全文获取类型
收费全文 | 13073篇 |
免费 | 2477篇 |
国内免费 | 1882篇 |
专业分类
电工技术 | 730篇 |
技术理论 | 2篇 |
综合类 | 1698篇 |
化学工业 | 405篇 |
金属工艺 | 492篇 |
机械仪表 | 1036篇 |
建筑科学 | 821篇 |
矿业工程 | 253篇 |
能源动力 | 189篇 |
轻工业 | 155篇 |
水利工程 | 185篇 |
石油天然气 | 164篇 |
武器工业 | 372篇 |
无线电 | 2462篇 |
一般工业技术 | 961篇 |
冶金工业 | 209篇 |
原子能技术 | 48篇 |
自动化技术 | 7250篇 |
出版年
2024年 | 123篇 |
2023年 | 363篇 |
2022年 | 621篇 |
2021年 | 616篇 |
2020年 | 665篇 |
2019年 | 494篇 |
2018年 | 471篇 |
2017年 | 575篇 |
2016年 | 590篇 |
2015年 | 689篇 |
2014年 | 940篇 |
2013年 | 965篇 |
2012年 | 1138篇 |
2011年 | 1188篇 |
2010年 | 949篇 |
2009年 | 900篇 |
2008年 | 932篇 |
2007年 | 998篇 |
2006年 | 850篇 |
2005年 | 741篇 |
2004年 | 492篇 |
2003年 | 476篇 |
2002年 | 317篇 |
2001年 | 256篇 |
2000年 | 214篇 |
1999年 | 164篇 |
1998年 | 107篇 |
1997年 | 102篇 |
1996年 | 104篇 |
1995年 | 81篇 |
1994年 | 61篇 |
1993年 | 55篇 |
1992年 | 33篇 |
1991年 | 37篇 |
1990年 | 32篇 |
1989年 | 26篇 |
1988年 | 9篇 |
1987年 | 4篇 |
1986年 | 9篇 |
1985年 | 8篇 |
1984年 | 10篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1975年 | 3篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
David F. Barrero Julio César Hernández‐Castro Pedro Peris‐Lopez David Camacho María D. R‐Moreno 《Expert Systems》2014,31(1):9-19
Radio frequency identification (RFID) is a powerful technology that enables wireless information storage and control in an economical way. These properties have generated a wide range of applications in different areas. Due to economic and technological constrains, RFID devices are seriously limited, having small or even tiny computational capabilities. This issue is particularly challenging from the security point of view. Security protocols in RFID environments have to deal with strong computational limitations, and classical protocols cannot be used in this context. There have been several attempts to overcome these limitations in the form of new lightweight security protocols designed to be used in very constrained (sometimes called ultra‐lightweight) RFID environments. One of these proposals is the David–Prasad ultra‐lightweight authentication protocol. This protocol was successfully attacked using a cryptanalysis technique named Tango attack. The capacity of the attack depends on a set of boolean approximations. In this paper, we present an enhanced version of the Tango attack, named Genetic Tango attack, that uses Genetic Programming to design those approximations, easing the generation of automatic cryptanalysis and improving its power compared to a manually designed attack. Experimental results are given to illustrate the effectiveness of this new attack. 相似文献
32.
33.
基于分层的改进A*算法在路径规划中的应用 总被引:1,自引:0,他引:1
智能交通中的路径诱导系统能够极大地提高人们的出行效率与出行体验。经典A*算法只注重搜索精度而忽略了搜索效率,在城市道路网络分层的基础上,对高层道路使用的A*算法进行了改进,对于道路网络中的不同节点,设置估价函数具有不同的权值,同时给定权值的一个上下限阈值,以平衡算法的搜索效率与搜索精度。实验表明,得到的最短路径虽然不是常规的距离最短却是实际行驶时间最优的。 相似文献
34.
Recently, physical layer security commonly known as Radio Frequency (RF) fingerprinting has been proposed to provide an additional layer of security for wireless devices. A unique RF fingerprint can be used to establish the identity of a specific wireless device in order to prevent masquerading/impersonation attacks. In the literature, the performance of RF fingerprinting techniques is typically assessed using high-end (expensive) receiver hardware. However, in most practical situations receivers will not be high-end and will suffer from device specific impairments which affect the RF fingerprinting process. This paper evaluates the accuracy of RF fingerprinting employing low-end receivers. The vulnerability to an impersonation attack is assessed for a modulation-based RF fingerprinting system employing low-end commodity hardware (by legitimate and malicious users alike). Our results suggest that receiver impairment effectively decreases the success rate of impersonation attack on RF fingerprinting. In addition, the success rate of impersonation attack is receiver dependent. 相似文献
35.
The prototyping of complex sheet metal parts using single point incremental forming (SPIF) requires the generation of optimal tool paths and/or tool path sequences that ensure that the formed part is within geometric design specifications. The presence of a multitude of features on complex parts leads to multiple inaccuracy inducing phenomena occurring simultaneously due to interactions between the features. This paper proposes a network analysis methodology using topological conceptual graphs to capture the effects of different phenomena on the final accuracy of a sheet metal part manufactured by SPIF. Using this framework optimized tool paths can be generated that compensate for the inaccuracy inducing behavior. Tool path generation algorithms to create partial tool paths that account for the accuracy of specific features in the part based on the proposed framework are also presented. Finally, the creation of integrated tool paths maintaining complementarity between tool paths and desired continuity behavior using non-uniform cubic B-splines is illustrated. A number of case studies demonstrating the applicability of the integrated framework are discussed, where the maximum deviations in the part are significantly reduced and the average absolute deviations for the complete part are brought down to less than 0.5 mm. 相似文献
36.
37.
This paper presents the trajectory tracking control of an autonomous underwater vehicle(AUV). To cope with parametric uncertainties owing to the hydrodynamic effect, an adaptive control law is developed for the AUV to track the desired trajectory. This desired state-dependent regressor matrix-based controller provides consistent results under hydrodynamic parametric uncertainties.Stability of the developed controller is verified using the Lyapunov s direct method. Numerical simulations are carried out to study the efficacy of the proposed adaptive controller. 相似文献
38.
针对移动机器人路径规划问题,提出一种基于QPSO算法的路径规划方法,并用概率论的方法分析了移动机器人路径规划的收敛性,阐明了该方法随均匀分布和正态分布的参数关系和收敛区间;然后根据移动机器人的运动特征提出一种改进的轨迹规划方法。移动机器人平台的实验结果表明了该方法在移动机器人路径规划中的有效性和可行性。 相似文献
39.
40.
提出一种虚拟场景中有宽度物体移动路径的优化方法,在地图掩码数据经过寻路算法搜索后,得到一组连续路径节点组成的节点集,从起始节点出发,沿着路径节点找出离起始节点最远且没有障碍物遮挡的可见节点,作为下一个起点,循环往复直至节点集的终止节点,并顺序连接这些可见节点,即可得到优化路径。通过合并节点集中的多余节点,使路径更平滑,从而减少物体移动过程中改变方向的次数,解决有宽度物体无法通过狭窄通道后,须重新计算路径的问题,达到了更好的用户体验效果。 相似文献