全文获取类型
收费全文 | 388篇 |
免费 | 52篇 |
国内免费 | 12篇 |
专业分类
化学 | 10篇 |
力学 | 3篇 |
数学 | 4篇 |
物理学 | 40篇 |
无线电 | 395篇 |
出版年
2023年 | 1篇 |
2022年 | 5篇 |
2021年 | 7篇 |
2020年 | 4篇 |
2019年 | 2篇 |
2018年 | 8篇 |
2017年 | 8篇 |
2016年 | 15篇 |
2015年 | 21篇 |
2014年 | 24篇 |
2013年 | 20篇 |
2012年 | 45篇 |
2011年 | 53篇 |
2010年 | 35篇 |
2009年 | 40篇 |
2008年 | 37篇 |
2007年 | 25篇 |
2006年 | 28篇 |
2005年 | 16篇 |
2004年 | 15篇 |
2003年 | 22篇 |
2002年 | 9篇 |
2001年 | 6篇 |
2000年 | 1篇 |
1997年 | 1篇 |
1985年 | 1篇 |
1982年 | 1篇 |
1979年 | 2篇 |
排序方式: 共有452条查询结果,搜索用时 31 毫秒
51.
对应用于相控阵雷达中的六位数字移相器的工作原理进行了深入的研究、并详细地介绍了它的设计方法和测试结果.主要叙述了采用高低通滤波器移相原理实现UHF波段的六位数字移相器,利用ADS软件设计仿真,实现了频带内高移相精度、低插入损耗和低VSWR等较好性能,最后通过矢量网络分析仪HP8753D对实物进行调试和检测.进而验证了设计方案. 相似文献
52.
53.
54.
55.
56.
针对ADS颗粒靶概念的研究和设计,中国科学院近代物理研究所自主研发了蒙特卡罗模拟软件GMT。为了提高GMT程序的计算效率,研究了MPI在GMT中的应用和发展,实现了大规模随机数在进程中的随机分配,并采用快速读写文件的方式替代了MPI相关数据通信函数,极大地提高了计算效率。并研究了不同规模计算实例进程数、加速比、效率之间的关系,确定了最大加速进程数及并行效率最高时的进程数,为科研工作者在计算资源和计算效率之间选择最优计算方案提供了科学依据。MPI在GMT中的成功应用使计算资源得到了充分、高效的利用,极大地提高了计算效率,解决了蒙特卡罗方法中大规模事件模拟计算时间长、计算不稳定等问题,在散裂靶大规模扫描计算中发挥了重要的作用。For the research and design of the ADS granular-flow target concept, the Institute of Modern Physics, CAS has developed a Monte Carlo simulation software (GPU-accelerated Monte Carlo Transport program, GMT). In order to improve the computational efficiency of the GMT program, development and application of MPI in GMT were studied, to realize random distribution of the large-scale random number in the sub processes. Rapid reading and writing files were employed instead of the MPI data communication function, which greatly improves the computational efficiency. Different scale calculations were performed to study the relationship of process instance number, speedup to find the maximum acceleration process number and the number of processes when parallel efficiency is highest, which provides a scientific basis for researchers to optimize the computational program between computational resources and computation efficiency. The successful application of MPI in GMT, utilizes the computing resources fully and efficiently, improves the computational efficiency, solve the long time cost and unstable problem of Monte Carlo method in large-scale event simulations, plays an important role in the large-scale scanning calculation of the spallation target. 相似文献
57.
Beam experiments with a non-intercepting beam induced f luorescence profile monitor for the ADS LINAC
下载免费PDF全文
![点击此处可从《中国物理C(英文版)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
XIE Hong-Ming WU Jun-Xia ZHANG Yong ZHU Guang-Yu XIA Jia-Wen YE Min-You 《中国物理C(英文版)》2015,39(11):117004-117004
An accelerator-driven subcritical system(ADS) project was launched in China in 2011, aiming to design and build an ADS demonstration facility with the capability of more than 1000 MW thermal power. The driver linac is defined to be a 10 m A current of high energy protons at 1.5 Ge V in continuous wave operation mode. To meet the extremely high power and intense beam accelerator requirements, non-interceptive monitors for the beam transverse profile are required for this proton linac. Taking advantage of the residual gas as active material, the Beam Induced Fluorescence(BIF) monitor exploits gas-excited fluorescence in the visible spectrum region for transverse profile measurements. The advantages of this non-intercepting method are that nothing is installed in the vacuum pipe,component design is compact and there is no need for expensive signal processing electronics. Beam experiments have been performed under constant beam conditions. The helium spectrum has been verified with different optical filters, showing that a proper optical band-pass filter covering 400–500 nm is necessary for fluorescence experiments with helium. By changing gas pressure, it is shown that gas pressure is proportional to the signal amplitude but has no influence on detected profile width. Finally, a comparison experiment between the BIF monitor and a wire scanner shows that the detected profile width results of both methods agree well. 相似文献
58.
59.
为有效进行700 MHz频段5G网络的规划和部署.本文通过链路预算,计算了700 MHz频段最大允许的路径损耗,再结合传播模型,给出了700 MHz频段的覆盖能力.在密集市区、一般市区、郊区和农村场景下,700 MHz频段的小区覆盖半径分别是447 m、623 m、877 m和2074 m.通过参数法给出了700 MH... 相似文献
60.
Wei-Long Chen Zhi-Jun Wang Chi Feng Wei-Ping Dou Yue Tao Huan Jia Wang-Sheng Wang Shu-Hui Liu Yuan He 《中国物理C(英文版)》2016,40(7):077003-077003
Beam-based BPM offset calibration was carried out for Injector II at the C-ADS demonstration facility at the Institute of Modern Physics(IMP), Chinese Academy of Science(CAS). By using the steering coils integrated in the quadrupoles, the beam orbit can be effectively adjusted and BPM positions recorded at the Medium Energy Beam Transport of the Injector II Linac. The studies were done with a 2 m A, 2.1 Me V proton beam in pulsed mode.During the studies, the "null comparison method" was applied for the calibration. This method is less sensitive to errors compared with the traditional transmission matrix method. In addition, the quadrupole magnet's center can also be calibrated with this method. 相似文献