全文获取类型
收费全文 | 161篇 |
免费 | 2篇 |
国内免费 | 2篇 |
专业分类
化学 | 119篇 |
力学 | 2篇 |
数学 | 18篇 |
物理学 | 26篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 3篇 |
2020年 | 2篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2015年 | 3篇 |
2014年 | 2篇 |
2013年 | 8篇 |
2012年 | 9篇 |
2011年 | 6篇 |
2010年 | 5篇 |
2009年 | 3篇 |
2008年 | 14篇 |
2007年 | 17篇 |
2006年 | 14篇 |
2005年 | 14篇 |
2004年 | 5篇 |
2003年 | 9篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1995年 | 2篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 3篇 |
1977年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1931年 | 1篇 |
排序方式: 共有165条查询结果,搜索用时 15 毫秒
31.
32.
Within nonrelativistic quantum mechanics, spatial cusps in initial wave functions can lead to nonanalytic behavior in time. We suggest a method for calculating the short-time behavior in such situations. For these cases, the density does not match its Taylor expansion in time, but the Runge-Gross proof of time-dependent density functional theory still holds, as it requires only the potential to be time analytic. 相似文献
33.
George Amato Vineetha Vasukuttan Danni Harris Lucas Laudermilk Jennifer Lucitti Scott Runyon Rangan Maitra 《Molecules (Basel, Switzerland)》2022,27(17)
Selective modulation of peripheral cannabinoid receptors (CBRs) has potential therapeutic applications in medical conditions, including obesity, diabetes, liver diseases, GI disorders and pain. While there have been considerable efforts to produce selective antagonists or full agonists of CBRs, there has been limited reports on the development of partial agonists. Partial agonists targeting peripheral CBRs may have desirable pharmacological profiles while not producing centrally mediated dissociative effects. Bayer reported that BAY 59-3074 is a CNS penetrant partial agonist of both CB1 and CB2 receptors with efficacy in rat models of neuropathic and inflammatory pain. In this report, we demonstrate our efforts to synthesize analogs that would favor peripheral selectivity, while maintaining partial agonism of CB1. Our efforts led to the identification of a novel compound, which is a partial agonist of the human CB1 (hCB1) receptor with vastly diminished brain exposure compared to BAY 59-3074. 相似文献
34.
A. Maitra Marina Dan A. K. Sen K. Bhattacharyya C. K. Sarkar 《International Journal of Infrared and Millimeter Waves》1993,14(3):703-713
Distortion of pulses with pulse widths ranging from 0.1 to 1 ns propagating with carrier frequencies in the range 10–100 GHz through rain filled medium has been estimated considering the absorptive and dispersive effects produced by rain drops on the propagation of millimeter waves. It is found that the rain induced broadening or compression can be quite appreciable for very short pulses in the window region of millimeter wave band under intense and extensive raining conditions. 相似文献
35.
In study of polymer-salt complexes usually one is interested in the dc conductivity, which can be extracted from impedance
spectroscopy. However, impedance spectroscopy yields a host of additional information, for example, frequency variation of
the measured admittance or impedance, nature of the Cole-Cole plot and dielectric function. Proper analysis of this information
reveals details of the microstructure and transport processes in the sample. This in turn, will lead to development of better
solid electrolytes with tailor-made properties. The polymer electrolyte PEO-NH4ClO4 shows an interesting variation in its properties in two different regimes, (1) where salt concentration is below ∼ 19 wt.%
and (2) above this concentration. In the present paper we suggest an equivalent circuit incorporating a constant phase element
(CPE), which reproduces the complex admittance behavior at different salt fractions.
Paper presented at the 2nd International Conference on Ionic Devices, Anna University, Chennai, India, Nov. 28–30, 2003. 相似文献
36.
Prithwiraj Byabartta 《Transition Metal Chemistry》2005,30(8):978-986
The reaction of ctc-[Ru(RaaiR′)2Cl2] (3a–3i) [RaaiR′=1-alkyl-2-(arylazo)imidazole, p-R—C6H4—N=N— C3H2NN(1)—R′, R=H, OMe, NO2, R′=Me, Et, Bz] with KS2COR′′ (R′′=Me, Et, Pr, Bu or CH2Ph) in boiling dimethylformamide afforded [RuII{o-S—C6H4(p-R-)—N=N—C3H2NN(1)—R′}2] (4a–4i), where the ortho-carbon atom of the pendant phenyl ring of both ligands has been selectively and directedly thiolated. The newly formed tridentate
thiolate ligands are bound in a meridional fashion. The solution electronic spectra exhibit a strong MLCT band near 700 nm
and near 550 nm, respectively in DCM. The molecular geometry of the complexes in solution has been determined by H n.m.r.
spectroscopy. Cyclic voltammograms show a Ru(II)/Ru(III) couple near 0.4 V and an irreversible oxidation response near 1.0
V due to oxidation of the coordinated thiol group, along with two successive reversible ligand reductions in the range −0.80–0.87
V (one electron), −1.38–1.42 V (one electron). Coulometric oxidation of the complexes at 0.6 V versus SCE in CH2Cl2 produced an unstable Ru(III) congener. When R=Me the presence of trivalent ruthenium was proved by a rhombic e.p.r. spectrum
having g1=2.349, g2=2.310. 相似文献
37.
U. K. Yadav T. Maitra I. Singh 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,84(3):365-370
Thermodynamic properties of the spinless Falicov-Kimball model are studied on a
triangular lattice using numerical diagonalization technique with Monte-Carlo simulation
algorithm. Discontinuous metal-insulator transition is observed at finite temperature.
Unlike the case of square lattice, here we observe that the finite temperature effect is
not able to smear out the discontinuous metal-insulator transition seen in the ground
state. Calculation of specific heat (C
v
)
shows single and double peak structures for different values of parameters like on-site
correlation strength (U), f-electron energy
(E
f
) and temperature. 相似文献
38.
Maitra NT 《The Journal of chemical physics》2006,125(1):014110
We discuss possibilities and challenges for describing correlated electron and nuclear dynamics within a surface-hopping framework using time-dependent density functional theory (TDDFT) for the electron dynamics. We discuss the recent surface-hopping method proposed by Craig et al. [Phys. Rev. Lett. 95, 163001 (2005)] that is based on Kohn-Sham potential energy surfaces. Limitations of this approach arise due to the Kohn-Sham surfaces generally having different gradients than the true TDDFT-corrected ones. Two mechanisms of the linear response procedure cause this effect: we illustrate these with examples. 相似文献
39.
Adiabatic time-dependent density functional theory fails for excitations of a heteroatomic molecule composed of two open-shell fragments at large separation. Strong frequency dependence of the exchange-correlation kernel is necessary for both local and charge-transfer excitations. The root of this is the static correlation created by the step in the exact Kohn-Sham ground-state potential between the two fragments. An approximate nonempirical kernel is derived for excited molecular dissociation curves at large separation. Our result is also relevant when the usual local and semilocal approximations are used for the ground-state potential, as static correlation there arises from the coalescence of the highest occupied and lowest unoccupied orbital energies as the molecule dissociates. 相似文献
40.
[Structure: see text] Chenodeoxycholic acid based PET sensors for alkali metal ions have been immobilized on Merrifield resin and on Tentagel. The fluorescence of the sensor beads is enhanced upon binding the cations. The modular nature of the sensor allows designing different sensors based on this concept. 相似文献