全文获取类型
收费全文 | 403篇 |
免费 | 35篇 |
国内免费 | 1篇 |
专业分类
化学 | 321篇 |
晶体学 | 6篇 |
力学 | 3篇 |
数学 | 57篇 |
物理学 | 52篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 6篇 |
2021年 | 9篇 |
2020年 | 21篇 |
2019年 | 22篇 |
2018年 | 25篇 |
2017年 | 7篇 |
2016年 | 24篇 |
2015年 | 25篇 |
2014年 | 18篇 |
2013年 | 29篇 |
2012年 | 30篇 |
2011年 | 43篇 |
2010年 | 29篇 |
2009年 | 16篇 |
2008年 | 34篇 |
2007年 | 29篇 |
2006年 | 25篇 |
2005年 | 12篇 |
2004年 | 10篇 |
2003年 | 8篇 |
2002年 | 9篇 |
2001年 | 1篇 |
1996年 | 1篇 |
1994年 | 1篇 |
排序方式: 共有439条查询结果,搜索用时 15 毫秒
101.
We introduce a deterministic dealer model which implements most of the empirical laws, such as fat tails in the price change distributions, autocorrelation of price change and non-Poissonian intervals. We also clarify the causality between microscopic dealers’ dynamics and macroscopic market's empirical laws. 相似文献
102.
Mitsunori Asada Takao Fujimori Kenta Fujii Ryo Kanzaki Yasuhiro Umebayashi Shin‐ichi Ishiguro 《Journal of Raman spectroscopy : JRS》2007,38(4):417-426
The solvation structure of magnesium, zinc(II), and alkaline earth metal ions in N,N‐dimethylformamide (DMF) and N,N‐dimethylacetamide (DMA), and their mixtures has been studied by means of Raman spectroscopy and DFT calculations. The solvation number is revealed to be 6, 7, 8, and 8 for Mg2+, Ca2+, Sr2+, and Ba2+, respectively, in both DMF and DMA. The δ (O C N) vibration of DMF shifts to a higher wavenumber upon binding to the metal ions and the shift Δν(= νbound − νfree) becomes larger, when the ionic radius of the metal ion becomes smaller. The ν (N CH3) vibration of DMA also shifts to a higher wavenumber upon binding to the metal ions. However, the shift Δν saturates for small ions, as well as the transition‐metal (II) ions, implying that steric congestion among solvent molecules takes place in the coordination sphere. It is also indicated that, despite the magnesium ion having practically the same ionic radius as the zinc(II) ion of six‐coordination, their solvation numbers in DMA are significantly different. DFT calculations for these metalsolvate clusters of varying solvation numbers revealed that not only solvent–solvent interaction through space but also the bonding nature of the metal ion plays an essential role in the steric congestion. The individual solvation number and the Raman shift Δν in DMF–DMA mixtures indicate that steric congestion is significant for the magnesium ion, but not appreciable for calcium, strontium, and barium ions, despite the solvation number of these metal ions being large. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
103.
Dmitry G. Luchinsky Halyna Hafiychuk Vasyl Hafiychuk Kenta Chaki Hiroya Nitta Taku Ozawa Kevin R. Wheeler Tracie J. Prater Peter V. E. McClintock 《Journal of polymer science. Part A, Polymer chemistry》2020,58(15):2051-2061
We consider an atomistic model of thermal welding at the polymer-polymer interface of a polyetherimide/polycarbonate blend, motivated by applications to 3D manufacturing in space. We follow diffusion of semiflexible chains at the interface and analyze strengthening of the samples as a function of the welding time tw by simulating the strain–stress and shear viscosity curves. The time scales for initial wetting, and for fast and slow diffusion, are revealed. It is shown that each component of the polymer blend has its own characteristic time of slow diffusion at the interface. Analysis of strain–stress demonstrates saturation of the Young's modulus at tw = 240 ns, while the tensile strength continues to increase. The shear viscosity is found to have a very weak dependence on the welding time for tw > 60 ns. It is shown that both strain–stress and shear viscosity curves agree with experimental data. 相似文献
104.
105.
106.
107.
Synthesis,Optical Properties,and Electronic Structures of Tetrakis(pentafluorophenyl)tetrathiaisophlorin Dioxide
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Vijay Lakshmi Mishra Prof. Taniyuki Furuyama Prof. Nagao Kobayashi Prof. Kenta Goto Dr. Takaaki Miyazaki Prof. Jye‐Shane Yang Prof. Teruo Shinmyozu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(27):9190-9197
The synthesis, structure, optical and redox properties, and electronic structure of tetrakis(pentafluorophenyl)tetrathiaisophlorin dioxide ( 12 ) are reported. Oxidation of tetrakis(pentafluorophenyl)tetrathiaisophlorin ( 11 ) with dimethyldioxirane afforded the oxidized product, which was the tetrathiaisophlorin with two thiophene 1‐oxide moieties ( 12 ). More significant nonplanarity and greater bond length alternation in 12 than those of 11 were observed by X‐ray structural analysis. The absorption spectrum of 12 contains two bands at λ=348 and 276 nm, with a weak tail that extends to λ≈650 nm. Analysis of the magnetic circular dichroism spectrum of 12 , based on Michl's 4N‐perimeter model and molecular orbital calculations, indicate that the broad band at λ=348 nm appears to contain N2 and P2 bands, and 12 is classified as a 4nπ system, similar to 11 . The nuclear‐independent chemical shift values and 1H NMR spectroscopy data indicate that 12 has more antiaromatic character than 11 . 相似文献
108.
109.
Sawada Takuya Fuji Hiroshi Yagasaki Kenta Fujioka Kana Minemoto Hisashi Yamamoto Kazuhisa 《Optical Review》2022,29(3):276-285
Optical Review - The AlN–Ce:YAG composite ceramic is an effective phosphor for high-power laser illumination. The thermal properties of an AlN–Ce:YAG composite phosphor were studied to... 相似文献
110.
Kenta Murayama Katsuo Tsukamoto Atul Srivastava Hitoshi Miura Etsuro Yokoyama Yuki Kimura 《Crystal Research and Technology》2014,49(5):315-322
The two‐dimensional (2D) distributions of surface supersaturation of sodium chlorate crystals with and without solutal convection have been measured by means of a multidirectional interferometry (MDI) technique coupled with the principles of three‐dimensional (3D) computer tomography. When solutal convection was present over a top face, the supersaturation at the center of the face was depleted by a factor of >0.9 with reference to the value at the edges of the crystal. When the convection was suppressed using an upside‐down geometry, the depletion of supersaturation at the center of the face was much smaller, <0.4. Therefore, the supersaturation difference between the edges and the face center, which is responsible for the morphological stability due to volume diffusion for the solute, becomes less important compared to the effect of convection due to hydrodynamic reasons. This result should give us a key to solve why the crystal quality is sometimes better in convection‐free microgravity conditions because of improved stability of a crystal face caused by more homogeneous distribution of supersaturation over the crystal surface. 相似文献