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排序方式: 共有135条查询结果,搜索用时 15 毫秒
41.
Efficient quenching of photoluminescence from functionalized single-walled carbon nanotubes by nitroaromatic molecules 总被引:2,自引:0,他引:2
Kose ME Harruff BA Lin Y Veca LM Lu F Sun YP 《The journal of physical chemistry. B》2006,110(29):14032-14034
The photoluminescence from functionalized single-walled carbon nanotubes was found to be highly sensitive to the presence of nitroaromatic compounds such as nitrobenzene, 4-nitrotoluene, and 2,4-dinitrotoluene. The strong luminescence quenching in solution was at the upper limit of diffusion-control and also showed significant static quenching contributions. Mechanistic implication of the results and potential applications are discussed. 相似文献
42.
Muhammet I
klan Zeynel Kl Nurcan Akduran Tuncer Hkelek 《Journal of Molecular Structure》2003,660(1-3):167-179
The reactions of 2-trans-6-N4P4(NHPrn)2Cl6 (2), which was obtained from N4P4Cl8 (1) and n-propylamine, with pyrrolidine and t-butylamine in different solvents have been studied. Compound (2) gave two different products, namely monocyclic (3 and 5) and bicyclic (4 and 6) phosphazenes. Compounds (2–6) have been characterized by elemental analysis, IR, 1H-, 13C-, 31P NMR, HETCOR and MS and the structure of compound (5) has been examined crystallographically. The bicyclic phosphazene (6) is the first exciting example of bicyclic phosphazenes containing chlorine atoms, in the literature. The formation mechanisms of bicyclic phosphazenes are re-considered by taking into account the synthesis of compound (6), which contains three stereogenic phosphorus atoms. Compound (5) crystallizes in the monocyclic space group P21/n with a=13.974(2), b=17.836(5), and c=18.683(4) Å, β=98.50(1)°, V=4605.4(2) Å3, Z=4 and Dx=1.051 g cm−3. It consists of a non-centrosymmetric, non-planar phosphazene ring in a saddle conformation, with two n-propylamino (in 2-trans-6 positions) and six bulky t-butylamino side groups. The bulky substituents are instrumental in determining the molecular geometry. 相似文献
43.
Sun YP Zhou B Lin Y Wang W Fernando KA Pathak P Meziani MJ Harruff BA Wang X Wang H Luo PG Yang H Kose ME Chen B Veca LM Xie SY 《Journal of the American Chemical Society》2006,128(24):7756-7757
We report that nanoscale carbon particles (carbon dots) upon simple surface passivation are strongly photoluminescent in both solution and the solid state. The luminescence emission of the carbon dots is stable against photobleaching, and there is no blinking effect. These strongly emissive carbon dots may find applications similar to or beyond those of their widely pursued silicon counterparts. 相似文献
44.
[reaction: see text] Asymmetric total syntheses of acid-sensitive (-)-caparrapi oxide (1) and (+)-8-epicaparrapi oxide (2) from farnesol (9) were achieved using Sharpless-Katsuki epoxidation and Lewis acid-assisted chiral Bronsted acid (chiral LBA)-induced polyene cyclization as key steps. Furthermore, (-)-1 could be directly synthesized from (S)-nerolidol (3) and (R)-LBA with 88% ds by reagent control which overcame substrate control, while (-)-2 was obtained from (R)-3 and (R)-LBA with >99% ds by the double-asymmetric induction. 相似文献
45.
46.
Köse ME 《The Journal of chemical physics》2011,135(24):244512
Energy transfer mechanism in conjugated materials has been demonstrated with an activated expression, which is equivalent to Fermi's golden rule. Spectral overlap integrals obtained from simulated spectra of model chromophores agree very well with the results obtained with the activated formula. Although this approach works best for chromophores with spectral profiles resembling a Gaussian distribution, the activated expression formula also performs quite well for chromophores with vibronically resolved spectra. Activation energies for exciton hopping can also be predicted using a phonon coupled exciton relaxation scheme. The accuracy of predictions with this new approach is quite attractive and hence should allow practical applications. 相似文献
47.
48.
The synthesis of upper rim-functionalized calix[4]arene-based l-proline was described, and its catalytic efficiency as organocatalyst for the enantioselective aldol reaction in water was investigated. The results showed that the nature of the hydrophobic cavity of calixarene is critical for catalytic activity in water. The products of the reaction between various ketones and aldehydes with anti-configuration were obtained in high yields (up to 94%) with high diastereo- (up to 95:5 dr) and enantioselectivities (up to 80% ee). 相似文献
49.
Yaprak Güldoan Dericiolu Muhammet Kurulay 《Mathematical Methods in the Applied Sciences》2019,42(16):5438-5445
We propose a numerical method for solving large‐scale differential symmetric Stein equations having low‐rank right constant term. Our approach is based on projection the given problem onto a Krylov subspace then solving the low dimensional matrix problem by using an integration method, and the original problem solution is built by using obtained low‐rank approximate solution. Using the extended block Arnoldi process and backward differentiation formula (BDF), we give statements of the approximate solution and corresponding residual. Some numerical results are given to show the efficiency of the proposed method. 相似文献
50.