displays (LCDs) made by Paintable LCD technology is presented. With this technology, LCDs are manufactured by a sequence of simple coating and UV curing processes. Since the process can be carried out on plastic substrates and the stack of optical layers is only tens of micrometers thick, the resulting LCDs are ultra‐thin and flexible. 相似文献