全文获取类型
收费全文 | 166篇 |
免费 | 3篇 |
专业分类
化学 | 91篇 |
晶体学 | 1篇 |
力学 | 11篇 |
数学 | 38篇 |
物理学 | 28篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 7篇 |
2019年 | 6篇 |
2018年 | 4篇 |
2017年 | 1篇 |
2016年 | 4篇 |
2015年 | 5篇 |
2014年 | 9篇 |
2013年 | 18篇 |
2012年 | 7篇 |
2011年 | 10篇 |
2010年 | 8篇 |
2009年 | 4篇 |
2008年 | 8篇 |
2007年 | 5篇 |
2006年 | 8篇 |
2005年 | 5篇 |
2004年 | 4篇 |
2003年 | 6篇 |
2002年 | 4篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1997年 | 2篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1973年 | 2篇 |
1970年 | 1篇 |
1939年 | 1篇 |
1938年 | 1篇 |
1935年 | 1篇 |
1933年 | 1篇 |
1932年 | 1篇 |
1930年 | 1篇 |
1905年 | 1篇 |
1882年 | 1篇 |
排序方式: 共有169条查询结果,搜索用时 15 毫秒
121.
R. Elie 《Applied Mathematics and Optimization》2008,58(3):411-431
We consider the optimal consumption-investment problem under the drawdown constraint, i.e. the wealth process never falls
below a fixed fraction of its running maximum. We assume that the risky asset is driven by the constant coefficients Black
and Scholes model and we consider a general class of utility functions. On an infinite time horizon, Elie and Touzi (Preprint,
[2006]) provided the value function as well as the optimal consumption and investment strategy in explicit form. In a more realistic
setting, we consider here an agent optimizing its consumption-investment strategy on a finite time horizon. The value function
interprets as the unique discontinuous viscosity solution of its corresponding Hamilton-Jacobi-Bellman equation. This leads
to a numerical approximation of the value function and allows for a comparison with the explicit solution in infinite horizon. 相似文献
122.
α-Amino cyclobutyl-, cyclopentyl-and cyclohexylphosphonic acids (13) were efficiently prepared from the related unsubstituted cycloalkylphosphonates (5), in three steps including electrophilic azidation of the corresponding lithiated carbanions, catalytic hydrogenation of the intermediate α-azido cycloalkyl-phosphonates (10) and acidic hydrolysis of the resulting α-amino cycloalkyl-phosphonates (12). 相似文献
123.
124.
Instability of elastic bodies 总被引:1,自引:1,他引:0
The study of the equilibrium of systems constitutes an important chapter of applied mechanics. Since Euler’s works on beam buckling, in 1774, many eminent specialists studied the problem of the elastic instability of structures.An examination of many works published in this field shows a large number of approaches or criteria adopted by various authors. The objective of this study is to show through a classical example the link between the different approaches to provide a multi-level basis and to propose a valid global approach for conservative as well as nonconservative systems. 相似文献
125.
Sans résuméExtrait d'une lettre à M. D. D. Kosambi. 相似文献
126.
Three enantiospecific syntheses of 1S (2S-benzyloxethyl) oxirane (9) from L-ascorbic acid, L(+) tartaric acid, and Z-butene 1,4-diol are reported. The conversion of 9 to 2S-hydroxy-3R-nonylamine (19) is also described. 相似文献
127.
Dr. Michael Capron Dr. Sergio Díaz‐Tendero Sylvain Maclot Dr. Alicja Domaracka Elie Lattouf Dr. Arkadiusz Ławicki Dr. Rémi Maisonny Prof. Jean‐Yves Chesnel Dr. Alain Méry Dr. Jean‐Christophe Poully Dr. Jimmy Rangama Prof. Lamri Adoui Prof. Fernando Martín Prof. Manuel Alcamí Dr. Patrick Rousseau Prof. Bernd A. Huber 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(30):9321-9332
Fragmentation of the γ‐aminobutyric acid molecule (GABA, NH2(CH2)3COOH) following collisions with slow O6+ ions (v≈0.3 a.u.) was studied in the gas phase by a combined experimental and theoretical approach. In the experiments, a multicoincidence detection method was used to deduce the charge state of the GABA molecule before fragmentation. This is essential to unambiguously unravel the different fragmentation pathways. It was found that the molecular cations resulting from the collisions hardly survive the interaction and that the main dissociation channels correspond to formation of NH2CH2+, HCNH+, CH2CH2+, and COOH+ fragments. State‐of‐the‐art quantum chemistry calculations allow different fragmentation mechanisms to be proposed from analysis of the relevant minima and transition states on the computed potential‐energy surface. For example, the weak contribution at [M?18]+, where M is the mass of the parent ion, can be interpreted as resulting from H2O loss that follows molecular folding of the long carbon chain of the amino acid. 相似文献
128.
Capron M Díaz-Tendero S Maclot S Domaracka A Lattouf E Ławicki A Maisonny R Chesnel JY Méry A Poully JC Rangama J Adoui L Martín F Alcamí M Rousseau P Huber BA 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(30):9321-9332
Fragmentation of the γ-aminobutyric acid molecule (GABA, NH(2)(CH(2))(3)COOH) following collisions with slow O(6+) ions (v≈0.3?a.u.) was studied in the gas phase by a combined experimental and theoretical approach. In the experiments, a multicoincidence detection method was used to deduce the charge state of the GABA molecule before fragmentation. This is essential to unambiguously unravel the different fragmentation pathways. It was found that the molecular cations resulting from the collisions hardly survive the interaction and that the main dissociation channels correspond to formation of NH(2)CH(2)(+), HCNH(+), CH(2)CH(2)(+), and COOH(+) fragments. State-of-the-art quantum chemistry calculations allow different fragmentation mechanisms to be proposed from analysis of the relevant minima and transition states on the computed potential-energy surface. For example, the weak contribution at [M-18](+), where M is the mass of the parent ion, can be interpreted as resulting from H(2)O loss that follows molecular folding of the long carbon chain of the amino acid. 相似文献
129.
[reaction: see text] To investigate the structural basis for the exceptional selectivity and activity of apoptolidin (1), a strategy has been devised that allows for selective functionalization of seven of its eight hydroxyl groups based on progressive silyl protection, derivatization, and deprotection. The syntheses of these derivatives and their ability to inhibit F(0)F(1)-ATPase are reported. 相似文献
130.
The calculated elastic scattering of 1.04-GeV protons by 208Pb, 58Ni, and 40Ca is compared with experiment. The effects of the spin-orbit potential, Pauli and short-range correlations, variations in the ratio of the real to the imaginary part of the nucleon-nucleon scattering amplitude at 0° are found to have similar effects. Further experiments are required before these effects can be disentangled. Changes of the neutron density compared to the proton density can be distinguished. The proton polarization by elastic scattering by 208Pb and 40Ca is calculated omitting the effects of correlations. 相似文献