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41.
Peter Brenneisen Jinsook Oh Meinhard Wlaschek Jutta Wenk Karlis Briviba Christina Hommel Gemot Herrmann Helmut Sies Karin Scharffetter-Kochanek 《Photochemistry and photobiology》1996,64(5):877-885
Abstract— The wavelength dependence for the regulation of two major matrix-metalloproteinases, interstitial collagenase (MMP-1) and stromelysin-1 (MMP-3), and their major inhibitor, tissue inhibitor of metalloproteinases (TIMP-1), was studied in human dermal fibroblasts in vitro. Monochromatic irradiation at 302, 307, 312 and 317 nm with intensities ranging from 20 to 300 J/m2 increased MMP-1 and MMP-3 mRNA steady-state levels and the secretion of the corresponding proteins up to 4.4-fold, whereas almost no increase was observed at wavelengths <290 nm. In contrast, the synthesis of TIMP-1 increased only marginally. This unbalance may contribute to the severe connective tissue damage related to photoaging of the skin. The wavelengths responsible for MMP-1 and MMP-3 induction reported here are distinct from the absorption spectrum of DNA and are different from results previously reported in the literature. Importantly, they overlap with wavelengths whose intensity is predicted to increase on the earth's surface upon ozone depletion. Intensities and particular wavelengths used in our studies in vitro can be absorbed readily by fibroblasts within the skin in vivo and, thus, are relevant for risk assessment and development of protective agents. 相似文献
42.
Herber U Pechmann T Weberndörfer B Ilg K Werner H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(1):309-319
A series of dinuclear chelate complexes of the general composition [Rh2(kappa2-L)2(mu-CR2)2(mu-SbiPr3)] (R = Ph, p-Tol; L = CF3CO2-, acac-, acac-f3-) and [Rh2Cl(kappa2-L)(mu-CR2)2(mu-SbiPr3)] (R = Ph, p-Tol; L = acac-, acac-f3-) has been prepared by replacement of the chloro ligands in the precursors [Rh2Cl2(mu-CR2)2(mu-SbiPr3)] by anionic chelates. The lability of the SbiPr3 bridge in the rhodium dimers is illustrated by the reactions of [Rh2(kappa2-acac)2(mu-CR2)2(mu-SbiPr3)] (7, 8) with Lewis bases such as CO, CNtBu, and SbEt3 which lead to the formation of the substitution products [Rh2(kappa2-acac)2(mu-CR2)2(mu-L')] (13-16) in excellent yields. Treatment of 7 and 8 with sterically demanding tertiary phosphanes PR3 (R3 = iPr3, iPr2Ph, iPrPh2, Ph3) affords the mixed-valence Rh0-RhII complexes [(kappa2-acac)2Rh(mu-CPh2)2Rh(PR3)] (21-24) and [(kappa2-acac)2Rh(mu-C(p-Tol)2]2Rh(PiPr3)] (25) for which there is no precedence. The terminal PiPr3 ligand of 21 is easily displaced by alkynes, CNtBu, and CO to give, by preserving the [(kappa2-acac)2Rh(mu-CPh2)2Rh] molecular core, the related dinuclear compounds 26-31 in which the coordination number of the Rh0 center is 3, 4, or 5. The molecular structures of [Rh2Cl(kappa2-acac)(mu-CPh2)2(mu-SbiPr3)] (5), [Rh2(kappa2-acac)2(mu-CPh2)2(mu-CO)] (13), [(kappa2-acac)2Rh(mu-CPh2)2Rh(PiPr3)] (21), and [(kappa2-acac)2Rh(mu-CPh2)2Rh(CNtBu)2] (30) have been determined crystallographically. 相似文献
43.
Comprehensive two-dimensional gas chromatography (GC x GC) offers new opportunities to develop relationships between molecular structure and retentions in the two dimensional (2D) separation space defined by the GC x GC retention in each dimension. Whereas single dimension GC provides only one retention property for a solute, and hence the specific relationship between retention and chemical property is not readily apparent or derivable, the 2D presentation of compounds in GC x GC provides a subtle and exquisite correlation of chemical property and retention unlike any other GC experiment. The 'orthogonality' of the two separation dimensions is intimately related to the manner in which different separation mechanisms, available through use of two dissimilar phases, are accessible to the different chemical compounds or classes in a sample mixture, and indeed the specific chemical classes present in the sample. The GC x GC experiment now permits various processes such as chemical decompositions, molecular interconversions, various non-linear chromatography effects, and processes such as slow reversible interactions that may arise with stationary phases or in the injector or column couplings, to be identified and further investigated. Here, we briefly review implementation of the GC x GC method, consider the molecular selectivity of GC x GC, and highlight a selection of molecular processes that can be probed by using GC x GC. 相似文献
44.
Zusammenfassung Es werden Methoden zur Darstellung der Diäthyldithiophosphorsäure und ihres Na-Salzes beschrieben, sowie Eigenschaften und Verfahren zur Bestimmung der genannten Verbindungen angegeben.Während das Na-Salz das aus wäßriger Lösung mit 3 Molen Wasser kristallisiert, über lange Zeit hinweg unzersetzt aufbewahrt werden kann, zersetzen sich wäßrige Lösungen der freien Säure im Laufe der Zeit. Verdünnte 1 n salzsaure Lösungen des Na-Salzes zerfallen bei Zimmer-temperatur nach einer Reaktion erster Ordnung mit einer Halbwertszeit von ungefähr 250 Std. Es werden weiterhin Angaben über die Verteilung der Diäthyldithiophosphorsäure zwischen CCl4 und wäßrigen Lösungen bei verschiedener Salzsäurekonzentration gemacht.Unsere Arbeit wurde durch Gaben der Deutschen Forschungsgemeinschaft und des Verbandes der Chemischen Industrie — Fonds der Chemie — gefördert, wofür auch an dieser Stelle gedankt sei. 相似文献
45.
The coordinative properties of the acceptor ligand CS are discussed on the basis of the new thiocarbonyl complexes CpCr(CO)(CS)(NO) (I), [CpCr(CS)(NO)2]PF6 (II), CpCr(CS)(L)(NO) (L = pyridine (III) or trimethylphosphane (IV) and related carbonyl complexes. The IR and NMR spectra (1H, 13C, 31P) of the complexes indicate ligand—ligand interactions between CS and both the nitrosyl group and the cyclopentadienyl ring. An attempt is made to compare CS with other sulphur-containing acceptor ligands such as NS (in CpCr(CO)2(NS)) and CS2 (in CpCr(CS2)(PMe3)(NO)). 相似文献
46.
47.
Joseph Schwarz Detlef Schrder Helmut Schwarz Christoph Heinemann Jan Hruk 《Helvetica chimica acta》1996,79(4):1110-1120
State-of-the-art ab initio studies demonstrate that the reaction Pd+ + CH3I → PdCH2I+ + H. is endothermic by ca. 20 kcal/mol, which translates into a bond dissociation energy (BDE) of ca. 83 kcal/mol for the Pd+? CH2I bond. This figure is in agreement with an experimental bracket of 68 kcal/mol < BDE(Pd+? CH2I) < 92 kcal/mol. Based on these findings, the previously studied Pd+/CH3I system was re-investigated, and double-resonance experiments demonstrate that the formation of PdCH2I+ occurs stepwise via PdCH as a reactive intermediate. Further, ion/molecule reactions of PdCH2I+ with unsaturated hydrocarbons are studied, which reveal the formation of carbon–carbon bonds in the gas phase. 相似文献
48.
Gaseous Acetates Thermoanalytical and mass-spectrometrical observations are undertaken with some acetates and oxiacetates. The volatilization of copper(I) acetate takes place like that of the silver acetate as M2Ac2+ (besides the deposition of Ag). On the volatilization of the anhydrous compounds Cu2Ac4, Cr2Ac4, Rh2Ac4, and Mo2Ac4 in the vacuum of a mass spectrometer is observed that Cu2Ac4 vaporizes dissociative as Cu2Ac2+ (+ 2 “Ac”), while the other compounds vaporize as M2Ac4+ and simultaneously is formed an oxidic (e.g. Cr2O4) or metallic residue. PdAc2 vaporizes in the mass spectrometer as a trimeric molecule Pd3Ac6. M4OAc6, which is formed from the dihydrates, vaporizes in a mass spectrometer with M ? Co, Mn as M4OAc6+. Other complexes of the same type appear as Be4OAc5+, Mg4OAc5+, and Zn4OAc5+. 相似文献
49.
Ralf Garbe Jürgen Pebler Kurt Dehnicke Dieter Fenske Helmut Goesmann Gerhard Baum 《无机化学与普通化学杂志》1994,620(4):592-598
Phosphorane Iminato Complexes of Antimony. The Crystal Structures of [Sb2Cl5(NPMe3)2][SbCl6] · CH3CN and [SbCl(NPPh3)]2[SbCl6]2 · 6 CH3CN The title compounds are formed by reaction of antimony pentachloride in acetonitrile solution with the phosphorane iminato complexes SbCl2(NPMe3) and SbCl2(NPPh3), respectively, which themselves are synthesized by reaction of antimony trichloride with Me3SiNPR3 (R = Me, Ph). The complexionic compounds are characterized by 121Sb Mössbauer spectroscopy and by crystal structure determinations. [Sb2Cl5(NPMe3)2][SbCl6] · CH3CN: Space group P41, Z = 4, 3 698 observed unique reflections, R = 0.022. Lattice dimensions at ?60°C: a = b = 1 056.0(1), c = 2 709.6(2) pm. The structure consists of SbCl6? ions and cations [Sb2Cl5(NPMe3)2(CH3CN)]+, in which one SbIII atom and one SbV atom are bridged by the N atoms of the phosphorane iminato ligands. [SbCl(NPPh3)]2[SbCl6]2 · 6 CH3CN: Space group P1 , Z = 2, 5 958 observed unique reflections, R = 0.033. Lattice dimensions at ?60°C: a = 989.4(11), b = 1 273(1), c = 1 396(1) pm, α = 78.33(7), β = 77.27(8)°, γ = 86.62(8)°. The structure consists of SbCl6? ions and centrosymmetric cations [SbCl(NPPh3)(CH3CN)2]22+, in which the antimony atoms are bridged by the N atoms of the phosphorane iminato ligands. 相似文献
50.
Bis(cyclopentadienyl)methane-bridged Dinuclear Complexes, V[1]. – Heteronuclear Co/Rh-, Co/Ir-, Rh/Ir-, and Ti/Ir Complexes with the Bis(cyclopentadienyl)methane Dianion as Bridging Ligand* The lithium and sodium salts of the [C5H5CH2C5H4]- anion, 1 and 2 , react with [Co(CO)4I], [Rh(CO)2Cl]2, and [Ir(CO)3Cl]n to give predominantly the mononuclear complexes [(C5H5-CH2C5H4)M(CO)2] ( 3, 5, 7 ) together with small amounts of the dinuclear compounds [CH2(C5H4)2][M(CO)2]2 ( 4, 6, 8 ). The 1H- and 13C-NMR spectra of 3, 5 , and 7 prove that the CH2C5H5 substituent is linked to the π-bonded ring in two isomeric forms. Metalation of 5 and 7 with nBuLi affords the lithiated derivatives 9 and 10 from which on reaction with [Co(CO)4I], [Rh(CO)2Cl]2, and [C5H5TiCl3] the heteronuclear complexes [CH2(C5H4)2][M(CO)2][M′(CO)2] ( 11–13 ) and [CH2(C5H4)2]-[Ir(CO)2][C5H5TiCl2] ( 17 ) are obtained. Photolysis of 11 and 12 leads almost quantitatively to the formation of the CO-bridged compounds [CH2(C5H4)2][M(CO)(μ-CO)M′(CO)] ( 14, 15 ). According to an X-ray crystal structure analysis the Co/Rh complex 14 is isostructural to [CH2(C5H4)2][Rh2(CO)2(μ-CO)] ( 16 ). 相似文献