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71.
From hydrolysis and solution measurements the enthalpies of formation of SbF5(?), LiSbF6(s), NaSbF6(s), KSbF6(s), CsSbF6(s), AgSbF6(s), and SbF6?aq. are estimated to be ?1324 ± 12, ?2062 ± 5, ?2060 ± 6, ?2080 ± 3, ?2082 ± 15, ?1653 ± 3, and ?1789 ± 4 kJ mol?1 respectively. Less precise estimates of the enthalpies of formation of O2SbF6 and of CsSb3F16 are also given. From the results the fluoride ion affinity of SbF5, the single ion hydration enthalpy of SbF6? (g), and the charge distribution within the SbF6? ion have been calculated. 相似文献
72.
73.
Turchini S Zema N Zennaro S Alagna L Stewart B Peacock RD Prosperi T 《Journal of the American Chemical Society》2004,126(14):4532-4533
We have measured for the first time the X-ray natural circular dichroism (XNCD) of a chiral molecule in an isotropic medium. In this condition the only surviving term contributing to CD is the cross product between the electric dipole and the magnetic dipole transition moments. The non-zero value of the magnetic dipole transition moment in a 1s-to-valence electron transition is attributed to contribution of valence states to core molecular orbitals. These results open the way to a "local" chiral molecular analysis and to the study of stereochemically selected photochemical processes. 相似文献
74.
The electronic absorption and circular dichroism (CD) spectra of the complexes produced by the one, two, and three electron reduction of Delta-[Ru(bipy)(3)](2+) and Delta-[Os(bipy)(3)](2+) are reported. The CD spectra give unequivocal proof that the added electrons are localized on individual bipiridine ligands and thus that the complexes are correctly formulated [M(bipy)(2)(bipy(-))](+), [M(bipy)(bipy(-))(2)](0), and [M(bipy(-))(3)](-). The absorption spectra of the triply reduced species [M(bipy(-))(3)](-) (M = Ru, Os) are compared to those of the Fe(II) and Ir(III) analogs. The luminescence spectra of the two triply reduced complexes [Ru(bipy(-))(3)](-) and [Os(bipy(-))(3)](-). are also presented. The MLCT luminescence found in the parent complexes is completely quenched and is replaced by a weak luminescence attributed to the pi(10) --> pi(7) transition of the (coordinated) [bipy](-) ion. 相似文献
75.
Measurements of the linear dichroism of anthracene in an stretched polythene film, the magnetic circular dichroism of the hydrocarbon in a range of solvents, including those giving Ham effect, and the mesophase-induced circular dichroism of the hydrocarbon in a cholesteric solvent, place the origin of the 1Lb transition near 28 kK, some 1500 cm?1 to the blue of the 1Lb origin, contrary to recent assingments locating the 1Lb origin at 25 kK. 相似文献
76.
77.
The first order rate constants for the tautomerization of the hydrio(alkynyl) clusters Ru3Pt(μ-H){μ4-ν2-C ≡ C1Bu}(CO)9(L2);1a: L2 = dppe,1b; L2 = dppet,1c; L2 = dppp and1d; L2 =S,S-dppb to the corresponding vinylidene clusters Ru3Pt{μ4-ν2-C = C(H)tBu}(CO)9(L2)2 have been measured, and they follow the orser1d <1a <1b ~1c. The reactions involving1a and1d exhibit an inverse kinetic deuterium isotope effect. The structures of1b, 2b, 2c, and2d were determined by X-ray crystallography, and are compared with those of1a and2a which have been previously reported. Crystal data for1b, space groupPbca,a = 13.338(4) Å,b = 17.771(6) Å,c = 36.092(8) Å,Z = 8,R(R w) = 0.059(0.058) for 2342 absorption corrected, observed data; for2b, space group P21/n,a = 10.566(2) Å,b = 20.234(5) Å,c = 20.270(3) Å,β = 96.11(1)°,Z = 4,R(R w) = 0.043(0.053) for 5865 absorption corrected, observed data; for2c, space group P21/n,a = 14.211(5) Å,b = 19.534(2) Å,c = 15.870(2) Å,β = 100.81(2)°,Z = 4,R(R w) = 0.055(0.031) for 6566 absorption corrected, observed data: for2d, space group P212121,a = 12.309(4) Å,b = 19.047(6) Å,c = 19.206(4) Å,Z = 4,R(R w) = 0.055(0.053) fpr 2151 absorption corrected, observed data. The fluxional behavior of1d and1e (which consists of two interconverting isomers) has been examined by variable temperature13C NMR spectroscopy and by31P EXSY. 相似文献
78.
Three new azamacrocyclic-cyclophane hybrid receptors L(1), L(2), and L(3) have been synthesized that incorporate either 1,4,7,10-tetraazacyclododecane (cyclen) or 1,4,7-triazacyclononane (tacn) unit(s) tethered via a short amidic spacer to an electron donor and a H-bonding crown ether polycycle. The crown ether is designed to act as a host toward biologically relevant guests, whereas the macrocycle can coordinate a zinc(II) or a copper(II) ion. The pK(a) of this bound water in the zinc(II) complex of L(1) and L(2) is approximately 7.5. Isothermal calorimetry experiments carried out on [ZnL(1)(L2)(OH(2))](CF(3)SO(3))(2) and [Zn(2)L(2)(OH(2))(2)](CF(3)SO(3))(4) in buffered water (pH 7.4) at 25 degrees C show that the host strongly binds a series of phosphate derivatives. In comparison, the complex [CuL(3)(OH(2))(2)](CF(3)SO(3))(2) is a poor receptor toward phosphate substrates. 相似文献
79.
Galloway KW Whyte AM Wernsdorfer W Sanchez-Benitez J Kamenev KV Parkin A Peacock RD Murrie M 《Inorganic chemistry》2008,47(16):7438-7442
An investigation of the magnetic properties of the cobalt(II) citrate cubane [C(NH 2) 3] 8{Co 4(cit) 4}.4H 2O reveals that the cluster is a new cobalt(II) single-molecule magnet, with an energy barrier to reorientation of the magnetization, Delta E/ k B = 21 K, and tau 0 = 8 x 10 (-7) s. The compound displays distinct, frequency-dependent peaks in the out-of-phase (chi') component of the ac magnetic susceptibility and magnetization versus field hysteresis loops that are temperature and sweep rate dependent. The hysteresis loops collapse at zero field due to very fast quantum tunneling of the magnetization (QTM). 相似文献
80.
Baril NF He R Day TD Sparks JR Keshavarzi B Krishnamurthi M Borhan A Gopalan V Peacock AC Healy N Sazio PJ Badding JV 《Journal of the American Chemical Society》2012,134(1):19-22
Hydrogenated amorphous silicon (a-Si:H) is one of the most technologically important semiconductors. The challenge in producing it from SiH(4) precursor is to overcome a significant kinetic barrier to decomposition at a low enough temperature to allow for hydrogen incorporation into a deposited film. The use of high precursor concentrations is one possible means to increase reaction rates at low enough temperatures, but in conventional reactors such an approach produces large numbers of homogeneously nucleated particles in the gas phase, rather than the desired heterogeneous deposition on a surface. We report that deposition in confined micro-/nanoreactors overcomes this difficulty, allowing for the use of silane concentrations many orders of magnitude higher than conventionally employed while still realizing well-developed films. a-Si:H micro-/nanowires can be deposited in this way in extreme aspect ratio, small-diameter optical fiber capillary templates. The semiconductor materials deposited have ~0.5 atom% hydrogen with passivated dangling bonds and good electronic properties. They should be suitable for a wide range of photonic and electronic applications such as nonlinear optical fibers and solar cells. 相似文献