全文获取类型
收费全文 | 64396篇 |
免费 | 5096篇 |
国内免费 | 2826篇 |
专业分类
电工技术 | 3630篇 |
技术理论 | 7篇 |
综合类 | 4229篇 |
化学工业 | 10999篇 |
金属工艺 | 3570篇 |
机械仪表 | 3937篇 |
建筑科学 | 5455篇 |
矿业工程 | 1855篇 |
能源动力 | 1876篇 |
轻工业 | 4052篇 |
水利工程 | 1158篇 |
石油天然气 | 4508篇 |
武器工业 | 450篇 |
无线电 | 7068篇 |
一般工业技术 | 8016篇 |
冶金工业 | 3104篇 |
原子能技术 | 719篇 |
自动化技术 | 7685篇 |
出版年
2024年 | 226篇 |
2023年 | 1038篇 |
2022年 | 1723篇 |
2021年 | 2443篇 |
2020年 | 1892篇 |
2019年 | 1644篇 |
2018年 | 1864篇 |
2017年 | 2095篇 |
2016年 | 1905篇 |
2015年 | 2369篇 |
2014年 | 3214篇 |
2013年 | 3669篇 |
2012年 | 4086篇 |
2011年 | 4426篇 |
2010年 | 3879篇 |
2009年 | 3685篇 |
2008年 | 3608篇 |
2007年 | 3510篇 |
2006年 | 3564篇 |
2005年 | 3083篇 |
2004年 | 2089篇 |
2003年 | 1876篇 |
2002年 | 1645篇 |
2001年 | 1599篇 |
2000年 | 1655篇 |
1999年 | 1771篇 |
1998年 | 1382篇 |
1997年 | 1170篇 |
1996年 | 1053篇 |
1995年 | 936篇 |
1994年 | 769篇 |
1993年 | 556篇 |
1992年 | 433篇 |
1991年 | 336篇 |
1990年 | 312篇 |
1989年 | 226篇 |
1988年 | 174篇 |
1987年 | 107篇 |
1986年 | 104篇 |
1985年 | 60篇 |
1984年 | 41篇 |
1983年 | 26篇 |
1982年 | 33篇 |
1981年 | 22篇 |
1980年 | 13篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
101.
Finite-time weighted average consensus with respect to a monotonic function and its application 总被引:1,自引:0,他引:1
The consensus state is an important and fundamental quantity for consensus problems of multi-agent systems, which indicates where all the dynamical agents reach. In this paper, weighted average consensus with respect to a monotonic function, which means that the trajectories of the monotonic function along the state of each agent reach the weighted average of their initial values, is studied for a group of kinematic agents with time-varying topology. By constructing a continuous nonlinear distributed protocol, such a consensus problem can be solved in finite time even though the time-varying topology involves unconnected graphs. Then the distributed protocol is employed to compute the maximum-likelihood estimation of unknown parameters over sensor networks. Compared with the existing results, the estimate scheme proposed here may reduce the costs of data communication, storage memory, book-keeping and computational overheads. 相似文献
102.
Given a set of points in the plane, and a sweep-line as a tool, what is best way to move the points to a target point using a sequence of sweeps? In a sweep, the sweep-line is placed at a start position somewhere in the plane, then moved orthogonally and continuously to another parallel end position, and then lifted from the plane. The cost of a sequence of sweeps is the total length of the sweeps. Another parameter of interest is the number of sweeps. Four variants are discussed, depending on whether the target is a hole or a pile, and whether the target is specified or freely selected by the algorithm. Here we present a ratio 4/π≈1.27 approximation algorithm in the length measure, which performs at most four sweeps. We also prove that, for the two constrained variants, there are sets of n points for which any sequence of minimum cost requires 3n/2?O(1) sweeps. 相似文献
103.
OMT在企业物流分析中的应用 总被引:2,自引:1,他引:1
文章介绍了面向对象的模型化技术(OMT)的基本概念,分析了它的实现过程,即对象模型、动态模型、和过程模型的建立,并以一个具体的实例说明其在企业物流分析中的应用。 相似文献
104.
本文针对复杂的人体步行的神经 -肌肉 -骨胳系统模型 ,分析了步行中的主要关系 ,对神经网络模型作了较大的简化和修改 ,提出了一个简单的神经网络模型 .该模型在步行状态、神经耦合、感觉信号反馈等方面都作了简化 .计算机仿真表明 ,该模型能产生稳定的步行运动 相似文献
105.
对上海市地铁列车中的三种不同车型的微机控制系统的总线进行分析与研究,并针对近年总线通信中出现的问题,提出改进方法。 相似文献
106.
107.
A method for observing the three-dimensional morphologies of inclusions by deeply eroding a steel sample with a kind of organic solution composed of bromine water,acetone,and HC1 (volume ratio,45∶45∶10... 相似文献
108.
In this paper, we consider the partial pole assignment problem (PPAP) for high order control systems. It is shown that solving the PPAP is essentially solving a pole assignment for a linear system of a much lower order, and the robust PPAP is then concerning the robust pole assignment problem for this linear system. Based on this theory, a rather simple algorithm for solving the robust PPAP is proposed, and numerical examples show that this algorithm does lead to comparable results with earlier algorithms, but at much lower computational cost. 相似文献
109.
Jun-Qiu Jiang Kun Wang Xue-Xuan Peng Qing-Liang Zhao Yun-Shu Zhang Xiu-Dong Zhou 《哈尔滨工业大学学报(英文版)》2013,20(4):1-6
This paper compared the degradation efficiency of sludge organic matters and electric-production by two typical microbial fuel cells——dual-chamber microbial fuel cell(DMFC)and single chamber air cathode microbial fuel cell(SAMFC),and the variations of sludge protein,polysaccharide and ammonia nitrogen within the systems were also investigated.The results showed that the concentration of sludge soluble chemical oxygen demand,protein and carbohydrate of DMFC are higher than these of SAMFC during the systems operation,while DMFC can achieve a better ammonia nitrogen removal than SAMFC.Under the same operation condition,the stable voltage output of DMFC and SAMFC is 0.61 V and 0.37 V;the maximum power density of DMFC and SAMFC is 2.79 W/m3and 1.25 W/m3;TCOD removal efficiency of DMFC and SAMFC is 34.14%and 28.63%for 12 d,respectively.Meanwhile,DMFC has a higher coulomb efficiency than SAMFC,but both are less than5%.The results showed that DMFC present a better performance on sludge degradation and electric-production. 相似文献
110.
孟政 《武汉理工大学学报(材料科学英文版)》2013,28(1):79-81
The oxidation state of sulfur is detected in Na2O-CaO-SiO2 float glass by synchrotron radiation X-ray absorption near edge structure (XANES) spectra at the sulfur K edge. The measured spectra show the only presence of S6+ in the Na2O-CaO-SiO2 float glass and the oxidation state of sulfur do not change with the increase of glass depth. It is also found that, after the melt has gone through the molten tin bath, the S6+ is the dominant species, but S2- is also present on both surfaces. It is not certain whether cation bonds to S2- or not, because there are many cations dissolved in the melted tin which makes the spectrum complicated. 相似文献