全文获取类型
收费全文 | 212篇 |
免费 | 6篇 |
国内免费 | 1篇 |
专业分类
化学 | 119篇 |
晶体学 | 8篇 |
力学 | 9篇 |
数学 | 40篇 |
物理学 | 43篇 |
出版年
2023年 | 4篇 |
2022年 | 11篇 |
2021年 | 15篇 |
2020年 | 6篇 |
2019年 | 6篇 |
2018年 | 13篇 |
2017年 | 10篇 |
2016年 | 3篇 |
2015年 | 4篇 |
2014年 | 9篇 |
2013年 | 11篇 |
2012年 | 10篇 |
2011年 | 14篇 |
2010年 | 11篇 |
2009年 | 3篇 |
2008年 | 13篇 |
2007年 | 9篇 |
2006年 | 10篇 |
2005年 | 9篇 |
2004年 | 12篇 |
2003年 | 3篇 |
2002年 | 8篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1988年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1971年 | 2篇 |
排序方式: 共有219条查询结果,搜索用时 31 毫秒
51.
Mohit L. Deb 《Tetrahedron letters》2007,48(12):2159-2163
Synthesis of some novel 3-alkylated indoles via an uncatalyzed Michael addition of indoles using three components in one-pot solvent-free conditions is reported. The mechanism was established by performing the reaction in two steps. The reaction was also studied in different solvents and an important solvent effect was noticed. 相似文献
52.
The single crystals of Lead Iodide have been grown by gel method. X‐ray diffraction studies on these crystals shows that the lattice parameters of grown crystals are almost matching with reported values. The results of detailed studies made on the microstructures of Lead Iodide crystals, have been described. The observations of the faces of these crystals revealed that they have grown by layer as well as spiral mechanisms. The probable role of these parameters is explained along with the surface microstructures on these various shaped crystals. 相似文献
53.
Experimental data of the dynamic viscoelastic properties, storage modulus (G′), loss modulus (G′′), and phase shift (δ) as well as of the viscosity, η, are reported for the polymerization of a free radical polymerization
system (methyl methacrylate) which exhibits the Trommsdorff effect. A rheometer-reactor assembly developed in our laboratory
is used for this purpose. It is observed that in the early stages of reaction, data lie in the terminal zone. As the polymerization
progresses, the Trommsdorff effect leads to a sharp increase in both the polymer concentration and the weight average molecular
weight, and the viscoelastic properties then lie in the entanglement zone. A modulus crossover point (when G′ = G′′) is identified that could be used as an identification of the point where the Trommsdorff effect starts assuming significance.
Received: 17 September 1998 Accepted: 9 December 1998 相似文献
54.
Alain Hach Mohit Malik Marcus Diem Lasha Tkeshelashvili Kurt Busch 《Photonics and Nanostructures》2007,5(1):29-36
We show that the sensitivity to disorder of certain physical properties of periodic media depends on whether the disorder is truly random or not. This allows to utilize periodic media for testing sequences of random numbers and to quantify their departure from true randomness via simple transmission and/or reflection data analysis. This physics-based model shows promises for device applications to test random data. 相似文献
55.
56.
57.
H. Saraf K. T. Ramesh A. M. Lennon A. C. Merkle J. C. Roberts 《Experimental Mechanics》2007,47(3):439-449
Traditionally, Kolsky bars are used to study the dynamic response of hard materials in uniaxial compression, tension or torsion.
We present modifications to the technique that allow loading of a soft tissue specimen in (a) hydrostatic compression and
(b) simple shear. The first modification is designed to determine the pressure vs. volume behavior of each material, and thence
to extract a measure of the dynamic compressibility or equivalently of the bulk modulus. The second modification is designed
to develop the shear stress versus shear strain behavior for a near-simple shear experiment. The critically important questions
of the proper acquisition of human tissue samples and protocols for appropriate experimentation have also been addressed.
The experimental techniques and the results are discussed in detail and the results compared to finite element simulations.
We present examples of the dynamic response of typical tissue simulants as well as human liver and stomach tissues. 相似文献
58.
J. R. Saraf 《Applied Scientific Research》1973,28(1):27-36
A variational principle has been utilized to study Couette flow, and Kramers' velocity slip problem with specular-diffuse
reflection. The method leads to extremely satisfactory analytic results for the velocity slip coefficient and also for the
variation of shear stress with inverse Knudsen number. This leads us to the conclusion that the present variational principle
even with extremely simple trial functions, essentially suggested by continuum flow theory, is a useful means of computing
macroscopic quantities of physical interest in rarefied gas dynamics. 相似文献
59.
Vivek K. Gupta Corresponding author Pankaj Bandhoria Mohit Kalyan Manoj Mathews C. V. Yelamaggad 《Liquid crystals》2013,40(6):741-747
The crystal structure of cholesteryl 4‐[4‐(4‐n‐butylphenylethynyl)phenoxy]butanoate [phase sequence: Cr 155°C (46.1?J?g?1) SmA 186.8°C (1.5?J?g?1) TGB‐N* 204.7 (6?J?g?1) I] has been solved from single crystal X‐ray diffraction data. The compound crystallizes in the monoclinic space group P21 with unit cell parameters: a?=?13.129(2), b?=?9.3904(10), c?=?17.4121(8)?Å, β?=?92.790(7)°, Z?=?2. The structure has been solved by direct methods and refined to R?=?0.0606 for 3?250 observed reflections. The bond distances and angles are in good agreement with the corresponding values for compounds containing phenyl and cholesterol moieties. The phenyl rings A and B are planar. The dihedral angle between the least‐squares planes of the two phenyl rings is 28°. The cholesterol moiety has the usual structure: the C and E rings have chair conformations, and the D and F rings adopt half‐chair conformations. The molecules in the unit cell are arranged in an antiparallel manner. The crystal structure is stabilized by an intermolecular C–H…O contact of 2.989(10)?Å. 相似文献
60.
Redox ions are deposited on a polyelectrolyte‐coated gold electrode by an electric field to fabricate an ion‐selective thin film electrode. The Fe(CN)${{{4- \hfill \atop 6\hfill}}}$ ions are deposited on a few monolayer‐coated polyelectrolyte gold electrode by a slow periodic potential cycle. The deposition process and electrode properties are quantitatively and simultaneously monitored by cyclic voltammetry and a novel technique, using a Scanning Electrometer for Electrical Double‐layers (SEED). No redox properties are obtained without the electric‐field‐deposition. Owing to the redox mediation and net charge due to the redox ion, the electrode is ion‐selective. We demonstrate the principle to detect 1 µM of dopamine in a mixture with 1 mM of ascorbic acid. 相似文献