全文获取类型
收费全文 | 173篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
化学 | 144篇 |
晶体学 | 5篇 |
力学 | 5篇 |
数学 | 11篇 |
物理学 | 10篇 |
出版年
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 1篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 14篇 |
2015年 | 4篇 |
2014年 | 5篇 |
2013年 | 4篇 |
2012年 | 7篇 |
2011年 | 8篇 |
2010年 | 3篇 |
2009年 | 4篇 |
2008年 | 7篇 |
2007年 | 9篇 |
2006年 | 8篇 |
2005年 | 8篇 |
2004年 | 4篇 |
2003年 | 6篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 4篇 |
1990年 | 7篇 |
1989年 | 12篇 |
1988年 | 11篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1980年 | 1篇 |
1975年 | 1篇 |
1973年 | 3篇 |
1970年 | 1篇 |
1965年 | 3篇 |
1964年 | 2篇 |
1934年 | 1篇 |
排序方式: 共有175条查询结果,搜索用时 15 毫秒
61.
This paper presents models for the estimation of stability constants (K 1 and β 2) of nickel(II), copper(II) and zinc(II) mono- and bis-complexes with 5 Schiff bases (salicylideneglycine, salicylidenealanine, salicylideneserine, salicylidenephenylalanine, and salicylidenetyrosine). The models were based on the molecular-graph theory and valence molecular connectivity index of the 3rd order, 3χ v , derived from it. Univariate linear models were developed for each metal separately, while in the common models for two and three metals, the indicator variable, In, was introduced. The standard error of models for the log K 1 constant was less than 0.12, while for log β 2 models, the S.E. did not exceed 0.14. 相似文献
62.
63.
64.
65.
66.
67.
Two‐Dimensional Boron Hydride Sheets: High Stability,Massless Dirac Fermions,and Excellent Mechanical Properties
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Yalong Jiao Fengxian Ma Prof. John Bell Dr. Ante Bilic Prof. Aijun Du 《Angewandte Chemie (International ed. in English)》2016,55(35):10292-10295
Two‐dimensional (2D) boron sheets have been successfully synthesized in recent experiments, however, some important issues remain, including the dynamical instability, high energy, and the active surface of the sheets. In an attempt to stabilize 2D boron layers, we have used density functional theory and global minimum search with the particle‐swarm optimization method to predict four stable 2D boron hydride layers, namely the C2/m, Pbcm, Cmmm, and Pmmn sheets. The vibrational normal mode calculations reveal all these structures are dynamically stable, indicating potential for successful experimental synthesis. The calculated Young's modulus indicates a high mechanical strength for the C2/m and Pbcm phases. Most importantly, the C2/m, Pbcm, and Pmmn structures exhibit Dirac cones with massless Dirac fermions and the Fermi velocities for the Pbcm and Cmmm structures are even higher than that of graphene. The Cmmm phase is reported as the first discovery of Dirac ring material among boron‐based 2D structures. The unique electronic structure of the 2D boron hydride sheets makes them ideal for nanoelectronics applications. 相似文献
68.
Models for estimation of the first (K1), second (K2), and overall stability constant (β2) of copper(II) chelates with naturally occurring amino acids, based on the valence connectivity index of the 3rd order (3 χ v), were improved by introduction of a square term and a new graph representation for mono‐complexes (MLcor). The models gave SE=0.07, 0.05–0.07 and 0.05–0.08 for lg K1, lg K2 and lg β2 constants, respectively; models that encompass both binary and ternary bis‐complexes included indicator variable. We also validated our models on the test set which included two mono‐, two binary and two ternary Cu(II) chelates with α‐aminobutanoic acid and α‐aminopentanoic acid, not included into the calibration. The absolute differences between experimental and predicted stability constants were in the range of 0.01–0.16. 相似文献
69.
Optimal configurations of functionalized fullerenes C
60
X
n
for n = 2, 4, 6, 8 have been determined by application of three topological stability measures. It has been found that the optimal
configurations with higher n contain optimal configurations with lower values of n. Two stability measures prefer configurations in which functional groups Xs are crowded while the third one points to configurations with isolated pairs of Xs. 相似文献
70.
水利工程中混凝土重力坝在地震等作用下的三维破坏形式以及破坏过程对大坝安全影响重大。本文建立了固体材料的联合有限元-离散元(Combined Finite-Discrete Element)三维数学模型,并引入Single/Smeared断裂损伤模型,模拟混凝土材料的破坏。数学模型经验证后,用于地震作用下混凝土重力坝破坏的三维数值模拟,结果表明,联合有限元-离散元方法能够有效模拟坝体的破坏模式和破坏阈值条件,且具有将坝体连续变形与不连续断裂有机结合的优点。通过一系列数值模拟工况的对比,分析了模型网格分辨率对破坏条件、破坏模式以及程序计算效率的影响,研究结果能够为大坝的抗震设计提供有价值的参考。 相似文献