全文获取类型
收费全文 | 2639篇 |
免费 | 197篇 |
国内免费 | 14篇 |
专业分类
电工技术 | 49篇 |
综合类 | 17篇 |
化学工业 | 688篇 |
金属工艺 | 65篇 |
机械仪表 | 39篇 |
建筑科学 | 146篇 |
矿业工程 | 6篇 |
能源动力 | 132篇 |
轻工业 | 102篇 |
水利工程 | 12篇 |
石油天然气 | 7篇 |
无线电 | 259篇 |
一般工业技术 | 579篇 |
冶金工业 | 126篇 |
原子能技术 | 8篇 |
自动化技术 | 615篇 |
出版年
2024年 | 6篇 |
2023年 | 61篇 |
2022年 | 124篇 |
2021年 | 160篇 |
2020年 | 107篇 |
2019年 | 107篇 |
2018年 | 111篇 |
2017年 | 122篇 |
2016年 | 133篇 |
2015年 | 101篇 |
2014年 | 159篇 |
2013年 | 189篇 |
2012年 | 216篇 |
2011年 | 222篇 |
2010年 | 136篇 |
2009年 | 141篇 |
2008年 | 121篇 |
2007年 | 99篇 |
2006年 | 81篇 |
2005年 | 43篇 |
2004年 | 47篇 |
2003年 | 44篇 |
2002年 | 33篇 |
2001年 | 28篇 |
2000年 | 23篇 |
1999年 | 25篇 |
1998年 | 37篇 |
1997年 | 17篇 |
1996年 | 9篇 |
1995年 | 18篇 |
1994年 | 9篇 |
1993年 | 10篇 |
1992年 | 11篇 |
1991年 | 13篇 |
1990年 | 16篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 14篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1983年 | 5篇 |
1981年 | 4篇 |
1979年 | 3篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1972年 | 4篇 |
1971年 | 2篇 |
排序方式: 共有2850条查询结果,搜索用时 15 毫秒
141.
Davide Bilò Hans-Joachim Böckenhauer Dennis Komm Richard Královič Tobias Mömke Sebastian Seibert Anna Zych 《Algorithmica》2011,61(2):227-251
A reoptimization problem describes the following scenario: given an instance of an optimization problem together with an optimal
solution for it, we want to find a good solution for a locally modified instance. 相似文献
142.
Sebastian Albrecht 《Optimization methods & software》2017,32(4):670-698
In this paper an inverse optimal control problem in the form of a mathematical program with complementarity constraints (MPCC) is considered and numerical experiences are discussed. The inverse optimal control problem arises in the context of human navigation where the body is modelled as a dynamical system and it is assumed that the motions are optimally controlled with respect to an unknown cost function. The goal of the inversion is now to find a cost function within a given parametrized family of candidate cost functions such that the corresponding optimal motion minimizes the deviation from given data. MPCCs are known to be a challenging class of optimization problems typically violating all standard constraint qualifications (CQs). We show that under certain assumptions the resulting MPCC fulfills CQs for MPCCs being the basis for theory on MPCC optimality conditions and consequently for numerical solution techniques. Finally, numerical results are presented for the discretized inverse optimal control problem of locomotion using different solution techniques based on relaxation and lifting. 相似文献
143.
Two commercially available carbon fibre reinforced composites (8552/IM7 and M18-1/G939) were exposed to heat above maximum operational temperature at various durations. Mass loss and mechanical properties were measured over time. A chemical analysis was also performed on these composites. The two primary components of each matrix, the epoxy resin and the thermoplastic, were observed to degrade at different rates under various thermal loading conditions. The epoxy resins degrade predominantly as measured by IR spectroscopy and thermal desorption/gas chromatography mass spectrometry. By using mass loss, strength, and IR spectroscopic data, a correlation was made between strength characteristics of each composite and the relative amount of the two primary matrix components. The developed relationship can be used to estimate rapidly the mechanical properties from the intensity ratio of IR bands characteristic of the two components. 相似文献
144.
Sebastian Biba 《国际水》2018,43(5):622-641
This article analyzes China’s Mekong River politics before and after the establishment of the Lancang-Mekong Cooperation (LMC) from a comparative benefit-sharing perspective. China’s pre-LMC approach focused too much on the creation of economic benefits from and beyond the river while neglecting ecological benefits to the river. Moreover, despite the problems this ‘old’ approach caused for China and its downstream neighbours, China’s current LMC strategy seems to essentially replicate its former approach. While sustainable water resources management is identified as a priority area, actual cooperation and benefit sharing in this field remain insufficient. 相似文献
145.
In contrast to combinational logic and master clocked sequential logical, asynchronous feedback circuits are partially defined due to analogous meta-stabilities. We present a novel formalism to exactly explore this digitally assisted analog phenomenon in order to build up a representative test bench that is able to enforce race constraints (meta-stable behavior) for non-deterministics, instabilities as well as for oscillations in feedback structures. Further, we introduce our definitions for consistently modeling under state transition graphs, we provide all entities for modeling asynchronous feedback structures and state our proposed methodology with an exemplary asynchronous circuitry. The given example is explained at a high level of abstraction, all data for revision is provided, too. The approach seems to be capable to test for meta-stabilities, analog behavior in feedback digital structures. 相似文献
146.
Sebastian WöckelAuthor Vitae 《Sensors and actuators. A, Physical》2011,172(1):322-329
This paper discusses a tomographic approach focusing on ultrasonic measurements to monitor liquid multiphase mixtures. Separately a capacitive tomography low-cost setup is regarded. Both sensor arrays aim for the localization of variable phase boundaries and the physical characterisation of spatially distributed phases. Focusing on a real time processing, a reduced number of transducers in combination with a fast linear modelling and direct image reconstruction methods are used. Experimental results of a layered 3-phase-system validate the potential and limits of physical resolution of both approaches. Finally, the prospectively intended data fusion of both approaches is discussed. 相似文献
147.
148.
Sorption behavior of nonylphenol in terrestrial soils 总被引:1,自引:0,他引:1
Nonylphenol (NP) as an intermediate from anaerobic degradation of widely used nonionic surfactants occurs widespread in the environment. Partition behavior of this toxic and endocrine-disrupting chemical between soil and water was not examined until yet. The objective of this investigation was to quantify sorption and desorption behavior of 4-nonyl[14C]phenol in a set of 51 soils using the batch equilibrium approach. Kinetic studies indicated apparent equilibrium within 20 h. Sorption was influenced by sorbate structure as could be shown with branched 4-nonyl[14C]phenol and the linear 4-n-NP, respectively. Linear 4-n-NP behaves differently from the branched isomers of 4-NP. Sorption of 4-nonyl[14C]phenol tested with five different initial concentrations resulted in linearly fitted isotherms that provided calculation of sorption partition coefficients (KP). Desorption partition coefficients (KP-des) revealed hysteresis independent of soil properties but decreasing with decreasing initial NP concentrations. KP values were correlated with organic carbon content of the soils yielding a log KOC of 3.97. 相似文献
149.
Nanoporous materials 总被引:1,自引:0,他引:1
150.
Winner-take-all networks have been proposed to underlie many of the brain's fundamental computational abilities. However, not much is known about how to extend the grouping of potential winners in these networks beyond single neuron or uniformly arranged groups of neurons. We show that competition between arbitrary groups of neurons can be realized by organizing lateral inhibition in linear threshold networks. Given a collection of potentially overlapping groups (with the exception of some degenerate cases), the lateral inhibition results in network dynamics such that any permitted set of neurons that can be coactivated by some input at a stable steady state is contained in one of the groups. The information about the input is preserved in this operation. The activity level of a neuron in a permitted set corresponds to its stimulus strength, amplified by some constant. Sets of neurons that are not part of a group cannot be coactivated by any input at a stable steady state. We analyze the storage capacity of such a network for random groups--the number of random groups the network can store as permitted sets without creating too many spurious ones. In this framework, we calculate the optimal sparsity of the groups (maximizing group entropy). We find that for dense inputs, the optimal sparsity is unphysiologically small. However, when the inputs and the groups are equally sparse, we derive a more plausible optimal sparsity. We believe our results are the first steps toward attractor theories in hybrid analog-digital networks. 相似文献