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181.
In the present work we outline the implications of a quantum-classical approach for modeling two-photon absorption of organic chromophores in solution. The approach joins many-photon absorption dynamic simulations with quantum chemical first principles calculations of corresponding excitation energies and transition matrix elements. Among a number of conclusions of the study, we highlight three: (i) The use of either short- or long-pulse excitation is demonstrated to switch the absorptive capacity of the nonlinear medium owing to enhancement of the nonlinear stepwise processes; (ii) The two-photon cross section strongly depends on the way in which the dephasing rate decays when the laser frequency is tuned off-resonant with the corresponding molecular transition; (iii) The results of the pulse propagation simulations based on electronic structure data obtained with a new Coulomb attenuated functional is shown to be in much better agreement with the experimental results than those based on data received with traditional density functionals. 相似文献
182.
183.
184.
We have explored the thermoluminescence (TL) properties of a few series of liquid crystal unsymmetrical and symmetrical azomethines and poly(azomethines) with different shapes. Rod-, bent- and star-shaped compounds were investigated as thermoluminescent detectors. All of the investigated compounds, except ASB3, AG2 and PAZ2, exhibited mesomorphic behavior. The thermoluminescence studies have shown that molecular structure of the compound along with shape influenced the TL properties of azomethines and poly(azomethines). Thermoluminescence intensity (I), temperature of maximum TL (T), activation energy values (E) and frequency factor (s) were detected. For the first time, to the best of our knowledge, thermoluminescence properties of liquid crystalline azomethines and polyazomethines were described and compared in this article. 相似文献
185.
Interpolation of Vector-Valued Real Analytic Functions 总被引:2,自引:0,他引:2
Let Rd be an open domain. The sequentially complete DF-spacesE are characterized such that for each (some) discrete sequence(zn) , a sequence of natural numbers (kn) and any family the infinite system of equations
has an E-valued real analytic solution f. 相似文献
186.
The following results are presented: 1) a characterization through the Liouville property of those Stein manifoldsU such that every germ of holomorphic functions on xU can be developed locally as a vector-valued Taylor series in the first variable with values inH(U); 2) ifT
is a surjective convolution operator on the space of scalar-valued real analytic functions, one can find a solutionu of the equationT
u=f which depends holomorphically on the parameterz wheneverf depends in the same manner. These results are obtained as an application of a thorough study of vector-valued real analytic maps by means of the modern functional analytic tools. In particular, we give a tensor product representation and a characterization of those Fréchet spaces or LB-spacesE for whichE-valued real analytic functions defined via composition with functionals and via suitably convergent Taylor series are the same. 相似文献
187.
Silvia Zamponi Anna M. Kijak André J. Sommer Roberto Marassi Pawel J. Kulesza James A. Cox 《Journal of Solid State Electrochemistry》2002,6(8):528-533
The inclusion of a generation-4 polyamidoamine (G4-PAMAM) dendrimer in a silica sol-gel yielded a solid electrolyte that
was used to encapsulate Prussian Blue (PB), iron(III) hexacyanoferrate(II), and cobalt hexacyanoferrate. The PB was synthesized
in the doped silica by sequential immersion of a monolith in 0.1 M K4Fe(CN)6, water, and 0.1 M FeCl3. Inclusion of G4-PAMAM resulted in a nanoporous anion-exchange material with a capacity of 10.1 mmol g–1, which is about four times greater than the capacity of silica alone. Relative to its G0 counterpart, the G4-PAMAM doped
silica increased the rate of formation of PB by a factor of ca. 20. The solid state voltammetry of PB in the doped silica
had the usual features for this compound. At 0.1 V vs. a Ag quasi-reference electrode, a reversible reduction was seen; the
relationship between current and scan rate was that for a surface-confined redox couple. The quasi-reversible oxidation of
PB was observed at 0.85 V. Inclusion of G4-PAMAM increased the lifetime of silica as a solid electrolyte from a few days to
at least three months. Raman microprobe mapping analysis demonstrated that PB was homogeneously distributed across the entire
width (ca. 1 mm) of the G4-doped monolith with 20-h immersions.
Electronic Publication 相似文献
188.
Double-proton transfer in adenine-thymine and guanine-cytosine base pairs. A post-Hartree-Fock ab initio study 总被引:2,自引:0,他引:2
Gorb L Podolyan Y Dziekonski P Sokalski WA Leszczynski J 《Journal of the American Chemical Society》2004,126(32):10119-10129
The results of a comprehensive study on the double-proton transfer in Adenine-Thymine (AT) and Guanine-Cytosine (GC) base pairs at room temperature in gas phase and with the inclusion of environmental effects are obtained. The double-proton-transfer process has been investigated in the AT and GC base pairs at the B3LYP/6-31G(d) and MP2/6-31G(d) levels of theory. It has been predicted that the hydrogen-bonded bases possess nonplanar geometries due to sp3 hybridization of nitrogen atoms and because of the soft intermolecular vibrations in the molecular complexes. An analysis of the energetic parameters of the local minima suggests that rare AT base pair conformation is not populated due to the shallowness of this minimum, which completely disappears from the Gibbs free energy surface. The stabilization of canonic or rare forms of the DNA bases by water molecules and metal cations has been predicted by calculating the optimal configuration of charges (using differential product/transition state stabilization approach) followed by calculations of the interactions between the base pair and a water/sodium cation. 相似文献
189.
Markuszewski MJ Wiczling P Kaliszan R 《Combinatorial chemistry & high throughput screening》2004,7(4):281-289
There is a need for fast testing of drug candidates for properties of pharmacokinetics and pharmacodynamics importance, in particular lipophilicity and acidity. These two parameters can conveniently be estimated by gradient reversed-phase HPLC. Appropriate conventional organic solvent gradient and the new pH gradient HPLC procedures are presented. The chromatographic parameter of lipophilicity, log kw, can be determined from two organic solvent gradient runs instead of 6-8 runs necessary in the standard isocratic (polycratic) approach. The newly introduced pH gradient reversed-phase HPLC consists in a programmed increase during the chromatographic run of the eluting power of the mobile phase with regards to ionizable analytes. The eluting strength of the mobile phase increases due to its increasing (in case of acidic analytes) or decreasing (basic analytes) pH, whereas the content of organic modifier remains constant. It has been theoretically and experimentally demonstrated that the pKa and log kw values can be evaluated based on retention data from a pH gradient run, combined with appropriate data from two organic solvent gradient runs. The gradient HPLC-derived log kw parameters correlate well with analogous parameters determined isocratically as well as with reference lipophilicity parameter log P (logarithm of n-octanol/water partition coefficient). Also, the HPLC-derived pKa parameters correlate to the literature pKa values (w(w)pKa), conventionally determined by titrations in water. The approach described allows rapid and high-throughput assessment of log kw and pKa for large series of drugs candidates, also when the analytes are available in a form of mixture, e.g. produced by combinatorial synthesis. 相似文献
190.
Francesco Fuso Cyril A. Grob Pawel Sawlewicz Guo Wei Yao 《Helvetica chimica acta》1986,69(8):2098-2107
The solvolysis rates and products of 4- and 5-exo-substituted 2-exo- and 2-endo-norbornyl tosylates 9 and 10 , respectively, are reported. The logarithms of the rate constants (log k) correlate linearly with the inductive constants σ for the substituents. A comparison of the reaction constants p1 for the 4-, 5-, 6-, and 7-substituted 2-exo- and 2-endo-tosylates 9 , 10 , 1 , and 2 respectively, indicates that inductivity is higher for 2-exo-ionization than for 2-endo-ionization in all series. This observation is attributed to the more favorable alignment of neighbouring C-atoms for dorsal participation in exo-ionization, especially, in the case of C(6). 相似文献