全文获取类型
收费全文 | 172篇 |
免费 | 6篇 |
国内免费 | 1篇 |
专业分类
化学 | 143篇 |
力学 | 1篇 |
数学 | 8篇 |
物理学 | 27篇 |
出版年
2023年 | 4篇 |
2022年 | 2篇 |
2021年 | 5篇 |
2020年 | 8篇 |
2019年 | 6篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 5篇 |
2015年 | 6篇 |
2014年 | 6篇 |
2013年 | 7篇 |
2012年 | 22篇 |
2011年 | 13篇 |
2010年 | 7篇 |
2009年 | 5篇 |
2008年 | 11篇 |
2007年 | 13篇 |
2006年 | 12篇 |
2005年 | 10篇 |
2004年 | 6篇 |
2003年 | 2篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1995年 | 4篇 |
1991年 | 1篇 |
1985年 | 1篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1975年 | 2篇 |
1974年 | 1篇 |
排序方式: 共有179条查询结果,搜索用时 250 毫秒
131.
132.
In this paper we have formulated an open-shell many-body perturbation theory (mbpt) that applies to an incomplete model space. The effective HamiltonianH
eff generated in our theory is hermitian. We follow the resolvent-operator based time-dependent formulation ofmbpt of Banerjeeet al, and show quite generally that, by classifying the various determinants spanning the Hilbert space as model valence spaceP, virtual valence spaceR and virtual spaceQ, a diagrammaticmbpt satisfying size consistency can be developed. The chief new features of the theory are (i) manifest hermiticity ofH
eff; (ii) presence of disconnected diagrams no part of which is a legitimate diagram (irreducible disconnected diagrams); (iii)
presence of folded diagrams with components that may be irreducible disconnected diagrams; (iv) a consistent treatment of
the variousn-valence sectors of the Hilbert space that may be interacting throughH
eft if valence-holes are present—in particular a modified treatment of the core-valence separation. The generalisation afforded
by the theory offers useful conceptual as well as computational advantages because the convergence difficulty encountered
in a complete valence space formulation may be bypassed here by keeping the offending valence space determinants out of the
model space. A brief critique of the developmentvis-a-vis the only other general model space development leading to a nonhermitianH
eff is also given. 相似文献
133.
In this paper we propose and numerically implement a specific scheme for calculating the excitation energies (EEs) within
the Fock space multireference coupled cluster framework, which includes the contributions from noniterative triples cluster
amplitudes. These contribute to the EEs at the third order. We present results for CH+ and N2, and study the effects of these noniterative triples on EEs.
Received: 28 July 1997 / Accepted: 8 December 1997 相似文献
134.
Debashis Mukherjee 《International journal of quantum chemistry》1974,8(2):247-253
The energies of the single-configuration lowest π – π* singlet and triplet states of some conjugated hydrocarbons have been calculated by the MC-SCF method using the conjugate-gradient technique of minimisation. The results are compared with those calculated by other methods currently in use, like (a) single-configuration calculation with VN?1 potential for virtual orbitals; (b) CI calculation involving singly excited states; and (c) TDHF method. It has been concluded that the results for the MC-SCF method are very good, considering that only a single open-shell configuration is involved. 相似文献
135.
The escape rate of a particle over a fluctuating barrier in a double-well potential exhibits resonance at an optimum value of correlation time of fluctuation. This has been shown to be important in several variants of kinetic model of chemical reactions. We extend the analysis of this phenomenon of resonant activation to quantum domain to show how quantization significantly enhances resonant activation at low temperature due to tunneling. 相似文献
136.
Debashis Banerjee Sanjib Bagchi Shampa Mondal Sanjib Ghosh 《Journal of photochemistry and photobiology. A, Chemistry》1995,90(2-3):171-176
The fluorescence characteristics of two ketocyanine dyes have been studied in six mixed binary solvents. Several parameters such as the maximum energy E12(F) of fluorescence, the quantum yield Φ12 of fluorescence and the normalized intensity of the fluorescence have been investigated as functions of solvent composition. In protic+aprotic binary mixtures a dramatic change at the aprotic end has been observed. The results point to a preferential solvation of the solute by the protic component. 相似文献
137.
138.
139.
Banerjee D Das PK Singha H Bagchi S 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,70(5):1109-1113
Interaction of merbromin with trypsin is of bovine origin has been studied by monitoring the absorption steady-state and time-resolved fluorescence spectral properties of the dye. Studies have been done in media of varying pH at different trypsin concentrations. It has been observed that trypsin brings about a quenching of fluorescence of the dye. The quenching is static in nature and the equilibrium constant of dye-trypsin interaction in the ground-state has been determined from quenching studies. Steady-state anisotropy of the dye increases in presence of trypsin in the medium. Values of micro-viscosity in the vicinity of the fluorophore in media containing trypsin have been determined from measurements of fluorescence anisotropy. Time-resolved fluorescence studies indicate the existence of two decaying states for the dye. The fractional contribution to the time-resolved decay changes with pH. The average lifetime, however, does not depend on the concentration of trypsin. 相似文献
140.
The first nickel complex bearing a boryl moiety, (PNP)Ni[B(catechol)](PNP = N[2-P(CHMe(2))(2)-4-methylphenyl](2)(-)), has been prepared, structurally characterized, and analyzed by DFT; this rare species is shown to be a recyclable reagent for the borylation of bromobenzene, via an unusual cycle, by applying the ingredients catecholborane and NaBH(4). 相似文献