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971.
Lutful Karim Nidal Nasser Tarek Sheltami 《Wireless Communications and Mobile Computing》2014,14(2):175-185
Energy efficiency in specific clustering protocols is highly desired in wireless sensor networks. Most existing clustering protocols periodically form clusters and statically assign cluster heads (CHs) and thus are not energy efficient. Every non‐CH node of these protocols sends data to the CH in every time slot of a frame allocated to them using the time division multiple access scheme, which is an energy‐consuming process. Moreover, these protocols do not provide any fault tolerance mechanism. Considering these limitations, we have proposed an efficient fault‐tolerant and energy‐efficient clustering protocol for a wireless sensor network. The performance of the proposed protocol was tested by means of a simulation and compared against the low energy adaptive clustering hierarchy and dynamic static clustering protocols. Simulation results showed that the fault‐tolerant and energy‐efficient clustering protocol has better performance than both the low energy adaptive clustering hierarchy and dynamic static clustering protocols in terms of energy efficiency and reliability. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
972.
Abduladhim Ashtaiwi Ahmed Iyanda Sulyman Hossam S. Hassanein 《Wireless Communications and Mobile Computing》2014,14(3):339-354
The demand for higher data rate has spurred the adoption of multiple‐input multiple‐output (MIMO) transmission techniques in IEEE 802.11 products. MIMO techniques provide an additional spatial dimension that can significantly increase the channel capacity. A number of multiuser MIMO system have been proposed, where the multiple antenna at the physical layer are employed for multiuser access, allowing multiple users to share the same bandwidth. As these MIMO physical layer technologies further evolve, the usable bandwidth per application increases; hence, the average service time per application decreases. However, in the IEEE 802.11 distributed coordination function‐based systems, a considerable amount of bandwidth is wasted during the medium access and coordination process. Therefore, as the usable bandwidth is enhanced using MIMO technology, the bandwidth wastage of medium access and coordination becomes a significant performance bottleneck. Hence, there is a fundamental need for bandwidth sharing schemes at the medium access control (MAC) layer where multiple connections can concurrently use the increased bandwidth provided by the physical layer MIMO technologies. In this paper, we propose the MIMO‐aware rate splitting (MRS) MAC protocol and examine its behavior under different scenarios. MRS is a distributed MAC protocol where nodes locally cooperate with one another to share bandwidth via splitting the spatial channels of MIMO systems. Simulation results of MRS protocol are obtained and compared with those of IEEE 802.11n protocol. We show that our proposed MRS scheme can significantly outperform the IEEE 802.11n in medium access delay and throughput. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
973.
The radiation dose delivered by the 90Sr beta source of a TL-OSL reader and the one delivered by a 137Cs gamma source were compared using OSL dating techniques and tools. Three sets of quartz of different origins (rock, sediment and loess) were studied and measured by the SAR protocol (Single aliquot regenerative dose protocol) after irradiations carried out either by the 90Sr source or by a 137Cs source. Measurements show that the values obtained by the SAR protocol must be corrected in order to provide an acceptable cross-calibration of the beta and gamma source. Once applied, measurement sets become self-consistent and compatible with expected values. The consequences of the above mentioned observations on the methodology of OSL dating are discussed and suggest that a mixed protocol be used including both the SAR protocol and an added dose techniques close to the SARA protocol (Single aliquot regenerative and added dose protocol). 相似文献
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计算可靠的Diffie-Hellman密钥交换协议自动证明 总被引:2,自引:0,他引:2
针对Diffie-Hellman密钥交换协议,提出了采用观测等价关系的建模方法,证明了该方法的可靠性,并利用该方法扩展了自动工具CryptoVerif的验证能力。发现了对公钥Kerberos协议自动证明中敌手能力模型的缺陷,并提出了修正方法。利用扩展的CryptoVerif自动证明了基于Diffie-Hellman的Kerberos协议的安全性,验证了该扩展方法的有效性。与现有大部分证明方法不同的是,该证明方法既保留了自动证明工具的易用性,又保证了计算模型下的强可靠性。 相似文献
979.
基于LEACH协议的无线传感器网络路由算法的改进与仿真 总被引:2,自引:0,他引:2
针对无线传感器网络中传感器能量有限的问题,从路由算法的角度出发,提出LEACH协议的低功耗改进方案.本文采用划定区域的方式对LEACH协议中的簇头选举进行改进,从而减少网络中节点分布不均匀的情况对簇头节点能量损耗所造成的影响,并使用NS-2进行协议改进前后的仿真.仿真实验结果表明,协议改进后网络生存期有效增长,能量消耗... 相似文献
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