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591.
Growth of microalgal biomass is driven by nutrient availability but also by species competition for these nutrients. In this study, a modeling procedure has been developed by means of which impacts of nutrient competition on microalgae cells can be investigated on a cell‐level. The goal of this modeling is to enhance the understanding of nutrient competition in a given biological environment and to enable predicting the biomass' species composition. These models are compared with experimental data and empirical assessments published earlier in this journal. Because these simulations have been built on very generic assumptions, transferring this chemometric methodology to other cell types is straightforward. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
592.
Prof. Donald G. Fleming Prof. Jörn Manz Kazuma Sato Prof. Toshiyuki Takayanagi 《Angewandte Chemie (International ed. in English)》2014,53(50):13706-13709
Isotope effects are important in the making and breaking of chemical bonds in chemical reactivity. Here we report on a new discovery, that isotopic substitution can fundamentally alter the nature of chemical bonding. This is established by systematic, rigorous quantum chemistry calculations of the isotopomers BrLBr, where L is an isotope of hydrogen. All the heavier isotopomers of BrHBr, BrDBr, BrTBr, and Br4HBr, the latter indicating the muonic He atom, the heaviest isotope of H, can only be stabilized as van der Waals bound states. In contrast, the lightest isotopomer, BrMuBr, with Mu the muonium atom, alone exhibits vibrational bonding, in accord with its possible observation in a recent experiment on the Mu+Br2 reaction. Accordingly, BrMuBr is stabilized at the saddle point of the potential energy surface due to a net decrease in vibrational zero point energy that overcompensates the increase in potential energy. 相似文献
593.
Comparing the recoil energy distributions of the fragments from one-photon dissociation of phenol-d(5) with those from vibrationally mediated photodissociation shows that initial vibrational excitation strongly influences the disposal of energy into relative translation. The measurements use velocity map ion imaging to detect the H-atom fragments and determine the distribution of recoil energies. Dissociation of phenol-d(5) molecules with an initially excited O-H stretching vibration produces significantly more fragments with low recoil energies than does one-photon dissociation at the same total energy. The difference appears to come from the increased probability of adiabatic dissociation in which a vibrationally excited molecule passes around the conical intersection between the dissociative state and the ground state to produce electronically excited phenoxyl-d(5) radicals. The additional energy deposited in electronic excitation of the radical reduces the energy available for relative translation. 相似文献
594.
Guillermo Diaz Fleming Freddy Clis Marcelo Campos‐Vallette Alvaro E. Aliaga Marcela Escobar Rainer Koch 《Journal of Raman spectroscopy : JRS》2011,42(7):1497-1504
Infrared, Raman and surface‐enhanced Raman scattering (SERS) spectra of 3‐(1‐phenylpropan‐2‐ylamino)propanenitrile (fenproporex) have been recorded. Density functional theory (DFT) with the B3LYP functional was used for optimizations of ground state geometries and simulation of Raman and SERS vibrational spectra of this molecule. Bands of the vibrational spectra were assigned in detail. The comparison of SERS spectra obtained by using colloidal silver and gold nanoparticles with the corresponding Raman spectrum reveals enhancement and shifts in bands, suggesting a possible partial charge‐transfer mechanism in the SERS effect. Information about the orientation of fenproporex on the nanometer‐sized metal structures is also obtained. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
595.
596.
Dunkelberger AD Kieda RD Shin JY Rossi Paccani R Fusi S Olivucci M Crim FF 《The journal of physical chemistry. A》2012,116(14):3527-3533
Recent experimental and theoretical studies on N-alkylated indanylidene pyrroline Schiff bases (NAIP) show that these compounds exhibit biomimetic photoisomerization analogous to that in the chromophore of rhodopsin. The NAIP compounds studied previously isomerize rapidly and often evolve coherently on the ground-electronic surface after reaction. We present the results of transient electronic absorption spectroscopy on dMe-OMe-NAIP, a newly synthesized NAIP analogue that differs from other NAIP compounds in the substituents on its pyrrolinium ring. Following excitation with 400 nm light, dMe-OMe-NAIP relaxes from the electronic-excited state in less than 500 fs, which is slower than in other analogues, and does not show the prominent oscillations observed in other NAIP compounds. A reduction in the amount of twisting between the rings caused by removal of the methyl group is likely responsible for the slower isomerization. Measurements in solvents of varying viscosity and structure suggest that intramolecular processes dominate the relaxation of nascent photoproducts. 相似文献
597.
Yao L Pitta B Ravikumar PC Purzycki M Fleming FF 《The Journal of organic chemistry》2012,77(7):3651-3657
A series of morinol-type lignans were rapidly assembled using a Grignard-based transmissive olefination. In combination with palladium-catalyzed arylations, the strategy provides stereoselective access to (7Z,7'E), (7E,7'E), and (7E,7'Z) morinol diastereomers and the (7Z,8'E) and (7E,8'E) conjugated analogues. Critical for the E/Z stereoselectivity is a new, general method for converting alkenenitriles to alkenemethanols that circumvents the enal E/Z isomerization commonly encountered during conventional i-Bu(2)AlH reduction. 相似文献
598.
Paglia G Hrafnsdóttir S Magnúsdóttir M Fleming RM Thorlacius S Palsson BØ Thiele I 《Analytical and bioanalytical chemistry》2012,402(3):1183-1198
Here we present an ultra-performance liquid chromatography–mass spectrometry (UPLC–MS) method for extracellular measurements
of known and unexpected metabolites in parallel. The method was developed by testing 86 metabolites, including amino acids,
organic acids, sugars, purines, pyrimidines, vitamins, and nucleosides, that can be resolved by combining chromatographic
and m/z dimensions. Subsequently, a targeted quantitative method was developed for 80 metabolites. The presented method combines
a UPLC approach using hydrophilic interaction liquid chromatography (HILIC) and MS detection achieved by a hybrid quadrupole–time
of flight (Q–ToF) mass spectrometer. The optimal setup was achieved by evaluating reproducibility and repeatability of the
analytical platforms using pooled quality control samples to minimize the drift in instrumental performance over time. Then,
the method was validated by analyzing extracellular metabolites from acute lymphoblastic leukemia cell lines (MOLT-4 and CCRF-CEM)
treated with direct (A-769662) and indirect (AICAR) AMP activated kinase (AMPK) activators, monitoring uptake and secretion
of the targeted compound over time. This analysis pointed towards a perturbed purine and pyrimidine catabolism upon AICAR
treatment. Our data suggest that the method presented can be used for qualitative and quantitative analysis of extracellular
metabolites and it is suitable for routine applications such as in vitro drug screening. 相似文献
599.
The synthesis of tetra-tetrazole macromolecules, containing various aromatic cores including benzene, pyridine and pyrazine directly attached to the tetrazole moieties, is described. This variation allowed for the generation of ligands with greater potential for metal ion complexation. Metal ion complexation reactions of the tetra-tetrazole macromolecules with the chelating pyridyl-tetrazole arms result in the formation of metal complexes where the metal ion was bound at the pendant arms rather than at the central core. 相似文献
600.
Edwards RG Fleming GT Hägler P Negele JW Orginos K Pochinsky AV Renner DB Richards DG Schroers W;LHPC Collaboration 《Physical review letters》2006,96(5):052001
The nucleon axial charge is calculated as a function of the pion mass in full QCD. Using domain wall valence quarks and improved staggered sea quarks, we present the first calculation with pion masses as light as 354 MeV and volumes as large as (3.5 fm)3. We show that finite volume effects are small for our volumes and that a constrained fit based on finite volume chiral perturbation theory agrees with experiment within 7% statistical errors. 相似文献