全文获取类型
收费全文 | 5776篇 |
免费 | 467篇 |
国内免费 | 113篇 |
专业分类
电工技术 | 251篇 |
综合类 | 202篇 |
化学工业 | 1011篇 |
金属工艺 | 208篇 |
机械仪表 | 187篇 |
建筑科学 | 351篇 |
矿业工程 | 53篇 |
能源动力 | 313篇 |
轻工业 | 505篇 |
水利工程 | 97篇 |
石油天然气 | 178篇 |
武器工业 | 4篇 |
无线电 | 652篇 |
一般工业技术 | 857篇 |
冶金工业 | 371篇 |
原子能技术 | 20篇 |
自动化技术 | 1096篇 |
出版年
2024年 | 18篇 |
2023年 | 98篇 |
2022年 | 183篇 |
2021年 | 234篇 |
2020年 | 186篇 |
2019年 | 187篇 |
2018年 | 232篇 |
2017年 | 205篇 |
2016年 | 245篇 |
2015年 | 221篇 |
2014年 | 241篇 |
2013年 | 455篇 |
2012年 | 349篇 |
2011年 | 450篇 |
2010年 | 354篇 |
2009年 | 355篇 |
2008年 | 288篇 |
2007年 | 238篇 |
2006年 | 238篇 |
2005年 | 189篇 |
2004年 | 129篇 |
2003年 | 149篇 |
2002年 | 195篇 |
2001年 | 142篇 |
2000年 | 104篇 |
1999年 | 60篇 |
1998年 | 92篇 |
1997年 | 65篇 |
1996年 | 60篇 |
1995年 | 59篇 |
1994年 | 50篇 |
1993年 | 37篇 |
1992年 | 21篇 |
1991年 | 9篇 |
1990年 | 17篇 |
1989年 | 12篇 |
1988年 | 16篇 |
1987年 | 14篇 |
1986年 | 12篇 |
1985年 | 9篇 |
1984年 | 23篇 |
1983年 | 10篇 |
1982年 | 13篇 |
1981年 | 12篇 |
1980年 | 6篇 |
1979年 | 9篇 |
1978年 | 10篇 |
1977年 | 9篇 |
1976年 | 13篇 |
1975年 | 7篇 |
排序方式: 共有6356条查询结果,搜索用时 0 毫秒
71.
Ramzi Guesmi Mohamed Amine Ben Farah Abdennaceur Kachouri Mounir Samet 《Multimedia Tools and Applications》2016,75(8):4753-4769
This paper proposes a color image encryption scheme using one-time keys based on crossover operator, chaos and the Secure Hash Algorithm(SHA-2). The (SHA-2) is employed to generate a 256-bit hash value from both the plain-image and the secret hash keys to make the key stream change in each encryption process. The SHA-2 value is employed to generate three initial values of the chaotic system. The permutation-diffusion process is based on the crossover operator and XOR operator, respectively. Experimental results and security analysis show that the scheme can achieve good encryption result through only one round encryption process, the key space is large enough to resist against common attacks,so the scheme is reliable to be applied in image encryption and secure communication. 相似文献
72.
Xin Lin Chris M. J. Tampère Francesco Viti Ben Immers 《Networks and Spatial Economics》2016,16(1):349-369
Increasing numbers of hard environmental constraints are being imposed in urban traffic networks by authorities in an attempt to mitigate pollution caused by traffic. However, it is not trivial for authorities to assess the cost of imposing such hard environmental constraints. This leads to difficulties when setting the constraining values as well as implementing effective control measures. For that reason, quantifying the cost of imposing hard environmental constraints for a certain network becomes crucial. This paper first indicates that for a given network, such cost is not only related to the attribution of environmental constraints but also related to the considered control measures. Next, we present an assessment criterion that quantifies the loss of optimality under the control measures considered by introducing the environmental constraints. The criterion can be acquired by solving a bi-level programming problem with/without environmental constraints. A simple case study shows its practicability as well as the differences between this framework and other frameworks integrating the environmental aspects. This proposed framework is widely applicable when assessing the interaction of traffic and its environmental aspects. 相似文献
73.
Lamia?Ben?HamoudaEmail author Mounir?Ayadi Nicolas?Langlois 《International Journal of Control, Automation and Systems》2016,14(2):443-451
This paper proposes a Fuzzy Fault Tolerant Predictive Control (FFTPC) with integral action method for a class of nonlinear systems. The Takagi-Sugeno (T-S) fuzzy approach is introduced as a modelling technique in order to consider the active control methods adapted to linear models. The proposed control strategy is based on a combination between Parallel Distributed Compensation (PDC) control law and Model Predictive Control (MPC) where the T-S fuzzy aspect uses the Unmeasurable Premise Variables (UPV). A T-S fuzzy observer provides an L2 norm estimation of system state vector and faults. The controller and observer gains are obtained by solving Linear Matrix Inequalities (LMIs) derived from the Lyapunov theory. The validity of the proposed Fault Tolerant Control (FTC) strategy is illustrated through an application to a Diesel Engine Air Path (DEAP) system. 相似文献
74.
提出了一种基于灰关联混合蛙跳算法的雷达波形设计方法,以混合蛙跳算法为主体,在局部更
新算子中引入遗传算法的遗传算子,并改进原始蛙跳算法的分组方法,丰富了种群的多样性,同时引入灰关联综合评价法则对适应度函数值加以关联度分析。文中以设计具有低自相关旁瓣和互相关特性的正交多相编码为例,将该算法用于雷达波形设计中。仿真结果表明使用本文算法产生
的波形具备较好的低自相关特性和互相关特性,表明了该算法是有效和可行的。 相似文献
75.
Dongyu Zhao Fan Fan Vladimir G. Chigrinov Hoi Sing Kwok Ben Zhong Tang 《Journal of the Society for Information Display》2015,23(5):218-222
Nowadays, liquid crystal displays (LCDs) with light‐emission are considered as energy‐efficient devices and are promising alternatives to conventional LCDs. To realize such possibility, strong fluorescent materials with a dichroic properties are required. Aggregate‐induced emission (AIE) is an unusual photophysical phenomenon shown by some luminogenic materials that will be highly emissive in their aggregate state. In this work, we studied the AIE effect of a luminescent liquid crystalline molecule TPE‐PPE in our LC system as a luminophore dopant. The result showed the excellent AIE effect that higher concentration of luminogen in the nematic LC host induced stronger luminescent intensity. Through exposure of a photoisomeriable alignment material sulfonic‐dye‐1, the photopatterning of a light‐emitting LC device was achieved with the use of the TPE‐PPE/nematic LC mixture. 相似文献
76.
77.
Ben W. Morrison Mark W. Wiggins Glenn Porter 《International journal of human-computer interaction》2013,29(4):297-316
This study examined trainee crime-scene investigators' preference for, and accuracy in using, four different computer-based decision support interface designs, each of which incorporated a different reduced processing information acquisition strategy. The interfaces differed on the basis of the number of options that could be considered simultaneously and the level of control that could be exercised over the number and sequence in which feature values were accessed. Forty trainee investigators completed six decision scenarios in which they were asked to acquire information and formulate a decision by selecting one of three options. The study comprised two phases, the first of which involved familiarizing participants with each of the four interface designs and collecting performance and subjective data. The second phase involved trainees selecting one of the four interfaces to engage in a fifth and sixth decision scenario involving high or low levels of time-pressure. The results indicated that the “all options, full control” interface was the preferred option in the low time-pressure condition. Although the strategy remained the most frequently selected in the high time-pressure condition, this preference was not significant. It was concluded that the perceptions of difficulty and the degree of user control over information acquisition were more important than perceived efficiency in the selection of computer-based interface designs. The outcomes have implications for the design of decision support systems. 相似文献
78.
This paper proposes a new nonlinear unknown input observer. The observer design approach utilizes the first order Taylor expansion. The observer gains are then obtained by a systematic method. In this paper, we added some improvements to this method. The developed approach also can enable observer design for a large class of differentiable nonlinear systems. The necessary and sufficient conditions for the existence of the observer are given. A numerical example is given to illustrate the attractiveness and the simplicity of the new design procedure. 相似文献
79.
徐奔 《数字社区&智能家居》2009,5(5):3478-3480
该文将二值水印嵌入到宿主图像的小波变换域的低频分量中,利用BP神经网络很好的非线性映射和自学习、自适应学习特点实现水印信息的盲提取,仿真实验结果表明该算法既能抵抗常规的图像处理攻击,也能抵抗一定程度的几何攻击,如JPEG压缩、剪切、加噪和滤波等,具有较好的鲁棒性和不可见性。 相似文献
80.
针对当前形势下炼油企业蒸汽动力系统存在的巨大改造潜力,提出了蒸汽动力系统改造的优化方法;该方法首先通过运行优化方案分析和系统设备诊断找出系统存在问题,然后通过专家知识系统提出一系列解决的方案,建立系统改造方案的超结构和考虑柔性调节的优化改造混合整数线性规划(MILP)模型,求解模型并确定最优的改造方案;文章最后部分给出了详细的案例分析,结果表明应用本文提出的改造优化策略方法确定的最佳改造方案可以为案例背景炼油企业蒸汽动力系统节约大约6%的运行费用,投资回收期约0.38年;本文提出的优化改造方法为推动炼油企业蒸汽动力系统的节能降耗提供了定的理论指导和技术支持. 相似文献