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1.
Björn O. Roos Valera Veryazov Per-Olof Widmark 《Theoretical chemistry accounts》2004,111(2-6):345-351
New basis sets of the atomic natural orbital (ANO) type have been developed for the atoms Li–Fr and Be–Ra. The ANOs have been obtained from the average density matrix of the ground states and the lowest excited states of the atom, the positive ion, and the dimer at its equilibirium geometry. Scalar realtivisitc effects are included through the use of a Douglas–Kroll Hamiltonian. Multiconfigurational wave functions have been used with dynamic correlation included using second-order perturbation theory (CASSCF/CASPT2). The basis sets are applied in calculations of the ground-state potentials for the dimers. Computed bond energies are accurate to within 0.05 eV for the alkaline dimers and 0.02 eV for the alkaline-earth dimers (except for Be2).Acknowledgments.ensp;B.O.R. would like to express his gratitude to Prof. Jacopo Tomasi for all the inspiration that his scientific work has given him through the years and continues to do in particular through the work on solvent effects on molecular properties. This work has been supported by a grant from the Swedish Science Research Council, VR.Contribution to the Jacopo Tomasi Honorary Issue 相似文献
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Zhou X Caravan P Clarkson RB Westlund PO 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2004,167(1):147-160
A generalization of the modified SBM theory is developed in closed analytical form. The theory is applied to describe the paramagnetically enhanced water proton spin-lattice relaxation rates of the aqueous-systems containing a gadolinium(S=7/2) complex(MS-325) in the presence or absence of human serum albumin (HSA). MS-325 binds to HSA: in the absence of the protein the reorientational time, tauR, is short, but when HSA is added tauR becomes much longer. In this way, the effect of reorientational motion, static (Delta s), and transient (Delta t) zero-field splitting (ZFS) interactions on both the water proton relaxivity and the Gd ESR lineshapes are investigated. Two dynamic models of electron spin relaxation are presented, characterized by transient and static ZFS-interactions. X-, Q-, and W-bands ESR spectra of MS-325+HSA are analyzed in order to describe the effect on the electron spin system upon binding to a macromolecule. A computer program based on this theory is developed which calculates solvent water proton T1 NMRD profiles and the corresponding X-, Q-, U-, and W-bands ESR lineshapes. 相似文献
5.
Per-Olof Fjällström Jyrki Katajainen Christos Levcopoulos Ola Petersson 《BIT Numerical Mathematics》1990,30(3):378-384
We present a parallel algorithm for finding the convex hull of a sorted set of points in the plane. Our algorithm runs inO(logn/log logn) time usingO(n log logn/logn) processors in theCommon crcw pram computational model, which is shown to be time and cost optimal. The algorithm is based onn
1/3 divide-and-conquer and uses a simple pointer-based data structure.Part of this work was done when the last three authors were at the Department of Computer and Information Science, Linköping University. The research of the second author was supported by the Academy of Finland. 相似文献
6.
One-dimensional NMR spectroscopy has proven to be a powerful technique for screening compound libraries in drug discovery. We report a novel water ligand-observed gradient spectroscopy (WaterLOGSY) pulse sequence, named Aroma WaterLOGSY, that selectively detects aromatic WaterLOGSY signals from compounds or ligands. In the Aroma WaterLOGSY, water magnetization is untouched after water excitation and utilizes the whole period of the remaining pulse sequence to relax back to the +z direction. Due to the phase cycling design, the water magnetization is allowed to relax for the period of two full scans before it gets inverted again. Therefore, the recycle delay can be significantly shortened. Within similar experimental time, Aroma WaterLOGSY shows approximately two times higher sensitivity than the standard scheme. This method also allows the use of non-deuterated reagents, thereby accelerating experimental set-up time for ligand-binding studies. 相似文献
7.
Cadmium was determined either by direct insertion of freeze-dried biological samples (1–13 μg) or by injection of 2-μl samples of perifusion medium into the graphite furnace. At 228.8 nm ? 10 fmol of cadmium could be measured. The endogenous cadmium contents in the endocrine and exocrine parts of the pancreas were 8.5 ± 2.0 and 15.1 ± 1.4 μ mol (dry wt.), respectively. A less sensitive wavelength (326.1 nm) was employed for measuring the larger amounts obtained after specimens had been incubated in the presence of cadmium. 相似文献
8.
Susanne Flygare Mats-Olle M⇘nnsson Per-Olof Larsson Klaus Mosbach 《Applied biochemistry and biotechnology》1982,7(1-2):59-61
Lactate dehydrogenase has been purified by precipitation with a bis-ligand. The precipitating agent in this case was Bis-NAD. This approach of affinity precipitation is also applicable to other enzymes. 相似文献
9.
Summary A method has been worked out for the determination of ultramicro quantities of potassium. The potassium is precipitated with sodium tetraphenylborate and the excess of the reagent is determined by turbidimetric titration with cetyltrimethylammomum bromide.
Zusammenfassung Eine Methode zur Bestimmung von Ultramikromengen Kalium wurde ausgearbeitet. Dieses wird mit Natriumtetraphenylborat gefällt und der Uberschuß des Fällungsmittels durch turbidimetrische Titration mit Cetyltrimethylammoniumbromid bestimmt.
Résumé Mise au point d'une méthode pour le dosage d'ultramicroquantités de potassium. Le potassium est précipité par le tétraphénylborate de sodium et l'excès de réactif est dosé par titrage turbidimétrique avec le bromure de cétyltriméthylammonium.相似文献
10.
Håkansson P Westlund PO 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(1-2):299-304
This paper discusses the process of energy migration transfer within reorientating chromophores using the stochastic master equation (SME) and the stochastic Liouville equation (SLE) of motion. We have found that the SME over-estimates the rate of the energy migration compared to the SLE solution for a case of weakly interacting chromophores. This discrepancy between SME and SLE is caused by a memory effect occurring when fluctuations in the dipole-dipole Hamiltonian (H(t)) are on the same timescale as the intrinsic fast transverse relaxation rate characterized by (1/T(2)). Thus the timescale critical for energy-transfer experiments is T(2) approximately 10(-13) s. An extended SME is constructed, accounting for the memory effect of the dipole-dipole Hamiltonian dynamics. The influence of memory on the interpretation of experiments is discussed. 相似文献