全文获取类型
收费全文 | 382篇 |
免费 | 117篇 |
国内免费 | 12篇 |
专业分类
化学 | 17篇 |
晶体学 | 1篇 |
力学 | 19篇 |
综合类 | 8篇 |
数学 | 94篇 |
物理学 | 372篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 10篇 |
2021年 | 6篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 11篇 |
2017年 | 14篇 |
2016年 | 14篇 |
2015年 | 10篇 |
2014年 | 28篇 |
2013年 | 32篇 |
2012年 | 21篇 |
2011年 | 31篇 |
2010年 | 22篇 |
2009年 | 26篇 |
2008年 | 40篇 |
2007年 | 16篇 |
2006年 | 15篇 |
2005年 | 16篇 |
2004年 | 27篇 |
2003年 | 27篇 |
2002年 | 14篇 |
2001年 | 19篇 |
2000年 | 17篇 |
1999年 | 19篇 |
1998年 | 13篇 |
1997年 | 9篇 |
1996年 | 9篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1992年 | 1篇 |
1991年 | 5篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有511条查询结果,搜索用时 31 毫秒
61.
62.
Huimin He Fengman Liu Haiyun Xue Haidong Wang Delong Qiu 《Fiber and Integrated Optics》2016,35(5-6):212-229
With the development of the multicore processor, the bandwidth and capacity of the memory, rather than the memory area, are the key factors in server performance. At present, however, the new architectures, such as fully buffered DIMM (FBDIMM), hybrid memory cube (HMC), and high bandwidth memory (HBM), cannot be commercially applied in the server. Therefore, a new architecture for the server is proposed. CPU and memory are separated onto different boards, and optical interconnection is used for the communication between them. Each optical module corresponds to each dual inline memory module (DIMM) with 64 channels. Compared to the previous technology, not only can the architecture realize high-capacity and wide-bandwidth memory, it also can reduce power consumption and cost, and be compatible with the existing dynamic random access memory (DRAM). In this article, the proposed module with system-in-package (SiP) integration is demonstrated. In the optical module, the silicon photonic chip is included, which is a promising technology to be applied in the next-generation data exchanging centers. And due to the bandwidth–distance performance of the optical interconnection, SerDes chips are introduced to convert the 64-bit data at 800 Mbps from/to 4-channel data at 12.8 Gbps after/before they are transmitted though optical fiber. All the devices are packaged on cheap organic substrates. To ensure the performance of the whole system, several optimization efforts have been performed on the two modules. High-speed interconnection traces have been designed and simulated with electromagnetic simulation software. Steady-state thermal characteristics of the transceiver module have been evaluated by ANSYS APLD based on finite-element methodology (FEM). Heat sinks are placed at the hotspot area to ensure the reliability of all working chips. Finally, this transceiver system based on silicon photonics is measured, and the eye diagrams of data and clock signals are verified. 相似文献
63.
The Bandwidth Theorem of Böttcher, et al. [Mathematische Annalen 343 (2009), 175–205] gives minimum degree conditions for the containment of spanning graphs H with small bandwidth and bounded maximum degree. We generalise this result to a‐arrangeable graphs H with , where n is the number of vertices of H. Our result implies that sufficiently large n‐vertex graphs G with minimum degree at least contain almost all planar graphs on n vertices as subgraphs. Using techniques developed by Allen, et al. [Combinatorica 33 (2013), 125–160] we can also apply our methods to show that almost all planar graphs H have Ramsey number at most . We obtain corresponding results for graphs embeddable on different orientable surfaces. © 2015 Wiley Periodicals, Inc. Random Struct. Alg., 48, 270–289, 2016 相似文献
64.
通道调制型偏振成像技术是一种体积紧凑、空间分辨率高且能够实时获取全偏振信息的新型偏振成像探测技术. 但该技术目前只能实现准单色光的全偏振探测, 严重制约了其实用化. 本文首先对宽带光通道调制型偏振成像出现混叠现象的原因进行了分析, 得出载波频率是限制波段宽度的主要因素. 据此在空间频谱域上分析并推导了通道调制型偏振成像系统的光谱宽度限制判据公式, 同时通过模型仿真得到了系统的极限有效光谱范围, 与理论推导公式结果进行了对比分析, 验证了判据的准确性. 基于该判据可预测给定通道调制型偏振成像系统的有效工作波段, 同时还可为扩展系统波段宽度提供理论支撑. 相似文献
65.
I. V. Bodnar V. F. Gremenok O. N. Obraztsova L. V. Rusak V. Yu. Rud' Yu. V. Rud' 《Journal of Applied Spectroscopy》1999,66(1):151-153
Based on single crystals of AgGaSe2, AgGaTe2, CuGaTe2 of the p-type, surface-barrier structures were manufactured by vacuum thermal deposition on illumination of which the photovoltaic
effect was observed. It is established that the longwave edge of the photosensitivity of such structures possesses several
inflections attributable to photoactive absorption involving paracipation of levels of lattice defects. It is shown that In/p-(Cu,
Ag)Ga(Se, Te)2 surface-barrier structures can be used as wide-band transducers and photoanalyzers of linearily polarized radiation.
Translated from Zhurrnal Prikladnoi Spektroskopii, Vol. 66, No. 1, pp. 141–144, January–February, 1999. 相似文献
66.
Optical phase conjugation is used to improve soliton communication system cascaded by distributed erbium-doped fibers. The results show that if its periodic length is chosen properly, optical phase conjugation can reduce the radiated energy and the time jitters, postpone the widening of soliton pulse width, also improve the stability of the soliton system. 相似文献
67.
The effect of the pump bandwidth on the quantum statistical properties of Raman lasers is investigated. It is shown that the pump bandwidth may lead to the enhancement of output intensity noise squeezing even though it reduces the Mandel Q parameter. 相似文献
68.
对由环境引起的环程光程扰动对光纤环形腔的影响作了详细的理论分析,在扰动为各态历经扰动假设下的理论分析表明:小的慢与快变化扰动的影响是不同的。慢变化扰动影响与人射光时间相干性相同,使有效带宽增大;而快变化扰动对有效带宽的影响很小。然而对大的慢或快变化扰动,都会使环形腔失去它的带通和带阻特性。实验结果证实了一结论。 相似文献
69.
自适应光学系统的控制残余方差分析 总被引:6,自引:4,他引:2
分析自适应光学系统的控制残余方差与控制带宽的关系.对于存在时间延迟的自适应光学系统,推导了计算大气湍流控制残余方差的近似方式,并给出了有探测噪声情况下确定系统最优控制带宽的公式.以61单元自适应光学系统为例,讨论了实验自适应光学系统中控制带宽的优化选择问题. 相似文献
70.
《Particuology》2023
Nanocomposites with heterogeneous structures and magneto-electric synergistic losses have broad prospects for improving electromagnetic wave (EMW) absorption performance. In this study, we synthesized Co2NiO4@MnCo2O4.5 nanoparticles with abundant hetero-interfaces and multiple magneto-electric loss mechanisms by a facile hydrothermal method. The excess 0.5 oxygen atoms in MnCo2O4.5 produce more vacancies and contribute to the enhancement of electrical conductivity. Sequential nanoneedle clusters facilitate multiple reflections and absorption of EMW in the materials, which are accompanied by an abundance of heterogeneous interfaces to improve the dielectric loss. The Co2NiO4@MnCo2O4.5 composites showed a minimum reflection loss (RLmin) of −30.01 dB and a superior effective absorption bandwidth (EAB) of 6.12 GHz (11.88 GHz–18 GHz) at a thickness of 2.00 mm. Computer Simulation Technology (CST) revealed that the obtained particles show very low radar cross-section (RCS) values and almost full coverage angles. The maximum reduction of RCS at vertical incidence reaches 19.98 dB m2. The Co2NiO4@MnCo2O4.5 nanoparticles exhibit outstanding radar attenuation properties, which can effectively inhibit the reflection and scattering of EMW. Therefore, the prepared Co2NiO4@MnCo2O4.5 absorbers have great application potential in the field of EMW absorption. 相似文献