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31.
Koumousi ES Zampakou M Raptopoulou CP Psycharis V Beavers CM Teat SJ Psomas G Stamatatos TC 《Inorganic chemistry》2012,51(14):7699-7710
Employment of the monoanion of 2,6-diacetylpyridine dioxime (dapdoH(2)) as a tridentate chelate in palladium(II) and platinum(II) chemistry is reported. The syntheses, crystal structures, spectroscopic and physicochemical characterization, and biological evaluation are described of [PdCl(dapdoH)] (1) and [PtCl(dapdoH)] (2). Reaction of PdCl(2) with 2 equivs of dapdoH(2) in MeOH under reflux gave 1, whereas the same reaction with PtCl(2) in place of PdCl(2) gave 2 in comparable yields (70-80%). The divalent metal center in both compounds is coordinated by a terminal chloro group and a N,N',N"-tridentate chelating (η(3)) dapdoH(-) ligand. Thus, each metal ion is four coordinate with a distorted square planar geometry. Characterization of both complexes with (1)H and (13)C NMR and UV-vis and electrospray ionization mass spectroscopies confirmed their integrity in DMSO solutions. Interaction of the complexes with human and bovine serum albumin has been studied with fluorescence spectroscopy, revealing their affinity for these proteins with relatively high values of binding constants. UV study of the interaction of the complexes with calf-thymus DNA (CT DNA) has shown that they can bind to CT DNA, and the corresponding DNA binding constants have been evaluated. Cyclic voltammograms of the complexes in the presence of CT DNA solution have shown that the interaction of the complexes with CT DNA is mainly through intercalation, which has been also shown by DNA solution viscosity measurements. Competitive studies with ethidium bromide (EB) have revealed the ability of the complexes to displace the DNA-bound EB, suggesting competition with EB. The combined work demonstrates the ability of pyridyl-dioxime chelates not only to lead to polynuclear 3d-metal complexes with impressive structural motifs and interesting magnetic properties but also to yield new, mononuclear 4d- and 5d-metal complexes with biological implications. 相似文献
32.
We introduce a new family of bipartite graphs which is the bipartite analogue of the class ofcomplement reduciblegraphs orcographs. Abi-complement reduciblegraph orbi-cographis a bipartite graphG = (W ∪ B, E) that can be reduced to single vertices by recursively bi-complementing the edge set of all connected bipartite subgraphs. Thebi-complementedgraphofGis the graph having the same vertex setW ∪ BasG, while its edge set is equal toW × B − E. The aim of this paper is to show that there exists an equivalent definition of bi-cographs by three forbidden configurations. We also propose a tree representation for this class of graphs. 相似文献
33.
Vassilis Kanellopoulos 《Transactions of the American Mathematical Society》2005,357(10):3865-3886
We show that for every rooted, finitely branching, pruned tree of height there exists a family which consists of order isomorphic to subtrees of the dyadic tree with the following properties: (i) the family is a subset of ; (ii) every perfect subtree of contains a member of ; (iii) if is an analytic subset of , then for every perfect subtree of there exists a perfect subtree of such that the set either is contained in or is disjoint from .
34.
Ioannis Polyzos Georgios Tsigaridas Mihalis Fakis John Parthenios Anastassios Fragos Vassilis Giannetas Peter Persephonis John Mikroyannidis 《Monatshefte für Chemie / Chemical Monthly》2001,132(1):169-175
Summary. Two-photon absorption induced fluorescence microscopy was used as a tool for the examination of the spatial distribution
of a thin dye film. The two-photon absorption induced fluorescence signal is essentially the same as that produced by excitation
with a single photon of equivalent energy. When femtosecond pulses are focused into a sample there is an intrinsic spatial
selectivity of the two-photon emission signal, since it is dependent upon the square of the light intensity. This has tremendous
implications in fluorescence microscopy. Since two-photon absorption is confined in a small region at the focal waist of an
objective lens, photodamage and photobleaching of the sample are significantly reduced. In addition, the two-photon signal
has inherent z-axis spatial resolution, which facilitates the construction of 3-D images. In the present work an application of this technique
to a thin film of a dye is presented. The method can generally be applied to thin films made from photonic polymers.
Received June 23, 2000. Accepted (revised) July 31, 2000 相似文献
35.
John Lucas‐Lekatsas Vassilis Kostopoulos 《Mathematical Methods in the Applied Sciences》2009,32(14):1844-1877
A plane wave is scattered by an acoustically soft or hard sphere, covered by a penetrable non‐concentric spherical lossless shell that disturbs the propagation of the incident wave field. The dimensions of the coated sphere are much smaller than the wavelength of the incident field. Low‐frequency theory reduces this scattering problem to a sequence of potential problems, which can be solved iteratively. Exactly one bispherical coordinate system exists that fits the given geometry of the obstacle. For the case of a soft and hard core, the exact low‐frequency coefficients of the zeroth and the first‐order for the near field as well as the first‐ and second‐order coefficients for the normalized scattering amplitude are obtained and the cross sections are calculated. Discussion of the results and their physical meaning is included. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
36.
We prove a density version of the Halpern–Läuchli Theorem. This settles in the affirmative a conjecture of R. Laver. 相似文献
37.
38.
39.
Kaloudi-Chantzea A Karakostas N Raptopoulou CP Psycharis V Saridakis E Griebel J Hermann R Pistolis G 《Journal of the American Chemical Society》2010,132(46):16327-16329
The two sp(3) hybridized fluorine atoms of a Bodipy dye have been synthetically replaced with the linear donor ligand 4-ethynylpyridine (-C≡C-Py) to form a rigid and highly symmetrical 109.5° building block in which the fluorophore subunit is vertically aligned to the plane formed by the -C≡C-Py donors. Upon reaction of the above tecton with a 90° organoplatinum acceptor unit, an intensely fluorescent rhomboid cavitand was manifested in solution. In contrast to the vast majority of coordination-driven self-assembled chromophoric systems, the present one fully conserves the excellent photophysical properties of the parent Bodipy dye. These unique features of the present metallosupramolecular entity constitute a fascinating metal-to-ligand self-assembled prototype for building compact and intensely luminescent materials with host-guest capabilities. 相似文献
40.
Vassilis J. Demopoulos Antonis Gavalas George Rekatas Ekaterini Tani 《Journal of heterocyclic chemistry》1995,32(4):1145-1148
In this work, the synthesis of 6,7,8,9-tetrahydro-N,N-di -n-propyl-1H-benz[g]indol-7-amine (1) is described. This compound was designed as an indole bioisostere to the known dopamine receptor agonist 5-OH-aminotetraline 2 . The key step of the synthesis was a Mukaiyama type aldol condensation between the dimethyl acetal of 1-(p-toluenesulfonyl)pyrrole-3-acetaldehyde ( 4 ) and 4-di-n-propylamino-1-trimethylsilyloxycyclohexene ( 8 ) followed by cycloaromatization to afford 1-p-toluenesulfonyl-6,7,8,9-tetrahydro-N,N-di-n- propyl-1H-benz[g]indol-7-amine ( 10 ). Scission of the sulfonamide bond in 10 gave the target compound 1 . A byproduct which was isolated was assigned to the structure of 1-(p-toluenesul-fonyl)-6-[3-[1-(p-toluenesulfonyl)]pyrrolyl]indole ( 11 ). This compound was also synthesized in good yield by an acid catalyzed dimerization of the dimethyl acetal of 1-(p-toluenesulfonyl)pyrrole-3-acetaldehyde ( 4 ). Preliminary screening of 1 indicated that it possesses central dopamine receptor agonist properties. 相似文献