全文获取类型
收费全文 | 2310篇 |
免费 | 129篇 |
国内免费 | 195篇 |
专业分类
电工技术 | 43篇 |
综合类 | 82篇 |
化学工业 | 27篇 |
金属工艺 | 19篇 |
机械仪表 | 81篇 |
建筑科学 | 37篇 |
矿业工程 | 13篇 |
能源动力 | 20篇 |
轻工业 | 39篇 |
水利工程 | 7篇 |
石油天然气 | 3篇 |
无线电 | 223篇 |
一般工业技术 | 67篇 |
冶金工业 | 4篇 |
原子能技术 | 1篇 |
自动化技术 | 1968篇 |
出版年
2024年 | 11篇 |
2023年 | 70篇 |
2022年 | 103篇 |
2021年 | 123篇 |
2020年 | 57篇 |
2019年 | 35篇 |
2018年 | 40篇 |
2017年 | 59篇 |
2016年 | 51篇 |
2015年 | 77篇 |
2014年 | 143篇 |
2013年 | 119篇 |
2012年 | 120篇 |
2011年 | 193篇 |
2010年 | 112篇 |
2009年 | 160篇 |
2008年 | 169篇 |
2007年 | 129篇 |
2006年 | 146篇 |
2005年 | 91篇 |
2004年 | 100篇 |
2003年 | 69篇 |
2002年 | 77篇 |
2001年 | 35篇 |
2000年 | 40篇 |
1999年 | 41篇 |
1998年 | 30篇 |
1997年 | 34篇 |
1996年 | 29篇 |
1995年 | 26篇 |
1994年 | 22篇 |
1993年 | 17篇 |
1992年 | 15篇 |
1991年 | 10篇 |
1990年 | 18篇 |
1989年 | 3篇 |
1988年 | 10篇 |
1987年 | 6篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 2篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1976年 | 3篇 |
1974年 | 2篇 |
1954年 | 1篇 |
排序方式: 共有2634条查询结果,搜索用时 0 毫秒
31.
马文宁 《数字社区&智能家居》2013,(9):5587-5588
数据库技术重要且应用广泛,文中介绍了数据库的三级模式和二级映像结构,在该结构下关系数据库的逻辑设计内容和设计方法,最后引入具体实例应用实践该方法并对实例作简单分析。 相似文献
32.
随着新一代测序技术的发展,一些新的全基因组组装算法应运而生,特别是针对第三代高通量测序仪产生的海量短序列的组装软件被不断开发出来,这些组装软件渐渐走向市场。但是,由于这些组装软件的适用性和其性能的差别,选择一款性能优良的组装工具或者开发并行高吞吐的组装工具成为了当前面临的一大难题。本文选取基于 De Bruijn 图算法开发的 4 款 De Novo 组装的软件(Velvet、SOAPdenovo、IDBA、ABySS)对 4 种物种的基因组的模拟数据进行测试,并从软件的算法、组装性能和组装质量 3 个方面分析这 4 个软件的性能,同时根据其算法特点推断影响这些软件性能的关键因素,并给出软件的使用建议以及开发并行序列组装工具来组装超大规模的基因数据应该注意的问题。 相似文献
33.
34.
We introduce a simple, linear time algorithm for recognizing trivially perfect (TP) graphs. It improves upon the algorithm of Yan et al. [J.-H. Yan, J.-J. Chen, G.J. Chang, Quasi-threshold graphs, Discrete Appl. Math. 69 (3) (1996) 247–255] in that it is certifying, producing a P4 or a C4 when the graph is not TP. In addition, our algorithm can be easily modified to recognize the complement of TP graphs (co-TP) in linear time as well. It is based on lexicographic BFS, and in particular the technique of partition refinement, which has been used in the recognition of many other graph classes [D.G. Corneil, Lexicographic breadth first search—a survey, in: WG 2004, in: Lecture Notes in Comput. Sci., vol. 3353, Springer, 2004, pp. 1–19]. 相似文献
35.
Mathieu Liedloff 《Information Processing Letters》2008,107(5):154-157
Finding a dominating set of minimum cardinality is an NP-hard graph problem, even when the graph is bipartite. In this paper we are interested in solving the problem on graphs having a large independent set. Given a graph G with an independent set of size z, we show that the problem can be solved in time O∗(2n−z), where n is the number of vertices of G. As a consequence, our algorithm is able to solve the dominating set problem on bipartite graphs in time O∗(2n/2). Another implication is an algorithm for general graphs whose running time is O(n1.7088). 相似文献
36.
We introduce and solve a problem motivated by integrity verification in third-party data distribution: Given an undirected tree, find a minimum-cardinality set of simple paths that cover all the tree edges and, secondarily, have smallest total path lengths. We give a linear time algorithm for this problem. 相似文献
37.
As part of the efforts to understand the intricacies of the k-colorability problem, different distributions over k-colorable graphs have been analyzed. While the problem is notoriously hard (not even reasonably approximable) in the worst case, the average case (with respect to such distributions) often turns out to be “easy”. Semi-random models mediate between these two extremes and are more suitable to imitate “real-life” instances than purely random models. In this work we consider semi-random variants of the planted k-colorability distribution. This continues a line of research pursued by Coja-Oghlan, and by Krivelevich and Vilenchik. Our aim is to study a more general semi-random framework than those suggested so far. On the one hand we show that previous algorithmic techniques extend to our more general semi-random setting; on the other hand we give a hardness result, proving that a closely related semi-random model is intractable. Thus we provide some indication about which properties of the input distribution make the k-colorability problem hard. 相似文献
38.
Hugo Zanghi Author Vitae Christophe Ambroise Author Vitae 《Pattern recognition》2008,41(12):3592-3599
In the context of graph clustering, we consider the problem of simultaneously estimating both the partition of the graph nodes and the parameters of an underlying mixture of affiliation networks. In numerous applications the rapid increase of data size over time makes classical clustering algorithms too slow because of the high computational cost. In such situations online clustering algorithms are an efficient alternative to classical batch algorithms. We present an original online algorithm for graph clustering based on a Erd?s-Rényi graph mixture. The relevance of the algorithm is illustrated, using both simulated and real data sets. The real data set is a network extracted from the French political blogosphere and presents an interesting community organization. 相似文献
39.
In this paper, we investigate the applicability of graph cuts to the SFS (shape-from-shading) problem. We propose a new semi-global method for SFS using graph cuts. The new algorithm combines the local method proposed by Lee and Rosenfeld [C.H. Lee, A. Rosenfeld, Improved methods of estimating shape from shading using the light source coordinate system, Artif. Intell. 26 (1985) 125-143] and a global method using an energy minimization technique. By employing a new global energy minimization formulation, the convex/concave ambiguity problem of Lee and Rosenfeld's method can be resolved efficiently. A new combinatorial optimization technique, the graph cuts method, is used for the minimization of the proposed energy functional. Experimental results on a variety of synthetic and real-world images show that the proposed algorithm reconstructs the 3-D shape of objects very efficiently. 相似文献
40.
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