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621.
Moumita Maiti 《Journal of Radioanalytical and Nuclear Chemistry》2011,290(1):11-16
The crux of the present work is to explore the various channels leading to the production of proton rich rhenium radionuclides,
181–186Re, for different applications. The possible production routes encompass both light and heavy ion induced reactions up to
a maximum 100 MeV projectile energy starting from threshold. The nuclear reaction model codes ALICE91 and PACE-II were employed
in this endeavour. Excitation functions of the rhenium radionuclides have been calculated using the aforesaid nuclear reaction
model codes and compared with the measured data wherever available. The contributions of preequilibrium and equilibrium reaction
mechanisms to the total reaction cross section were analysed. For the first time, this study talks about the possibility of
light-heavy ion (6,7Li and 9Be) induced production of proton rich rhenium radionuclides. 相似文献
622.
We present herein a simple method for enhancing the emission of DNA intercalators in homogeneous nanobiohybrids of unlabeled oligonucleotides and unmodified gold nanoparticles (GNPs). Pristine single‐stranded DNA (ss‐DNA) has been wrapped around unmodified GNPs to induce metal‐enhanced fluorescence (MEF) of DNA intercalators, such as ethidium bromide and propidium iodide. The thickness of the ss‐DNA layer on the gold nanosurface determines the extent of MEF, since this depends on the position of the intercalator in relation to the metal surface. Presumably, at a suitable thickness of this DNA layer, more of the intercalator is localized at the optimum distance from the nanoparticle to give rise to MEF. Importantly, no external spacer or coating agent was needed to induce the MEF effect of the GNPs. The concentration ratios of Au to DNA in the nanohybrids, as well as the capping agents applied to the GNPs, play key roles in enhancing the emission of the intercalators. The dimensions of both components of the nanobiohybrids, that is, the size of the GNPs and the length of the oligonucleotide, have considerable influences on the emission enhancement of the intercalators. Emission intensity increased with increasing size of the GNPs and length of the oligonucleotide only when the DNA efficiently wrapped the nanoparticles. An almost 100 % increment in the quantum yield of ethidium bromide was achieved with the GNP–DNA nanobiohybrid compared with that with DNA alone (in the absence of GNP), and the fluorescence emission was enhanced by 50 % even at an oligonucleotide concentration of 2 nM . The plasmonic effect of the GNPs in the emission enhancement was also established by the use of similar nanobioconjugates of ss‐DNA with nonmetallic carbon nanoparticles and TiO2 nanoparticles, with which no increase in the fluorescence emission of ethidium bromide was observed. 相似文献
623.
We prove that a tight-binding ladder network composed of atomic sites with on-site potentials distributed according to the quasiperiodic Aubry model can exhibit a metal-insulator transition at multiple values of the Fermi energy. For specific values of the first and second neighbor electron hopping, the result is obtained exactly. With a more general model, we numerically calculate the two-terminal conductance. The numerical results corroborate the analytical findings. 相似文献
624.
We study the thermodynamic and kinetic consequences of the competition between single-protein folding and protein-protein
aggregation using a phenomenological model, in which the proteins can be in the unfolded (U), misfolded (M) or folded (F)
states. The phase diagram shows the coexistence between a phase with aggregates of misfolded proteins and a phase of isolated
proteins (U or F) in solution. The spinodal at low protein concentrations shows non-monotonic behavior with temperature, with
implications for the stability of solutions of folded proteins at low temperatures. We follow the dynamics upon “quenching”
from the U-phase (cooling) or the F-phase (heating) to the metastable or unstable part of the phase diagram that results in
aggregation. We describe how interesting consequences to the distribution of aggregate size, and growth kinetics arise from
the competition between folding and aggregation. 相似文献
625.
Mazen Elsaid Robbie Ge Dr. Chong Liu Prof. Dr. Debabrata Maiti Prof. Haibo Ge 《Angewandte Chemie (International ed. in English)》2023,62(25):e202303110
Carbazole alkaloids hold great potential in pharmaceutical and material sciences. However, the current approaches for C1 functionalization of carbazoles rely on the use of a pre-installed directing group, severely limiting their applicability and hindering their overall efficiency. Herein, we report for the first time the development of direct Pd-catalyzed C−H alkylation and acylation of carbazoles assisted by norbornene (NBE) as a transient directing mediator. Notably, the involvement of a six-membered palladacycle intermediate was suggested in this case, representing the first example of such intermediacy within the extensively studied Pd/norbornene reactions realm. 相似文献
626.
In this work, we consider a frustrated two-leg spin-1/2 ladder composed of Heisenberg ferromagnetic and antiferromagnetic spin-1/2 chains, and nearest spins from different legs interact via Heisenberg type rung exchange interactions that can be either ferromagnetic or antiferromagnetic in nature. The competing exchange interactions in the system lead to five different quantum phases like ferromagnetic, non-collinear ferrimagnetic (NCF), , antiferromagnetic and dimer phases. The quantum phase diagram is constructed for the Heisenberg spin-1/2 model and the phases are characterized using the correlation functions which are calculated by the density matrix renormalization group method. We also analyze the stability of phase and calculate the pitch angle in the NCF phase. 相似文献
627.
A new route to obtain a large figure of merit (>1) is reported, for the first time, by considering a one-dimensional quasiperiodic lattice where an electron can hop beyond usual nearest-neighbor sites. A finite positional correlation is imposed among the constituent lattice sites, following the well-known Aubry-André-Harper (AAH) form. In the presence of second-neighbor hopping, the AAH lattice exhibits energy dependent mobility edge which plays the central role for efficient energy conversion. Employing a tight-binding framework, all the thermoelectric quantities are computed based on the standard nonequilibrium Green's function formalism. The analysis can be utilized to investigate thermoelectric phenomena in similar kinds of other aperiodic systems possessing higher order electron hopping. 相似文献
628.