全文获取类型
收费全文 | 379篇 |
免费 | 27篇 |
国内免费 | 1篇 |
专业分类
化学 | 219篇 |
晶体学 | 4篇 |
力学 | 10篇 |
数学 | 36篇 |
物理学 | 78篇 |
无线电 | 60篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 8篇 |
2021年 | 7篇 |
2020年 | 11篇 |
2019年 | 12篇 |
2018年 | 17篇 |
2017年 | 18篇 |
2016年 | 20篇 |
2015年 | 16篇 |
2014年 | 12篇 |
2013年 | 18篇 |
2012年 | 27篇 |
2011年 | 30篇 |
2010年 | 14篇 |
2009年 | 21篇 |
2008年 | 21篇 |
2007年 | 16篇 |
2006年 | 14篇 |
2005年 | 11篇 |
2004年 | 14篇 |
2003年 | 16篇 |
2002年 | 10篇 |
2001年 | 7篇 |
2000年 | 8篇 |
1999年 | 9篇 |
1998年 | 2篇 |
1997年 | 6篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 4篇 |
1986年 | 1篇 |
1985年 | 7篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1979年 | 4篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1971年 | 2篇 |
1966年 | 1篇 |
排序方式: 共有407条查询结果,搜索用时 15 毫秒
91.
Madhu Rayabhari 《中国电子商情》2005,(9):54-56
LED正成为中小型彩色显示器背光照明应用的主流器件。LED的选择是决定显示子系统设计最佳性价比的关键因素。此外,LED驱动IC,尤其是最新的产品,能与较低成本的LED协同工作,透过多种方法提升现有LED的性能。除亮度控制外,这些驱动IC还能实现精确的亮度匹配,或允许使用一系列具备不同VF特性的LED。 相似文献
92.
P. Sambasiva Rao T. M. Rajendiran R. Venkatesan N. Madhu A. V. Chandrasekhar B. J. Reddy Y. P. Reddy R. V. S. S. N. Ravikumar 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2001,57(14):285-2787
Single crystal electron paramagnetic resonance (EPR) studies on Cu(II) doped zinc potassium phosphate hexahydrate (ZPPH) were carried out at room temperature. The angular variation spectra in the three orthogonal planes indicate that the paramagnetic impurity has entered the lattice substitutionally in place of Zn(II) and the spin Hamiltonian parameters calculated from these spectra are g(xx) = 2.188, g(yy) = 2.032, g(zz) = 2.373, Axx = 50 G, Ayy = 65.0 G and Azz = 80 G. The g and A tensors were coincident and these values matched fairly well with the values obtained from powder spectrum. The bonding parameters have also been calculated. 相似文献
93.
Emma R. L. Brisson James C. Griffith Ayana Bhaskaran George V. Franks Luke A. Connal 《Journal of polymer science. Part A, Polymer chemistry》2019,57(18):1964-1973
Histidine functional block copolymers are thermally self‐assembled into polymer micelles with poly‐N‐isopropylacrylamide in the core and the histidine functionality in the corona. The thermally induced self‐assemblies are reversible until treated with Cu2+ ions at 50 °C. Upon treatment with 0.5 equivalents of Cu2+ relative to the histidine moieties, metal‐ion coordination locks the self‐assemblies. The self‐assembly behavior of histidine functional block copolymers is explored at different values of pH using DLS and 1H NMR. Metal‐ion coordination locking of the histidine functional micelles is also explored at different pH values, with stable micelles forming at pH 9, observed by DLS and imaged by atomic force microscopy. The thermal self‐assembly of glycine functional block copolymers at pH 5, 7, and 9 is similar to the histidine functional materials; however, the self‐assemblies do not become stable after the addition of Cu2+, indicating that the imidazole plays a crucial role in metal‐ion coordination that locks the micelles. The reversibility of the histidine‐copper complex locking mechanism is demonstrated by the addition of acid to protonate the imidazole and destabilize the polymer self‐assemblies. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1964–1973 相似文献
94.
B. Madhu Babu G. Santosh KumarPramod B. Thakur Vikas M. BangadeH.M. Meshram 《Tetrahedron letters》2014
A mild and novel approach is described for the synthesis of functionalized fused imidazole analogues in solvent-free and catalyst-free condition in ionic liquid. The short reaction time, good isolated yields, generality and environmentally benign reaction media are the significant features of this protocol. 相似文献
95.
In this paper we address the problem that impulses might occur when a to-be-controlled plant is connected to a suitable controller. In the behavioral literature this issue is dealt when studying the so-called ‘regular feedback interconnection’ (RFI) of the plant and the controller behaviors. We address the question of when a given controlled behavior satisfying desired specifications can be obtained by RFI of the plant and some suitable controller. The paper presents an algorithm to construct a controller that yields the controlled behavior by RFI, if such a controller exists, and then parametrizes all such controllers. We extend the results to the more general case when all the to-be-controlled variables might not be available for interconnection. We show that any disturbances in the plant continue to remain free in the controlled behavior if and only if the interconnection is an RFI. This is also equivalent to the well-posedness of an interconnection. This paper also makes concrete the intuitive relation between absence of inadmissibility of initial conditions and RFI. A door closing mechanism is analysed in relation to the results in this paper. 相似文献
96.
Amir Goldbourt Shifi Kababya Shimon Vega P. K. Madhu 《Solid state nuclear magnetic resonance》2000,18(1-4)
A rigorous examination of the various multiple-quantum magic angle spinning sequences is carried out with reference to sensitivity enhancement in the isotropic dimension and the lineshapes of the corresponding MAS peaks in the anisotropic dimension. An echo efficiency parameter is defined here, which is shown to be an indicator of the performance aspects of the various sequences. This can be used in the design of further new experiments in this field. A consequence of such a systematic analysis has been the combination of a spin-lock pulse for excitation of multiple-quantum coherences and an amplitude-modulated pulse for their conversion to observable single-quantum coherences. This approach has resulted in an improved performance over other sequences with respect to both the anisotropic lineshapes and the isotropic intensities. 相似文献
97.
98.
Three fringe photoelasticity (TFP) can give the total fringe order from a single colour isochromatic fringe field by suitably
comparing the colour with a calibration specimen. The fringe order evaluation can be erroneous when the materials for the
calibration specimen and the application specimen are different. This is because of the colour variation between the two materials.
This is conventionally handled by preparing individual calibration tables for each application. A new methodology to tune
the calibration table obtained for a single material to accommodate the tint variation in TFP is proposed for the use of different
specimen materials. Discontinuities in fringe order variation are smoothed using the refined TFP (RTFP) procedure. The elegance
of the new methodology for solving a multi-material system is bought out by solving the problem of a bi-material Brazilian
disc. The results obtained are compared with the phase shifting technique. 相似文献
99.
100.
Madhu Raka 《印度理论与应用数学杂志》2015,46(6):809-825
Let \(\mathbb{F}_q\) be a finite field with q = p m elements, where p is any prime and m ≥ 1. In this paper, we explicitly determine all the μ-constacyclic codes of length ? n over \(\mathbb{F}_q\), where ? is an odd prime coprime to p and the order of μ is a power of ?. All the repeated-root λ- constacyclic codes of length ? n p s over \(\mathbb{F}_q\) are also determined for any nonzero λ in \(\mathbb{F}_q\). As examples all the λ-constacyclic codes of length 3 n p s over \(\mathbb{F}_q\) for p = 5, 7, 11, 19 for n ≥ 1, s ≥ 1 are derived. We also obtain all the self-orthogonal negacyclic codes of length ? n over \(\mathbb{F}_q\) when q is odd prime power and give some illustrative examples. 相似文献