全文获取类型
收费全文 | 3312篇 |
免费 | 310篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 38篇 |
化学工业 | 915篇 |
金属工艺 | 115篇 |
机械仪表 | 77篇 |
建筑科学 | 89篇 |
矿业工程 | 16篇 |
能源动力 | 89篇 |
轻工业 | 476篇 |
水利工程 | 17篇 |
石油天然气 | 16篇 |
无线电 | 188篇 |
一般工业技术 | 826篇 |
冶金工业 | 69篇 |
原子能技术 | 25篇 |
自动化技术 | 669篇 |
出版年
2023年 | 56篇 |
2022年 | 42篇 |
2021年 | 122篇 |
2020年 | 110篇 |
2019年 | 111篇 |
2018年 | 196篇 |
2017年 | 198篇 |
2016年 | 217篇 |
2015年 | 159篇 |
2014年 | 187篇 |
2013年 | 393篇 |
2012年 | 204篇 |
2011年 | 220篇 |
2010年 | 211篇 |
2009年 | 169篇 |
2008年 | 115篇 |
2007年 | 71篇 |
2006年 | 45篇 |
2005年 | 23篇 |
2004年 | 30篇 |
2003年 | 34篇 |
2002年 | 35篇 |
2001年 | 33篇 |
2000年 | 26篇 |
1999年 | 26篇 |
1998年 | 24篇 |
1997年 | 22篇 |
1996年 | 28篇 |
1995年 | 21篇 |
1994年 | 29篇 |
1993年 | 23篇 |
1992年 | 16篇 |
1991年 | 18篇 |
1990年 | 13篇 |
1989年 | 12篇 |
1987年 | 17篇 |
1986年 | 14篇 |
1985年 | 27篇 |
1984年 | 31篇 |
1983年 | 28篇 |
1982年 | 26篇 |
1981年 | 24篇 |
1980年 | 20篇 |
1979年 | 17篇 |
1978年 | 13篇 |
1977年 | 18篇 |
1976年 | 18篇 |
1975年 | 19篇 |
1974年 | 18篇 |
1973年 | 19篇 |
排序方式: 共有3625条查询结果,搜索用时 15 毫秒
71.
Kannan Balakrishnan Boštjan Brešar Manoj Changat Sandi Klavžar Matjaž Kovše Ajitha R. Subhamathi 《Algorithmica》2010,57(2):207-216
The median (antimedian) set of a profile π=(u
1,…,u
k
) of vertices of a graph G is the set of vertices x that minimize (maximize) the remoteness ∑
i
d(x,u
i
). Two algorithms for median graphs G of complexity O(n idim(G)) are designed, where n is the order and idim(G) the isometric dimension of G. The first algorithm computes median sets of profiles and will be in practice often faster than the other algorithm which
in addition computes antimedian sets and remoteness functions and works in all partial cubes. 相似文献
72.
73.
74.
Filip Goldefus Tomáš Masopust Alexander Meduna 《Theoretical computer science》2010,411(40-42):3661-3667
A left-forbidding grammar, introduced in this paper, is a context-free grammar, where a set of nonterminal symbols is attached to each context-free production. Such a production can rewrite a nonterminal provided that no symbol from the attached set occurs to the left of the rewritten nonterminal in the current sentential form. The present paper discusses cooperating distributed grammar systems with left-forbidding grammars as components and gives some new characterizations of language families of the Chomsky hierarchy. In addition, it also proves that twelve nonterminals are enough for cooperating distributed grammar systems working in the terminal derivation mode with two left-forbidding components (including erasing productions) to characterize the family of recursively enumerable languages. 相似文献
75.
Urban environments possess many regularities which can be efficiently exploited for 3D dense reconstruction from multiple
widely separated views. We present an approach utilizing properties of piecewise planarity and restricted number of plane
orientations to suppress reconstruction and matching ambiguities causing failures of standard dense stereo methods. We formulate
the problem of the 3D reconstruction in MRF framework built on an image pre-segmented into superpixels. Using this representation,
we propose novel photometric and superpixel boundary consistency terms explicitly derived from superpixels and show that they
overcome many difficulties of standard pixel-based formulations and handle favorably problematic scenarios containing many
repetitive structures and no or low textured regions. We demonstrate our approach on several wide-baseline scenes demonstrating
superior performance compared to previously proposed methods. 相似文献
76.
The paper deals with a numerical analysis of the incomplete interior penalty Galerkin (IIPG) method applied to one dimensional
Poisson problem. Based on a particular choice of the interior penalty parameter σ (order of O(h
−1)), we derive the optimal error estimate in the L
2-norm for odd degrees of polynomial approximation for locally quasi-uniform meshes. Moreover, we show that only the mentioned
choice of the penalty parameter leads to optimal orders of convergence. Finally, presented numerical experiments verify the
theoretical results. 相似文献
77.
We investigated intrinsic noise in plasmonic sensors caused by adsorption and desorption of gaseous analytes on the sensor
surface. We analyzed a general situation when there is a larger number of different analyte species. We applied our model
to calculate various analyte mixtures, including some environmental pollutants, toxic and dangerous substances. The spectral
density of mean square refractive index fluctuations follows a dependence similar to that of generation-recombination noise
in photodetectors, flat at lower frequencies and sharply decreasing at higher. Some of the calculated noise levels are well
within the detection range of conventional surface plasmon resonance sensors. An AD noise peak is observed in temperature
dependence of mean square refractive index fluctuations, thus sensor operating temperature may be optimized to obtain larger
signal to noise ratio. A significant property of AD noise is its rise with the decreasing plasmon sensor area, which means
that it will be even more pronounced in modern nanoplasmonic devices. Our consideration is valid both for conventional surface
plasmon resonance devices and for general nanoplasmonic devices. 相似文献
78.
79.
80.
We present a theoretical model for self-assembling DNA tiles with flexible branches. We encode an instance of a “problem” as a pot of such tiles for which a “solution” is an assembled complete complex without any free sticky ends. Using the number of tiles in an assembled complex as a measure of complexity we show how NTIME classes (such as NP and NEXP) can be represented with corresponding classes of the model. 相似文献