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71.
Mihai Cristea 《Complex Analysis and Operator Theory》2017,11(8):1789-1799
We give a generalization of a known theorem from classical complex analysis, namely the univalence on the boundary theorem. We apply this result to obtain some univalence conditions for Sobolev mappings \(f\in C({\overline{D}},{\mathbb {R}}^n)\bigcap W_{loc}^{1,q}(D,{\mathbb {R}}^n)\) which are injective on \(\partial D\), in connection with a known result of Ball from (Proc R Soc Edinb Sect A 88(3–4):315–328, 1981) modeling nonlinear elasticity. 相似文献
72.
Alexandru C. Razus Liviu Birzan Mihaela Cristea Eugenia Andreea Dragu Anamaria Hanganu 《Monatshefte für Chemie / Chemical Monthly》2011,40(9):1271-1282
Abstract
Two synthesis strategies were used for the generation of azulene-1-yl diazenes substituted at C-3 with a phenyl-chalcogenyl moiety, the synthesis of azulenes substituted at C-3 followed by azo-coupling and azulene substitution at C-3 in azulene-azo dyes. The last synthetic route seems to give more satisfactory results for the synthesis of the desired chalcogenic derivatives. Another target of this study was to investigate the changes induced by the phenyl-chalcogenic substitution on the NMR and UV-vis spectra, and also to compare this effect with the one exerted by halogen atoms and by strongly electron donating groups such as AcNH or PhCOO. Whereas the latter groups exhibit a strong influence on the NMR and UV-vis spectra, PhS, PhSe, or PhTe groups as well as halogen atoms produce only a small effect because of the moderate change in electron distribution over the entire molecule. 相似文献73.
Barbieriková Z Bella M Kučerák J Milata V Jantová S Dvoranová D Veselá M Staško A Brezová V 《Photochemistry and photobiology》2011,87(1):32-44
Novel 7‐substituted 6‐oxo‐6,9‐dihydro[1,2,5]selenadiazolo[3,4‐h]quinoline ( SeQ(1–6) ) and 8‐substituted 9‐oxo‐6,9‐dihydro[1,2,5]selenadiazolo[3,4‐f ]quinoline derivatives ( SeQN(1–5) ) with R7, R8 = H, COOC2H5, COOCH3, COOH, COCH3 or CN were synthesized and their spectral characteristics were obtained by UV/Vis spectroscopy. Ultraviolet A photoexcitation of the selenadiazoloquinolones in dimethylsulfoxide or acetonitrile resulted in the formation of paramagnetic species coupled with molecular oxygen activation generating the superoxide radical anion or singlet oxygen, evidenced by electron paramagnetic resonance spectroscopy. The cytotoxic/photocytotoxic impact of selenadiazoloquinolones on murine and human cancer cell lines was demonstrated using the derivative SeQ5 (with R7 = COCH3). 相似文献
74.
Fernandez FM Hostetler D Powell K Kaur H Green MD Mildenhall DC Newton PN 《The Analyst》2011,136(15):3073-3082
Throughout history, poor quality medicines have been a persistent problem, with periodical crises in the supply of antimicrobials, such as fake cinchona bark in the 1600s and fake quinine in the 1800s. Regrettably, this problem seems to have grown in the last decade, especially afflicting unsuspecting patients and those seeking medicines via on-line pharmacies. Here we discuss some of the challenges related to the fight against poor quality drugs, and counterfeits in particular, with an emphasis on the analytical tools available, their relative performance, and the necessary workflows needed for distinguishing between genuine, substandard, degraded and counterfeit medicines. 相似文献
75.
Heger D Nachtigallová D Surman F Krausko J Magyarová B Brumovský M Rubeš M Gladich I Klán P 《The journal of physical chemistry. A》2011,115(41):11412-11422
A combined experimental-computational approach was used to study the self-organization and microenvironment of 1-methylnaphthalene (1MN) deposited on the surface of artificial snow grains from vapors at 238 K. The specific surface area of this snow (1.1 × 10(4) cm(2) g(-1)), produced by spraying very fine droplets of pure water from a nebulizer into liquid nitrogen, was determined using valerophenone photochemistry to estimate the surface coverage by 1MN. Fluorescence spectroscopy at 77 K, in combination with molecular dynamics simulations, and density functional theory (DFT) and second-order coupled cluster (CC2) calculations, provided evidence for the occurrence of ground- and excited-state complexes (excimers) and other associates of 1MN on the snow grains' surface. Only weak excimer fluorescence was observed for a loading of 5 × 10(-6) mol kg(-1), which is ~2-3 orders of magnitude below monolayer coverage. However, the results indicate that the formation of excimers is favored at higher surface loadings (>5 × 10(-5) mol kg(-1)), albeit still being below monolayer coverage. The calculations of excited states of monomer and associated moieties suggested that a parallel-displaced arrangement is responsible for the excimer emission observed experimentally, although some other associations, such as T-shape dimer structures, which do not provide excimer emission, can still be relatively abundant at this surface concentration. The hydrophobic 1MN molecules, deposited on the ice surface, which is covered by a relatively flexible quasi-liquid layer at 238 K, are then assumed to be capable of dynamic motion resulting in the formation of energetically preferred associations to some extent. The environmental implications of organic compounds' deposition on snow grains and ice are discussed. 相似文献
76.
Reinemann DN Wright AM Wolfe JD Tschumper GS Hammer NI 《The journal of physical chemistry. A》2011,115(24):6426-6431
N-methyliminodiacetic acid (MIDA)-protected boronate esters are a new class of reagents that offer great promise in iterative Suzuki-Miyaura cross-coupling reactions. Compared to earlier reagents, MIDA esters are easily handled and are benchtop stable under air indefinitely. The success of this new species is tied to its unique molecular architecture. Compared to the simpler B-N containing molecules ammonia borane and trimethylamine borane, MIDA esters are much larger, and the sp(3) hybridized boron atom is secured by two five membered rings, making this molecular class stable for spectroscopic study. Here, we present infrared, Raman, and surface enhanced Raman (SERS) spectra of methylboronic acid MIDA ester. Comparisons of the spectroscopic results to those from electronic structure calculations suggest that the B-N stretching mode in this molecule lies in the range 560-650 cm(-1), making it among the lowest energy vibrations observed to date that can be primarily attributed to B-N stretching. 相似文献
77.
Alberola A Carter E Constantinides CP Eisler DJ Murphy DM Rawson JM 《Chemical communications (Cambridge, England)》2011,47(9):2532-2534
The β-sheet structure associated with chlorinated aromatics (d(Cl···Cl)≈ 4.0 ?) has been implemented to drive formation of π-stacked structures of dithiadiazolyl radicals. Both title compounds exhibit an increase in paramagnetism above 150 K but solid-state EPR studies indicate that the origin of the paramagnetism in these two systems is different. 相似文献
78.
Rodica Olar Mihaela Badea Dana Marinescu Larisa Calu Cristina Bucur 《Journal of Thermal Analysis and Calorimetry》2011,105(2):571-575
Novel complexes of type [M2LCl4]·nH2O ((1) M:Ni, n = 5; (2) M:Cu, n = 0 and (3) M:Zn, n = 2; L: ligand resulted from 1,2-phenylenediamine, 3,6-diazaoctane-1,8-diamine and formaldehyde template condensation) were
synthesised and characterised. The features of complexes have been assigned from microanalytical, IR and UV–Vis data. The
thermal analyses have evidenced the thermal intervals of stability and also the thermodynamic effects that accompany them.
Processes as water or hydrochloric acid elimination as well as oxidative degradation of the organic ligand were observed.
Complexes display a different thermal behaviour as result of dissimilar chemical interaction of metal ions with chloride anions.
The final product of decomposition was metal(II) oxide as powder X-ray diffraction indicated. 相似文献
79.
Mihaela Badea Rodica Olar Valentina Uivarosi Dana Marinescu Victoria Aldea Stefania Felicia Barbuceanu George Mihai Nitulescu 《Journal of Thermal Analysis and Calorimetry》2011,105(2):559-564
Two new complexes having general formula VOL2·nH2O [(1) L: 5-hydroxyflavone, n = 1; (2) L: chrysin, n = 4] were synthesized and characterized. Based on IR and electronic data we concluded that studied flavones act as bidentate
ligands in complexes with metallic ion coordinated in a square-pyramidal stereochemistry. The thermal analysis (TG, DTA) elucidated
the composition and also the number and nature of the water molecules. The thermal behavior also indicated strong interactions
between oxovanadium (IV) and these oxygen donor ligands. 相似文献
80.
Barbatti M Aquino AJ Szymczak JJ Nachtigallová D Lischka H 《Physical chemistry chemical physics : PCCP》2011,13(13):6145-6155
Deactivation of UV-excited cytosine is investigated by non-adiabatic dynamics simulations, optimization of conical intersections, and determination of reaction paths. Quantum chemical calculations are performed up to the MR-CISD level. Dynamics simulations were performed at multiconfigurational level with the surface hopping method including four electronic states. The results show the activation of four distinct reaction pathways at two different subpicosecond time scales and involving three different conical intersections. Most trajectories relax to a minimum of the S(1) state and deactivate with a time constant of 0.69 ps mainly through a semi-planar conical intersection along the n(O)π* surface. A minor fraction deactivate along ππ* regions of the S(1) surface. Sixteen percent of trajectories do not relax to the minimum and deactivate with a time constant of only 13 fs. 相似文献