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121.
van der Heden van Noort GJ Verhagen CP van der Horst MG Overkleeft HS van der Marel GA Filippov DV 《Organic letters》2008,10(20):4461-4464
A one-pot procedure for the preparation of phosphoramidates, phosphorothioates, pyrophosphates, phosphodiesters, and phosphofluoridates has been devised using di(p-methoxybenzyl)-N,N-diisopropylphosphoramidite as the common phosphitylating reagent. 相似文献
122.
Brown NJ Eckert PK Fox MA Yufit DS Howard JA Low PJ 《Dalton transactions (Cambridge, England : 2003)》2008,(4):433-436
Reactions of half-sandwich ruthenium metal acetylide complexes with 1-cyano-4-dimethylaminopyridinium salts afford complexes containing mono- or di-cyanovinylidene ligands; the procedure can be adapted to permit the simple synthesis of a cyanoacetylide complex, via the in situ deprotonation of a primary cyanovinylidene complex. 相似文献
123.
The polarizable continuum model (PCM) for describing the solvent effect was combined with the fragment molecular orbital-based time-dependent density functional theory (TDDFT). Several levels of the many-body expansion were implemented, and the importance of the many-body contributions to the singlet-excited states was discussed. To calibrate the accuracy, we performed a number of the model calculations using our method and the regular TDDFT in solution, applying them to phenol and polypeptides at the long-range corrected BLYP/6-31G* level. It was found that for systems up to 192 atoms the largest error in the excitation energy was 0.006 eV (vs. the regular TDDFT/PCM of the full system). The solvent shifts and the conformer effects were discussed, and the scaling was found to be nearly linear. Finally, we applied our method to the lowest singlet excitation of the photoactive yellow protein (PYP) in aqueous solution and determined the excitation energy to be in reasonable agreement with experiment. The excitation energy analysis provided the contributions of individual residues, and the main factors as well as their solvent shifts were determined. 相似文献
124.
Bronstein LM Kostylev M Shtykova E Vlahu T Huang X Stein BD Bykov A Remmes NB Baxter DV Svergun DI 《Langmuir : the ACS journal of surfaces and colloids》2008,24(21):12618-12626
Small iron oxide and Co-doped iron oxide nanoparticles (NPs) were synthesized in a commercial amphiphilic block copolymer, poly(ethylene oxide)-b-poly(methacrylic acid) (PEO 68-b-PMAA8), in aqueous solutions. The structure and composition of the micelles containing guest molecules (metal salts) or NPs (metal oxides) were studied using transmission electron microscopy, dynamic light scattering, X-ray photoelectron spectroscopy, and X-ray powder diffraction. The enlarged micelle cores after incorporation of metal salts are believed to be formed by both PMAA blocks containing metal species and penetrating PEO chains. The nanoparticle size distributions in PEO 68-b-PMAA8 were determined using small-angle X-ray scattering (SAXS) in bulk. Two independent methods for SAXS data interpretation for comprehensive analysis of volume distributions of metal oxide NPs showed presence of both small particles and larger entities containing metal species which are ascribed to organization of block copolymer micelles in bulk. The magnetometry measurements revealed that the NPs are superparamagnetic and their characteristics depend on the method of the NP synthesis. The important advantage of the PEO 68-b-PMAA8 stabilized magnetic nanoparticles described in this paper is their remarkable solubility and stability in water and buffers. 相似文献
125.
Au-PbS core-shell nanocrystals: plasmonic absorption enhancement and electrical doping via intra-particle charge transfer 总被引:1,自引:0,他引:1
We present a comparative study of optical and electronic properties for PbS nanocrystals and Au-PbS core-shell nanostructures. In Au-PbS nanostructures, we observed two nontrivial synergistic effects: (i) extinction enhancement due to coupling of surface plasmon resonance in the Au core to the excitonic states in the semiconducting PbS shell, and (ii) strong p-type electronic doping of Au-PbS nanocrystal solids that we explained by the intraparticle charge transfer between the PbS shell and the Au core. 相似文献
126.
Dmitri I. Panyushev 《Journal of Algebraic Combinatorics》2016,43(2):325-338
We graph-theoretically characterize triangle-free Gorenstein graphs G. As an application, we classify when \(I(G)^2\) is Cohen–Macaulay. 相似文献
127.
128.
Khozikov V Kosobokova O Citver G Tyshko G Gavrilov DN Gudkov G Gorfinkel V 《Electrophoresis》2007,28(3):317-321
A novel, nondamaging method for experimental characterization of the formation and propagation of high-resistivity zones in CE, based on the measurement of time-dependent Joule heating on the outer capillary surface is proposed. The method detects propagation of resistive regions in capillaries in real time and allows the estimation of their velocity and resistance. The presented experimental data are in agreement with the results of the computer simulation as well as with previous data on the subject. The proposed method is useful for the development of new polymers as well as for the refinement and optimization of new CE protocols. 相似文献
129.
Kazakov DV Kazakov VP Maistrenko GY Mal'zev DV Schmidt R 《The journal of physical chemistry. A》2007,111(20):4267-4273
The acetone-catalyzed decomposition of monoperoxysulfate ions, the molybdate ion-induced decay of hydrogen peroxide, and the reactions of N-chlorosuccinimide or N-bromosuccinimide with hydrogen peroxide and of dimethyldioxirane with tertiary amines as well as the thermal decomposition of 1,4-dimethylnaphthalene endoperoxide lead to the chemiluminescence of singlet-oxygen dimol species (1O2)2 emitting at 634 and 703 nm. In contrast to the expected enhancement of (1O2)2 chemiluminescence upon addition of 1,4-diazabicyclo[2.2.2]octane (DABCO) [Deneke, C.F.; Krinsky, N. I. J. Am. Chem. Soc. 1976, 98, 3041. Di Mascio, P.; Sies, H. J. Am. Chem. Soc. 1989, 111, 2909.], quenching has been observed. Our data show that enhancement of singlet-oxygen dimol chemiluminescence is not a general phenomenon and, consequently, DABCO is not a reliable chemiluminescent probe for the presence of (1O2)2 in chemical and biochemical systems. 相似文献
130.
Closed-shell BO(2)(-) and BO(-) anions are proposed as high-efficiency luminescence centres in boron-nitrogen systems, which makes the anions localized and leads to a radiation transition. 相似文献