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91.
[structure: see text] The synthesis of unsaturated beta-linked C-disaccharides by the Lewis acid-mediated reaction of 3-O-acetylated glycals with monosaccharide-derived alkenes is described. Deprotection and selective hydrogenation of an exocyclic carbon-carbon double, in the presence of an endocyclic double bond, for representative targets is also illustrated. 相似文献
92.
Deevi Basavaiah Vanampally Chandrashekar Utpal Das Gone Jayapal Reddy 《Tetrahedron: Asymmetry》2005,16(24):3955-3962
Representative diastereomeric pairs of chiral catalysts, containing the (5S)-1,3-diaza-2-phospha-2-oxo-3-phenylbicyclo(3.3.0)octane moiety, with different stereochemistry at the phosphorus stereogenic center, have been synthesized and their stereoselection in the borane-mediated asymmetric reduction of representative prochiral ketones has been described. 相似文献
93.
Walsh PJ Gordon KC Lundin NJ Blackman AG 《The journal of physical chemistry. A》2005,109(26):5933-5942
Copper(I) and rhenium(I) complexes [Cu(PPh(3))(2)(dppz-11-COOEt)]BF(4), [Cu(PPh(3))(2)(dppz-11-Br)]BF(4), [Re(CO)(3)Cl(dppz-11-COOEt)] and [Re(CO)(3)Cl(dppz-11-Br)] (dppz-11-COOEt = dipyrido-[3,2a:2',3'c]phenazine-11-carboxylic ethyl ester, dppz-11-Br = 11-bromo-dipyrido[3,2a:2',3'c]-phenazine) have been studied using Raman, resonance Raman, and transient resonance Raman (TR(2)) spectroscopy, in conjunction with computational chemistry. DFT (B3LYP) frequency calculations with a 6-31G(d) basis set for the ligands and copper(I) centers and an effective core potential (LANL2DZ) for rhenium in the rhenium(I) complexes show close agreement with the experimental nonresonance Raman spectra. Modes that are phenazine-based, phenanthroline-based, and delocalized across the entire ligand structure were identified. The nature of the absorbing chromophores at 356 nm for ligands and complexes was established using resonance Raman spectroscopy in concert with vibrational assignments from calculations. This analysis reveals that the dominant chromophore for the complexes measured at 356 nm is ligand-centered (LC), except for [Re(CO)(3)Cl(dppz-11-Br)], which appears to have additional chromophores at this wavelength. Calculations on the reduced complexes, undertaken to model the metal-to-ligand charge transfer (MLCT) excited state, show that the reducing electron occupies a ligand MO that is delocalized across the ligand structure. Resonance Raman spectra (lambda(exc) = 514.5 nm) of the reduced rhenium complexes show a similar spectral pattern to that observed in [Re(CO)(3)Cl(dppz)](*-); the measured bands are therefore attributed to ligand radical anion modes. These bands lie at 1583-1593 cm(-1) for [Re(CO)(3)Cl(dppz-11-COOEt)] and 1611 cm(-1) for [Re(CO)(3)Cl(dppz-11-Br)]. The thermally equilibrated excited states are examined using nanosecond-TR(2) spectroscopy (lambda(exc) = 354.7 nm). The TR(2) spectra of the ligands provide spectral signatures for the (3)LC state. A band at 1382 cm(-1) is identified as a marker for the (3)LC states of both ligands. TR(2) spectra of the copper and rhenium complexes of dppz-11-Br show this (3)LC band, but it is not prominent in the spectra of [Cu(PPh(3))(2)(dppz-11-COOEt)](+) and [Re(CO)(3)Cl(dppz-11-COOEt)]. Calculations suggest that the lowest triplet states of both of the rhenium(I) complexes and [Cu(PPh(3))(2)(dppz-11-Br)](+) are metal-to-ligand charge transfer in nature, but the lowest triplet state of [Cu(PPh(3))(2)(dppz-11-COOEt)](+) appears to be LC in character. 相似文献
94.
Michael I. Bruce Brian W. Skelton Allan H. White Natasha N. Zaitseva 《Journal of organometallic chemistry》2002,650(1-2):188-197
Reactions of FcCCH (a), HCCCCFc (b) and FcCCCCFc (c) with Ru3(CO)10(NCMe)2 (all) and Ru3(μ-dppm)(CO)10 (b and c only) are described. Among the products, the complexes Ru3(μ3-RC2R′)(μ-CO)(CO)9 (R=H, R′=Fc 1, CCFc 2; R=R′=Fc 5), Ru3(μ-H)(μ3-C2CCFc)(μ-dppm)(CO)7 3, Ru3(μ3-FcC2CCFc)(μ-dppm)(μ-CO)(CO)7 6 and Ru3{μ3-C4Fc2(CCFc)2}(μ-dppm)(μ-CO)(CO)5 7 were characterised, including single-crystal structure determinations for 1, 3, 5 and 7; that of 7 did not differ significantly from an earlier study of a mixed CH2Cl2–C6H6 solvate. 相似文献
95.
Lars-Erik Persson Natasha Samko Peter Wall 《Journal of Fourier Analysis and Applications》2016,22(2):413-426
We find conditions for the weighted boundedness of a general class of multidimensional singular integral operators in generalized Morrey spaces \(\mathcal {L}^{p,\varphi }(\mathbb {R}^n,w),\) defined by a function \(\varphi (x,r)\) and radial type weight \(w(|x-x_0|), x_0\in {\mathbb {R}}^{n}.\) These conditions are given in terms of inclusion into \(\mathcal {L}^{p,\varphi }(\mathbb {R}^n,w),\) of a certain integral constructions defined by \(\varphi \) and w. In the case of \(\varphi =\varphi (r)\) we also provide easy to check sufficient conditions for that in terms of indices of \(\varphi \) and w. 相似文献
96.
Background
Sortin2 is a low mass compound that interferes with vacuolar delivery of proteins in plants and yeast. The Sortin2 phenotype was tested in Arabidopsis thaliana and found to be reversible upon drug removal, demonstrating the ability of chemical genomics to induce reversible phenotypes that would be difficult to achieve using conventional genetics [1]. However, standard genetic methods can be used to identify drug target pathways in a high-throughput manner.Results
In this study, we analyzed structure-function relationships of Sortin2 using structural analogues. The results show the key roles of sulphite substitution and a benzoic acid group. A Sortin 2 hypersensitivity screen for the induced secretion of a vacuolar cargo protein was done utilizing a yeast haploid deletion library. Using bioinformatics approaches, we highlighted functional information about the cellular pathways affected by drug treatment which included protein sorting and other endomembrane system-related processes.Conclusion
Chemical, genomic and genetics approaches were used to understand the mode of action of Sortin2, a bioactive chemical that affects the delivery of a vacuolar protein. Critical features of Sortin2 structure necessary for bioactivity suggest a binding pocket that may recognize two ends of Sortin2. The genome-wide screen shows that Sortin2 treatment in yeast affects primarily components within the endomembrane system. This approach allowed us to assign putative functions in protein sorting for fifteen genes of previously unknown function. 相似文献97.
Michael I. Bruce Natasha N. Zaitseva Brian W. Skelton Allan H. White 《Journal of organometallic chemistry》2008,693(8-9):1400-1404
The reaction between RuCl(PPh3)2Cp1 and {Cu(CCPh)}n in refluxing benzene afforded Ru2Cu2(C2Ph)5H2(Cl)(PPh3)Cp12, which contains an unusual tetramer of the phenylethynyl group which interacts with an Ru…Cu…Cu…Ru chain. The second Ru atom is part of a ruthenocenyl moiety which interacts weakly with the second Cu atom, and bears a vinylidene which bridges an Ru–Cu vector. The structure of a second modification of Ru(CCPh)(CO)(PPh3)Cp1 is also reported. 相似文献
98.
Michael I. Bruce Maryka Gaudio Giovanni Melino Natasha N. Zaitseva Brian K. Nicholson Brian W. Skelton Allan H. White 《Journal of Cluster Science》2008,19(1):147-170
Several new gold-containing cluster complexes have been prepared from the reactions of gold alkynyl complexes, L
n
M-C
x
-Au(PPh3), (x = 3, 4, 6) with Ru3(CO)10(NCMe)2. The bis-cluster complex 1,4-{AuRu3(CO)9(PPh3)(μ3-C2)}2C6H4 was obtained from Ru3(CO)10(NCMe)2 and 1,4-{(Ph3P)Au(C≡C)}2C6H4. The complexes Ru3(μ-H){μ3-C2C≡C[Ru(PP)Cp′]}(CO)9 [PP = (PPh3)2, Cp′ = Cp; PP = dppe, Cp′ = Cp*] were also obtained as minor by-products and synthesised independently from Ru(C≡CC≡CH)(PP)Cp′.
A reaction between Co3{μ3-CC≡CC≡CAu(PPh3)}(μ-dppm)(CO)7 and Ru3(CO)12 afforded {(Ph3P)(OC)9AuRu3}C≡CC≡CC{Co3(μ-dppm)(CO)7} 7. Related complexes AuRu3{μ3-C2C≡[M(CO)2Tp]}(CO)9(PPh3) (M = Mo 8, W 9) were obtained from {Tp(OC)2M}≡CC≡C{Au(PPh3)}, while the mixed metal cluster complexes MoM2(C2Me)(CO)8Tp (M = Ru 13, Fe 14) were obtained from M(≡CC≡CSiMe3)(CO)2Tp (M = Mo, W) with Fe2(CO)9 and Ru3(CO)12, respectively. Reactions of the Mo carbyne complex with Co2(LL)(CO)6 [LL = (CO)2, μ-dppm] or nickelocene afforded complexes 15–17 in which Co2 and Ni2 fragments, respectively, had coordinated to the C≡C triple bond. XRD structural determinations of 7, 8, 14, 16 and {Tp(OC)2W}≡CC≡CC≡{Co3(μ-dppm)(CO)7} (18-W) are reported.
In memoriam: F. Albert Cotton (1930–2007). 相似文献
99.
Priya Anbu Kadarkarai Murugan Pari Madhiyazhagan Devakumar Dinesh Jayapal Subramaniam Chellasamy Panneerselvam 《Natural product research》2016,30(18):2077-2084
The impact of green-synthesised mosquitocidal nanoparticles on non-target aquatic predators is poorly studied. In this research, we proposed a single-step method to synthesise silver nanoparticles (Ag NP) using the seed extract of Melia azedarach. Ag NP were characterised using a variety of biophysical methods, including UV–vis spectrophotometry, scanning electron microscopy, energy-dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy. In laboratory assays on Anopheles stephensi, Ag NP showed LC50 ranging from 2.897 (I instar larvae) to 14.548 ppm (pupae). In the field, the application of Ag NP (10 × LC50) lead to complete elimination of larval populations after 72 h. The application of Ag NP in the aquatic environment did not show negative adverse effects on predatory efficiency of the mosquito natural enemy Cyclops vernalis. Overall, this study highlights the concrete possibility to employ M. azedarach-synthesised Ag NP on young instars of malaria vectors. 相似文献
100.
Humaira Yasmeen Amir Zada Sharafat Ali Imran Khan Wajid Ali Waliullah Khan Muhammad Khan Natasha Anwar Asif Ali Ali M. Huerta-Flores Fazle Subhan 《中国化学会会志》2020,67(9):1611-1617
To effectively address environmental pollution, we synthesized Au-loaded ZnO nanocomposites and applied for the photocatalytic degradation of 2-chlorophenol (2-CP) under visible light irradiation. The as-prepared nanophotocatalysts delivered much improved photocatalytic degradation activities as compared to the bare ZnO nanoparticles and 32% of the pollutant was degraded with 2AuZnO in 1 hr. These improved photoactivities are attributed to the extended visible light absorption due to the surface plasmon resonance property of the loaded Au nanoparticles. Moreover, Au nanoparticles played important role in charge separation by inducting excited electrons to the conduction band of ZnO photocatalyst and surface catalysis as confirmed from photoluminescence spectra and amount of the generated hydroxyl radicals. The trapping experiments confirmed that positive holes were the major degrading species during the photocatalytic degradation of 2-CP. This work provides a feasible way to improve the photocatalysis by introducing a proper amount of noble metals over the surface of semiconductor photocatalysts. 相似文献