全文获取类型
收费全文 | 58446篇 |
免费 | 6586篇 |
国内免费 | 3852篇 |
专业分类
电工技术 | 4439篇 |
技术理论 | 1篇 |
综合类 | 5214篇 |
化学工业 | 7950篇 |
金属工艺 | 3614篇 |
机械仪表 | 3865篇 |
建筑科学 | 4788篇 |
矿业工程 | 2243篇 |
能源动力 | 1634篇 |
轻工业 | 5952篇 |
水利工程 | 1822篇 |
石油天然气 | 2403篇 |
武器工业 | 570篇 |
无线电 | 6371篇 |
一般工业技术 | 6033篇 |
冶金工业 | 2554篇 |
原子能技术 | 999篇 |
自动化技术 | 8432篇 |
出版年
2024年 | 372篇 |
2023年 | 1183篇 |
2022年 | 2258篇 |
2021年 | 2957篇 |
2020年 | 2206篇 |
2019年 | 1603篇 |
2018年 | 1734篇 |
2017年 | 2053篇 |
2016年 | 1822篇 |
2015年 | 2601篇 |
2014年 | 3218篇 |
2013年 | 3843篇 |
2012年 | 4420篇 |
2011年 | 4698篇 |
2010年 | 4193篇 |
2009年 | 3956篇 |
2008年 | 4008篇 |
2007年 | 3894篇 |
2006年 | 3365篇 |
2005年 | 2907篇 |
2004年 | 1921篇 |
2003年 | 1430篇 |
2002年 | 1296篇 |
2001年 | 1241篇 |
2000年 | 1046篇 |
1999年 | 809篇 |
1998年 | 627篇 |
1997年 | 496篇 |
1996年 | 536篇 |
1995年 | 433篇 |
1994年 | 370篇 |
1993年 | 283篇 |
1992年 | 219篇 |
1991年 | 185篇 |
1990年 | 136篇 |
1989年 | 116篇 |
1988年 | 105篇 |
1987年 | 71篇 |
1986年 | 48篇 |
1985年 | 36篇 |
1984年 | 33篇 |
1983年 | 22篇 |
1982年 | 16篇 |
1981年 | 19篇 |
1980年 | 28篇 |
1979年 | 14篇 |
1978年 | 8篇 |
1976年 | 7篇 |
1959年 | 12篇 |
1951年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Research on the group decision-making about emergency event based on network technology 总被引:1,自引:1,他引:0
Kefan Xie Gang Chen Qian Wu Yang Liu Pan Wang 《Information Technology and Management》2011,12(2):137-147
In order to improve decision-making efficiency about emergency event, this paper proposes a novel concept, i.e., Agile-Delphi
Method, which is an integration of agile decision and Delphi Method implicating that the decision-makers instantly deliver,
respond, treat, and utilize information via Delphi process while conducting group decision-making about emergency event. The
paper details the mechanism of group decision-making about emergency event based on network technology and Agile-Delphi Method.
Finally, the paper conducts an empiric analysis taking the “111 event”, i.e., the liquid ammonia spill event happened on November
1, 2006 in a phosphorus chemical company in China, as an example. 相似文献
52.
基于HLA的卫星协同仿真系统研究与实现 总被引:1,自引:0,他引:1
基于HLA体系规范,研究协同仿真软件体系结构,设计了一个卫星协同仿真系统CSS(Coordinated Simulation System).首先简要介绍了系统研究的意义,以系统功能以及系统要素为基础分析了系统的需求、提出了基于"协同"的设计原则以及系统性能评估指标,然后介绍了实现CSS的关键技术--使命空间的任务体现结构和多分辨率建模技术 ,以及CSS的分层设计的系统结构,并以仿真任务管理成员和卫星成员为例分析了设计CSS联邦成员的设计思路,最后提出了一个原型系统.该系统仿真了卫星侦查、数据通信、数据评估等整个过程对大型复杂系统的仿真具有很好的借鉴意义. 相似文献
53.
潘春平 《数值计算与计算机应用》2011,32(4):267-273
为了改善古典迭代法的收敛速度,本文提出一种带参数的新预条件方法,并对参数的选择给出必要条件,证明了对于非奇异不可约M一矩阵,新预条件方法收敛且可以加速Gauss—Seidel迭代法的收敛速度,数值例子表明新预条件方法是有效的. 相似文献
54.
The defect of process equipments is a major factor that impairs the yields in the mass production of semiconductor wafer fabrication and it is a main supervision means to use high-resolution defect inspection tools to detect and monitor the defect damage. Due to the high investment costs of these inspection tools and the resulting decrease in the throughput, how to improve the sampling rate is an important issue for the associated inspection strategy. This paper proposes a new concept and implementation of virtual inspection (VI) to enhance the detection and monitoring of defect in semiconductor production process. The underlying theory of the VI concept is that the state variables identifications (SVIDs) of process equipments can reflect the process quality effectively and loyally. The approach of VI is to combine the application of the fault detection and classification (FDC), and the defect library and the re-engineering of inspection procedure to reach the full-scope of strategic objective. VI enables the defect monitoring to enter a new era by promoting the monitoring level of defect inspection from the previous lot-sampling basis to the wafer-sampling level, and hence upgrades the sampling strategy from random-sampling to full and right-sampling. In this study, various typical defect cases are utilized to illustrate how to create VI models and verify the reliability of the proposed approach. Furthermore, a feasible architecture of the VI implementation for mass production in semiconductor factory is presented in the paper. 相似文献
55.
Construction of 1-Resilient Boolean Functions with Optimal Algebraic Immunity and Good Nonlinearity 总被引:1,自引:0,他引:1 下载免费PDF全文
This paper presents a construction for a class of 1-resilient functions with optimal algebraic immunity on an even number
of variables. The construction is based on the concatenation of two balanced functions in associative classes. For some n, a part of 1-resilient functions with maximum algebraic immunity constructed in the paper can achieve almost optimal nonlinearity.
Apart from their high nonlinearity, the functions reach Siegenthaler's upper bound of algebraic degree. Also a class of 1-resilient
functions on any number n > 2 of variables with at least sub-optimal algebraic immunity is provided. 相似文献
56.
CCA-secure unidirectional proxy re-encryption in the adaptive corruption model without random oracles 总被引:1,自引:0,他引:1
DENG Robert 《中国科学:信息科学(英文版)》2010,(3):593-606
Up to now, it is still an open question of how to construct a chosen-ciphertext secure unidirectional proxy re-encryption scheme in the adaptive corruption model. To address this problem, we propose a new unidirectional proxy re-encryption scheme, and prove its chosen-ciphertext security in the adaptive corruption model without random oracles. Compared with the best known unidirectional proxy re-encryption scheme proposed by Libert and Vergnaud in PKC’08, our scheme enjoys the advantages of both higher effi... 相似文献
57.
58.
Wei-Hung Lin Yuh-Rau Wang Shi-Jinn Horng Tzong-Wann Kao Yi Pan 《Expert systems with applications》2009,36(9):11509-11516
This paper proposes a blind watermarking algorithm based on maximum wavelet coefficient quantization for copyright protection. The wavelet coefficients are grouped into different block size and blocks are randomly selected from different subbands. We add different energies to the maximum wavelet coefficient under the constraint that the maximum wavelet coefficient is always maximum in a block. The watermark is embedded the local maximum coefficient which can effectively resist attacks. Also, using the block-based watermarking, we can extract the watermark without using the original image or watermark. Experimental results show that the proposed method is quite robust under either non-geometry or geometry attacks. 相似文献
59.
The output feedback robust model predictive control (MPC), for the linear parameter varying (LPV) system with norm-bounded disturbance, is addressed, where the model parametric matrices are only known to be bounded within a polytope. The previous techniques of norm-bounding technique, quadratic boundedness (QB), dynamic output feedback, and ellipsoid (true-state bound; TSB) refreshment formula for guaranteeing recursive feasibility, are fused into the newly proposed approaches. In the notion of QB, the full Lyapunov matrix is applied for the first time in this context. The single-step dynamic output feedback robust MPC, where the infinite-horizon control moves are parameterised as a dynamic output feedback law, is the main topic of this paper, while the multi-step method is also suggested. In order to strictly guarantee the physical constraints, the outer bound of the true state replaces the true state itself, so tightness of this bound has a major effect on the control performance. In order to tighten the TSB, a procedure for refreshing the real-time ellipsoid based on that of the last sampling instant is given. This paper is conclusive for the past results and far-reaching for the future researches. Two benchmark examples are given to show the effectiveness of the novel results. 相似文献
60.
Huan Xie Xin Luo Xiong Xu Haiyan Pan Xiaohua Tong 《International journal of remote sensing》2016,37(8):1826-1844
The successful launch of the Landsat 8 satellite continues the Earth observation of the Landsat series, which has been taking place for nearly 40 years. With the increase in the band number and the improved spectral range compared with the previous Landsat imagery, it will be possible to expand the application of the new Landsat 8 imagery. The purpose of this study is to explore water extraction based on the new Landsat 8 Operational Land Imager (OLI) imagery. According to the specific inland water conditions (clear water, turbid water, and eutrophic water), a number of highly adaptable water indices are assessed for water extraction using Landsat OLI imagery. The results show that clear water is the easiest to extract among the different types of waterbodies, with the highest average accuracy of 97%. The highest-accuracy methods are the automated water extraction index for shadow pixels (AWEIsh), the normalized difference water index using bands 4 and 7 (NDWI47), and the normalized difference water index using bands 3 and 7 (NDWI37), with accuracies of 98.55%, 95.50%, and 96.61%, corresponding to clear water, turbid water, and eutrophic water, respectively. Through the analysis of the different methods for optimal band selection, the seventh band OLI7 (shortwave infrared 2, SWIR-2) of Landsat OLI shows the best performance in water identification. When applying the water indices to water extraction, Otsu’s algorithm has been used to automatically select the water threshold. Using extensive experiments with Otsu’s algorithm and a manual method, it was found that Otsu’s algorithm can replace manual selection and has the ability to select an accurate threshold for water extraction. 相似文献