全文获取类型
收费全文 | 2654篇 |
免费 | 178篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 43篇 |
综合类 | 6篇 |
化学工业 | 665篇 |
金属工艺 | 50篇 |
机械仪表 | 42篇 |
建筑科学 | 89篇 |
矿业工程 | 1篇 |
能源动力 | 107篇 |
轻工业 | 287篇 |
水利工程 | 7篇 |
石油天然气 | 2篇 |
无线电 | 279篇 |
一般工业技术 | 487篇 |
冶金工业 | 244篇 |
原子能技术 | 42篇 |
自动化技术 | 487篇 |
出版年
2023年 | 24篇 |
2022年 | 41篇 |
2021年 | 73篇 |
2020年 | 56篇 |
2019年 | 52篇 |
2018年 | 70篇 |
2017年 | 76篇 |
2016年 | 73篇 |
2015年 | 91篇 |
2014年 | 111篇 |
2013年 | 175篇 |
2012年 | 153篇 |
2011年 | 250篇 |
2010年 | 162篇 |
2009年 | 146篇 |
2008年 | 149篇 |
2007年 | 107篇 |
2006年 | 102篇 |
2005年 | 90篇 |
2004年 | 71篇 |
2003年 | 90篇 |
2002年 | 55篇 |
2001年 | 35篇 |
2000年 | 38篇 |
1999年 | 47篇 |
1998年 | 75篇 |
1997年 | 36篇 |
1996年 | 51篇 |
1995年 | 23篇 |
1994年 | 41篇 |
1993年 | 34篇 |
1992年 | 28篇 |
1991年 | 19篇 |
1990年 | 18篇 |
1989年 | 12篇 |
1988年 | 12篇 |
1987年 | 11篇 |
1986年 | 7篇 |
1985年 | 10篇 |
1984年 | 7篇 |
1983年 | 10篇 |
1982年 | 7篇 |
1980年 | 6篇 |
1979年 | 6篇 |
1978年 | 7篇 |
1977年 | 10篇 |
1976年 | 22篇 |
1975年 | 7篇 |
1974年 | 7篇 |
1970年 | 5篇 |
排序方式: 共有2838条查询结果,搜索用时 15 毫秒
61.
Acceptance testing is a time-consuming task for complex software systems that have to fulfill a large number of requirements.
To reduce this effort, we have developed a widely automated method for deriving test plans from requirements that are expressed
in natural language. It consists of three stages: annotation, clustering, and test plan specification. The general idea is
to exploit redundancies and implicit relationships in requirements specifications. Multi-viewpoint techniques based on RM-ODP
(Reference Model for Open Distributed Processing) are employed for specifying the requirements. We then use linguistic analysis
techniques, requirements clustering algorithms, and pattern-based requirements collection to reduce the total effort of testing
against the requirements specification. In particular, we use linguistic analysis for extracting and annotating the actor,
process and object of a requirements statement. During clustering, a similarity function is computed as a measure for the
overlap of requirements. In the test plan specification stage, our approach provides capabilities for semi-automatically deriving
test plans and acceptance criteria from the clustered informal textual requirements. Two patterns are applied to compute a
suitable order of test activities. The generated test plans consist of a sequence of test steps and asserts that are executed
or checked in the given order. We also present the supporting prototype tool TORC, which is available open source. For the
evaluation of the approach, we have conducted a case study in the field of acceptance testing of a national electronic identification
system. In summary, we report on lessons learned how linguistic analysis and clustering techniques can help testers in understanding
the relations between requirements and for improving test planning. 相似文献
62.
Florie VidbergAuthor Vitae Rabah ZeggariAuthor Vitae Christian PieralliAuthor Vitae Clotilde Amiot Christophe RouxAuthor Vitae Bruno WacogneAuthor Vitae 《Sensors and actuators. B, Chemical》2011,157(1):19-25
We present a simple optical micro-system used to measure the transmission spectra of oocytes in order to qualify their maturation stage. Two applications of the device are possible: (i) the evaluation of the maturation stages of oocytes, and (ii) the development of a fertilization indicator. For the first application, GV, MI and MII oocytes were also analysed. Transmission spectra allow the 3 maturation stages to be identified but cannot be used to estimate the maturity of an unknown oocyte. Oocytes are subject to continuous development. This is why spectral separation of the 3 maturation stages cannot be made although they can be visually identified. However, the visual observation remains biologist-dependent. We therefore investigated the temporal maturation evolution of the oocytes in terms of transmission spectra and probability analysis. Results show that oocytes to be fertilized should not only be chosen in the MII stage, but also at the right time during the MII stage. This particular aspect requires further investigation. However, spectral measurements could be used as a technique for monitoring the maturation evolution of the oocytes. Fertilized oocytes exhibiting fertilization abnormalities were also tested. The device proved to be an efficient fertilization indicator. 相似文献
63.
64.
An empirical study examined the impact of prototype fidelity on user behaviour, subjective user evaluation and emotion. The independent factors of prototype fidelity (paper prototype, computer prototype, fully operational appliance) and aesthetics of design (high vs. moderate) were varied in a between-subjects design. The 60 participants of the experiment were asked to complete two typical tasks of mobile phone usage: sending a text message and suppressing a phone number. Both performance data and a number of subjective measures were recorded. The results suggested that task completion time may be overestimated when a computer prototype is being used. Furthermore, users appeared to compensate for deficiencies in aesthetic design by overrating the aesthetic qualities of reduced fidelity prototypes. Finally, user emotions were more positively affected by the operation of the more attractive mobile phone than by the less appealing one. 相似文献
65.
66.
Christophe Vandekerckhove Ioannis Kevrekidis Dirk Roose 《Journal of scientific computing》2009,39(2):167-188
The long-term dynamic behavior of many dynamical systems evolves on a low-dimensional, attracting, invariant slow manifold,
which can be parameterized by only a few variables (“observables”). The explicit derivation of such a slow manifold (and thus,
the reduction of the long-term system dynamics) is often extremely difficult or practically impossible. For this class of
problems, the equation-free framework has been developed to enable performing coarse-grained computations, based on short
full model simulations. Each full model simulation should be initialized so that the full model state is consistent with the
values of the observables and close to the slow manifold. To compute such an initial full model state, a class of constrained
runs functional iterations was proposed (Gear and Kevrekidis, J. Sci. Comput. 25(1), 17–28, 2005; Gear et al., SIAM J. Appl. Dyn. Syst. 4(3), 711–732, 2005). The schemes in this class only use the full model simulator and converge, under certain conditions, to an approximation
of the desired state on the slow manifold. In this article, we develop an implementation of the constrained runs scheme that
is based on a (preconditioned) Newton-Krylov method rather than on a simple functional iteration. The functional iteration
and the Newton-Krylov method are compared in detail using a lattice Boltzmann model for one-dimensional reaction-diffusion
as the full model simulator. Depending on the parameters of the lattice Boltzmann model, the functional iteration may converge
slowly or even diverge. We show that both issues are largely resolved by using the Newton-Krylov method, especially when a
coarse grid correction preconditioner is incorporated. 相似文献
67.
Jordan Navarro Elsa Yousfi Jonathan Deniel Christophe Jallais Mercedes Bueno Alexandra Fort 《Ergonomics》2016,59(12):1553-1564
In the past, lane departure warnings (LDWs) were demonstrated to improve driving behaviours during lane departures but little is known about the effects of unreliable warnings. This experiment focused on the influence of false warnings alone or in combination with missed warnings and warning onset on assistance effectiveness and acceptance. Two assistance unreliability levels (33 and 17%) and two warning onsets (partial and full lane departure) were manipulated in order to investigate interaction. Results showed that assistance, regardless unreliability levels and warning onsets, improved driving behaviours during lane departure episodes and outside of these episodes by favouring better lane-keeping performances. Full lane departure and highly unreliable warnings, however, reduced assistance efficiency. Drivers’ assistance acceptance was better for the most reliable warnings and for the subsequent warnings. The data indicate that imperfect LDWs (false warnings or false and missed warnings) further improve driving behaviours compared to no assistance.
Practitioner Summary: This study revealed that imperfect lane departure warnings are able to significantly improve driving performances and that warning onset is a key element for assistance effectiveness and acceptance. The conclusion may be of particular interest for lane departure warning designers. 相似文献
68.
In this study, we propose a simple and efficient texture-based algorithm for image segmentation. This method constitutes computing textons and bag of words (BOWs) learned by support vector machine (SVM) classifiers. Textons are composed of local magnitude coefficients that arise from the Q-Shift Dual-Tree Complex Wavelet Transform (DT-CWT) combined with color components. In keeping with the needs of our research context, which addresses land cover mapping from remote images, we use a few small texture patches at the training stage, where other supervised methods usually train fully representative textures. We accounted for the scale and rotation invariance issue of the textons, and three different invariance transforms were evaluated on DT-CWT-based features. The largest contribution of this study is the comparison of three classification schemes in the segmentation algorithm. Specifically, we designed a new scheme that was especially competitive and that uses several classifiers, with each classifier adapted to a specific size of analysis window in texton quantification and trained on a reduced data set by random selection. This configuration allows quick SVM convergence and an easy parallelization of the SVM-bank while maintaining a high segmentation accuracy. We compare classification results with textons made using the well-known maximum response filters bank and speed up robust features features as references. We show that DT-CWT textons provide better distinguishing features in the entire set of configurations tested. Benchmarks of our different method configurations were made over two substantial textured mosaic sets, each composed of 100 grey or color mosaics made up of Brodatz or VisTex textures. Lastly, when applied to remote sensing images, our method yields good region segmentation compared to the ENVI commercial software, which demonstrates that the method could be used to generate land cover maps and is suitable for various purposes in image segmentation. 相似文献
69.
Simultaneous automated design of structured QFT controller and prefilter using nonlinear programming 下载免费PDF全文
Harsh Purohit Alexandre Goldsztejn Christophe Jermann Laurent Granvilliers Frédéric Goualard P. S. V. Nataraj Bhagyesh Patil 《国际强度与非线性控制杂志
》2017,27(15):2529-2548
》2017,27(15):2529-2548
This paper describes a nonlinear programming‐based robust design methodology for controllers and prefilters of a predefined structure for the linear time‐invariant systems involved in the quantitative feedback theory. This controller and prefilter synthesis problem is formulated as a single optimization problem with a given performance optimization objective and constraints enforcing stability and various specifications usually enforced in the quantitative feedback theory. The focus is set on providing constraints expression that can be used in standard nonlinear programming solvers. The nonlinear solver then computes in a single‐step controller and prefilter design parameters that satisfy the prescribed constraints and maximizes the performance optimization objective. The effectiveness of the proposed approach is demonstrated through a variety of difficult design cases like resonant plants, open‐loop unstable plants, and plants with variation in the time delay. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
70.
Klaus Julisch Christophe Suter Thomas Woitalla Olaf Zimmermann 《Computers & Security》2011,30(6-7):410-426
System and process auditors assure – from an information processing perspective – the correctness and integrity of the data that is aggregated in a company’s financial statements. To do so, they assess whether a company’s business processes and information systems process financial data correctly. The audit process is a complex endeavor that in practice has to rely on simplifying assumptions. These simplifying assumptions mainly result from the need to restrict the audit scope and to focus it on the major risks. This article describes a generalized audit process. According to our experience with this process, there is a risk that material deficiencies remain undiscovered when said simplifying assumptions are not satisfied. To address this risk of deficiencies, the article compiles thirteen control patterns, which – according to our experience – are particularly suited to help information systems satisfy the simplifying assumptions. As such, use of these proven control patterns makes information systems easier to audit and IT architects can use them to build systems that meet audit requirements by design. Additionally, the practices and advice offered in this interdisciplinary article help bridge the gap between the architects and auditors of information systems and show either role how to benefit from an understanding of the other role’s terminology, techniques, and general work approach. 相似文献