全文获取类型
收费全文 | 5288篇 |
免费 | 293篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 79篇 |
综合类 | 2篇 |
化学工业 | 1369篇 |
金属工艺 | 67篇 |
机械仪表 | 130篇 |
建筑科学 | 199篇 |
矿业工程 | 6篇 |
能源动力 | 208篇 |
轻工业 | 704篇 |
水利工程 | 36篇 |
石油天然气 | 16篇 |
无线电 | 473篇 |
一般工业技术 | 928篇 |
冶金工业 | 529篇 |
原子能技术 | 40篇 |
自动化技术 | 802篇 |
出版年
2024年 | 10篇 |
2023年 | 60篇 |
2022年 | 238篇 |
2021年 | 277篇 |
2020年 | 144篇 |
2019年 | 164篇 |
2018年 | 175篇 |
2017年 | 131篇 |
2016年 | 196篇 |
2015年 | 165篇 |
2014年 | 226篇 |
2013年 | 370篇 |
2012年 | 321篇 |
2011年 | 384篇 |
2010年 | 312篇 |
2009年 | 263篇 |
2008年 | 282篇 |
2007年 | 210篇 |
2006年 | 174篇 |
2005年 | 165篇 |
2004年 | 120篇 |
2003年 | 131篇 |
2002年 | 121篇 |
2001年 | 71篇 |
2000年 | 62篇 |
1999年 | 77篇 |
1998年 | 148篇 |
1997年 | 90篇 |
1996年 | 74篇 |
1995年 | 60篇 |
1994年 | 49篇 |
1993年 | 41篇 |
1992年 | 25篇 |
1991年 | 21篇 |
1990年 | 16篇 |
1989年 | 22篇 |
1988年 | 20篇 |
1987年 | 16篇 |
1986年 | 14篇 |
1985年 | 13篇 |
1984年 | 14篇 |
1983年 | 9篇 |
1982年 | 15篇 |
1981年 | 13篇 |
1980年 | 10篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1977年 | 7篇 |
1976年 | 10篇 |
1975年 | 6篇 |
排序方式: 共有5588条查询结果,搜索用时 359 毫秒
91.
92.
93.
Nano Research - The widespread and increasing interest in enhancing biosensing technologies by increasing their sensitivities and lowering their costs has led to the exploration and application of... 相似文献
94.
The
4
He wetting transition on a Cs surface is for the first time studied by Path Integral Monte Carlo simulation. Numerical results for a system of 64
4
He atoms are qualitatively consistent with a wetting transition at a temperature T 2 K. 相似文献
95.
Ugo Andreaus Michele Colloca Daniela Iacoviello Marcello Pignataro 《Structural and Multidisciplinary Optimization》2011,43(1):43-59
The objective of this paper was solving the optimization problem of lightweight stiffened structures modelled as a two-dimensional
domain in an efficient computational way. The underlying premise was that mass should be distributed in an efficient way,
so as to use a minimum amount of material to accomplish the mechanical function. This premise was expressed as a global, multi-objective
optimization problem in which stiffness and mass were conflicting objectives. Alternative local evolution rules were implemented
to update mass density or Young’s modulus at each step of the iterative procedure. The solution of the structural optimization
problem was accomplished by a novel automatic procedure consisting of two consecutive stages of control and optimization.
In the first stage of Proportional Integral Derivative (PID) control gains were manually selected whereas in the second stage
the finding of optimal values of control gains, target, and cost indices was allowed. In this study a bone-like material was
adopted and a thin slab was analysed as a sample problem. 相似文献
96.
Michele Barletta Silvio Ranise Luca Vigan�� 《Service Oriented Computing and Applications》2011,5(2):105-137
The specification of distributed service-oriented applications spans several levels of abstraction, e.g., the protocol for
exchanging messages, the set of interface functionalities, the types of the manipulated data, the workflow, the access policy,
etc. Many (even executable) specification languages are available to describe each level in separation. However, these levels
may interact in subtle ways (for example, the control flow may depend on the values of some data variables) so that a precise
abstraction of the application amounts to more than the sum of its per level components. This problem is even more acute in
the design phase when automated analysis techniques may greatly help the difficult task of building “correct” applications
faced by designers. To alleviate this kind of problems, this paper introduces a framework for the formal specification and
automated analysis of distributed service-oriented applications in two levels: one for the workflow and one for the authorization
policies. The former allows one to precisely describe the control and data parts of an application with their mutual dependencies.
The latter focuses on the specification of the criteria for granting or denying third-party applications the possibility to
access shared resources or to execute certain interface functionalities. These levels can be seen as abstractions of one or
of several levels of specification mentioned above. The novelty of our proposal is the possibility to unambiguously specify
the—often subtle—interplay between the workflow and policy levels uniformly in the same framework. Additionally, our framework
allows us to define and investigate verification problems for service-oriented applications (such as executability and invariant
checking) and give sufficient conditions for their decidability. These results are non-trivial because their scope of applicability
goes well beyond the case of finite state spaces allowing for applications manipulating variables ranging over infinite domains.
As proof of concept, we show the suitability and flexibility of our approach on two quite different examples inspired by industrial
case studies. 相似文献
97.
Massimo Merro 《Acta Informatica》2010,47(2):111-132
We apply powerful proof-techniques of concurrency theory to study the observational theory of Thielecke’s CPS-calculus, a distillation of the target language of Continuation-Passing Style transforms. We define a labelled transition system from which we derive a (weak) labelled bisimilarity that completely characterises Morris’ context-equivalence. We prove a context lemma showing that Morris’ context-equivalence coincides with a simpler context-equivalence closed under a smaller class of contexts.
Then we profit of the determinism of the CPS-calculus to give a simpler labelled characterisation of Morris’ equivalence,
in the style of Abramsky’s applicative bisimilarity. We enhance our bisimulation proof-methods with up to bisimilarity and up to context proof techniques. We use our bisimulation proof techniques to investigate a few algebraic properties on diverging terms that
cannot be proved using the original axiomatic semantics of the CPS-calculus. 相似文献
98.
In this paper, we introduce and analyze a modification of the Hermitian and skew-Hermitian splitting iteration method for solving a broad class of complex symmetric linear systems. We show that the modified Hermitian and skew-Hermitian splitting (MHSS) iteration method is unconditionally convergent. Each iteration of this method requires the solution of two linear systems with real symmetric positive definite coefficient matrices. These two systems can be solved inexactly. We consider acceleration of the MHSS iteration by Krylov subspace methods. Numerical experiments on a few model problems are used to illustrate the performance of the new method. 相似文献
99.
Enabling energy-efficient and lossy-aware data compression in wireless sensor networks by multi-objective evolutionary optimization 总被引:1,自引:0,他引:1
Nodes of wireless sensor networks (WSNs) are typically powered by batteries with a limited capacity. Thus, energy is a primary constraint in the design and deployment of WSNs. Since radio communication is in general the main cause of power consumption, the different techniques proposed in the literature to improve energy efficiency have mainly focused on limiting transmission/reception of data, for instance, by adopting data compression and/or aggregation. The limited resources available in a sensor node demand, however, the development of specifically designed algorithms. To this aim, we propose an approach to perform lossy compression on single node based on a differential pulse code modulation scheme with quantization of the differences between consecutive samples. Since different combinations of the quantization process parameters determine different trade-offs between compression performance and information loss, we exploit a multi-objective evolutionary algorithm to generate a set of combinations of these parameters corresponding to different optimal trade-offs. The user can therefore choose the combination with the most suitable trade-off for the specific application. We tested our lossy compression approach on three datasets collected by real WSNs. We show that our approach can achieve significant compression ratios despite negligible reconstruction errors. Further, we discuss how our approach outperforms LTC, a lossy compression algorithm purposely designed to be embedded in sensor nodes, in terms of compression rate and complexity. 相似文献
100.
To what extent do people behave in immersive virtual environments as they would in similar situations in a physical environment? There are many ways to address this question, ranging from questionnaires, behavioral studies, and the use of physiological measures. Here, we compare the onsets of muscle activity using surface electromyography (EMG) while participants were walking under three different conditions: on a normal floor surface, on a narrow ribbon along the floor, and on a narrow platform raised off the floor. The same situation was rendered in an immersive virtual environment (IVE) Cave-like system, and 12 participants did the three types of walking in a counter-balanced within-groups design. The mean number of EMG activity onsets per unit time followed the same pattern in the virtual environment as in the physical environment-significantly higher for walking on the platform compared to walking on the floor. Even though participants knew that they were in fact really walking at floor level in the virtual environment condition, the visual illusion of walking on a raised platform was sufficient to influence their behavior in a measurable way. This opens up the door for this technique to be used in gait and posture related scenarios including rehabilitation. 相似文献