全文获取类型
收费全文 | 6979篇 |
免费 | 347篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 105篇 |
综合类 | 14篇 |
化学工业 | 1725篇 |
金属工艺 | 160篇 |
机械仪表 | 137篇 |
建筑科学 | 453篇 |
矿业工程 | 32篇 |
能源动力 | 157篇 |
轻工业 | 630篇 |
水利工程 | 58篇 |
石油天然气 | 8篇 |
无线电 | 528篇 |
一般工业技术 | 1349篇 |
冶金工业 | 575篇 |
原子能技术 | 46篇 |
自动化技术 | 1356篇 |
出版年
2024年 | 11篇 |
2023年 | 106篇 |
2022年 | 145篇 |
2021年 | 240篇 |
2020年 | 160篇 |
2019年 | 146篇 |
2018年 | 210篇 |
2017年 | 182篇 |
2016年 | 277篇 |
2015年 | 255篇 |
2014年 | 335篇 |
2013年 | 428篇 |
2012年 | 413篇 |
2011年 | 505篇 |
2010年 | 383篇 |
2009年 | 370篇 |
2008年 | 362篇 |
2007年 | 349篇 |
2006年 | 267篇 |
2005年 | 232篇 |
2004年 | 174篇 |
2003年 | 173篇 |
2002年 | 149篇 |
2001年 | 100篇 |
2000年 | 110篇 |
1999年 | 86篇 |
1998年 | 176篇 |
1997年 | 104篇 |
1996年 | 103篇 |
1995年 | 99篇 |
1994年 | 50篇 |
1993年 | 61篇 |
1992年 | 50篇 |
1991年 | 36篇 |
1990年 | 25篇 |
1989年 | 30篇 |
1988年 | 35篇 |
1987年 | 22篇 |
1986年 | 25篇 |
1985年 | 27篇 |
1984年 | 39篇 |
1983年 | 24篇 |
1982年 | 19篇 |
1981年 | 14篇 |
1980年 | 13篇 |
1979年 | 15篇 |
1978年 | 24篇 |
1977年 | 21篇 |
1976年 | 30篇 |
1974年 | 15篇 |
排序方式: 共有7333条查询结果,搜索用时 15 毫秒
41.
B. Fishbain Dorit S. Hochbaum Stefan Mueller 《Journal of Real-Time Image Processing》2016,11(3):589-609
Rapid advances in image acquisition and storage technology underline the need for real-time algorithms that are capable of solving large-scale image processing and computer-vision problems. The minimum s–t cut problem, which is a classical combinatorial optimization problem, is a prominent building block in many vision and imaging algorithms such as video segmentation, co-segmentation, stereo vision, multi-view reconstruction, and surface fitting to name a few. That is why finding a real-time algorithm which optimally solves this problem is of great importance. In this paper, we introduce to computer vision the Hochbaum’s pseudoflow (HPF) algorithm, which optimally solves the minimum s–t cut problem. We compare the performance of HPF, in terms of execution times and memory utilization, with three leading published algorithms: (1) Goldberg’s and Tarjan’s Push-Relabel; (2) Boykov’s and Kolmogorov’s augmenting paths; and (3) Goldberg’s partial augment-relabel. While the common practice in computer-vision is to use either BK or PRF algorithms for solving the problem, our results demonstrate that, in general, HPF algorithm is more efficient and utilizes less memory than these three algorithms. This strongly suggests that HPF is a great option for many real-time computer-vision problems that require solving the minimum s–t cut problem. 相似文献
42.
43.
44.
This paper studies a new class of single-machine scheduling problems, which are faced by Just-in-Time-suppliers satisfying a given demand. In these models the processing of jobs leads to a release of a predefined number of product units into inventory. Consumption is triggered by predetermined time-varying, and product-specific demand requests. While all demands have to be fulfilled, the objective is to minimize the resulting product inventory. We investigate different subproblems of this general setting with regard to their computational complexity. For more restricted problem versions strongly polynomial time algorithms are presented. In contrast to this, NP-hardness in the strong sense is proven for more general problem versions. Moreover, for the most general version, even finding a feasible solution is shown to be strongly NP-hard. 相似文献
45.
We study a generalized job-shop problem called the body shop scheduling problem (BSSP). This problem arises from the industrial application of welding in a car body production line, where possible collisions between industrial robots have to be taken into account. BSSP corresponds to a job-shop problem where the operations of a job have to follow alternating routes on the machines, certain operations of different jobs are not allowed to be processed at the same time and after processing an operation of a certain job a machine might be unavailable for a given time for operations of other jobs. As main results we will show that for three jobs and four machines the special case where only one machine is used by more than one job is already $\mathcal NP $ -hard. This also implies that the single machine scheduling problem that asks for a makespan minimal schedule of three chains of operations with delays between the operations of a chain is $\mathcal NP $ -hard. On the positive side, we present a polynomial algorithm for the two job case and a pseudo-polynomial algorithm together with an FPTAS for an arbitrary but constant number of jobs. Hence for a constant number of jobs we fully settle the complexity status of the problem. 相似文献
46.
LUO Yu ZHAO RongKuo FERNANDEZ-DOMINGUEZ Antonio I. MAIER Stefan A. PENDRY John B. 《中国科学:信息科学(英文版)》2013,56(12):1-13
Transformation optics (TO) is a new tool for controlling electromagnetic fields. In the context of metamaterial technology, it provides a direct link between a desired electromagnetic (EM) phenomenon and the material response required for its occurrence. Recently, this powerful framework has been successfully exploited to study surface plasmon assisted phenomena such as light harvesting. Here, we review the general strategy based on TO to design plasmonic devices capable of harvesting light over a broadband spectrum and achieving considerable field confinement and enhancement. The methodology starts with two-dimensional (2D) cases, such as 2D metal edges, crescent-shaped cylinders, nanowire dimers, and rough metal surfaces, and is well extended to fully-fledged three-dimensional (3D) situations. The largely analytic approach gives physical insights into the processes involved and suggests a way forward to study a wide variety of plasmonic nanostructures. 相似文献
47.
Yazdan Shirvany Fredrik Edelvik Stefan Jakobsson Anders Hedström Mikael Persson 《Applied Soft Computing》2013,13(5):2515-2525
Surgical therapy has become an important therapeutic alternative for patients with medically intractable epilepsy. Correct and anatomically precise localization of an epileptic focus is essential to decide if resection of brain tissue is possible. The inverse problem in EEG-based source localization is to determine the location of the brain sources that are responsible for the measured potentials at the scalp electrodes. We propose a new global optimization method based on particle swarm optimization (PSO) to solve the epileptic spike EEG source localization inverse problem. In a forward problem a modified subtraction method is proposed to reduce the computational time. The good accuracy and fast convergence are demonstrated for 2D and 3D cases with realistic head models. The results from the new method are promising for use in the pre-surgical clinic in the future. 相似文献
48.
Nicolas Gisin Sandu Popescu Valerio Scarani Stefan Wolf Jürg Wullschleger 《Natural computing》2013,12(1):13-17
We show that from a communication-complexity perspective, the primitive called oblivious transfer—which was introduced in a cryptographic context—can be seen as the classical analogue to a quantum channel in the same sense as non-local boxes are of maximally entangled qubits. More explicitly, one realization of non-cryptographic oblivious transfer allows for the perfect simulation of sending one qubit and measuring it in an orthogonal basis. On the other hand, a qubit channel allows for realizing non-cryptographic oblivious transfer with probability roughly 85 %, whereas 75 % is the classical limit. 相似文献
49.
50.
The profile of a graph is an integer-valued parameter defined via vertex orderings; it is known that the profile of a graph
equals the smallest number of edges of an interval supergraph. Since computing the profile of a graph is an NP-hard problem,
we consider parameterized versions of the problem. Namely, we study the problem of deciding whether the profile of a connected
graph of order n is at most n−1+k, considering k as the parameter; this is a parameterization above guaranteed value, since n−1 is a tight lower bound for the profile. We present two fixed-parameter algorithms for this problem. The first algorithm
is based on a forbidden subgraph characterization of interval graphs. The second algorithm is based on two simple kernelization
rules which allow us to produce a kernel with linear number of vertices and edges. For showing the correctness of the second
algorithm we need to establish structural properties of graphs with small profile which are of independent interest.
A preliminary version of the paper is published in Proc. IWPEC 2006, LNCS vol. 4169, 60–71. 相似文献