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141.
We derive symplectically invariant uncertainty relations for a set of canonically conjugated variables. The uncertainty relations obtained are multimode analogs of the Robertson–Schrödinger inequalities. Our uncertainty relations are equivalent to the necessary and sufficient conditions for a matrix to be a correlation matrix of some quantum state, obtained by R. Simon and coauthors. The advantage of our inequalities, compared to that suggested by Simon, consists in its simplicity and more obvious symplectic invariance. We derive our inequalities for the case of a two-mode system in explicit form. Particular cases of small and large degrees of correlation between the first and second modes are analyzed in detail. 相似文献
142.
The physical behavior of a fluid in contact with solid layers is still not fully understood. The present work focuses on the
study and understanding of thermodynamic and structural properties of gold–water nanolayer mixtures using molecular dynamics
simulations. Two different systems are considered, where approximately 1,700 water molecules are confined between gold nanolayers
with separations of 7.4 and 6.2 nm, respectively. Novelties of the present work are in the use of accurate force fields for
modeling the inter- and intra-molecular interactions of the components, and providing comprehensive thermodynamic properties
of the mixtures. The results are validated by examination of the pure fluid and pure solid properties. Results indicate that
the thermodynamics of the system does not behave as an ideal mixture. The structure of the pure fluid is also analyzed and
compared against the structure of the confined fluid in the mixture. Anisotropicity is observed in the fluid structure close
to the surface of the nanolayer. Higher ordering and higher flux are detected in the fluid molecules close to the fluid–solid
interface. Unusual thermodynamic behavior, anisotropicity, liquid layering, and higher interfacial fluid flux could be just
some of the factors leading to the enhanced energy transport observed in mixtures involving at least one nanoscale component,
such as nanofluids. 相似文献
143.
The Er3+ -Yb3+ codoped in Li2O content tungsten -tellurite (TWL) transparent glasses are synthesized and measured the absorption, Raman and upconversion
luminescence (UPL) spectra. At room temperature intense green emission peak at 560 nm ( 4S3/2→4I15/2) and red emission peak at 670 nm ( 4F9/2→4I15/2) of Er3+ observed even at minimum 86 mW pumping power of infrared 980 nm excitation. For structure of the TWL glass, Raman spectrum
result revealed that an important role of WO3 in the formation of glass network linkage with Li2O. Under this influence estimated lifetime of the 4I11/2 of Er3+ was 1.89 μs and due to lower phonon energy of the glass produce strong upconversion signal. The effect of Er2O3 concentration on emission intensity result indicated that green emission intensity initially increase in compare to red emission.
Under the 980 nm pump power variation measured the relatively increases the red emission to the green emission intensity and
analyze the possible upconversion mechanism and process. 相似文献
144.
Ethynylated phenothiazine based fluorescent boronic acid probes were prepared. Sonogashira coupling reaction was used to introduce
substituted phenylethynylene fragments to the phenothiazine fluorophore to extend the π-conjugation and to enhance the emission
property. The photophysical properties and the binding properties of these probes with hydroxyl acids were investigated. We
found that the probes with significant ICT effect show emissions which are sensitive to solvent polarity. The phenothiazine
moiety is proved to be electron-donating. We found the substitution profile imparts significant effect on the photophysical
properties of the probes. For example, one of the probes shows d-PeT effect, whereas the regioisomer probe with similar π-conjugation
fragment but different substitution profile shows the a-PeT effect. The easy derivatization of phenothiazine fluorophore,
the structure-photophysical property relation and the novel d-PeT fluorescence transduction profile of the phenothiazine based
probes described herein may inspire more investigation into this fascinating research area. 相似文献
145.
Jung A. Jung Young Baek Kim Young A. Kim Seung Bum Ryu Veronica Kim 《Journal of nanoparticle research》2011,13(6):2361-2374
Functional spherical solid and hollow particles of polysilsesquioxanes (PSQs) containing amine, thiol, and vinyl groups were
prepared by polymerizing organotrialkoxysilanes (OTASs) containing corresponding chemical groups. Fluorescent PSQ particles
were prepared by physically entrapping Rhodamine 6G, Coumarin 7, and Fluoresceine sodium salts. The intensity of fluorescent
light increased initially with increasing amount of entrapped fluorophores and then leveled off or decreased slightly after
reaching a maximum value. PSQ particles containing gold nanoparticles (GNPs), both inside and on the surface, were prepared
by the in situ reduction of gold ions by the PSQ particles. When the reduction reaction was carried out for extended periods
of time, the GNP that had formed inside the poly(3-mercaptopropyl)silsesquioxane (PMPSQ) and polyvinylsilsesequioxane (PVSQ)
particles underwent interesting morphological changes. PSQ particles containing amine and thiol groups fixed the GNPs on the
surface, which could be utilized further in binding amine-modified oligo-DNA strands. The aggregation of PSQ/GNP particles
combined with complementary oligo-DNA strands was examined to demonstrate that these particles could be applied to DNA assays
and isolation. The particles were characterized by scanning electron microscopy, transmission electron microscopy, solid state
nuclear magnetic resonance spectroscopy, ultraviolet/visible spectroscopy, and fluorescence microscopy. 相似文献
146.
AlF3-coating is attempted to improve the performance of LiNi0.5Mn1.5O4 cathode materials for Li-ion batteries. The prepared powders are characterized by scanning electron microscope, powder X-ray
diffraction, charge/discharge, and impedance. The coated LiNi0.5Mn1.5O4 samples show higher discharge capacity, better rate capability, and higher capacity retention than the uncoated samples.
Among the coated samples, 1.0 mol% AlF3-coated sample shows highest capacity after charge–discharged at 30 mA/g for 3 cycles, but 4.0 mol% coated sample exhibits
the highest capacity and cycling stability when cycled at high rate of 150 and 300 mA/g. The 40th cycle discharge capacity
at 300 mA/g current still remains 114.8 mAh/g for 4.0 mol% AlF3-coated LiNi0.5Mn1.5O4, while only 84.3 mAh/g for the uncoated sample. 相似文献
147.
We find sufficient conditions for the absence of harmonic L 2 spinors on spin manifolds constructed as cone bundles over a compact Kähler base. These conditions are fulfilled for certain perturbations of the Euclidean metric, and also for the generalized Taub-NUT metrics of Iwai-Katayama, thus proving a conjecture of Vi?inescu and the second author. 相似文献
148.
The effect of resonant fluorescent enhancement from a photonic crystal surface upon the fluorescent photobleaching rate of
Cyanine-5 labeled protein has been investigated. We show that the enhanced excitation mechanism for photonic crystal enhanced
fluorescence, in which the device surface resonantly couples light from an excitation laser, accelerates photobleaching in
proportion to the coupling efficiency of the laser to the photonic crystal. We also show that the enhanced extraction mechanism,
in which the photonic crystal directs emitted photons approximately normal to the surface, does not play a role in the rate
of photobleaching. We show that the photobleaching rate of dye molecules on the photonic crystal surface is accelerated by
30x compared to an ordinary glass surface, but substantial signal gain is still evident, even after extended periods of continuous
illumination at the resonant condition. 相似文献
149.
Ramón Herrera Eugenio San Martin 《The European Physical Journal C - Particles and Fields》2011,71(7):1701
Warm-intermediate inflationary universe models in the context of braneworld cosmologies are studied. This study is done in
the weak and strong dissipative regimes. We find that the scalar potentials and dissipation coefficients in terms of the scalar
field evolve as type-power-law and powers of logarithms, respectively. General conditions required for these models to be
realizable are derived and discussed. We also study the scalar and tensor perturbations for each regime. We use recent astronomical
observations to constrain the parameters appearing in the braneworld models. 相似文献
150.
Andreas Schwenke Philipp Wagener Stefan Nolte Stephan Barcikowski 《Applied Physics A: Materials Science & Processing》2011,104(1):77-82
The influence of fundamental and second harmonic wavelength on ablation efficiency and nanoparticle properties is studied
during picosecond laser ablation of silver, zinc, and magnesium in polymer-doped tetrahydrofuran. Laser ablation in stationary
liquid involves simultaneously the fabrication of nanoparticles by ablation of the target material and fragmentation of dispersed
nanoparticles by post irradiation. The ratio in which the laser pulse energy contributes to these processes depends on laser
wavelength and colloidal properties. For plasmon absorbers (silver), using the second harmonic wavelength leads to a decrease
of the nanoparticle productivity over process time along with exponential decrease in particle diameter, while using the fundamental
wavelength results in a constant ablation rate and linear decrease in particle diameter. For colloids made of materials without
plasmon absorption (zinc, magnesium), laser scattering is the colloidal property that limits nanoparticle productivity by
Mie-scattering of dispersed nanoparticle clusters. 相似文献