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71.
George A Maijenburg AW Nguyen MD Maas MG Blank DH ten Elshof JE 《Langmuir : the ACS journal of surfaces and colloids》2011,27(20):12760-12768
We present a general methodology to pattern functional materials on the nanometer scale using self-assembled molecular templates on conducting substrates. A soft lithographic gas phase edge patterning process using poly(dimethylsiloxane) molds was employed to form electrically isolating organosilane patterns of a few nanometer thickness and a line width that could be tuned by varying the time of deposition. Electrodeposition was employed to deposit patterns of Ni and ZnO on these prepatterned substrates. Deposition occurred only on patches of the substrate where no organosilane monolayer was present. The process is simple, inexpensive, and scalable to large areas. We achieved formation of metallic and oxide material patterns with a lateral resolution of 80 nm. 相似文献
72.
J. Premakumari G. Allan Gnana Roy A. Antony Muthu Prabhu G. Venkatesh V. K. Subramanian N. Rajendiran 《Journal of solution chemistry》2011,40(2):327-347
The spectral characteristics of 2,4-dihydroxyazobenzene (DHAB, sudan orange G) and 4-hydroxyazobenzene (HAB) have been studied
in various solvents, different hydrogen ion and β-cyclodextrin (β-CD) concentrations, and are compared with azobenzene (AB). The inclusion complexes of the above molecules with β-CD were analyzed by UV-vis spectrometry, flourometry, FT-IR, 1H NMR, SEM and DFT methods. The solvent study shows that only the azo form is present in DHAB and HAB molecules. The unusually
large red shift observed in acidic solutions indicates both molecules exhibit azo-hydrazo tautomerization. In the β-CD solutions, the increase in fluorescence intensity and large bathochromic shift in the S1 state indicates that DHAB and HAB form 2:2 inclusion complexes, whereas AB forms a 1:1 inclusion complex. 相似文献
73.
Memboeuf A Jullien L Lartia R Brasme B Gimbert Y 《Journal of the American Society for Mass Spectrometry》2011,22(10):1744-1752
Collision induced dissociation tandem mass spectrometry experiments were performed to unequivocally separate compounds from
an isobaric mixture of two products. The Survival Yield curve was obtained and is shown to consist in a linear combination
of the curves corresponding to the two components separately. For such a mixture, a plateau appears on the diagram in lieu
of the continuous decrease expected allowing for the structural study of the two components separately. The width of the plateau
critically relates to the fragmentation parameters of the two molecular ions, which need to be sufficiently different structurally
for the plateau to be observed. However, at constant fragmentation parameters, we have observed the width significantly increases
at large m/z. This makes the separation more and more efficient as isobars have larger m/z and the technique complementary to those applicable at low m/z only. We have observed that the vertical position of the plateau relates linearly to the relative concentration of the two
compounds that may be useful for quantification. Repeatability was estimated at 2% on a quadrupole ion trap. An advantage
of using survival yield curves only, is that a priori knowledge of the respective fragmentation patterns of the two isobars
becomes unnecessary. Consequently, similar performances are obtained if fragments are isobaric, which is also demonstrated
in our study. The critical case of reverse peptides, at low m/z and similar fragmentation parameters, is also presented as a limitation of the method. 相似文献
74.
Weaver JF Hakanoglu C Antony A Asthagiri A 《Journal of the American Chemical Society》2011,133(40):16196-16200
We investigated regioselectivity in the initial C-H bond activation of propane σ-complexes on the PdO(101) surface using temperature programmed reaction spectroscopy (TPRS) experiments. We observe a significant kinetic isotope effect (KIE) in the initial C-H(D) bond cleavage of propane on PdO(101) such that the dissociation yield of C(3)H(8) is 2.7 times higher than that of C(3)D(8) at temperatures between 150 and 200 K. Measurements of the reactivity of (CH(3))(2)CD(2) and (CD(3))(2)CH(2) show that deuteration of the methyl groups is primarily responsible for the lower reactivity of C(3)D(8) relative to C(3)H(8), and thus that 1° C-H bond cleavage is the preferred pathway for propane activation on PdO(101). By analyzing the rate data within the context of a kinetic model for precursor-mediated dissociation, we estimate that 90% of the propane σ-complexes which dissociate on PdO(101) during TPRS do so by 1° C-H bond cleavage. 相似文献
75.
76.
Antony Bulanov Igor N. Shcherbakov Leonid D. Popov E. Y. Shasheva P. A. Belikov Zoya A. Starikova 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(3):o85-o88
The structures of new oxaindane spiropyrans derived from 7‐hydroxy‐3′,3′‐dimethyl‐3′H‐spiro[chromene‐2,1′‐isobenzofuran]‐8‐carbaldehyde (SP1), namely N‐benzyl‐2‐[(7‐hydroxy‐3′,3′‐dimethyl‐3′H‐spiro[chromene‐2,1′‐isobenzofuran]‐8‐yl)methylidene]hydrazinecarbothioamide, C27H25N3O3S, (I), at 120 (2) K, and N′‐[(7‐hydroxy‐3′,3′‐dimethyl‐3′H‐spiro[chromene‐2,1′‐isobenzofuran]‐8‐yl)methylidene]‐4‐methylbenzohydrazide acetone monosolvate, C27H24N2O4·C3H6O, (II), at 100 (2) K, are reported. The photochromically active Cspiro—O bond length in (I) is close to that in the parent compound (SP1), and in (II) it is shorter. In (I), centrosymmetric pairs of molecules are bound by two equivalent N—H...S hydrogen bonds, forming an eight‐membered ring with two donors and two acceptors. 相似文献
77.
Prashant S. Umare Ajaykumar J. Tiwari Robin Antony Gopal L. Tembe Bhavna Trivedi 《应用有机金属化学》2007,21(8):652-660
Complexes of titanium(IV) with bulky phenolic ligands such as 2‐tert‐butyl‐4 methylphenol, 2, 4‐di‐tert‐butyl phenol and 3,5‐di‐tert‐butyl phenol were prepared and characterized. These catalyst precursors, formulated as [Ti(OPh*)n(OPri)4?n] (OPh* = substituted phenol), were found to be active in polymerization of ethylene at higher temperatures in combination with ethylaluminum sesquichloride (Et3Al2Cl3) as co‐catalyst. It was observed that the reaction temperature and ethylene pressure had a pronounced effect on polymerization and the molecular weight of polyethylene obtained. In addition, this catalytic system predominantly produced linear, crystalline ultra‐low‐molecular‐weight polyethylenes narrow dispersities. The polyethylene waxes obtained with this catalytic system exhibit unique properties that have potential applications in surface coating and adhesive formulations. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
78.
This paper reports the investigation of the nanostructured surface morphology of novel arborescent polyisobutylene-block-polystyrene (PIB-PS) copolymers, in comparison with linear PS-PIB-PS triblock copolymers, using atomic force microscopy (AFM) in tapping mode. Arborescent PIB-PS samples displayed interesting new phase morphologies, which changed dramatically upon annealing but remained irregular. Linear PS-PIB-PS samples showed morphologies similar to those previously found by transmission electron microscopy (TEM) in cryomicrotomed bulk samples, ranging from spherical/cylindrical to lamellar nanometer-sized discreet PS phases dispersed in a continuous PIB matrix. Annealing the samples resulted in more ordered structures.Three-dimensional AFM image and section analysis indicated a height difference between PIB and PS in the block copolymers, which became more prominent during annealing. This feature was verified on compression moulded and protein coated samples. The arborescent PIB-PS materials displayed thermoplastic elastomeric behaviour with a tensile strength between 7 and 10 MPa and elongation ranging from 1000% to 1830%. In comparison, linear triblock samples had a tensile strength between 7 and 20 MPa and elongation ranging from 380% to 640%. Block copolymers with irregular elastomeric midsegments may emerge as a new class of TPEs. 相似文献
79.
80.