全文获取类型
收费全文 | 58425篇 |
免费 | 6090篇 |
国内免费 | 3281篇 |
专业分类
电工技术 | 4335篇 |
技术理论 | 6篇 |
综合类 | 4488篇 |
化学工业 | 8986篇 |
金属工艺 | 3357篇 |
机械仪表 | 3964篇 |
建筑科学 | 4572篇 |
矿业工程 | 1968篇 |
能源动力 | 1518篇 |
轻工业 | 5612篇 |
水利工程 | 1195篇 |
石油天然气 | 2621篇 |
武器工业 | 567篇 |
无线电 | 7163篇 |
一般工业技术 | 6155篇 |
冶金工业 | 2299篇 |
原子能技术 | 625篇 |
自动化技术 | 8365篇 |
出版年
2024年 | 364篇 |
2023年 | 1131篇 |
2022年 | 2274篇 |
2021年 | 2930篇 |
2020年 | 2256篇 |
2019年 | 1813篇 |
2018年 | 2058篇 |
2017年 | 2236篇 |
2016年 | 2040篇 |
2015年 | 3043篇 |
2014年 | 3629篇 |
2013年 | 3994篇 |
2012年 | 4487篇 |
2011年 | 4507篇 |
2010年 | 4003篇 |
2009年 | 3634篇 |
2008年 | 3470篇 |
2007年 | 3182篇 |
2006年 | 2992篇 |
2005年 | 2402篇 |
2004年 | 1763篇 |
2003年 | 1583篇 |
2002年 | 1742篇 |
2001年 | 1413篇 |
2000年 | 1067篇 |
1999年 | 879篇 |
1998年 | 539篇 |
1997年 | 462篇 |
1996年 | 440篇 |
1995年 | 343篇 |
1994年 | 256篇 |
1993年 | 206篇 |
1992年 | 163篇 |
1991年 | 119篇 |
1990年 | 102篇 |
1989年 | 83篇 |
1988年 | 52篇 |
1987年 | 26篇 |
1986年 | 23篇 |
1985年 | 11篇 |
1984年 | 8篇 |
1983年 | 6篇 |
1982年 | 9篇 |
1981年 | 11篇 |
1980年 | 24篇 |
1979年 | 3篇 |
1977年 | 1篇 |
1966年 | 1篇 |
1959年 | 6篇 |
1951年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
Multimedia Systems - Camouflage effect evaluation and examination is an important procedure in digital camouflage pattern design as it is helpful in improving the objectivity and effectiveness... 相似文献
42.
Jing Wang Ming Li Hongfang Li Shao-Ming Fei Xianqing Li-Jost 《Quantum Information Processing》2016,15(10):4211-4218
We present an analytical lower bound of multipartite concurrence based on the generalized Bloch representations of density matrices. It is shown that the lower bound can be used as an effective entanglement witness of genuine multipartite entanglement. Tight lower and upper bounds for multipartite tangles are also derived. Since the lower bounds depend on just part of the correlation tensors, the result is experimentally feasible. 相似文献
43.
近年来,岩土工程勘察技术发展得非常快,研究领域不断拓展,取得了较多的成就。但是,在发展过程中也存在一些不足。重点分析了岩土工程勘察工作,并结合实际工作提出一些个人意见,以期能为相关工作提供帮助。 相似文献
44.
45.
根据UDP协议的特点,结合视频网络传输的要求对其进行扩展,给UDP数据包定义了一个8个字节的包头结构,用来加载数据包的序列号、时戳等信息。在发送端对传榆进行平滑处理,控制数据包大小和时戳间隔,减小了图像抖动的发生。应用给出了一种在Delphi下实现的视频数据打包流程,能够满足多种网络平台上的视频传输的要求。 相似文献
46.
Lei Guo Xingwei Wang Qingyang Song Weigang Hou Fei Yang 《Information Sciences》2008,178(18):3635-3644
With the development of intelligent optical networks and the general multi-protocol label switching (GMPLS) technique, the seamless convergence between IP network and optical network is no longer be a dream but a practical reality. Similar to the Internet, current optical networks have been divided into multiple domains each of which has its own network provider and management policy. Therefore, the development of multi-domain optical networks will be the trend of new-generation intelligent optical networks, and GMPLS-based survivability for multi-domain optical networks will become a hot topic of research in the future. This paper provides a comprehensive review of the existing survivable schemes in multi-domain optical networks and analyzes the shortcomings of current research. Based on previous studies, we present possible challenges and propose new ideas to design efficient survivable schemes to guide the future work of researchers in multi-domain optical networks. 相似文献
47.
This paper deals with the global exponential stability problems for stochastic neutral Markov jump systems (MJSs) with uncertain parameters and multiple time-delays. The delays are respectively considered as constant and time varying cases, and the uncertainties are assumed to be norm bounded. By selecting appropriate Lyapunov-Krasovskii functions, it gives the sufficient condition such that the uncertain neutral MJSs are globally exponentially stochastically stable for all admissible uncertainties. The stability criteria are formulated in the form of linear matrix inequalities (LMIs), which can be easily checked in practice. Finally, two numerical examples are exploited to illustrate the effectiveness of the developed techniques. 相似文献
48.
This paper deals with the creep effect on dynamic visco-elastic properties of short fibre reinforced polymer SMC composite. The vibration-creep-vibration test procedure was applied to examine the influence of creep on dynamic modulus E and loss tangent tg of the material. The results show that creep causes appreciable influence on E and tg. 相似文献
49.
随着互联网技术的不断发展,网络已成为社会经济发展的重要支撑工具。然而,受限于传统通信技术的约束,网络通信信息存在被共享、泄露等风险。基于云计算技术的区域安全通信技术可以有效解决无线通信技术按身份分配不同通信权限的问题,用户拥有“普通域”与“安全域”功能,以保证通信网络的安全。文中以云计算技术的概念为切入点,阐述了云计算技术在区域通信中的应用价值,最后提出了构建基于云计算区域安全通信系统的具体方案,并通过实验验证了该系统具有良好的应用性能。 相似文献
50.
Xiaobin Zou Haikuan Liang Yan Li Yichao Zou Fei Tian Yong Sun Chengxin Wang 《Advanced functional materials》2023,33(18):2213807
Following logic in the silicon semiconductor industry, the existence of native oxide and suitable fabrication technology is essential for 2D semiconductors in planar integronics, which are surface-sensitive to typical coating technologies. To date, very few types of integronics are found to possess this feature. Herein, the 2D Bi2O2Te developed recently is reported to possess large-area synthesis and controllable thermal oxidation behavior toward single-crystal native oxides. This shows that surface-adsorbed oxygen atoms are inclined to penetrate across [Bi2O2]n2n+ layers and bond with the underlying [Te]n2n− at elevated temperatures, transforming directly into [TeO4]n2n− with the basic architecture remaining stable. The oxide can be adjusted to form in an accurate layer-by-layer manner with a low-stress sharp interface. The native oxide Bi2TeO6 layer (bandgap of ≈2.9 eV) exhibits visible-light transparency and is compatible with wet-chemical selective etching technology. These advances demonstrate the potential of Bi2O2Te in planar-integrated functional nanoelectronics such as tunnel junction devices, field-effect transistors, and memristors. 相似文献