全文获取类型
收费全文 | 4338篇 |
免费 | 555篇 |
国内免费 | 766篇 |
专业分类
电工技术 | 318篇 |
综合类 | 439篇 |
化学工业 | 561篇 |
金属工艺 | 85篇 |
机械仪表 | 293篇 |
建筑科学 | 290篇 |
矿业工程 | 183篇 |
能源动力 | 177篇 |
轻工业 | 406篇 |
水利工程 | 211篇 |
石油天然气 | 732篇 |
武器工业 | 30篇 |
无线电 | 300篇 |
一般工业技术 | 305篇 |
冶金工业 | 191篇 |
原子能技术 | 534篇 |
自动化技术 | 604篇 |
出版年
2024年 | 21篇 |
2023年 | 97篇 |
2022年 | 139篇 |
2021年 | 166篇 |
2020年 | 195篇 |
2019年 | 180篇 |
2018年 | 161篇 |
2017年 | 169篇 |
2016年 | 213篇 |
2015年 | 180篇 |
2014年 | 246篇 |
2013年 | 436篇 |
2012年 | 302篇 |
2011年 | 326篇 |
2010年 | 260篇 |
2009年 | 212篇 |
2008年 | 214篇 |
2007年 | 249篇 |
2006年 | 261篇 |
2005年 | 235篇 |
2004年 | 206篇 |
2003年 | 197篇 |
2002年 | 129篇 |
2001年 | 136篇 |
2000年 | 106篇 |
1999年 | 91篇 |
1998年 | 76篇 |
1997年 | 68篇 |
1996年 | 55篇 |
1995年 | 58篇 |
1994年 | 61篇 |
1993年 | 32篇 |
1992年 | 34篇 |
1991年 | 30篇 |
1990年 | 23篇 |
1989年 | 19篇 |
1988年 | 16篇 |
1987年 | 13篇 |
1986年 | 9篇 |
1985年 | 7篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 9篇 |
1980年 | 4篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1959年 | 7篇 |
排序方式: 共有5659条查询结果,搜索用时 15 毫秒
51.
Semi-global finite-time observers for nonlinear systems 总被引:5,自引:0,他引:5
It is well known that high gain observers exist for single output nonlinear systems that are uniformly observable and globally Lipschitzian. Under the same conditions, we show that these systems admit semi-global and finite-time converging observers. This is achieved with a derivation of a new sufficient condition for local finite-time stability, in conjunction with applications of geometric homogeneity and Lyapunov theories. 相似文献
52.
Yuan Deng Yihai Yang Yuanhang Xiao He-Lou Xie Ruochen Lan Lanying Zhang Huai Yang 《Advanced functional materials》2023,33(35):2301319
Switchable passive radiative cooling (PRC) smart windows can modulate sunlight transmission and spontaneously emit heat to outer space through atmospheric transparent window, presenting great potential in building energy conservation. However, realizing stable and on-demand control of the cooling efficiency for PRC materials is still challenging. Herein, an electro-controlled polymer-dispersed liquid crystal (PDLC) smart window showing PRC property is designed and prepared by adding mid-infrared emitting reactive monomers into the conventional PDLC matrix. It is found that not only the electro-optical properties but also the PRC efficiency of PRC PDLC film are tunable by regulating the content of the mid-infrared emitting components, film thickness, and micromorphology. This advanced PRC PDLC material achieves a near/sub-ambient temperature when the solar irradiance is below 400 W m−2 and can dynamically manage daytime cooling efficiency. Importantly, its PRC efficiency is capable of being tuned in an on-demand and ultrafast millisecond-scale way, whose controllable transparency enables multistage heat regulation. This study is hoped to provide new inspiration in the preparation of advanced optical devices and energy-efficient equipment. 相似文献
53.
In today's Internet routing infrastructure, designers have addressed scaling concerns in routing constrained multiobjective optimization problems examining latency and mobility concerns as a secondary constrain. In tactical Mobile Ad-hoc Network (MANET), hubs can function based on the work plan in various social affairs and the internally connected hubs are almost having the related moving standards where the topology between one and the other are tightly coupled in steady support by considering the touchstone of hubs such as a self-sorted out, self-mending and self-administration. Clustering in the routing process is one of the key aspects to increase MANET performance by coordinating the pathways using multiple criteria and analytics. We present a Group Adaptive Hybrid Routing Algorithm (GAHRA) for gathering portability, which pursues table-driven directing methodology in stable accumulations and on-request steering strategy for versatile situations. Based on this aspect, the research demonstrates an adjustable framework for commuting between the table-driven approach and the on-request approach, with the objectives of enhancing the output of MANET routing computation in each hub. Simulation analysis and replication results reveal that the proposed method is promising than a single well-known existing routing approach and is well-suited for sensitive MANET applications. 相似文献
54.
为提升船载稳定平台的运动学性能,针对■并联机构的尺度参数优化问题,以机构的工作空间体积和全域力传递率为综合评价指标,采用小生境遗传算法优化得到稳定平台的最佳几何构形。具体地,采用数值法与解析法相结合的方式判断支链长度、关节转角、奇异位形等约束条件的生效情况,求解出并联稳定平台的工作空间;基于力雅可比矩阵逆矩阵的最小奇异值定义机构的局部力传递性能,以工作空间内局部力传递率的平均值作为全域力传递性能评价指标;以工作空间体积和全域力传递率的加权和为优化目标,采用小生境自适应遗传算法完成优化求解,获得最优尺度参数。与初始构形的性能对比分析表明,优化构形在力传递性能方面有35%的提升,具有更好的综合运动学性能。制作试验样机并完成相关实验,验证了所提尺度参数优化方法的有效性。最后探讨了多目标优化过程中不同的权重系数取值对优化结果的作用规律,发现选用均衡的权重可获得更佳的综合性能。 相似文献
55.
To attain the general form of stable coalition structure, this paper addressed the problem of retailers’ coalition stability in a two-stage supply chain consisting of one supplier and multiple retailers. A profit gain function was established via introducing market gain coefficient and coalition cost coefficient for different coalition structures. Based on the function, the profit of each retailer in all kinds of coalition structures was analysed, and the general feature of a stable coalition structure was attained by the largest consistent set method and the stable set method. Furthermore, some insights were obtained. For example, stable coalition structures are equidistributed or approximate equidistributed; with supplier’s cost increasing, the size of the retailers’ coalition increases. Finally, the above conclusions are verified by numerical simulation. The results of this paper provide a reference for retailers’ coalition in a supply chain, such as automobile or Information Technology supply chain. 相似文献
56.
Highly Conductive,Air‐Stable Silver Nanowire@Iongel Composite Films toward Flexible Transparent Electrodes 下载免费PDF全文
57.
58.
Polyethylene Glycol–CaCl2 Coordination Compounds as a Novel Form‐Stable Phase Change Material with Excellent Thermophysical Properties 下载免费PDF全文
Qinrong Sun Haiquan Zhang Yanping Yuan Xiaoling Cao Liangliang Sun 《Advanced Engineering Materials》2018,20(3)
59.
60.
非线性延迟积分微分方程单支方法的散逸性 总被引:1,自引:0,他引:1
本文研究了非线性延迟积分微分方程单支方法的散逸性.把G(c3P30)-代数稳定的单支方法应用到以上方程中,得到了在有限维空间和无限维空间的散逸性结果.文章最后,数值试验验证了本文的结论. 相似文献