全文获取类型
收费全文 | 96篇 |
免费 | 6篇 |
专业分类
化学 | 43篇 |
力学 | 3篇 |
数学 | 2篇 |
物理学 | 26篇 |
无线电 | 28篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 3篇 |
2020年 | 5篇 |
2019年 | 5篇 |
2018年 | 7篇 |
2016年 | 4篇 |
2015年 | 3篇 |
2014年 | 10篇 |
2013年 | 13篇 |
2012年 | 5篇 |
2011年 | 7篇 |
2010年 | 2篇 |
2009年 | 3篇 |
2008年 | 7篇 |
2007年 | 4篇 |
2006年 | 4篇 |
2005年 | 3篇 |
2004年 | 1篇 |
2003年 | 2篇 |
2002年 | 1篇 |
2001年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
排序方式: 共有102条查询结果,搜索用时 31 毫秒
41.
The purpose of this study is to explore the second harmonic generation (SHG) of a high power Cosh-Gaussian beam in cold collisionless plasma. The ponderomotive force causes carrier redistribution from high field to low field region in presence of a Cosh-Gaussian beam thereby producing density gradients in the transverse direction. The density gradients so produced the results in electron plasma wave (EPW) generation at the frequency of the input beam. The EPW interacts with the input beam resulting in the production of 2nd harmonics. WKB and paraxial approximations are employed for obtaining the 2nd order differential equation describing the behavior of the beam's spot size against normalized distance. The impact of well-established laser-plasma parameters on the behavior of the beam's spot size and SHG yield are also analyzed. The focusing behavior of the beam and SHG yield is enhanced with an increase in the density of plasma, the radius of the beam and the decentred parameter, and with a decrease in the intensity of the beam. The results of the current problem are really helpful for complete information of laser-plasma interaction physics. 相似文献
42.
Hugall JT Finnemore AS Baumberg JJ Steiner U Mahajan S 《Langmuir : the ACS journal of surfaces and colloids》2012,28(2):1347-1350
Templating against atomically flat materials allows creation of smooth metallic surfaces. The process of adding the backing (superstrate) to the deposited metals has proven to be the most difficult part in producing reliable, large-area, solvent-resistant substrates and has been the subject of recent research. In this paper we describe a simple and inexpensive liquid glass template-stripping (lgTS) method for the fabrication of large area ultraflat gold surfaces. Using our lgTS method, ultraflat gold surfaces with normals aligned along the <111> crystal plane and with a root-mean-square roughness of 0.275 nm (over 1 μm(2)) were created. The surfaces are fabricated on silica-based substrates which are highly solvent resistant and electrically insulating using silicate precursor solution (commonly known as "liquid glass") and concomitant mild heat treatment. We demonstrate the capabilities of such ultraflat gold surfaces by imaging nanoscale objects on top and fabricating microelectrodes as an example application. Because of the simplicity and versatility of the fabrication process, lgTS will have wide-ranging application in imaging, catalysis, electrochemistry, and surface science. 相似文献
43.
Walia S Weber R Balendhran S Yao D Abrahamson JT Zhuiykov S Bhaskaran M Sriram S Strano MS Kalantar-zadeh K 《Chemical communications (Cambridge, England)》2012,48(60):7462-7464
Exothermic chemical reactions of nitrocellulose are coupled onto thermoelectric zinc oxide (ZnO) layers to generate self-propagating thermopower waves resulting in highly oscillatory voltage output of the order of 500 mV. The peak specific power obtained from ZnO based sources is approximately 0.5 kW kg(-1). 相似文献
44.
Semiconductors: Two‐Dimensional Molybdenum Trioxide and Dichalcogenides (Adv. Funct. Mater. 32/2013)
45.
Sumeet Chougule Sanjib Dey Behnam Pourhassan Mir Faizal 《The European Physical Journal C - Particles and Fields》2018,78(8):685
We analyze certain aspects of BTZ black holes in massive theory of gravity. The black hole solution is obtained by using the Vainshtein and dRGT mechanism, which is asymptotically AdS with an electric charge. We study the Hawking radiation using the tunneling formalism as well as analyze the black hole chemistry for such system. Subsequently, we use the thermodynamic pressure-volume diagram to explore the efficiency of the Carnot heat engine for this system. Some of the important features arising from our solution include the non-existence of quantum effects, critical Van der Walls behaviour, thermal fluctuations and instabilities. Moreover, our solution violates the Reverse Isoperimetric Inequality and, thus, the black hole is super-entropic, perhaps which turns out to be the most interesting characteristics of the BTZ black hole in massive gravity. 相似文献
46.
Sidra Farooq Thomas Feeney Joao O. Mendes Vaishnavi Krishnamurthi Sumeet Walia Enrico Della Gaspera Joel van Embden 《Advanced functional materials》2021,31(52):2104788
Chalcohalide semiconductors are an emergent class of materials for optoelectronics. Here, the first work on BiSI chalcohalide thin film photodetectors (PDs) is presented. An entirely new method for the fabrication of bismuth chalcohalide thin films (BiOI and BiSI) is developed. This method circumvents the use of any ligands or counter ions during fabrication and provides highly pure thin films free of carbon residues and other contaminants. When integrated into lithographically patterned lateral PDs these BiSI thin films show outstanding performances and high stability. The direct ≈1.55 eV bandgap of BiSI perfectly accommodates optical sensing over the full visible spectrum. The responsivity (R) of the BiSI PDs reaches 62.1 A W−1, which is the best value reported to date across chalcohalide materials of any type. The BiSI PDs display remarkable sensitivity to low light levels, supporting a broad operational detectivity ≈1012 Jones over four decades in light intensity, with a peak specific detectivity (D*) of 2.01 × 1013 Jones. The dynamics of photocurrent generation are demonstrated to be dominated by photoconductive gain. These results cement BiSI as an exciting candidate for high performance photodetector applications and encourage ongoing work in BiSX (X = Cl, Br, I) materials for optoelectronics. 相似文献
47.
This paper presents the performance of Parallel Big Bang–Big Crunch (PB3C) global optimization algorithm on CEC-2014 test suite. The performance is compared with 16 other algorithms. It has been observed that PB3C gave best performance on 7 functions of the test bench. Out of seven, for 6 functions it gave the unmatched best performance whereas on one count its performance was equaled by other algorithm as well. Further this paper proposes a PB3C based new routing approach to wireless mesh networks (WMNs). Being dynamic; routing is a challenging issue in WMNs. The approach is a near shortest path route evaluation approach. The approach was simulated on MATLAB. The performance was compared with 7 other approaches namely ad hoc on-demand distance vector, dynamic source routing, ant colony optimization, biogeography based optimization, firefly algorithm, BAT and simple Big Bang–Big Crunch based approaches. For WMNs of size 1000 nodes and above the PB3C was observed to outperform rest of the 7 algorithms. 相似文献
48.
The Bhagirthi and Alaknanda valleys of Garhwal Himalaya, were rocked, respectively, by two major earthquakes: the Uttarkashi earthquake of magnitude mb=6.5, Ms=7.0 on October 20, 1991 and the Chamoli earthquake of mb=6.8, Ms=6.5 on March 29, 1999, during this decade. Both these seismic events are associated with ongoing deformation along the main central thrust of the Himalayas. Helium and radon anomalies on March 24 and March 27, 1999, respectively, were recorded at Palampur which is about 393 km from the Chamoli earthquake epicentre. A He/Rn ratio anomaly was recorded on March 20, 9 days before the Chamoli earthquake. The precursory nature of radon and helium anomalies is a strong indicator of the physical basis of earthquake prediction and a preliminary test for the proposed conceptual He/Rn ratio model. 相似文献
49.
50.
Natarajan A Burns A Takemori M Jain S Boden E Vasudevan V Puthamane K Naik SN Kuriakose G 《Photochemistry and photobiology》2012,88(2):250-256
We have explored the utility of pyrophthalones as violet-blue light filtering dyes in polymer matrices for wavelengths below 450 nm. Further, we have investigated the photodegradation of these molecules in thermoplastic media and the mechanisms behind their degradation. Finally, a range of additives have been explored to improve the photostability of these molecules to achieve the desired performance. 相似文献