全文获取类型
收费全文 | 118篇 |
免费 | 14篇 |
国内免费 | 26篇 |
专业分类
化学 | 109篇 |
晶体学 | 3篇 |
力学 | 5篇 |
数学 | 9篇 |
物理学 | 32篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 6篇 |
2020年 | 7篇 |
2019年 | 11篇 |
2018年 | 7篇 |
2017年 | 5篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 10篇 |
2013年 | 12篇 |
2012年 | 10篇 |
2011年 | 14篇 |
2010年 | 9篇 |
2009年 | 8篇 |
2008年 | 5篇 |
2007年 | 1篇 |
2006年 | 5篇 |
2005年 | 7篇 |
2004年 | 3篇 |
2003年 | 1篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
排序方式: 共有158条查询结果,搜索用时 402 毫秒
101.
Junyi Yang Xueru Zhang Yuxiao Wang Changwei Li Min Shui Xiao Jin 《Optics Communications》2011,284(19):4723-4726
A reversal 4f coherent imaging system with phase objects is presented to measure nonlinear refraction of the materials. The modified system can increase the sensitivity compared with the conventional nonlinear-imaging technique with phase objects. The sensitivity enhancement of the modified system is about two times greater than the conventional technique within 0 ≤ ΔφNL ≤ 1. CS2 is used to demonstrate the measurement using the reversal 4f coherent imaging system with phase objects. 相似文献
102.
Changwei Wang David Danovich Sason Shaik Wei Wu Yirong Mo 《Journal of computational chemistry》2019,40(9):1015-1022
Intermolecular attractive interaction between electrophilic sites is a counterintuitive phenomenon, as the electrostatic interaction therein is repulsive and destabilizing. Here, we confirm this phenomenon in four representative complexes, using state-of-the-art quantum mechanical methods. By employing the block-localized wavefunction (BLW) method, which can turn off intermolecular charge transfer interactions, we profoundly demonstrated the significance of charge transfer interactions in these seemingly counterintuitive complexes. Indeed, after being “turned off” the intermolecular charge transfer interaction in, for example, the FNSi···BrF complex, the originally attractive intermolecular interaction turns to be repulsive. The energy decomposition approach based on the BLW method (BLW-ED) can partition the overall stability gained on the formation of intermolecular noncovalent interaction into several physically meaningful components. According to the BLW-ED analysis, the electrostatic repulsion in these counterintuitive cases is overwhelmed by the stabilizing polarization, dispersion interaction, and most importantly, the charge transfer interaction, resulting in the eventual counterintuitive overall attraction. The present study suggests that, predicting bonding sites of noncovalent interactions using only the “hole” concept may be not universally sufficient, because other significant stabilizing factors will contribute to the stability and sometimes, play even bigger roles than the electrostatic interaction and consequently govern the complex structures. © 2018 Wiley Periodicals, Inc. 相似文献
103.
104.
Prof. Dr. Yirong Mo Dr. Changwei Wang Liangyu Guan Prof. Dr. Benoît Braïda Prof. Dr. Philippe C. Hiberty Prof. Dr. Wei Wu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(27):8444-8452
The block‐localized wave function (BLW) method can derive the energetic, geometrical, and spectral changes with the deactivation of electron delocalization, and thus provide a unique way to elucidate the origin of improper, blueshifting hydrogen bonds versus proper, redshifting hydrogen bonds. A detailed analysis of the interactions of F3CH with NH3 and OH2 shows that blueshifting is a long‐range phenomenon. Since among the various energy components contributing to hydrogen bonds, only the electrostatic interaction has long‐range characteristics, we conclude that the contraction and blueshifting of a hydrogen bond is largely caused by electrostatic interactions. On the other hand, lengthening and redshifting is primarily due to the short‐range n(Y)→σ*(X?H) hyperconjugation. The competition between these two opposing factors determines the final frequency change direction, for example, redshifting in F3CH ??? NH3 and blueshifting in F3CH ??? OH2. This mechanism works well in the series FnCl3?nCH ??? Y (n=0–3, Y=NH3, OH2, SH2) and other systems. One exception is the complex of water and benzene. We observe the lengthening and redshifting of the O?H bond of water even with the electron transfer between benzene and water completely quenched. A distance‐dependent analysis for this system reveals that the long‐range electrostatic interaction is again responsible for the initial lengthening and redshifting. 相似文献
105.
106.
107.
In this paper, we use the inverse curvature flow to prove a sharp geometric inequality on star-shaped and two-convex hypersurface in hyperbolic space. 相似文献
108.
Total synthesis of (+)-epilupinine was accomplished in nine steps and in 48% overall yield, in which INOC was used as the key step for the construction of the quinolizidine skeleton. We found that it was an extremely difficult task to prepare the key intermediates (R)-N-(3-nitropropyl)-2-vinylpiperidine or (R)-(2-vinylpiperid-1-yl)propanal by routine methods. Thus, by using Fukuyama's oxime synthesis, a general method was developed for highly efficient conversion of 3-(N,N-dialkylamino)propanols into 3-(N,N-dialkylamino)propanal oximes without using the corresponding aldehydes. 相似文献
109.
Changwei Jiang Wei Feng Hui Zhong Qiangming Zhu Junyong Zeng 《Transport in Porous Media》2014,102(2):167-183
The natural convection heat transfer of air in a porous media can be controlled by gradient magnetic field. Thermomagnetic convection of air in a porous cubic enclosure with an electric coil inclined around the $Y$ axis was numerically investigated. The Biot–Savart law was used to calculate the magnetic field. The governing equations in primitive variables were discretized by the finite-volume method and solved by the SIMPLE algorithm. The flow and temperature fields for the air natural convection were presented and the mean Nusselt number on the hot wall was calculated and compared. The results show that both the magnetic force and coil inclination have significant effect on the flow field and heat transfer in a porous cubic enclosure, the natural convection heat transfer of air can be enhanced or controlled by applying gradient magnetic field. 相似文献
110.
In this paper, we prove a positive mass theorem and Penrose-type inequality of the Gauss–Bonnet–Chern mass $m_2$ for the graphic manifold with flat normal bundle. 相似文献