全文获取类型
收费全文 | 482篇 |
免费 | 19篇 |
专业分类
电工技术 | 8篇 |
化学工业 | 161篇 |
金属工艺 | 25篇 |
机械仪表 | 19篇 |
建筑科学 | 7篇 |
矿业工程 | 2篇 |
能源动力 | 18篇 |
轻工业 | 9篇 |
水利工程 | 2篇 |
无线电 | 47篇 |
一般工业技术 | 87篇 |
冶金工业 | 11篇 |
原子能技术 | 4篇 |
自动化技术 | 101篇 |
出版年
2023年 | 5篇 |
2022年 | 34篇 |
2021年 | 28篇 |
2020年 | 6篇 |
2019年 | 11篇 |
2018年 | 21篇 |
2017年 | 13篇 |
2016年 | 21篇 |
2015年 | 17篇 |
2014年 | 26篇 |
2013年 | 45篇 |
2012年 | 27篇 |
2011年 | 45篇 |
2010年 | 21篇 |
2009年 | 38篇 |
2008年 | 26篇 |
2007年 | 21篇 |
2006年 | 16篇 |
2005年 | 10篇 |
2004年 | 12篇 |
2003年 | 7篇 |
2002年 | 9篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1997年 | 7篇 |
1996年 | 5篇 |
1995年 | 1篇 |
1993年 | 2篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有501条查询结果,搜索用时 15 毫秒
461.
Florian A. Potra Mihai Anitescu Bogdan Gavrea Jeff Trinkle 《International journal for numerical methods in engineering》2006,66(7):1079-1124
We present a hard constraint, linear complementarity based, method for the simulation of stiff multibody dynamics with contact, joints and friction. The approach uses a linearization of the modified trapezoidal method, incorporates a Poisson restitution model at collision, and solves only one linear complementarity problem per time step when no collisions are encountered. We prove that, under certain assumptions, the method has order two, a fact that is also demonstrated by our numerical simulations. For the unconstrained (ODE) case, the method achieves second‐order convergence and absolute stability while solving only one linear system per step. When we use a special approximation of the Jacobian matrix for the case where the stiff forces originate in springs and dampers attached to two points in the system, the linear complementarity problem can be solved for any value of the time step and numerical simulation demonstrate that the method is stiffly stable. The method was implemented in UMBRA, an industrial‐grade virtual prototyping software. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
462.
Global wireless networks have opened the way to a ubiquitous Internet computing environment in which a variety of portable devices remain connected to the Internet fabric - even as their locations change continuously - and access to data and services is independent of both device type and location. In this environment, applications must be able to change the location of their execution. In addition, they must allow heterogeneous and resource-limited portable devices to download only the device-specific software components needed for execution. Code mobility enables dynamic customization and configuration of ubiquitous Internet applications. Mobility complicates application programming by requiring developers to define when and where to move which components under varying operating conditions. A policy-based implementation framework supports high-level reconfiguration strategies that separate mobility concerns from application functionality. 相似文献
463.
Jerzy Bodzenta Justyna Juszczyk Anna Kaźmierczak-Bałata Piotr Firek Austin Fleming Mihai Chirtoc 《International Journal of Thermophysics》2016,37(7):73
Quantitative thermal measurements with spatial resolution allowing the examination of objects of submicron dimensions are still a challenging task. The quantity of methods providing spatial resolution better than 100 nm is very limited. One of them is scanning thermal microscopy (SThM). This method is a variant of atomic force microscopy which uses a probe equipped with a temperature sensor near the apex. Depending on the sensor current, either the temperature or the thermal conductivity distribution at the sample surface can be measured. However, like all microscopy methods, the SThM gives only qualitative information. Quantitative measuring methods using SThM equipment are still under development. In this paper, a method based on simultaneous registration of the static and the dynamic electrical resistances of the probe driven by the sum of dc and ac currents, and examples of its applications are described. Special attention is paid to the investigation of thin films deposited on thick substrates. The influence of substrate thermal properties on the measured signal and its dependence on thin film thermal conductivity and film thickness are analyzed. It is shown that in the case where layer thicknesses are comparable or smaller than the probe–sample contact diameter, a correction procedure is required to obtain actual thermal conductivity of the layer. Experimental results obtained for thin SiO\(_{\mathrm {2}}\) and BaTiO\(_{\mathrm {3 }}\)layers with thicknesses in the range from 11 nm to 100 nm are correctly confirmed with this approach. 相似文献
464.
Mihai Oltean 《人工智能实验与理论杂志》2013,25(4):333-353
An intelligent system should be able to solve a wide range of problems from different domains. In this paper we propose a complex and adaptive system capable of solving various data analysis problems without needing human help for parameter settings. The system, called A-Brain, consists of several interconnected components (a decision-maker, a trainer, and several problem solvers) which provide a base for building complex problem solvers. The parameters of the trainer's algorithm are problem independent. This fact is a requirement for intelligent systems which cannot rely on human intervention while operating. The A-Brain system is used to solve some well-known problems in the field of symbolic regression and classification. Numerical experiments show that the A-Brain system is able to perform very well on the considered test problems. 相似文献
465.
In this paper we study the scheduling of parallel and real-time recurrent tasks on multiprocessor platforms. Firstly, we propose a new parallel task model which allows recurrent tasks to be composed of several phases, each one composed of several threads. Each thread requires a single processor for execution and can be scheduled simultaneously. We then propose an algorithm to transpose popular Fork-Join task model to our MPMT task model. Secondly, we define several kinds of real-time schedulers that can be applied to our parallel task model. We distinguish between two scheduling classes: Hierarchical schedulers and Global Thread schedulers. We present and prove correct an exact schedulability test for each class. Lastly, we also evaluate the performance of our scheduling paradigm in comparison with Gang scheduling by means of simulations. In this work we extend the work of Lupu and Goossens in Scheduling of hard real-time multi-thread periodic tasks (Real-Time and Network Systems, 2011) which considers mono-phase multi-thread task model. We extend their previous results to a Multi-Phase Multi-Thread task model. 相似文献
466.
The paper focuses on the automatic control of aircraft in the lateral‐directional plane during the landing approach phase, taking into account crosswind and sensor errors. Two new automatic landing systems are designed using the H‐inf control, dynamic inversion, optimal observers, and reference models. To validate them, we use the dynamics associated with the landing of a light airplane, we software implement the theoretical results, and analyze the accuracy of the results and the precision standards’ achievement with respect to the requirements of the Federal Aviation Administration for lateral error during the lateral‐directional motion of the aircraft during the landing approach phase. 相似文献
467.
Amir Hossein Taghvaei Mihai StoicaGavin Vaughan Mohammad GhaffariSaeed Maleksaeedi Kamal Janghorban 《Journal of Alloys and Compounds》2012,512(1):85-93
In this work, microstructural evolution and amorphous phase formation in Co40Fe22Ta8B30 alloy produced by mechanical alloying (MA) of the elemental powder mixture under argon gas atmosphere was investigated. Milling time had a profound effect on the phase transformation, microstructure, morphological evolution and thermal behavior of the powders. These effects were studied by the X-ray powder diffraction (XRD) in reflection mode using Cu Kα and in transmission configuration using synchrotron radiation, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The results showed that at the early stage of the milling, microstructure consisted of nanocrystalline bcc-(Fe, Co) phases and unreacted tantalum.Further milling, produced an amorphous phase, which became a dominant phase with a fraction of 96 wt% after 200 h milling. The DSC profile of 200 h milled powders demonstrated a huge and broad exothermic hump due to the structural relaxation, followed by a single exothermic peak, indicating the crystallization of the amorphous phase. Further XRD studies in transmission mode by synchrotron radiation revealed that the crystalline products were (Co, Fe)20.82Ta2.18B6, (Co, Fe)21 Ta2 B6, and (Co, Fe)3B2. The amorphization mechanisms were discussed in terms of severe grain refinement, atomic size effect, the concept of local topological instability and the heat of mixing of the reactants. 相似文献
468.
Ion Anghel Carmen Limban Alexandru Mihai Grumezescu Alina Georgiana Anghel Coralia Bleotu Mariana Carmen Chifiriuc 《Nanoscale research letters》2012,7(1):513
In this paper, we report the design of a new nanofluid for anti-pathogenic surface coating. For this purpose, new 2-((4-ethylphenoxy)methyl)-N-(substituted-phenylcarbamothioyl)-benzamides were synthesized and used as an adsorption shell for Fe3O4/C12 core/shell nanosized material. The functionalized specimens were tested by in vitro assays for their anti-biofilm properties and biocompatibility. The optimized catheter sections showed an improved resistance to Staphylococcus aureus ATCC 25923 and Pseudomonas aeruginosa ATCC 27853 in vitro biofilm development, as demonstrated by the viable cell counts of biofilm-embedded bacterial cells and by scanning electron microscopy examination of the colonized surfaces. The nanofluid proved to be not cytotoxic and did not influence the eukaryotic cell cycle. These results could be of a great interest for the biomedical field, opening new directions for the design of film-coated surfaces with improved anti-biofilm properties. 相似文献
469.
Alexandru Mihai Bica 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2007,11(11):1099-1105
Using a classic algebraic construction additive and multiplicative structures (as commutative monoids) for fuzzy numbers are
obtained. Moreover, we realize here an isomorphism between these structures. 相似文献
470.
Tanja Vidaković Mihai Christov Kai Sundmacher 《Journal of Applied Electrochemistry》2009,39(2):213-225
A method for a rough estimation of the catalyst surface area in a fuel cell is developed. It is based on the deconvolution
of experimental CO oxidation data by use of a mathematical model. The kinetic parameters of the model are determined by fitting
the experimental curves. The experimental data are collected at different sweep rates (2–100 mV s−1) and at different temperatures (room −60.0 °C). The model can predict the sweep rate dependence of the CO oxidation onset
potential, the peak current, the peak potential and the peak broadness. The model is further used for the prediction of the
baseline in the presence of CO and for calculation of the CO charge consumed up to half peak potential. It is obtained that
the latter value is constant at different sweep rates and that the baseline deviates from linearity already at low sweep rates
(2 mV s−1), but not very significantly (2.0% in comparison to 8.8% at 100 mV s−1, based on calculated CO charge). It is suggested that lower sweep rates should be used for experimental surface area determination. 相似文献