全文获取类型
收费全文 | 2816篇 |
免费 | 16篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 20篇 |
综合类 | 6篇 |
化学工业 | 701篇 |
金属工艺 | 66篇 |
机械仪表 | 47篇 |
建筑科学 | 114篇 |
矿业工程 | 9篇 |
能源动力 | 221篇 |
轻工业 | 16篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 232篇 |
一般工业技术 | 518篇 |
冶金工业 | 18篇 |
原子能技术 | 23篇 |
自动化技术 | 840篇 |
出版年
2023年 | 27篇 |
2022年 | 14篇 |
2021年 | 16篇 |
2020年 | 41篇 |
2019年 | 31篇 |
2018年 | 11篇 |
2017年 | 84篇 |
2016年 | 55篇 |
2015年 | 81篇 |
2014年 | 175篇 |
2013年 | 181篇 |
2012年 | 137篇 |
2011年 | 201篇 |
2010年 | 182篇 |
2009年 | 192篇 |
2008年 | 154篇 |
2007年 | 170篇 |
2006年 | 116篇 |
2005年 | 131篇 |
2004年 | 73篇 |
2003年 | 94篇 |
2002年 | 87篇 |
2001年 | 82篇 |
2000年 | 53篇 |
1999年 | 67篇 |
1998年 | 38篇 |
1997年 | 31篇 |
1996年 | 52篇 |
1995年 | 31篇 |
1994年 | 30篇 |
1993年 | 27篇 |
1992年 | 26篇 |
1991年 | 16篇 |
1990年 | 22篇 |
1989年 | 12篇 |
1988年 | 9篇 |
1987年 | 5篇 |
1986年 | 7篇 |
1985年 | 13篇 |
1984年 | 18篇 |
1983年 | 16篇 |
1982年 | 11篇 |
1981年 | 8篇 |
1980年 | 7篇 |
排序方式: 共有2834条查询结果,搜索用时 288 毫秒
71.
This paper presents a hybrid evolutionary algorithm (HEA) to solve heterogeneous fleet vehicle routing problems with time windows. There are two main types of such problems, namely the fleet size and mix vehicle routing problem with time windows (F) and the heterogeneous fixed fleet vehicle routing problem with time windows (H), where the latter, in contrast to the former, assumes a limited availability of vehicles. The main objective is to minimize the fixed vehicle cost and the distribution cost, where the latter can be defined with respect to en-route time (T) or distance (D). The proposed unified algorithm is able to solve the four variants of heterogeneous fleet routing problem, called FT, FD, HT and HD, where the last variant is new. The HEA successfully combines several metaheuristics and offers a number of new advanced efficient procedures tailored to handle the heterogeneous fleet dimension. Extensive computational experiments on benchmark instances have shown that the HEA is highly effective on FT, FD and HT. In particular, out of the 360 instances we obtained 75 new best solutions and matched 102 within reasonable computational times. New benchmark results on HD are also presented. 相似文献
72.
Batch sequencing and cooperation 总被引:1,自引:0,他引:1
Game theoretic analysis of sequencing situations has been restricted to manufacturing systems which consist of machines that can process only one job at a time. However, in many manufacturing systems, operations are carried out by batch machines which can simultaneously process multiple jobs. This paper aims to extend the game theoretical approach to the cost allocation problems arising from sequencing situations on systems that consist of batch machines. To analyze the allocation problem at hand, it focusses on the existence of core elements, convexity, and the Shapley value. 相似文献
73.
We study a motion planning problem where items have to be transported from the top room of a tower to the bottom of the tower, while simultaneously other items have to be transported in the opposite direction. Item sets are moved in two baskets hanging on a rope and pulley. To guarantee stability of the system, the weight difference between the contents of the two baskets must always stay below a given threshold. We prove that it is $\varPi_{2}^{p}$ -complete to decide whether some given initial situation of the underlying discrete system can lead to a given goal situation. Furthermore we identify several polynomially solvable special cases of this reachability problem, and we also settle the computational complexity of a number of related questions. 相似文献
74.
《Computer Languages, Systems and Structures》2013,39(4):142-162
Corecursion is the ability of defining a function that produces some infinite data in terms of the function and the data itself, as supported by lazy evaluation. However, in languages such as Haskell strict operations fail to terminate even on infinite regular data, that is, cyclic data.Regular corecursion is naturally supported by coinductive Prolog, an extension where predicates can be interpreted either inductively or coinductively, that has proved to be useful for formal verification, static analysis and symbolic evaluation of programs.In this paper we use the meta-programming facilities offered by Prolog to propose extensions to coinductive Prolog aiming to make regular corecursion more expressive and easier to program with.First, we propose a new interpreter to solve the problem of non-terminating failure as experienced with the standard semantics of coinduction (as supported, for instance, in SWI-Prolog). Another problem with the standard semantics is that predicates expressed in terms of existential quantification over a regular term cannot directly defined by coinduction; to this aim, we introduce finally clauses, to allow more flexibility in coinductive definitions.Then we investigate the possibility of annotating arguments of coinductive predicates, to restrict coinductive definitions to a subset of the arguments; this allows more efficient definitions, and further enhance the expressive power of coinductive Prolog.We investigate the effectiveness of such features by showing different example programs manipulating several kinds of cyclic values, ranging from automata and context free grammars to graphs and repeating decimals; the examples show how computations on cyclic values can be expressed with concise and relatively simple programs.The semantics defined by these vanilla meta-interpreters are an interesting starting point for a more mature design and implementation of coinductive Prolog. 相似文献
75.
In our global village, distance is not a barrier anymore for traveling. People experience new cultures and face accompanying difficulties in order to live anywhere. Social support can help these sojourners to cope with difficulties, such as culture shock. In this paper, we investigate how computer-mediated communication (CMC) tools can facilitate social support when living physically separated from loved-ones in different cultures. The goal is to understand the design considerations necessary to design new CMC tools. We studied communication practices of Chinese sojourners living in the Netherlands and the use of a technology probe with a novel video communication system. These results led to recommendations which can help designers to design interactive communication tools that facilitate communication across cultures. We conclude the paper with an interactive communication device called Circadian, which was designed based on these recommendations. We experienced the design recommendations to be abstract enough to leave space for creativity while providing a set of clear requirements which we used to base design decisions upon. 相似文献
76.
We present a new method for automatically proving termination of term rewriting. It is based on the well-known idea of interpretation
of terms where every rewrite step causes a decrease, but instead of the usual natural numbers we use vectors of natural numbers,
ordered by a particular nontotal well-founded ordering. Function symbols are interpreted by linear mappings represented by
matrices. This method allows us to prove termination and relative termination. A modification of the latter, in which strict
steps are only allowed at the top, turns out to be helpful in combination with the dependency pair transformation. By bounding
the dimension and the matrix coefficients, the search problem becomes finite. Our implementation transforms it to a Boolean
satisfiability problem (SAT), to be solved by a state-of-the-art SAT solver. 相似文献
77.
Ting Wang Jochem Vonk Benedikt Kratz Paul Grefen 《Distributed and Parallel Databases》2008,23(3):235-270
Transactions have been around since the Seventies to provide reliable information processing in automated information systems.
Originally developed for simple ‘debit-credit’ style database operations in centralized systems, they have moved into much
more complex application domains including aspects like distribution, process-orientation and loose coupling. The amount of
published research work on transactions is huge and a number of overview papers and books already exist. A concise historic
analysis providing an overview of the various phases of development of transaction models and mechanisms in the context of
growing complexity of application domains is still missing, however. To fill this gap, this paper presents a historic overview
of transaction models organized in several ‘transaction management eras’, thereby investigating numerous transaction models
ranging from the classical flat transactions, via advanced and workflow transactions to the Web Services and Grid transaction
models. The key concepts and techniques with respect to transaction management are investigated. Placing well-known research
efforts in historical perspective reveals specific trends and developments in the area of transaction management. As such,
this paper provides a comprehensive, structured overview of developments in the area. 相似文献
78.
We present a novel approach for extreme simplification of point set models, in the context of real-time rendering. Point sets
are often rendered using simple point primitives, such as oriented discs. However, this requires using many primitives to
render even moderately simple shapes. Often, one wishes to render a simplified model using only a few primitives, thus trading
accuracy for simplicity. For this goal, we propose a more complex primitive, called a splat, that is able to approximate larger and more complex surface areas than oriented discs. We construct our primitive by decomposing
the model into quasi-flat regions, using an efficient algebraic multigrid algorithm. Next, we encode these regions into splats
implemented as planar support polygons textured with color and transparency information and render the splats using a special
blending algorithm. Our approach combines the advantages of mesh-less point-based techniques with traditional polygon-based
techniques. We demonstrate our method on various models. 相似文献
79.
Christian Struck Pieter J.C.J. de Wilde Jan L.M. Hensen 《Advanced Engineering Informatics》2009,23(4):386-395
This article describes research conducted to gather empirical evidence on size, character and content of the option space in building design projects. This option space is the key starting point for the work of any climate engineer using building performance simulation who is supporting the design process. The underlying goal is to strengthen the role of advanced computing in building design, especially in the early conceptual stage, through a better integration of building performance simulation tools augmented with uncertainty analysis and sensitivity analysis. Better integration will need to assist design rather than automate design, allowing a spontaneous, creative and flexible process that acknowledges the expertise of the design team members. This research investigates and contrasts emergent option spaces and their inherent uncertainties in an artificial setting (student design studios) and in real-life scenarios (commercial design project case studies). The findings provide empirical evidence of the high variability of the option space that can be subjected to uncertainty analysis and sensitivity analysis. 相似文献
80.
A classification of methods for distributed system optimization based on formulation structure 总被引:2,自引:1,他引:1
S. Tosserams L. F. P. Etman J. E. Rooda 《Structural and Multidisciplinary Optimization》2009,39(5):503-517
Augmented Lagrangian coordination (ALC) is a provably convergent coordination method for multidisciplinary design optimization
(MDO) that is able to treat both linking variables and linking functions (i.e. system-wide objectives and constraints). Contrary
to quasi-separable problems with only linking variables, the presence of linking functions may hinder the parallel solution
of subproblems and the use of the efficient alternating directions method of multipliers. We show that this unfortunate situation
is not the case for MDO problems with block-separable linking constraints. We derive a centralized formulation of ALC for
block-separable constraints, which does allow parallel solution of subproblems. Similarly, we derive a distributed coordination
variant for which subproblems cannot be solved in parallel, but that still enables the use of the alternating direction method
of multipliers. The approach can also be used for other existing MDO coordination strategies such that they can include block-separable
linking constraints.
This work is funded by MicroNed, grant number 10005898. 相似文献